HB239

HB 239:2011

HB 239:2011

Handbook Guidance on the repair and overhaul of electrical equipment for explosive atmospheres

HB 239:2011 This Joint Australian/New Zealand Handbook was prepared by Joint Technical Committee EL-023, Electrical Equipment in Mines. It was approved on behalf of the Council of Standards Australia on 8 December 2010 and on behalf of the Council of Standards New Zealand on 1 July 2011. This Handbook was published on 19 July 2011.

The following are represented on Committee EL-023: Australian Chamber of Commerce and Industry Australian Coal Association Australian Industry Group Consult Australia Department of Industry and Investment NSW Department of Mines & Petroleum (WA) Department of Mines and Energy (Qld) Electrical Apparatus Service Association Mining Electrical and Mining Mechanical Engineering Society National Association of Testing Authorities Australia Queensland Department of Environment and Resource Management Solid Energy New Zealand The Aviation and Marine Engineers Association University of Newcastle WorkCover New South Wales

Keeping Standards up-to-date Standards are living documents which reflect progress in science, technology and systems. To maintain their currency, all Standards are periodically reviewed, and new editions are published. Between editions, amendments may be issued. Standards may also be withdrawn. It is important that readers assure themselves they are using a current Standard, which should include any amendments which may have been published since the Standard was purchased. Detailed information about joint Australian/New Zealand Standards can be found by visiting the Standards Web Shop at www.saiglobal.com.au or Standards New Zealand web site at www.standards.co.nz and looking up the relevant Standard in the on-line catalogue. For more frequent listings or notification of revisions, amendments and withdrawals, Standards Australia and Standards New Zealand offer a number of update options. For information about these services, users should contact their respective national Standards organization. We also welcome suggestions for improvement in our Standards, and especially encourage readers to notify us immediately of any apparent inaccuracies or ambiguities. Please address your comments to the Chief Executive of either Standards Australia or Standards New Zealand at the address shown on the back cover.

HB 239:2011

Handbook Guidance on the repair and overhaul of electrical equipment for explosive atmospheres

First published as HB 239:2011.

COPYRIGHT © Standards Australia Limited/Standards New Zealand All rights are reserved. No part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including photocopying, without the written permission of the publisher, unless otherwise permitted under the Copyright Act 1968 (Australia) or the Copyright Act 1994 (New Zealand). Jointly published by SAI Global Limited under licence from Standards Australia Limited, GPO Box 476, Sydney, NSW 2001 and by Standards New Zealand, Private Bag 2439, Wellington 6140.

ISBN 978 0 7337 9891 7

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PREFACE This Handbook was prepared by Standards Australia/Standards New Zealand Committee EL-023, Electrical Equipment in Mines. The objective of this Handbook is to provide practical guidance for the overhaul and repair of electrical equipment for explosive atmospheres. It contains performance-based information on process and procedures that have been part of AS/NZS 3800 that may not transfer to the revised 2011 version IEC 60079.19, the recognised international Standard for the repair and overhaul of explosion-protected electrical equipment. Additionally, information on the key processes for the repair of reeling and trailing cable is included. The Handbook offers additional guidance regarding techniques and special processes necessary to ensure consistent and reliable delivery of repaired and overhauled equipment and cables. Also included are appendices covering quality management systems, measurement and calibration, and history of equipment and service facilities approval schemes. The Handbook has been written to assist repair facilities, owners and operators of electrical equipment in explosive atmospheres.

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CONTENTS Page SECTION 1 GENERAL 1.1 SCOPE ........................................................................................................................ 7 1.2 REFERENCED DOCUMENTS .................................................................................. 7 SECTION 2 DEFINITIONS 2.1 GENERAL .................................................................................................................. 9 2.2 ADDITIONAL DEFINITIONS ................................................................................... 9 SECTION 3 TECHNICAL PRINCIPLES AND PROCESSES 3.1 INTRODUCTION ..................................................................................................... 11 3.2 BACKGROUND ....................................................................................................... 11 3.3 COMPETENCIES ..................................................................................................... 11 3.4 SERVICE FACILITY RELATIONSHIPS WITH THE EXPLOSION-PROTECTED EQUIPMENT OWNER/OPERATOR ......................... 12 3.5 CONSULTATION WITH OTHER PARTIES: MANUFACTURERS AND REGULATORS................................................................................................ 13 3.6 DOCUMENTATION—VERIFICATION DOSSIER ................................................ 13 3.7 TRANSITION OF STANDARDS ............................................................................. 14 3.8 SELECTION OF SERVICE FACILITY.................................................................... 16 3.9 SERVICE FACILITY CAPABILITIES..................................................................... 16 3.10 WORK FLOW........................................................................................................... 17 3.11 COMMENTARY ON MATERIALS......................................................................... 27 3.12 COMMENTARY ON INSPECTION TECHNIQUES ............................................... 30 3.13 MECHANICAL REPAIR PROCESSES.................................................................... 31 SECTION 4 GENERIC TESTING PROCESSES FOR VERIFICATION OF EXPLOSION-PROTECTION TECHNIQUES 4.1 NON-DESTRUCTIVE TEST (NDT)......................................................................... 37 4.2 DIELECTRIC WITHSTAND (HIGH POTENTIAL OR HI-POT) TESTING ................................................................................................................. 37 4.3 INSULATION RESISTANCE................................................................................... 39 4.4 COMPONENT TESTING ......................................................................................... 39 4.5 TEMPERATURE MEASUREMENT........................................................................ 40 SECTION 5 OVERHAUL OF ROTATING MACHINES 5.1 GENERAL ................................................................................................................ 41 5.2 REPAIR/OVERHAUL ............................................................................................. 41 5.3 OWNER/OPERATOR RESPONSIBILITIES............................................................ 42 5.4 QUALITY-MANAGED ASSESSMENT STRATEGIES .......................................... 42 5.5 EVALUATION PROCEDURES FOR ROTATING MACHINES............................. 43 5.6 ADDITIONAL NOTES FOR COPY WINDING....................................................... 47 5.7 AFTER WINDING.................................................................................................... 47 5.8 REPAIR OF ROTORS .............................................................................................. 48 5.9 TEMPERATURE SENSORS .................................................................................... 48 5.10 ENCLOSURES.......................................................................................................... 48 5.11 SPECIFIC TESTS APPLICABLE TO ROTATING MACHINES............................. 49 5.12 SPECIFIC REQUIREMENTS FOR REPORTING ON ROTATING MACHINES .............................................................................................................. 50

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Page 5.13 SPECIFIC REQUIREMENTS FOR PACKAGING AND DESPATCH OF ROTATING MACHINES ......................................................................................... 50 5.14 REINSTALLATION RECOMMENDATIONS FOR ROTATING MACHINES .............................................................................................................. 50 SECTION 6 EX ‘d’ FLAMEPROOF EQUIPMENT 6.1 INTRODUCTION ..................................................................................................... 51 6.2 OVERHAUL ............................................................................................................. 54 6.3 REPAIR..................................................................................................................... 54 6.4 RECLAMATION ...................................................................................................... 54 6.5 CATEGORIES OF REPAIR...................................................................................... 54 6.6 CHECKS AND REPORTING ................................................................................... 55 6.7 IN-SITU TEMPORARY REPAIR FOR HOLE OR THREAD .................................. 64 6.8 HYDROSTATIC PRESSURE TESTS....................................................................... 66 6.9 FINAL VERIFICATION ........................................................................................... 69 6.10 PACKAGING AND DESPATCH ............................................................................. 69 SECTION 7 EX ‘e’ INCREASED SAFETY 7.1 INTRODUCTION ..................................................................................................... 70 7.2 OWNER/OPERATOR............................................................................................... 71 7.3 INSPECTION/OVERHAUL ..................................................................................... 71 7.4 SPECIFIC ISSUES FOR ROTATING MACHINES ................................................ 73 7.5 REPAIR..................................................................................................................... 74 7.6 FINAL VERIFICATION ........................................................................................... 75 7.7 PACKAGING AND DESPATCH ............................................................................. 75 7.8 REPORTING............................................................................................................. 75 SECTION 8 EX ‘i’ INTRINSIC SAFETY 8.1 GENERAL ................................................................................................................ 76 8.2 OWNER/OPERATOR RESPONSIBILITIES............................................................ 78 8.3 INITIAL ASSESSMENT .......................................................................................... 81 8.4 OVERHAUL ............................................................................................................. 82 8.5 PASS/FAIL CRITERIA FOR OVERHAULED EQUIPMENT ................................. 84 8.6 COMPONENTS FORMING PART OF INTRINSICALLY SAFE EQUIPMENT.................................................................................................. 84 8.7 TESTING/ASSESSMENT ........................................................................................ 86 8.8 REPAIR..................................................................................................................... 87 8.9 RECLAMATION ...................................................................................................... 88 8.10 TESTING .................................................................................................................. 88 8.11 ALTERATIONS AND MODIFICATIONS .............................................................. 88 8.12 REPORTING............................................................................................................. 88 8.13 PACKAGING AND DESPATCH ............................................................................. 89 SECTION 9 EX ‘m’ ENCAPSULATION 9.1 INTRODUCTION ..................................................................................................... 90 9.2 REPAIR/OVERHAUL PROCEDURES .................................................................... 90 SECTION 10 EX ‘n’ NON-SPARKING 10.1 INTRODUCTION ..................................................................................................... 93 10.2 INSPECTION AND OVERHAUL ............................................................................ 94 10.3 ROTATING MACHINE SPECIFIC ISSUES ............................................................ 96 10.4 REPAIR..................................................................................................................... 96 10.5 FINAL VERIFICATION ........................................................................................... 97

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Page 10.6 PACKAGING AND DESPATCH ............................................................................. 97 10.7 REPORTING............................................................................................................. 97 SECTION 11 EX ‘tD’ (DIP) 11.1 INTRODUCTION ..................................................................................................... 98 11.2 INSPECTION AND OVERHAUL ............................................................................ 98 11.3 OVERHAUL ........................................................................................................... 100 11.4 FINAL VERIFICATION AND TESTS ................................................................... 100 11.5 PACKAGING AND DESPATCH ........................................................................... 101 11.6 REPORTING........................................................................................................... 101 SECTION 12 EX ‘p’ PRESSURISED 12.1 INTRODUCTION ................................................................................................... 102 12.2 INITIAL INSPECTION........................................................................................... 102 12.3 ENCLOSURES........................................................................................................ 103 12.4 TEMPERATURE RATING..................................................................................... 103 12.5 OVERHAUL AND REPAIR PROCEDURES FOR PRESSURISED EQUIPMENT................................................................................ 104 12.6 GROUP I EXPLOSION PROTECTED TRANSFORMERS ................................... 105 SECTION 13 EX ‘o’ OIL FILLED 13.1 INTRODUCTION ................................................................................................... 107 13.2 NON-SPARKING PROTECTION .......................................................................... 107 13.3 OIL CONDITIONING............................................................................................. 107 13.4 TESTING ................................................................................................................ 107 SECTION 14 EX ‘v’ VENTILATED..................................................................................... 108 SECTION 15 EX ‘s’ SPECIAL PROTECTION..................................................................... 109 SECTION 16 GROUP I HAZARDOUS AREA REELING AND TRAILING CABLES 16.1 SCOPE .................................................................................................................... 110 16.2 CABLE COMPONENTS......................................................................................... 110 16.3 GUIDANCE ON ASSESSING CABLE CONDITION............................................ 115 16.4 EVALUATION BEFORE REPAIR AND HISTORY RECORD............................. 115 16.5 PROCEDURE FOR HARD SOLDERING REELING AND TRAILING CABLES .............................................................................................. 118 SECTION 17 PRE-OVERHAUL INSPECTION (CODE C1) FOR GROUP I 17.1 PRE-OVERHAUL REQUIREMENTS.................................................................... 120 17.2 FLAMEPROOF....................................................................................................... 120 17.3 INCREASED SAFETY EQUIPMENT.................................................................... 120 17.4 PRESSURISED EQUIPMENT ............................................................................... 121 SECTION 18 COMPLIANCE OF LEGACY PLANT 18.1 GENERAL .............................................................................................................. 122 18.2 HISTORY................................................................................................................ 122 18.3 USING THE FACTS ............................................................................................... 122 18.4 ASSUMPTIONS...................................................................................................... 122 18.5 VERIFICATION DOSSIER .................................................................................... 122 18.6 FACT GATHERING ............................................................................................... 122

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Page APPENDICES A QUALITY MANAGEMENT SYSTEM COMPONENT ......................................... 125 B MEASUREMENT AND CALIBRATION IN Ex WORKSHOPS ........................... 131 C SAMPLE CERTIFICATES AND FORMS.............................................................. 153 D E

HISTORICAL INFORMATION RELATING TO EQUIPMENT APPROVAL SCHEMES.................................................................. 190 HISTORICAL INFORMATION RELATING TO SERVICE FACILITY APPROVAL SCHEMES ......................................................................................... 195

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STANDARDS AUSTRALIA/STANDARDS NEW ZEALAND Handbook Guidance on the repair and overhaul of electrical equipment for explosive atmospheres

S E C T I O N

1

G E N E RA L

1.1 SCOPE This Handbook provides guidance for the repair and overhaul of explosion-protected electrical equipment used in hazardous areas (defined in AS/NZS 60079.0). The Handbook covers equipment with a Group I designation for coal mining; Group II where flammable gases and vapours may be present; and Group III which includes equipment used in the presence of combustible dusts. This Handbook details the methods of overhaul, repair, examination and the testing required to ensure safety and compliance with the relevant Standards for the different equipment explosion-protection techniques. It covers the several types of explosion-protection techniques currently in use and provides guidance for repair and overhaul service facilities. The soon to be published revision of AS/NZS 3800 (and IEC 60079-19 Edition 3) offer a performance-based approach to the overhaul of electrical equipment for use in hazardous areas. In many applications it was felt it was necessary to establish guidance to standardise the approach for inspection, repair and overhaul techniques and methods, and to provide a repository where expert knowledge can be accumulated from experience and disseminated for the benefit of stakeholders. The objective of this Handbook is to provide service facilities, equipment owner and/or operators and relevant regulatory authorities involved in the repair and overhaul of electrical equipment in hazardous areas with guidance to ensure safety and compliance with the relevant existing Standards. The Handbook also offers additional guidance on techniques and special processes necessary to ensure consistent and reliable delivery of repaired and overhauled equipment and cables. This document is to be read initially in conjunction with AS/NZS 3800 and IEC 60079-19 Edition 3, the recognized international Standard for repair and overhaul of explosionprotected electrical equipment. In anticipation of the soon-to-be published revised AS/NZS 3800 (and IEC 60079 Edition 3), where possible, reference to these documents has been quoted throughout the text. 1.2 REFERENCED DOCUMENTS AS/NZS 1299

Electrical equipment for coal mines—Flameproof restrained plugs and receptacles

1300

Electrical equipment for coal mines—Bolted flameproof cable coupling devices

1747

Reeling, trailing and feeder cables used for mining—Repair, testing and fitting of accessories

1802

Electric cables—Reeling and trailing—For underground coal mining

1972

Electric cables—Underground coal mines—Other than reeling and trailing COPYRIGHT

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Electrical equipment for coal and shale mines—Electrical protection devices (series)

2290

Electrical equipment for coal mines—Maintenance and inspection (series)

2381

Electrical equipment for explosive atmospheres—Selection, installation and maintenance

2802

Electric cables-Reeling and trailing-for mining and general use (other than underground coal mining)

3800

Electrical equipment for explosive atmospheres—Repair and overhaul

4761

Competencies for working with electrical equipment for hazardous areas (series)

4871

Electrical equipment for coal mines, for use underground (series)

60079

Explosive atmospheres (series)

61241

Electrical apparatus for use in the presence of combustible dust (series)

62013

Caplights for use in mines susceptible to firedamp (series)

AS/NZS ISO 9001 Quality management systems AS 60529

Degrees of protection provided by enclosures (IP Code)

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SECT ION

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DEF I N I T I ONS

2.1 GENERAL The Definitions in the standards listed in Referenced Documents apply to this document. 2.2 ADDITIONAL DEFINITIONS The following definitions also apply. 2.2.1 Verification Dossier A set of documents showing the compliance of electrical equipment and installations, including certificates, manufacturer instructions, records of previous repairs, overhaul and reclamation. 2.2.2 Metal spray (also known as thermal spray) A coating deposition technique in which melted droplets of material are sprayed onto a substrate material. The resulting coating is comprised of small pancake-like ‘splats’, often with voids and incomplete bonding. The technique allows deposition of materials dissimilar to the substrate and does not heat the substrate, but requires controlled application to ensure consistency of material and bonding. 2.2.3 Laser welding A metal joining technique using lasers to generate the melt heat and precisely deposit material at the required location. Laser welding offers control and high power input, reducing the size of the heat affected zones around the welds. 2.2.4 Solder Solder is metal alloy with a low melting point used to join materials through melting and physical keying onto the surface while cooling. Traditionally, solders were tin-lead alloys. However, environmental concerns with lead have seen restrictions on the use of lead in electrical and electronic equipment. As a consequence many recent solders have been formulated to be lead-free alloys. Many different lead-free formulations exist and these may not be compatible with each other. In addition, over time some lead-free solders have grown metallic (tin) whiskers, which in some instances have affected clearance distances in Ex ‘i’ equipment. 2.2.5 Controlled temperature burn-out Removal of insulating materials (commonly varnishes, plastics and epoxy in windings) by heating. Temperatures are selected to melt and oxidise the insulating materials without comprising the magnetic properties or interlamination insulation of the iron core. 2.2.6 Final inspection The last inspection of an item while under the control or responsibility of the inspecting body. 2.2.7 Competent person Refer to AS/NZS 3800. A person who can demonstrate a combination of knowledge and skills to effectively, efficiently and safely carry out activities in hazardous areas covered by AS/NZS 4761. Competency in some cases may be limited to one or more specific types of protection techniques, e.g. Ex ‘d’, Ex ‘i’, and or activity (e.g. design, selection, installation, maintenance, testing and inspection). A competent person may also be referred to as a responsible person.

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2.2.8 Special processes Processes that cannot be fully verified by test, therefore requiring adherence to specific procedures to ensure tasks fulfil the processes satisfactorily.

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SECT ION

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TECHN IC A L PR I NC I P L ES P R O CE SSES

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3.1 INTRODUCTION This Section describes aspects of the technical infrastructure of relevance to the repair and overhaul of Ex equipment, and the general processes of overhaul. Particular emphasis is placed on competencies, access to information (covering both documentation and postrepair marking of equipment) and the planning of workflow. Central to the efficient and effective delivery of overhauls and repaired equipment are relationships with significant stakeholders, such as the equipment owner, user and possibly the designer and manufacturer. 3.2 BACKGROUND Explosion-protected equipment and high integrity reeling and trailing cables are essential risk controls for the safe use of electricity within a hazardous area. Certified and approved explosion-protected equipment have passed rigorous compliance reviews of the original equipment design. The more recent (Type 5) certification schemes also include quality audits of the equipment manufacture. These programs aid to improve the compliance level of hazardous area equipment, while regular inspections and maintenance by the owner or operator assist to maintain the equipment in its ‘as built’ condition. No item of engineered equipment can last indefinitely and it is generally acknowledged that failure of an explosion-protection technique is not ‘self-revealing’. In order to verify the continued integrity of the equipment, periodic overhaul of electrical equipment situated in hazardous areas is recommended to verify the integrity of the equipment safeguards. Hazardous areas are defined in AS/NZS 60079.0 as follows: ‘In underground coal mines, hazardous areas are termed hazardous zones and are generally geographically defined in legislation. In operating areas the hazardous zone is considered to be zone 1 while ever ventilation is effective. However, on the loss of ventilation the hazardous zone is often considered to be zone 0. There are hazardous zones in mines that are not accessible to people, but which are considered to be zone 0.’ Because equipment usage affects its explosion-protection properties, the equipment is regularly removed from service and overhauled, as timetabled in AS/NZS 2290.1 for Group I applications. In Group II and III applications there is no published timetable for overhaul, and the equipment may be overhauled either periodically or on an as-needs basis. 3.3 COMPETENCIES Inspection, repair and the verification of compliance after overhaul of explosion-protected electrical equipment requires specialist knowledge and experience not generally achieved in general industrial equipment overhaul. AS/NZS 4761 details competency requirements for hazardous area equipment work, but these competencies should only be considered a starting point; experience working on the types of equipment overhauled is essential. Incorrect actions and/or conformity evaluation may impair or incorrectly diagnose the subsequent explosion-protected properties of that equipment. Therefore all work and verification activities should be performed by, or under the supervision of, a person who has a recognised competency for the particular explosion-protection technique. This person is often termed a ‘competent person’. Effective overhauls sometimes require use of specialist processes such as welding, metal spraying and non-destructive testing. It may not be possible for the overhaul workshop to possess the facilities or competencies for all techniques used in any particular overhaul, and COPYRIGHT

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it is common for these type of services to be subcontracted to specialist providers. Often, these specialist processes are supported by industry-based competence schemes that recognise individuals or approved suppliers. Whether these specialist processes are provided in-house or outsourced, the competent person should be aware of the presence and relevance of such schemes. They should take steps to ensure that operatives, who are engaged in all actions and processes that may affect the Ex properties of the equipment under overhaul, are appropriately skilled in the processes employed. Records supporting these steps should be kept, either as skills matrices for staff performing specialist tasks inhouse, or as part of the sub-contractor evaluation process. 3.4 SERVICE FACILITY RELATIONSHIPS PROTECTED EQUIPMENT OWNER/OPERATOR

WITH

THE

EXPLOSION-

The repair and overhaul of equipment requires effective communication among a number of parties who have interests in the equipment. These can include the owner, the operator and the repair facility. These are explained in further detail below: (a)

The equipment owner is the specifier and provider of instruction information.

(b)

The operator typically has day-to-day involvement in using the equipment and may, through that involvement, identify issues demanding attention.

(c)

The combination of owner/operator and Service Facility are typically responsible for identifying a suitable scope of work for equipment repair or overhaul and agreeing to any associated variations. Responsibilities between the owner/operator and Service facility are normally established through contractual relationships outside the scope of this document.

Facilities involved in repair and overhaul should consult with all parties to attempt to confirm that dossiers are maintained and reflect the current (rather than as-provided) status of the equipment. Clear communication ensures that— (i)

there is a holistic approach to the safety of the affected hazardous area installation (rather than a focus on individual items of equipment);

(ii)

documentation associated with the equipment is available and reflects the compliance status of equipment;

(iii) problems identified within the equipment are addressed; (iv)

necessary or desired upgrades are included;

(v)

options in the repair process are discussed and agreed on;

(vii) the compliance status of returned equipment is clearly agreed; (viii) there is a timely delivery of post-overhaul documentation; and (ix)

post-contractual disputes are minimised.

Consultation regarding the equipment verification dossier may highlight issues in the history of the equipment, recurrent or known failure modes, or environmental deficiencies that are relevant to the repair and overhaul of the equipment. In some cases, clients may ask the repair and overhaul facility not to proceed with some elements of the overhaul activity. In these cases there should be a clearly agreed scope of work. It is acknowledged that clients may employ alternative means of establishing explosion-protection; the omission of operations mandated in AS/NZS 3800 should be clearly justified and identified in post-overhaul documentation. Repair facilities should be careful in the assertion of compliance in such cases.

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3.5 CONSULTATION REGULATORS

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MANUFACTURERS

AND

Other parties may provide information relevant to equipment overhaul and repair. Manufacturers, certification bodies and regulators may issue post-manufacture information updates or safety alerts. Facilities involved in the overhaul and repair of Ex equipment should be aware of the possible issue of additional information and ask for relevant information to be provided by the owner or operator. Normally this type of information is included in the relevant verification dossier. 3.6 DOCUMENTATION—VERIFICATION DOSSIER It is not unusual for a service facility to receive electrical explosion-protected equipment from an owner /operator with little to no information on the history of repair and overhaul, or known deficiencies within the delivered equipment. Therefore, it is important for the service facility to seek the necessary verification dossier and owner/operator’s instructions and guidance before proceeding. All hazardous area installations are required to have a verification dossier in accordance with AS/NZS 60079.14, which is mandated by AS/NZS 3000. For Group I, hazardous areas are typically predefined and the verification dossiers are established for individual explosion-protected plant items. Information normally available on the supply of equipment forms the basis for a dossier, which is kept up-to-date by the owner/operator so that the dossier reflects the current compliance status and service history of the equipment. (The implementation of this may vary between clients and industries and with the age of the installation.) Equipment certification regimes may affect the information available. Appendix D offers additional information on a range of equipment approval and certification systems currently in use in Australia. Recent obligations cited in the IEC Ex certification scheme include manufacturer’s information regardless of the Ex equipment Group. Some older equipment may only have been evaluated for compliance with national or international Standards and issued with a Certificate of Conformity attesting to the validity of the explosion-protection characteristics of the equipment. Other older equipment may only have regulatory approval. Approved equipment will generally be compliant with the national Standards at the date of issue, however alternative risk controls that were deemed equivalent were sometimes approved. In fact, compliance to Standards is a minimum requirement for certification and equipment may be designed and certified using more stringent specifications than those detailed in Standards. For these reasons a service facility should review the compliance specifications prior to repair or overhaul. In all cases, the preferred approach to overhaul is to refer to certification or approval documentation, including the drawings that identify the explosion-protected features of the equipment. In the event that the owner/operator cannot provide the verification dossier the workshop may be able to assist in gathering the relevant information. As previously mentioned, Group I equipment has a strong history of evaluating the suitability and compliance of explosion-protected equipment prior to use in a hazardous area, and has insisted that compliance documentation, including drawings, are maintained and used for the purposes of repair and overhaul to verify that the explosion-protected characteristics of the equipment are maintained as originally evaluated. Groups II and III do not have the same strong history of evaluation and maintenance of documentation and therefore could use an alternative approach. In circumstances where COPYRIGHT

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certificate documents are not available, then a service facility should liaise with the owner/operator who may elect to initiate the repair or overhaul of the explosion-protected equipment to achieve compliance with the relevant Standards. However, the more recent certification/approval scheme makes the provision of compliance documentation mandatory with the supply of the equipment (refer to AS/NZS 60079.0 Clause 30, ‘Instructions’). In instances of legacy equipment without compliance documents, steps taken to obtain the certificate documents should be recorded in the repair facility records. Figure 3.1 provides a flowchart as a guide to assist in determining whether a particular piece of explosionprotected electrical equipment can be satisfactorily repaired or needs to be replaced. Clearly, there are issues for service facilities (workshops) in establishing that they have all relevant documentation when overhauling legacy equipment, but there are also issues when overhauling recently-issued equipment. Recently-issued equipment will be accompanied by a comprehensive verification dossier, however, it is possible mine management practice is to hold multiple copies of the dossier. While the verification dossier is supposed to include details of maintenance and inspections performed over the operating life of the equipment, it is possible that all of this information is not present in the copy of the dossier provided to the service facility. Efforts should be made to confirm that the dossiers provided to the service facility include all relevant information, including shift inspection reports, outcomes from previous pre-overhaul inspections and the reports associated with any previous overhaul. The data in the verification dossier that’s necessary for the repair or overhaul includes, but is not limited to, the following details: (a)

Technical specification.

(b)

Drawings.

(c)

Type(s) of protection (explosion-protection).;

(d)

Operating conditions, such as environment, supply (inverter), lubricants, duty, etc).

(e)

Dismantling and assembly instructions.

(f)

Certificate limitations (specific conditions of use), where specified.

(g)

Marking (including Ex marking).

(h)

Recommended methods of installation, operation, maintenance, repair or overhaul for the equipment.

(i)

List of spare parts.

(j)

Summary of previous history, including previous overhauls and any pre-overhaul inspections and repairs carried out. NOTE: Manufacturers have and are likely to make small changes to identical equipment and have these certified to meet specific client requirements. In these instances the change may be in the form of a ‘supplementary certificate/approval’ and the original drawing may well have been used but with a revision. Therefore, it is strongly recommended that if the repair house decides to make a copy of the documents for its work files, the equipment serial number should be documented to ensure correct reference for future overhauls or, more importantly, that incorrect reference material is not used.

3.7 TRANSITION OF STANDARDS The evolution of Standards is usually driven by a number of issues that relate to— (a)

experience in the use of the Standards and the identification of deficiencies;

(b)

changes and improvements to materials and process conditions; and COPYRIGHT

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specific application of equipment.

In fact, the updating of Standards is a regular and consistent process. The adoption of IEC Hazardous Area Standards as Australian and New Zealand Standards (AS/NZS) began in 1999 and the transition, particularly for the equipment Standards, is now complete. This means that the reference numbers for AS/NZS Standards have changed to match the adopted IEC Standard numbers. To further complicate the numbering, the original series numbers for Standards covering ‘combustible dusts’ is undergoing another change in order to bring all Standards into the 60079 series. The following provides assistance in selection of Standards: TABLE 1 APPLICABLE STANDARDS FOR HAZARDOUS AREAS Description of explosion protection technique

Applicable Standards and designated symbol

Remarks

Zone 0 Intrinsically safe, Ex ‘ia’

AS 2380.7 (see Note 1) AS/NZS 60079.11

Encapsulated, Ex ‘ma’

AS/NZS 60079.18

Special protection, Ex ‘s’

AS 1826 IEC 60079-33 (see Note 2)

In accordance with the requirements for Zone 0

Zone 1 Intrinsically safe

AS 2380.7 (see Note 1) AS/NZS 60079.11 Ex ‘ib’

Special protection, Ex ‘s’

AS 1826 IEC 60079-33 Ex ‘s’ (see Note 2)

Flameproof enclosure, Ex ‘d’

AS 2380.2 AS/NZS 60079.1

Encapsulated, Ex ‘m’

AS 2431 AS/NZS 60079.18 Ex ‘mb’

Pressurized rooms or pressurized enclosures

AS 2380.4 AS/NZS 60079.2 Ex ‘p’

Increased safety

AS 2380.6

In accordance with the requirements for Zone 1

AS/NZS 60079.7 Ex ‘e’ Ventilation

AS 1482 Ex ‘v’

Powder filling

AS/NZS 60079.5 Ex ‘q’

Oil immersion

AS/NZS 60079.6 Ex ‘o’

Zone 2 Special protection

AS 1826 Ex ‘s’ IEC 60079-33 Ex ‘s’ (see Note 2)

In accordance with the requirements for Zone 2

Non-sparking

IEC 60079-15 AS/NZS 60079.15 Ex ‘n’

2nd Edition (2001) of IEC 6007915 is not acceptable

Ventilation

AS 1482 Ex ‘v’

In accordance with the requirements for Zone 2

Pressurized rooms or pressurized enclosures

AS 2380.4 AS/NZS 60079.2 Ex ‘p’

In accordance with the requirements for Zone 2

AS 2380.9

(continued)

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TABLE 1 (continued) Description of explosion protection technique

Applicable Standards and designated symbol

Remarks

Zone 20 Intrinsically safe

AS 2380.7 (see Note 1) AS/NZS 60079.11 Ex ‘ia’ AS/NZS 61241.11 Ex ‘iaD’

Encapsulated

AS/NZS 60079.18 Ex ‘ma’

Dust enclosure protection

AS/NZS 60079.31 Ex ‘ta

Special protection

AS 1826 Ex ‘s’ IEC 60079-33 Ex ‘s’ (see Note 2)

In accordance with the requirements for Zone 2

Zone 21 Intrinsically safe

AS 2380.7 (see Note 1) AS/NZS 60079.11 Ex ‘ib’ AS/NZS 61241.11 Ex ‘ibD’

Encapsulated

AS/NZS 61241.18 Ex ‘mD’

Dust enclosure protection

AS 2236 ‘DIP’ AS/NZS 61241.1.1 ‘DIP’ A21 AS/NZS 61241.1 Ex ‘tD’ A21 AS/NZS 60079.31 Ex ‘tb’

Pressurized enclosures

AS/NZS 61241.4 Ex ‘pD’

Pressurized rooms

AS 2380.4

Zone 22 Dust enclosure protection

AS/NZS 61241.1.1 ‘DIP’ A22 AS/NZS 61241.1 Ex ‘tD’ A22 AS/NZS 60079.31 Ex ‘tc’

NOTES: 1

Superseded Standard.

2

Under development

3.8 SELECTION OF SERVICE FACILITY The owner or operator of the equipment requiring repair or overhaul should ensure that the service facility has available (either in-house or through subcontracts) all the equipment and facilities to allow completion of repairs and overhauls it attempts without compromising the quality and effectiveness of the repair or overhaul. Third-party quality and technical surveillance schemes assist the equipment owner/operator to achieve this requirement, with periodic reviews of service facilities against a specific standard, providing a higher level of confidence that inspections, repairs and tests are completed to the highest possible standards. The recently established ANZEx Service Facility Certification Scheme also ensures technical governance of the individual surveillance bodies and a consistent level of reporting service facility capabilities. Selecting a repair or service facility without the appropriate requirements increases the likelihood that the equipment may not be compliant with certification/approval documentation. 3.9 SERVICE FACILITY CAPABILITIES The service facility should possess all the equipment and facilities to do overhauls and repairs, and operate a management system that ensures the quality and effectiveness of overhauls and repairs. Appendix A identifies key elements of the management system. COPYRIGHT

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A service facility may subcontract work to an outside facility, provided that the service facility is responsible for the assessment of and compliance with the Standards and certification/approval documents. A workshop that requires recognition for the overhaul and repair of an Ex component must be able to satisfy the following basic requirements as required in MP 87.2 and they must have the in-house knowledge, skills, equipment and required competency to fully undertake the following: (a)

The initial assessment, inspection and tests to ascertain the incoming Ex condition and functionality.

(b)

The ability to restore worn, failed or damaged equipment to its original compliance, and robustly retain this specification in future service.

(c)

The final assembly, inspection, tests and reporting to ensure Ex compliance and functionality.

(d)

Notwithstanding the capabilities of a subcontracted third party, the repair facility should conduct rechecks on the repair work and include this report documentation with all other job sheets for inclusion with the final report.

3.10 WORK FLOW 3.10.1 Overview In most cases the management of equipment sent to a service facility for overhaul will follow a common sequence of events. Typically, the equipment will be logged and inspection documentation prepared prior to an initial inspection to identify features demanding attention in the overhaul process. It is normal practice to allow the service facility to strip and quote, and to develop an agreed work scope based on its findings. The initial inspection by a competent person will result in a comprehensive report that should form the basis for the scope of works associated with the overhaul. This scope of works should be confirmed with the owner/operator prior to the commencement of works. Service facilities are reminded that in cases where significant work is required to restore a piece of equipment to the condition described by certification/approval documents, it may be more cost-effective to consider full replacement of the equipment. Assuming owner/operator acceptance of the scope of works, overhaul should proceed under the supervision of a competent person. Guidance on possible outcomes of the overhaul is provided in Fig 3.1, while guidance on specific techniques and methods of verification is provided in subsequent sections.

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Goods inward review for ex equip

Is equip ex?

No

Overhaul as nonex equipment

Remove ex marking

Yes

Does customer want non-ex OHaul?

No

Return as scrap

Yes Document equip details

Contact customer and request verification dossier

Advise customer unable to ex-OHaul Yes

Enter equip details in job system

No Are they available?

No

No

No

Yes Do you have cert documents?

Is equip Group 1?

Obtain authority from customer and obtain

Do you have the copy of manufacturing Standard?

Yes Yes

Do you have OHaul document?

No

Create OHaul document from certification documents

Create OHaul document from Standards requirements No

Yes Strip, inspect and measure fill in detailson report

Are there any nonconformance?

Go to

Yes

Yes

No Are any repairs required?

Can they be resolved?

Yes

Quote/report to customer

No

Complete OHaul and document

Attached OHaul label

Carry out final inspection and dispatch with OHaul documents

Place copies of OHaul documents in job file

Close job and archive

FIGURE 3.1 SERVICE FACILITY MANAGEMENT OF EXPLOSION PROTECTED EQUIPMENT

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3.10.2 Initial inspection Equipment submitted for repair or overhaul should be subjected to a preliminary examination to identify work necessary to allow the equipment to be returned to its previously certified condition. This inspection should take into account the outcomes of previous pre-overhaul inspections (if available), owner/operator comments associated with the return, known deleterious conditions associated with the working environment and use, and relevant documentation including safety alerts, certification/approval documentation, asset manuals and history. The inspection should be conducted in an orderly manner, typically from equipment identification to external and final internal examination. Owner/operator comments may lead the inspector directly to significant non-conformance, however these may describe symptoms rather than identify root causes. Care should be applied to ensure that all areas of non-conformance arising from a failure are identified and documented. This should consider both the sequence of failure and consequential damage that may arise. Inspections should, where possible, be conducted in a sequence that minimises unnecessary work. Where other certified parts are attached to the equipment, the attached parts should be checked for compliance with their relevant certification/approval documentation. A checklist for initial inspections of equipment is provided for each protection technique in the relevant Sections of this document. 3.10.3 Failure analysis Failure analysis should be conducted during the initial inspection process and during the review of past history (based on information from the verification dossier, owner/operator comments and safety alerts) on this equipment and against equipment having similar features (design/construction/operating environment). Failures of not-obvious underlying causes should be also investigated, e.g. associated equipment (pump or fan) causing premature failure of primary drive (motor). 3.10.4 Determination of conformity Following the initial inspection, the repair facility should establish all areas where the equipment under inspection is not in conformance with the specification parameters agreed with the client and the certification/approval documents. In establishing conformity, consideration should be given to the measurement capability of the workshop equipment. 3.10.5 Determination of pass/fail criteria The competent person should establish and document pass/fail criteria for explosionprotected characteristics of the equipment that is to be repaired or overhauled. Pass/fail criteria will be determined by certification/approval documentation, verification dossier documentation, protection techniques and owner/operator specification. The range and precision of measurement equipment can then be determined to fulfil the inspection, test and verification activities. 3.10.6 Exceptional circumstances 3.10.6.1 General Occasionally, repairs to explosion-protection characteristics on large equipment can be safely completed in-situ without relocating the equipment to a service facility. Where repairs are required to a removable part that is well defined in certification/approval documentation, the removable part may be transferred to a service facility for repairs. Alternatively, in-situ temporary repair that can be completed safely and that ensures the robust ongoing maintenance of the explosion-protection characteristics may be considered.

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3.10.6.2 Repair and partial acceptance of component parts of explosion-protected equipment In the event of damage to a component part of explosion-protected equipment, it may be possible to repair a ‘well defined’ part at a service facility and refit the repaired part to the main explosion-protected equipment that remained (isolated) in the hazardous area. This procedure is unlikely to be suitable for component parts that require dynamic testing of the equipment, such as balance and/or load testing of rotating machines, but more likely to be suitable for doors on enclosures, etc. Although the service facility may receive only a component part, it must endeavour to fulfil all the usual inspections, tests and reporting functions that would be completed if the whole equipment item had been submitted, e.g. hydrostatically testing a large flameproof door after structural repairs, with the door bolted to a mock enclosure. Similarly, if a piece of defined equipment is delivered to the service facility missing a component, say a potted gland that has been left attached to the cable at the installation site, the service facility may continue the repairs or overhaul on the equipment and then carry out inspection of the gland at reinstallation, or leave that activity to a competent person employed by the owner/operation. In all of the these situations, the service facility must clearly report what equipment components had been repaired, and the relevant final dimensions, tests and inspections that have been completed to verify the equipment components and the main equipment item when the repaired component has been reinstalled. 3.10.6.3 In-situ temporary repairs of component parts in explosion-protected equipment In-situ repairs may be undertaken with the support of the operator with local site safety provisions. It is preferable that hot work or work with non-explosion protected tools is completed outside the hazardous zone. The operator will need to undertake a specific safety risk assessment for the work completion and any residual risk that a temporary repair may entail. Temporarily repaired equipment must be scheduled for permanent restoration at the earliest possible opportunity. Should a service facility be contracted to undertake an in-situ temporary repair, although this will need to be completed with the necessary cooperation of the site operator, it is the role of the service facility’s competent person to verify that the temporary repair has sufficient integrity to ensure that the explosion-protected characteristics have not been impaired. The competent person may need to devise alternatative test procedures or increase the detailed (in-situ) inspection frequency to ensure that the temporary repair retains the necessary explosion-protection integrity while in-service. An example of a temporary thread repair for flameproof equipment is detailed in Section 6. 3.10.7 Resolution of Scope of Works 3.10.7.1 General In establishing a scope of works the following considerations are relevant: (a)

The service facility should consult with the owner/operator in defining the scope of work required in the various categories after ensuring that the equipment is of an appropriate type, and certification/approval documentation is available in sufficient detail to carry out all checks and tests, as required by the appropriate Standard.

(b)

Once a repair/overhaul procedure has been established and accepted by the owner/operator, the repair facility should ensure that no variation to the scope of work is conducted without first receiving written acceptance of the proposed change from the owner/operator.

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3.10.7.2 Overhaul—No repair Compliance with current certification/approval and equipment identification is established by carrying out all checks, measurements and tests as required by the overhaul Standard. The results should be recorded on the overhaul and examination report. In some cases equipment may be found to be fully compliant with the explosion-protected Standards, however documentation is not complete or adequate. The documentation issues should be addressed as outlined in Clauses 3.10.7.5 and 3.10.7.6. 3.10.7.3 Overhaul—Repair The competent person should establish the actions necessary to restore the equipment to the agreed condition. This should consider: (a)

Rectification of the explosion-protection characteristics.

(b)

Replacement of component parts.

(c)

Processes to strip, repair and reassemble equipment.

3.10.7.4 Compliance documentation essentials National Standards for repair and overhaul of explosion-protected equipment highlight the essential requirements to verify adherence to the original certification/approval documentation. Safety components, critical parts and dimensions are defined in the manufacturer’s documentation and certification/approval documents to enable verification of the integrity of the explosion-protected characteristics of the equipment. The owner/operator of the equipment is required by AS/NZS 60079.14 to maintain a verification dossier (refer to Clause 3.6) that retains the necessary reference documentation for the service facility to validate the explosion-protection characteristics of the equipment to be repaired and/or overhauled. 3.10.7.5 Management of documentation inconsistencies For some equipment, the repair facility may be able to assess the equipment as compliant, while documentation is inconsistent with current expectations, or incomplete. Where inconsistencies in documentation are found that do not affect the explosion-protection status of the equipment, these should be drawn to the attention of the owner/operator for rectification. These inconsistencies should be clearly identified in the concluding reports. 3.10.7.6 Deficiencies in compliance documentation Should the service facility be confronted with a situation where certification/approval documentation is not available but sufficient information is available to identify the type of protection and Standard to which the equipment was manufactured, the owner/operator of the equipment needs to be consulted to obtain all available information to aid service to validate the integrity of the equipment’s explosion-protection characteristics. It should be noted that this practice is unacceptable in Group I and some explosionprotection techniques. As stated in AS/NZS 3800, repair and overhaul without compliance documentation is not permitted for the following equipment: (a)

Equipment for Group I applications.

(b)

Equipment certified as intrinsically safe Ex ‘i’.

(c)

Equipment certified as encapsulated apparatus Ex ‘m’.

Where multi-group (i.e. Group I/II) equipment cannot be validated against the relevant certification/approval documentation and alternate means of validation are used, the equipment label plate and overhaul and examination report need to clearly state that the equipment is not suitable for use in a Group I hazardous area.

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For all other equipment, the recognized service facility needs to make every effort to obtain the certification/approval documentation prior to carrying out any repair. The effort to obtain the information needs to be fully documented, and included in the verification dossier for the equipment. Where the nameplate, and a copy of the original Standard to which the equipment was manufactured are available to determine the protection technique, the equipment may be repaired by or under the supervision of a competent person working in a recognized service facility. The owner/operator should recognize that service facilities are not explosion-protected equipment test authorities that test and verify the design compliance to Standards. Rather, they perform a quality service of returning equipment to a functional condition and validating the explosion-protection features typically set out in the equipment’s compliance documentation. The owner/operator may elect for a key item of explosion-protected infrastructure to be repaired or overhauled with limited availability of the equipment’s design characteristics, but must retain the responsibility to ensure ongoing safe use of the equipment. Typically, a risk assessment is carried out prior to the repaired equipment being installed. The risk assessment may identify that the overall consequence of reinstating this equipment is acceptable when full and detailed compliance documentation is not available for ongoing validation of the explosion-protection characteristics of the equipment. It is typical in contemporary OHS management that alternative proof of compliance must be available and it must demonstrate an equivalent or greater level of safety to AS, NZS or IEC Standards. Should a risk assessment be undertaken, it would be advisable to retain a copy of the report within the verification dossier for the equipment. The owner/operator may seek the assistance of the service facility’s expertise during the risk assessment. It may also be beneficial that this risk assessment be undertaken, prior to completion of the repair and overhaul, because some outcomes of the risk assessment may be required to be installed within the equipment while it is stripped down, e.g. the installation of additional temperature sensors. Should copy winding on motors be considered, refer to Section 5. Additional reporting requirements and special compliance label marking are required for repaired or overhauled explosion-protected equipment that has not been validated against original certification/approval documentation (refer to Clauses 3.10.13 and 3.10.14). 3.10.7.7 Insufficient information Where insufficient information is available to satisfy the requirements in Clause 3.10.7.6 or for equipment excluded from the alternative means of verification described in Clause 3.10.5, the equipment needs to be brought into line with the current applicable Standard. If this is the case, proof of compliance with the current Standard needs to be sourced. A certificate of conformity or other means that may be acceptable to the local regulatory authority should be obtained. Alternative management techniques as outlined in AS/NZS 2381.1 may be considered. This will require consultation with the owner/operator and lies outside the scope of the overhaul repair Standards.

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3.10.8 Changes to equipment 3.10.8.1 Changes to equipment described in certificate documents Changes to equipment described in certificate documents are defined as alterations. For such changes, the following should apply: (a)

The service facility should obtain the necessary certification/approval documentation.

(b)

The service facility should sign an undertaking that the equipment still complies with the original certificate.

3.10.8.2 Changes not described in certificate documents, affecting the explosionprotection characteristics of the equipment Changes to equipment that affect the explosion-protected properties of the equipment that are not described in certificate documents are defined as modifications. Where such changes are performed, the service facility should attempt the following: (a)

If the original certificate holder is still trading, the certificate holder should be notified prior to any work being undertaken.

(b)

The service facility should attempt to obtain the necessary certification/approval documentation. Refer to Section 18 for certification options.

(c)

The service facility should inform the owner/operator that the equipment no longer complies with the original certificate and that an application for a new certificate should be made. If the owner/operator does not wish to proceed with re-certification, the service facility may continue to repair or overhaul the equipment but should provide a report and clear statement that it is no longer suitable for use in a hazardous area and also remove the Ex marking from the equipment.

NOTE: Modifications that affect the explosive protection parameters of the equipment are not allowed, by AS/NZS 3800.

3.10.8.3 Changes not described in certificate documents, not affecting the explosionprotection characteristics of the equipment Some changes to equipment may not affect the explosion-protected properties of the equipment. Such changes can be considered providing that the following is applied: (a)

Any proposed change not covered by the certificate should be assessed by a competent person who has independently verified qualifications and experience (e.g. units of competency 407 and 705 in AS/NZS 4761).

(b)

The competent person should provide an assessment statement demonstrating that an equivalent level of safety is achieved according to the applicable Standard.

(c)

The assessment may determine that additional testing is required under the applicable Standards.

(d)

The assessment should, where possible, include consultation with the certificate holder.

(e)

The assessment on internal equipment changes should demonstrate the following:

(f)

(i)

Adequate internal relief area to eliminate potential for pressure piling.

(ii)

Adequate techniques used for all arc fault limitation, electrical circuit protection and surface temperature limitation under normal and expected overload conditions.

All documentation pertaining to the change, resultant tests and engineering assessments should be recorded and retained by the service facility.

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(g)

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The equipment owner/operator and certification/approval holder should be advised of the alteration.

Changes not affecting explosion-protected properties may include the following: (i)

An alteration to the equipment such as the addition, removal or relocation of hinge supports, mounts and glands.

(ii)

Replacement of internal electrical equipment by a component of similar physical size and identical or better rating, such as power contactors, overloads, control and monitoring apparatus.

(iii) To minimise the possibility of pressure piling occurring, the internal volume should not be increased by more than 10% in total from the original free volume when replacing internal components. (iv)

Alterations to the layout form or function of the internal electrical arrangement under the following provisions: (A)

The enclosure is of simple geometry, i.e. only square, rectangular or cylindrical with a taper not exceeding 10% and no overall internal dimension exceeding any other bymore than 4:1.

(B)

The internal equipment is arranged so that at least 20% of each plane area cross-section is free to permit unimpeded gas flow to eliminate the potential for pressure piling. (Separate relief areas may be aggregated provided that each area has a minimum dimension of 12.5 mm in any direction.)

3.10.9 Repair Repair and reclamation activities must not degrade the explosion-protection technique. It is typical to use Ex-specific repair and reclamation processes and these are documented in the specific Ex technique Sections of this Handbook. When undertaking a repair or reclamation, the process would normally involve initial assessment of the equipment against compliance documents and drawings to determine the extent of repair or reclamation required. Depending on the extent of work, the competent person can determine a viable method of repair that will achieve not only immediate compliance, but also maintain compliance after the equipment is returned to service. 3.10.10 Verification of repair When selecting a repair process there are generally two paths to ensuring compliance. The first path is to complete the repair and then test the viability of the repair. The alternative path, for those processes that cannot be readily tested, is to follow a precise application method that ensures a consistent viable repair. For example, structural welding on a flameproof enclosure would require a hydrostatic pressure test to verify the integrity of the enclosure, however where actual testing is not applicable such as replacement of coatings, compounds or varnishing (e.g. the application of conformal coatings after component replace on intrinsically safe printed circuit board, Ex ‘m’ compound replacement, vacuum impregnation of Ex ‘e’ winding or the assemble of compression glands) the repair and assembly must consistently follow a manufacturer’s or workshop’s method of work to ensure the in-service viability of the repair when the equipment is installed in a hazardous area. After repair or reclamation, irrespective of the verification path, a thorough inspection must be completed to ensure the integrity of the repair and that compliance with certification/approval is retained. Verification should be against documented criteria. The results of the verification process and inspections must be recorded, including actual measurements that can be verified against the original measurements.

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3.10.11 Justification for the omission of verification tests If the competent person considers that a test or verification process detailed in Standards cannot be fulfilled, or is inappropriate for an item of explosion-protected equipment, then it is appropriate for the competent person to document that information in the compliance report and ensure the owner/operator is fully cognisant of the approach prior to returning the equipment to service. The reasons, justifications and considerations should be thoroughly documented in the job file. In these circumstances, alternative means to verify compliance as required by Standards and certification/approval should be undertaken. 3.10.12 Final inspection The final inspection is to be undertaken by the competent person to confirm that the specifications have been achieved and the equipment has been verified and tested for compliance. A detailed report identifying the scope of work undertaken, reclamation work completed, and measurements and tests undertaken is to be completed and forwarded to the owner/operator and a copy retained by the service facility. 3.10.13 Equipment compliance reporting As the work, tests and inspections on the equipment are being finalized, a report must be completed by the service facility and must include supporting documentation that will be provided to the equipment owner/operator for inclusion in the equipment’s verification dossier. Reporting requirements are specified in Appendix A. It is important that the owner/operator has an opportunity to review the completed work and verification report from the service facility prior to the installation of the equipment. A typical repair and overhaul must define the exact item of equipment, initial inspection finding, parts replaced, repairs completed, method of repair, statement of compliance and disclosure of final critical dimensions or observation that describe the explosion-protection characteristics. In all instances it is highly recommended that the work-scope and acceptance criteria are agreed prior to the work proceeding. At the completion of the repair and overhaul, the owner/operator should ensure a detailed report is received from the repair house identifying: (a)

Original condition of product, complete with dimensional and clearance data.

(b)

Scope of work identified and agreed on.

(c)

New dimensional data where repairs to these areas have been undertaken.

(d)

Tests results.

This document should be filed in the verification dossier and supplied to the repair house for reference at the next repair or overhaul. NOTE: Refer to Appendix C for sample report forms.

A more comprehensive disclosure will be required if the equipment is repaired without validation to certification/approval documents. This report documentation should include all of the following: (i)

A repair and overhaul report.

(ii)

A statement that the repair and overhaul has been carried out in accordance with the relevant manufacturing Standard.

(iii) A statement that conformance of the equipment with the certificate of conformity cannot be guaranteed. COPYRIGHT

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A statement that any special conditions of use have not been identified or considered in the repair or overhaul.

3.10.14 Equipment compliance labelling Repaired and overhauled equipment should be marked with the appropriate marking as detailed in national or international repair and overhaul Standards on the main equipment in a visible place. This marking should be legible and durable, taking into account all relevant environmental conditions. The marking should include the following: (a)

The relevant symbol (see below).

(b)

The repair and overhaul Standard number used for compliance verification.

(c)

The name of the repairer or their, registered trademark and workshop certification No.,

(d)

The repairer’s reference number relating to the job.

(e)

The date of the overhaul/repair.

The marking may be on a plate permanently attached to the repaired equipment. In the event of subsequent repairs, the earlier repair or overhaul plate should be removed, and a record made of all the markings on it. If an earlier plate has been removed and it had an inverted triangular symbol (as shown below), then the symbol on subsequent plates should also be an inverted triangular unless the repairer restores the whole equipment to full conformity with the certification/approval documents. Equipment that after repair or overhaul conforms neither to the certification/approval documents nor to the explosion-protected requirements in Standard should have all its marking details relating to the explosion-protected characteristics removed with the agreement of the owner/operator. The standardized symbols for marking cover two categories depending on the method of validating compliance of the explosion-protected equipment. Where the repair or reclamation is in accordance with Standards and the repairer has sufficient evidence of full compliance with the certification/approval documents and the manufacturer’s specification, either one of the following marks is to be used.

Where the repair or overhaul is validated in accordance with Standards but not the certification/approval documents, the following mark is to be used, provided that— (i)

the equipment altered during repair or reclamation has been judged by the repairer to still comply with the restrictions imposed by the overhaul Standard and the explosion-protection technique Standards to which it was manufactured. but the repairer has insufficient evidence of full compliance with the certification/approval documents; or

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the Standards to which the previously certified equipment was manufactured are not known, but the requirements of the overhaul Standard and the current edition of the relevant explosion-protect ion technique Standards have been applied, but the repairer has insufficient evidence to assert full compliance with the certification/approval documents, then an assessment, by a competent person who has the appropriate units of competency (typically UTE NES 407 in accordance with AS/NZS 4761) has been conducted to verify compliance with the relevant level of safety prior to release of the equipment by the repairer.

In these situations the certification/approval labels should not be removed. NOTE: The markings are required for the benefit of subsequent repairers and the only difference between the markings is the method of compliance.

Equipment that after repair or reclamation does not conform with the above should have its original manufacturer’s certification/approval label removed or altered to give a clear indication that the equipment is not certified, until a supplementary certificate is obtained to cover the repair or overhaul. If the equipment is returned to its owner before the supplementary certification is obtained the record described in the repair report should indicate that the equipment is not in serviceable condition and is not to be used in an explosive atmosphere area. It is advisable that this report does not look similar to a compliance report. Where changes mean the equipment no longer complies with the original certification/approval, the marking relating to the certificate of conformity or approval should be struck out on the compliance plate so that the equipment is not accidentally returned to service in a hazardous area. 3.10.15 Pre-delivery inspection It is advisable that the pre-delivery inspection be undertaken by a competent person that is not directly associated with the repair or overhaul so that a ‘fresh set of eyes’ are used to confirm that the specifications have been achieved, documentation has been completed and the equipment has been verified and tested for compliance. This operation is normally undertaken prior to despatch of equipment. The equipment can then be packed for safe dispatch. The owner/operator should be advised that the equipment may be returned with conditions to be fulfilled prior to energising (the removal and blanking of ports, addition of lubrication fluids) to ensure maintenance of explosion-protected characteristics. 3.11 COMMENTARY ON MATERIALS 3.11.1 Introduction It is important to verify that materials used in repair and overhaul are as per original design specifications, or where permitted, compatible with original materials, in order not to introduce an inferior repair. For example, brazing on flamepaths is considered inappropriate due to likely dislodgement after thermal cycling. Replacement parts and reclamation materials must be suitable for their intended use and operating environment (e.g. the use of aluminium, lead-free solders, UV-sensitive materials, heat resistance and FRAS rating are some of the important issues to be considered). COPYRIGHT

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The following items are typical examples of materials requiring special consideration when undertaking repair and overhaul of explosion-protected equipment. 3.11.2 Aluminium and light alloys AS/NZS 60079.0 gives guidance on the chemical composition of aluminium components permitted in hazardous areas. The use of aluminium or light metal alloys in Group I applications should be avoided where practical. The use of light metal alloys or aluminium is only permitted if it complies with AS 3584 or AS 4871.1. 3.11.3 Cast irons Cast irons are commonly used engineering materials with higher carbon contents than steels. Their use is widespread on account of their low cost, ease of casting and ease of machining. Grades of cast iron are distinguished by their microstructure, which is determined by chemical composition and heat treatment. Different heat treatments after casting can yield different grades of cast iron from a common composition, although small additions of alloying elements are included to promote the formation of preferred structures in commercial foundries. Metallographic analysis is required to distinguish between grades of cast iron. The various grades of cast iron are described in AS 1830, AS 1831, AS 1832, AS 1833 and AS 2027. Grey cast irons (flake graphite cast irons) belong to a specific grade of cast iron requiring special attention, because they have very different properties to spheroid graphite or SG irons. Grey cast irons have microstructures containing flakes of graphite. The presence of graphite flakes causes the fracture surface to be grey in colour and can cause the metal to be very brittle. The incidence of brittle failure is promoted by in-service damage or preexisting manufacturing stresses and may be initiated by an apparently minor stress. The use of grey cast irons demands higher care in high-integrity applications such as explosionprotected enclosures. Some explosion-protected enclosures include components of grey cast iron and consequently, service facilities must be aware of the materials of construction. Components contributing to the explosion-protected properties of an enclosure that are suspected of being grey cast iron may be confirmed by one of the following means: (a)

Reviewing materials of construction listed in the manufacturer’s drawings.

(b)

Contacting the manufacturer to confirm the materials of construction.

(c)

Undertaking metallurgical microstructural analysis. This may involve cutting a sample, or in-situ polishing and replication, or visual examination using a metallurgical microscope.

Where components contributing to the explosion-protected properties of an enclosure are suspected (or have been confirmed by one of the means above) of being grey cast iron, the service facility must perform additional verification work. All such enclosures should be over-pressure tested, or magnetic particle tested, irrespective of the category of work performed at time of repair or overhaul. 3.11.4 Corrosion inhibitors (‘grease’) and their application Where required, only suitable lubricants or corrosion inhibitors should be used on flanges, spindles, push-button operators and the like (refer to AS/NZS 60079.1). Some lubricants have extremely low flashpoints and under conditions of a temperature increase, spark or internal explosion could enhance flame propagation or aid flame transmission through a flamepath. It is standard industry practice to obtain the material safety data sheet (MSDS) from the manufacturer or supplier with all chemicals and compounds used in commercial and industry environments. The MSDS will define the necessary characteristics to be considered, such as flashpoint, toxicity and corrosives. A COPYRIGHT

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further important aspect that may not be readily determined from the MSDS is the chemical/compound’s reaction to insulation materials, conformal coating or reduction in comparative tracking index. Two corrosion inhibitors are commonly used with explosion-protected equipment, mostly to protect flamepath surfaces from corrosion. One inhibitor is a fluid type and the other is a thicker grease, however both are lanolin-based and thixotropic in performance. A thixotropic gel displays a reduced viscosity on the application of a finite smear, but recovers its original viscosity when the smear action is discontinued, thus the gel maintains a self-restoring compound. AS/NZS 60079.1 states that ‘A corrosion inhibiting grease may be applied to joint surfaces before assembly. The grease, if applied, should be of a type that does not harden because of ageing, does not contain an evaporating solvent and does not cause corrosion of the joint surfaces. Verification of suitability should be in accordance with the grease manufacturer’s specifications.’ Overcoating with this product is not recommended because it can lead to exfoliation of any rusted areas. It is recommended that it is applied then wiped off to leave a smear coating with just a greasy feel. The thicker grease is recommended in damp areas to limit moisture ingress at flamepath joints. However, this should not be a substitute for a properly designed moisture barrier required to achieve specific IP compliance. Caution also needs to be taken to ensure that the corrosion inhibitor’s application does not contribute to a variation in enclosure reference pressure. Operators are cautioned that silicon-based corrosion inhibitors and lubricates can be detrimental to gas detectors, d.c. commutators and binding of bolts. Some corrosion inhibitors may still exhibit an approval number from the former Mines Department approval scheme, however these approvals have not been supported for over a decade and no verification occurs that the current product retains the same composition to the previously approved inhibitors. Therefore, the service facility needs to verify that the compound is suitable for use in a hazardous area. 3.11.5 Insulation materials When selecting insulation materials the following should be taken into consideration: (a)

Dielectric strength.

(b)

Temperature rating.

(c)

Sheath hardness.

(d)

Comparative tracking index (CTI).

(e)

Physical properties (strength, moisture resistance, etc).

(f)

Chemical properties (anti-embrittlement and suitable resistance to environmental contaminants, etc).

(g)

Solid flow properties (resistance to material flow from a gland).

3.11.6 Plastics and rubber When sourcing plastic materials, care needs to be taken to ensure the selected material will not introduce an electrostatic discharge hazard into hazardous areas. AS/NZS 60079.1 defines acceptable material parameters that may be introduced into a hazardous area that possess a risk of significant electrostatic charge accumulation. When these limits are exceeded the material must be verified by a test authority as acceptable for use in a hazardous area. COPYRIGHT

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Materials must also be verified as being fire retarding. Therefore, materials rated as FRAS (fire retarding anti-static materials) should be used wherever possible. In some hazardous area installations ventilation is restricted and personnel may be exposed to fumes from burnt plastics and/or rubber compounds. Consequently, it is important to consider the toxicity of any by-products. This might occur when a material is exposed to excessive heat. 3.12 COMMENTARY ON INSPECTION TECHNIQUES 3.12.1 General The fundamental inspection skills of a competent person are based on their familiarity with the equipment subjected to overhaul, the operating environment of that equipment and their understanding of common failure modes for the equipment and environment. An eye for detail and for conditions that ‘don’t look right’ may lead the inspector to identify otherwise unnoticed forms of equipment failure. While there is a tendency in some industries to use checklists in a ‘tick and flick’ manner, careful inspection may identify signs of heat stress in cables and insulation, or traces of dust or moisture inside enclosures that demand further investigation. In many items of equipment, the explosion-protection properties are highly dependent on precise dimensional characteristics that are required to be confirmed or determined during overhaul. Overhaul facilities should be familiar with the conduct of a range of measurements, covering dimensional, thermal, electrical and electronic quantities. The following subclauses offer some guidance on the selection and use of a range of commonly used measuring equipment. For further guidance please see Appendix B. 3.12.2 Mechanical inspection techniques and equipment 3.12.2.1 General A surprising number of Ex protection techniques are dependent upon mechanical inspections and determinations of critical quantities. Mechanical inspections are one of the key determining factors where repairs are to be undertaken, especially when testing is not typically expected (e.g. maintenance for the IP rating) or testing is not conducted unless a mechanical flaw is detected. However, many explosion-protection techniques are almost wholly dependent on critical linear dimensions being met, such as the performance of Ex ‘d’ equipment, but also linear clearances also relevant in Ex ‘e’ and Ex ‘i’ equipment. Fortunately, in Australia, there is a comprehensive technical infrastructure, and a number of types of common measuring equipment that are described in Australian Standards. Many factors contribute to a reliable measurement, and these are handled in some detail in HB 86.1. It is good practice to perform before-and-after confirmations of equipment performance to establish continued suitability of the measuring equipment. All measurement equipment used to determine the explosion-protected characteristics of repaired or overhauled equipment will need to be periodically calibrated so that they are traceable to SI units of measurement. Calibration activities are aligned with the expected scale and range of measurement to be undertaken in the compliance verification of explosion-protected equipment.

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3.12.2.2

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Inspection and maintenance of IP rating

IP-rated equipment is very prevalent in industry environments and the IP characteristics of this equipment may also contribute to its explosion-protection properties. While an IP rating is achieved through a certification type test and is therefore a property of the ‘design’ (not a property of individual items of equipment) ., During overhaul, the components and arrangements necessary to the IP rating may be affected. There is typically no requirement for a workshop to perform the reasonably complex IP testing on an overhauled item of equipment. Nonetheless, a workshop must verify the IP rating to its best ability and local means. Inspection of the mechanical parts for degradation, erosion of mechanical surfaces, or loss of elasticity or damage to O-rings or gaskets is an essential activity. However, tests may be devised to ‘indicate’ the viability of the equipment’s IP rating by verifying the short-term retention of a pressure slightly above, or a vacuum slightly below, atmospheric pressure applied to the enclosure via a convenient access point. 3.12.2.3 Length measuring techniques and devices The application of length-measuring equipment needs to be carefully considered to determine an accurate portrayal of the equipment condition and that the measured results are repeatable. It is unlikely that service facilities will need laboratory-grade measurement instruments, but the industry-grade instruments typically used in a service facility still require careful handling, regular calibration and correct application. 3.12.3 Electronic inspection techniques Electronic inspection and repair techniques are highly specialized and have been developed by equipment manufacturers utilizing specialist skills and equipment, therefore it may be necessary to refer to the OEM for guidance. The circuit design and component list may be held as the intellectual property of the manufacturer and unless these items are available, repair of electronic equipment should not be undertaken. 3.13 MECHANICAL REPAIR PROCESSES 3.13.1 General This Section provides guidance on the applications of a range of commonly-used mechanical repair processes. For many techniques, achieving repairs of an integrity appropriate to the high-risk application of explosion-protection demands additional care beyond that encountered in basic workshop practice. Any reclamation should be carried out by competent personnel, skilled in the processes to be employed and using good engineering practices. Operators of reclamation techniques (e.g. welding, metal spraying) must show their level of competence by undertaking a practical skills test in the technique before being permitted to utilize the technique for the first time, then every three years thereafter. If the operator has not used the technique in the previous six months they should undertake a re-test. If any proprietary process is used, the instructions of the originator of the process should be followed. All reclamation should be properly documented and records retained. Such records include: (a)

Identification of the component part.

(b)

Method of reclamation.

(c)

Details on any dimensions that differ from those in relevant certification/approval documents or the original dimensions of the component part.

(d)

Drawings showing reclamation details including material removed and replaced. COPYRIGHT

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(e)

Date.

(f)

Name of the organization carrying out the reclamation.

If the reclamation is carried out other than by the owner/operator or service facility, the owner/operator and service facility should be provided with a copy of the record. A reclamation procedure that would result in dimensions or other integral aspects affecting explosion-protection integrity being different from those given in relevant certification/approval documents is considered inappropriate without additional certification. In the event of any uncertainty regarding the permissibility (from an explosion-protection safety point of view) of an intended reclamation procedure, the advice of the manufacturer or certifying authority should be sought. It will be necessary to carry out tests afterwards to verify that the reclamation procedure is acceptable. 3.13.2 Welding 3.13.2.1 General Workshops are reminded that Ex equipment enclosures may be subjected to extreme service conditions. Weld repairs must ensure that the mechanical properties of the repaired item are not significantly altered by the methods of repair. Weld repair is a common technique used for both rectifying defects and imperfections and for deposition of additional metal prior to machining. However, welding techniques can have a significant impact on the properties of the repaired item. Every effort must be made to ensure controlled welding conditions. In particular, the heat employed in welding can cause internal stresses that cause distortion in adjacent structures. Welding on mounting structures as well as on enclosures can cause distortion that impacts on the integrity and functionality of enclosures, and close tolerance dimensions should be rechecked after the completion of welding. 3.13.2.2

Materials of construction

Materials of construction will determine the approach to repair of explosion-protected enclosures. Some materials, such as cast iron, SG iron and phosphor-bronze have limited weld-ability. Before attempting any weld repair the suitability of the materials of construction must be established from relevant certification/approval documents. 3.13.2.3 Quality welding principles High-integrity welded construction is qualified through a two-step process. The procedure (combining configuration, consumables and welding parameters) is qualified through the creation of a test piece that is destructively tested. Other welding personnel may then be qualified (by using the same qualified procedure) to create a test piece that is examined non-destructively, through macroscopic examination or through destructive testing. This is detailed in AS/NZS 3992:1998. Some configurations have been used so extensively that further weld qualification is not required, just welder qualification—refer to Table 2.1 in AS/NZS 3992. Because of the unique nature of many weld repair configurations, the following recommendations set out a means of qualifying welding in a manner equivalent to that used in the fabrication Standards The threaded hole repair configuration recommended by AS/NZS 3800 requires some form of qualification. The use of weld metal as an overlay deposit prior to machining should be addressed in a similar manner. (See AS/NZS 3992, Section 8.)

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3.13.2.4 Welding procedure qualification For most weld repairs it will be necessary to create a job-specific repair procedure that includes procedures to qualify and control welding. Workshops should qualify the proposed procedure by creating a defect equivalent to that being repaired, in similar material, perform the proposed weld repair and test to establish that suitable properties have been achieved. The tests applied should be agreed on by the parties concerned. Examples of suitable tests may include destructive tensile, bend and impact tests, macroscopic examination of the weld deposit, with hardness traverse, or stud pull-out tests, depending upon the nature of the repair. All welders doing the job must repeat this procedure using either the agreed test or a cut specimen demonstrating full fusion to qualify as a welder for the process. Procedures should be documented in a manner equivalent to AS/NZS 3992, Appendix B. 3.13.2.5 Typical considerations in welding activities 3.13.2.5.1 General There are many considerations in establishing a suitable weld procedure and service facilities are advised to consult with persons having appropriate expertise prior to undertaking and welding an item of explosion protected. 3.13.2.5.2 Welding joint preparation Items for repair must be gouged to remove all traces of cracking. This should be checked using a suitable non-destructive testing method, such as magnetic particle testing in accordance with AS 1171, Non-destructive testing—Magnetic particle testing of ferromagnetic products, components and structures, or dye-penetrant testing in accordance with AS 2062, Non-destructive testing—Penetrant testing of products and components for non-magnetic materials. Particularly when using weld metal deposition to fill holes or gouges, care must be taken to ensure that a suitable bevel is applied to promote fusion of weld metal to parent metal. While commonly used as a means of restoring damaged threaded holes, fill-and-tap techniques present particular problems regarding side-wall fusion and slag inclusions. Slagless techniques (such as GMAW) are recommended. Surfaces must be cleaned immediately prior to commencement of welding. 3.13.2.5.3 Welding position In large enclosures it may be necessary to weld in a position other than the preferred flat orientation. This should be considered when qualifying welding procedures. 3.13.2.5.4 Welding energy input In some instances, thin-walled enclosures may distort under high heat input. Heat input can also change the properties of adjacent parent metal. This is particularly relevant in metal deposition, such as gouge-and-hole filling activities, where heat is more concentrated than normally occurs in fabrication welding. 3.13.2.6 Post-weld testing Each item repaired should be subjected to relevant post-repair testing. Depending on the nature of the repair, this could include a non-destructive test (NDT), possibly radiographic examination in accordance with AS 2177, Non-destructive testing—Radiography of welded butt joints in metal or ultrasonic testing in accordance with AS 2207, Non-destructive testing—Ultrasonic testing of fusion welded joints in carbon and low alloy steel. Acceptance criteria should be as per AS 1554 Part 1 grade SP. Weld-repaired enclosures should be subjected to a suitable and relevant mechanical test, such as a hydrostatic pressure test, or possibly a pull-test on a threaded stud.

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3.13.3 Metal spraying Thermal spray techniques are increasingly used to build up worn or eroded surfaces prior to re-machining to the desired surface finish. Thermal spraying melts a filler or feeder wire to droplets that are deposited onto the target surface. These droplets key onto the surface, with additional bonding provided through diffusion and other chemical/physical processes. The bonding of the sprayed droplets to the target surface, and to previously deposited material, is influenced by— (a)

target cleanliness;

(b)

surface finish/profile;

(c)

temperature of the deposited spray and cooling rates;

(d)

deposition velocity; and

(e)

physical and chemical properties and reactions between the target surface, the molten droplet and the entrainment media (typically air or inert gas).

Cleaning and grit blasting are important for substrate preparation. A rough and clean target area provides the surface needed for good bonding. Both chemical and mechanical bonding is relevant. Sprayed material cools rapidly, however the applied temperature remains important in promotion of diffusion bonding. In some cases, bonding can be improved through application of a pre-heat to the target surface, although the formation of oxidation products may impair the bonding. An increase in thermal and kinetic energy increases chances of metallurgical bonding. Poor deposition can result in a number of failure modes including— (i)

porosity;

(ii)

stress;

(iii) thermal shock; and (iv)

cracking.

3.13.4 Sleeving Should the fitting of a sleeve be considered a form of reclamation, serious consideration must be given to the process and materials to be used because incorrect procedures can lead to development of a second flamepath or distortion of casing through effects of heat from brazing. Once the sleeve has been securely fitted, the surface is to be machined. AS/NZS 60079.1 states that the surfaces of joints should be such that their average roughness Ra does not exceed 6.3 μm. This may be readily checked through the use of a surface roughness comparator. 3.13.5 Thread repair 3.13.5.1 General AS/NZS 60079.1 requires that the quality of threads be of medium or fine tolerance according to ISO 965-1 and ISO 965-3 In addition threaded fasteners are required to be in accordance with AS/NZS 60079.0:2008, Clause 9.2. These ISO Standards for thread form are reproduced in AS 1721.

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Thread form measurement is a technically involved activity demanding a deep understanding of the thread phenomena. AS 1721 recommends thread forms be verified by gauging in accordance with AS 1014. However, it is impractical for workshops to hold gauges for all thread forms likely to be encountered. As an alternative verification measure, the workshop should follow these steps: (a)

Establish that the threaded fasteners provided with the enclosure are all similar and show appropriate markings.

(b)

Conduct a visual examination for damage to the thread form.

(c)

Confirm the depth of penetration and numbers of threads engaged.

(d)

Perform a physical test to establish that the threads engage without seizing.

(e)

Establish that the engaged fastener does not allow axial movement.

If any doubt exists to the suitability of threaded fasteners arising from these checks, the final arbiter should be gauging. Where uncertainty over the suitability of a threaded fastener exists, it is recommended that the fastener be replaced. 3.13.5.2 Reclamation of threaded holes Particularly when using weld metal deposition to fill holes or gouges, care must be taken to ensure that the hole is suitably prepared. This should involve the following Steps: (a)

Removal of metal in excess of original hole depth.

(b)

Ensuring a suitable bevel is applied to promote fusion of weld metal to parent metal.

(c)

Thorough cleaning of the hole immediately prior to welding.

Although commonly used as a means of restoring damaged threaded holes, fill-and-tap techniques present particular problems regarding side-wall fusion and slag inclusions. Instead, GMAW techniques are recommended. Tapped holes must comply with the depth requirements of AS 60079.1 in order to accommodate threaded fasteners. After tapping, threaded holes should have their quality of reclamation verified through nondestructive testing for weld faults (typically inclusions, cracking and lack of side-wall fusion) and undergo a physical test involving the insertion of a stud and application of a tensile pull-out load. The applied load when testing a reclaimed threaded hole should reflect the load that would be placed on that hole during the conduct of the relevant hydrostatic test for the enclosure. 3.13.6 Bolt fit—Fixing bolts, studs and nuts Broken or missing fasteners should be replaced with the fasteners described in the certification/approval documents, or equivalent new fasteners where fastener information is not detailed in the certification/approval documents. Stud or bolt holes that could pass into the flameproof enclosure should always be blind holes, with a thickness of metal at the bottom of the hole of not less than 3 mm or one-third of the hole diameter, whichever is the greater. If, for reasons of construction, holes have to penetrate such enclosure walls, they should be plugged for not less than 6 mm or the diameter of the hole, whichever is the greater, by a screwed plug complying with thread pitch requirements, which is permanently fixed in place. Permanently attached studs should be screwed in place and securely fixed. No washers (plain or lock) should be placed under bolt heads, screw heads or nuts unless they form part of the original approval.

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For coal mines, bolt heads, nuts and the like used on flameproof equipment and enclosures should be suitably shrouded or designed (e.g. with a button or pyramid head so that they can only be loosened and removed with the aid of a special tool). A pyramid or buttonheaded bolt should only be used if the surface around the hole has been spot machined to ensure that the axis of the bolt is normal to the surface. Where replacement bolts are used, they should be of the same type, diameter, pitch and length, and at least the same tensile strength. Any broken or damaged attachment, which could affect the flameproof properties of an enclosure, should be replaced with a part that does not void the current certification. For Group II equipment, shrouding is no longer a requirement, however for Group 1 enclosures, shrouding is still a requirement. 3.13.7 Distortion repair Bent and distorted enclosures may be restored to their original shape. However, cold forming can change the mechanical properties of the parent metal, particularly in cast structures. Enclosures subjected to cold forming repairs should be subjected to a hydrostatic pressure test after repair.

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S E C T I O N 4 G E N E R IC T E ST IN G PROCESSES FOR VER I F I CAT I ON O F E XP L O S I O N - PRO T E CT I O N TECHN I QUE S 4.1 NON-DESTRUCTIVE TEST (NDT) Non-destructive testing techniques may be used by the repair facility to: (a)

Identify volume defects (voids or porosity) in metal.

(b)

Determine wall thickness of metal and bonded dissimilar metal materials (e.g. bearings).

(c)

Locate and size cracks, both surface breaking and sub-surface.

Techniques available include: (i)

Magnetic particle testing, which uses magnetic fields to identify and size surface and near-surface defects.

(ii)

Dye-penetrant testing, which uses coloured dyes to identify surface breaking defects, usually on non-magnetic materials.

(iii) Ultrasonic testing, which uses non-audible high frequency sound to locate and size cracks and voids in bulk material, and can be used to determine the thickness of materials. (iv)

Radiography, which uses gamma or X-rays to identify and size voids and larger cracks in bulk materials.

(v)

Eddy-current testing, which uses magnetic fields to identify surface-breaking cracks in magnetic materials.

General testing techniques are specified in Australian Standards, but specific details and acceptance criteria will be job dependent. The selection of the most appropriate technique depends onof the following factors: (A)

The configuration and materials of construction used in the equipment for overhaul.

(B)

The presence of surface coating materials (paint) and surface finish used on the equipment for overhaul.

(C)

The anticipated type and size of the expected defect.

Care should be exercised to ensure that the technique selected is appropriate for the testing task, and to establish that should defects be identified, they are evaluated for significance to the integrity of the item under test and/or to the integrity of the explosion-protection properties of the equipment. Non-destructive testing is a group of highly specialised techniques and overhaul facilities using NDT should be familiar with the relevant Standards, techniques and competence systems, or use an appropriately qualified subcontract supplier. 4.2 DIELECTRIC WITHSTAND (HIGH POTENTIAL OR HI-POT) TESTING 4.2.1 General Dielectric Withstand or high-potential testing is commonly abbreviated as hi-pot testing. Hi-pot is the term given to a class of electrical testing instruments that uses a power frequency test voltage to verify electrical insulation in finished equipment cables or other wired assemblies, printed circuit boards, electric motors and transformers. COPYRIGHT

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A hi-pot test verifies the insulation of a piece of equipment or component to identify excessive electrical leakage and deterioration in the insulation scheme. Under normal conditions, any electrical device will produce a minimal amount of leakage current due to the voltages and internal capacitance present within the device. Yet due to design flaws or other factors, the insulation in a piece of equipment can break down, resulting in excessive leakage current flow. This failure condition can cause shock or death to anyone who comes in contact with the faulty equipment. A hi-pot test applies a high voltage between a device’s current-carrying conductors and its metallic chassis or screen. The resulting current that flows through the insulation, known as leakage current, is monitored by the hi-pot tester (detailed in the next Clause). The theory behind the test is providing a controlled over-stressing of the insulation scheme to verify its Dielectric Withstand performance for future service. In addition to over-stressing the insulation scheme, the test can also be performed to detect material and workmanship defects, most importantly small gap spacing between currentcarrying conductors and earth ground. When a piece of equipment is operated under normal conditions, environmental factors such as humidity, vibration, contaminants, and dirt can close these small gaps and allow current to flow. This condition can create a shock hazard if the defects are not corrected. No other test can uncover this type of defect as well as the Dielectric Withstand (hi-pot) test. 4.2.2 Hi-pot (high voltage, line frequency or Dielectric Withstand) test A hi-pot tester is a test instrument used to stress test the electrical insulation in a device or other wired assembly that could fail and cause someone to receive an electric shock. It generally consists of a— (a)

variable high (a.c.) voltage source;

(b)

leakage current indication meter; and

(c)

switching matrix to connect the high voltage source and leakage current indicator to all of the contact points in a cable or device.

Hi-pot testers may also have a microprocessor and a display to automate the testing process and display the results. A hi-pot tester can be very similar to a cable tester and often the two are combined in a single unit. In a commonly wired assembly, a hi-pot tester connects all circuits in common to ground. Each circuit is then individually disconnected from ground and connected to the high voltage. The current that flows is monitored to ensure that it is low enough. Typical test levels are twice the system phase voltage (U) plus 2500 V for high voltage equipment or twice the system phase voltage (U) plus 1000 V for low voltage equipment. These tests are generally done on each phase in turn, with other phase and auxiliary equipment bonded to ground. Where the testing configuration does not require a lengthy charging period to achieve the test voltage, the test duration may be just a few seconds. A testing configuration with lengthy cables may require substantial amounts of charging time to achieve the required test voltage. NOTE: The above test voltages are for new equipment only. De-rating factors need to be applied to repaired and overhauled equipment (see AS/NZS 4871.1, Table H3). For further guidance on hi-pot testing, refer to AS/NZS 4871.1, Appendix H.

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WARNING: HI-POT TEST EQUIPMENT UTILIZES HIGH AC VOLTAGES OF 25KV AND GREATER. IT IS CRITICAL THAT SUITABLE SAFE WORK PROCEDURES ARE DOCUMENTED AND UTILIZED FOR THIS TESTING.

The hi-pot tester is intended for use by experienced electrical personnel only and requires the use of established safety procedures and proper personal protective equipment (PPE). The test is performed only on de-energized, out-of-service isolated equipment. The ramp-up voltage is usually about 2 kV/s and the hi-pot tester should be wound fully down at the end of the task to avoid injecting extremely high voltage spikes into the tested equipment. Care should be taken to ensure the equipment under test is completely discharged (noting that some equipment has the tendency to recover charge), at the end of the test prior to disconnecting the hi-pot tester. 4.3 INSULATION RESISTANCE An insulation resistance test is necessary to ensure that the insulation resistance between all live conductors and earth or, as the case may be, all live parts and earth is adequate to ensure the integrity of the insulation. Refer to AS/NZS 4871.1, Appendix H for the insulation resistance test procedure and acceptability of results. 4.4 COMPONENT TESTING 4.4.1 Circuit breakers The testing of circuit breakers for use in explosion-protected equipment can be performed at the service facility. There are a number of different methods of achieving this. The most common method is by current injection where a test unit injects a set current and measures the time taken for the circuit breaker to trip. The results of multiple tests at different currents may be plotted and are compared with specified current and time curves that are usually supplied by the circuit breaker manufacturer. Test units should be accurate to within a few percent. The results of circuit breaker tests are supplied as part of the overhaul report. Together with these tests the report should note the unit’s general physical condition, and include comments on the condition of contact tips, under voltage trip units and no volt trip units, if applicable. The test unit’s details and a calibration date (if relevant) should also be noted. 4.4.2 Overloads Overload testing is similar to testing circuit breakers, using the same test rig and the appropriate manufacturer’s test curve. The maximum current, the condition of the overload, condition of any heaters, external condition of the unit under test and the results at various stages of the test should be recorded. 4.4.3 Current transformers 4.4.3.1 Primary injection testing This test is used to test the overall operation of a current transformer. In this type of test, a high current is injected in the current transformer (CT) primary winding and the resulting secondary current is measured in each secondary CT. This test is mainly conducted during a major circuit modification or rewire. This is part of the overhaul process. The polarity of the current may also be critical and other equipment, such as a phase angle meter, may be used in conjunction with the high-current test source. NOTE: Care should be taken to ensure that the current transformer is always connected. Open circuit secondary windings can produce very high voltages.

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4.4.3.2 Secondary injection testing This test is performed on the individual devices, such as relays and meters, to verify the accuracy and proper operation of the equipment. These devices receive their input current from the CT secondary winding so these tests are at a much lower level of current than that used for primary injection. The correct operation of the current-sensing protective equipment can be verified by comparing the device operating characteristics with the manufacturer’s published time-current characteristic curves. Ensure that the equipment nameplate data complies with drawings and specifications. Every CT test sheet should include the information included in AS 1675. 4.5 TEMPERATURE MEASUREMENT Monitoring of temperature is undertaken during numerous test processes, including the following: (a)

Motor and transformer load and no-load testing.

(b)

Winding removal.

Temperature sensing can take the form of contact, infra-red or embedded devices. Other less frequent forms of temperature measurement may also be employed.

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SECT ION 5 OVERHAU L O F ROTAT I NG MACH I NES 5.1 GENERAL Unlike enclosures, rotating machines generally cannot be routinely inspected ‘in the field application’ due to the spigot design, mounting arrangements and inaccessibility of the plant. Therefore, when conducting a repair or overhaul, it is imperative that the rotating equipment leaves the workshop in a condition that will retain its explosion-protection characteristics until the next scheduled overhaul. The importance of correct repair and overhaul of rotating machines is critical to ensure the performance of the machine is returned to original manufacturer’s design, performance and construction. Key issues affecting performance relate to heat generation, the mechanical damage caused by stress, impact and vibration, and the structural strength of the enclosure. Other key factors to consider are the degree of protection, winding data, condition of bearings housing and journals, terminal boxes and termination blocks as well as water jackets (when applicable). This Section endeavours to highlight specific areas that require attention when conducting repairs and overhauls on Ex rotating machines. 5.2 REPAIR/OVERHAUL When conducting the repair or overhaul, the objective of the repair facility is to identify the cause of any failure and submit recommendations to be considered to limit possible reoccurrence and to ensure the piece of equipment is returned to the owner/operator fully complying to the applicable certification/approval documentation. Due to the importance of ensuring compliance to certification/approval, the repair facility should ensure that only competent persons (defined in Section 3) are utilised to work on this equipment during repair and overhaul. In the event that repairs by third parties are involved, the repair facility must ensure that the third party understands the importance of compliance, has the capabilities to carry out the work, and has the ability to test for compliance after completion of the repair. NOTE: Both the ANZEx and IECEx equipment certification schemes require regular audits of manufacturers to verify continued manufacture of equipment in a certified condition. Unless certification specifically allows the use of non-OEM parts and components, then only OEMsupplied parts and components should be used. The use of non-OEM parts and components may invalidate the certificate of conformity.

Notwithstanding the capabilities of the third party, the repair facility should conduct rechecks on the repair work and include this report documentation with all other job sheets for inclusion with the final report. Following the inspection, the repair facility will be able to identify a detailed scope of work, which identifies the possible cause of failure (if applicable), a possible course of action to ensure re-occurrence is limited, whether it is economical to proceed with repair and overhaul and any other alternative option that could arise, bearing in mind the need to maintain compliance to the hazardous area and type of protection required. Ideally there should be designated hold points where discussion is held with the owner/operator to review the status of the job. This should be conducted with the competent person or a designated person who fully understands the type of protection involved. COPYRIGHT

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The scope of work should also have re-verification points for reworked/repaired components. Past experience has shown that the use of components or parts supplied by a source other than the manufacturer can be quite dangerous and may also result in the piece of equipment not meeting the certification/approval documents. These issues arise mainly because of a difference in the materials used or in some instances by incorrect dimensions, brought about by copying worn components. It is highly recommended that if components require replacement, these are acquired directly from the original manufacturer. In the event that the manufacture or his representative no longer exists, then the recommendation should be to replace the complete unit with a new fully compliant item. 5.3 OWNER/OPERATOR RESPONSIBILITIES Having acquired a piece of rotating equipment for use in a hazardous area, the owner/operator is responsible to ensure that they are in possession of the following material (a)

Certification/approval documentation.

(b)

Maintenance and installation manuals.

(c)

Any relevant documentation referring to special instructions or tools applicable for installation and maintenance of the equipment, in accordance with the certification/approval documents and other regulatory requirements.

This documentation is available from the manufacturer and should be filed for future use in each repair and overhaul, then filed in a verification dossier and retained by the owner/operator of the equipment. Prior to powering up the item initially, the owner/operator must ensure that the equipment complies with documentation, documents have been received, the termination of power leads is in accordance with regulations, gaps where applicable have been checked and recorded for compliance and installation is in accordance with regulations. By design and the location, it may be difficult to conduct regular maintenance/inspections for compliance to certified documentation. Therefore, the designated person should establish a routine schedule to ensure the equipment is appropriately removed from service for inspection, repair or overhaul. 5.4 QUALITY-MANAGED ASSESSMENT STRATEGIES Due to the difficulty of routine site inspections and the critical importance to ensure that explosion protection is maintained, it is recommended the service facility introduce a quality programme for rotating machines’ repair and overhaul, including procedures and where applicable acceptance criteria for— (a)

winding removal technique;

(b)

controlled temperature burn out oven temperature and method of measurement with relevance to the inter-laminar core insulation types. These insulation types include organic and oxide insulants;

(c)

refurbishing of materials to be re-used (with material and dimensional acceptance criteria);

(d)

re-design of windings if allowed within certification/approval (establishing equivalence of machine-wound and hand-wound coils);

(e)

test of old core (after stripping, before and after winding);

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(f)

core loss evaluation (if required as criterion for proceeding with rewinding);

(g)

Testing of rotating parts (rotor assembly or laminated core, cage winding, pole face dampers, spider cracks, rim bolts, permanent magnets);

(h)

specifications and installation procedures for new windings, wedges and winding overhang support systems (vacuum-pressure impregnated or resin rich), armature overhang banding);

(i)

testing of vacuum/pressure impregnation processes, type and frequency of resin quality tests (dielectric tests pre and post-curing);

(j)

commutator repairs (bar-to-bar tests, over-speed tests, seasoning);

(k)

banding of armatures (type and composition of bands);

(l)

brazing of cages (braze alloy to exclude phosphorous if motor used in a hydrocarbon or H 2 S atmosphere);

(m)

leakage test of cooler and cooling circuits;

(n)

material acceptance for anti-corona tapes and paints;

(o)

performance and quality of anti-corona tapes and paints after application;

(p)

acceptance of run-out and balancing results;

(q)

acceptance of rotor electrical tests after balancing;

(r)

acceptance of results of magnetic core proving;

(s)

dismantling and restacking of magnetic cores and poles; NOTE: Because these procedures will require the re-stacking to be under pressure, it is recommended that the owner/operator ensures that the repair facility has the capability to carry out these procedures, otherwise the original manufacturer should be consulted or undertake to complete the procedure.

(t)

performance verification reference documents, which include IEC 60034-1, IEC 60034-2, IEC 60034-2A, IEC 60034-3,IEC 60034-4, IEC 60034-9, IEC 6003410, IEC 60034-11, IEC 60034-12, IEC 60034-14, IEC 60034-15 and IEC 60034-16;

(u)

determination of pass/fail criteria for critical dimensional checks, the water flow test and the water jacket thickness test from certification/approval drawings, and the recording of test results to establish the pass/fail status. NOTE: Pass/fail determination and status verification should also be verified following repair work carried out by third-party facilities.

5.5 EVALUATION PROCEDURES FOR ROTATING MACHINES 5.5.1 General It may be necessary to conduct preliminary processes prior to removing a piece of equipment for repair or overhaul. In these circumstances it is recommended that as much operational information as possible prior to shutdown of power is obtained. The following pages provide some scenarios. 5.5.2 Before power shutdown (typically for large machines only, i.e. ≥1 MW In order to establish the correct operating conditions of a rotating machine that is to be repaired/overhauled it is strongly recommended that ‘before’ shutdown (on-load or no-load, excited or unexcited, as applicable) the following conditions and parameters are established: (a)

Operating voltage, current, power factor, speed and frequency.

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(b)

Operating characteristics needed for re-design if applicable within certification/approval (for example, open-circuit or short-circuit curves for d.c. machines and generators).

(c)

Voltage unbalance and harmonic distortion (for example, motors for run-up of gas turbines and pumped storage machines).

(d)

Current unbalance or fluctuation, or spectral analysis.

(e)

Leakage flux spectral analysis (for example, industrial motors).

(f)

Ambient temperature, humidity, air pressure or altitude.

(g)

Ozone emission of machine windings (windings with high electric stresses).

(h)

Brush sparking inspection (commutator and slip ring machines).

(i)

Commutation test (IEC 60034-19), d.c. machines.

(j)

Bearing temperatures (where sensors are fitted).

(k)

Bearing and shaft vibration (where sensors are fitted).

(l)

Coolant temperatures, flows, pressures (where sensors are fitted).

(m)

Winding temperatures (where sensors are fitted).

(n)

Winding vibration (where sensors are fitted).

(o)

Lubricant temperatures, flows, pressures (where sensors are fitted).

(p)

Core vibration (where sensors are fitted).

(q)

Frame vibration.

(r)

Shaft voltages and currents.

(s)

Stator winding insulation partial discharges or dielectric loss analysis (bars or formwound coils with high dielectric stress).

(t)

Rotor cage integrity.

(u)

Rotor winding inter-turn insulation (impedance measurement) for cylindrical rotors.

(v)

Rotor winding ground insulation resistance for wound rotors.

5.5.3 After shutdown In the event that the equipment is to be removed to a service facility it is strongly recommended that footprint positions are clearly recorded to aid in alignment checking when the equipment is to be repositioned. This task is to be completed before any work is undertaken to remove hold-down bolts. It should also be noted that in many instances shims are used to assist in achieving correct height alignment. Where these are found to have been used, correct recording of the quantity, position and thickness of each shim must be undertaken. 5.5.4 Before dismantling Upon receipt of the equipment at the repair facility an assessment should be undertaken to determine the following: (a)

Reference to documents from owner/operator.

(b)

Cause or contributing factors of failure or work to be undertaken, as instructed by owner/operator.

(c)

Visual external condition (for example, damage noted).

(d)

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(e)

Full nameplate data including certification references.

(f)

When applicable, water jacket flow test.

(g)

Shaft straightness—Run out.

(h)

Electrical tests—Insulation resistance of bearings, couplings, pedestals and shaft seals (where insulated).

(i)

Stator winding insulation d.c. leakage currents (form-wound coils or bars).

(j)

Stator winding insulation resistance and polarization index.

(k)

Dismantle noting condition of bearing caps, bearings, end-shield spigots, stator flamepaths, etc.

(l)

Dimensional checks of commutators and sliprings, journals, seal faces, shaft run-out couplings and bolts, shaft extensions, keys and keyways, and other parts subject to wear.

(m)

Dimensional checks to stator housing ovality, spigoted joints, terminal boxes, terminal blocks and terminals including bushes where applicable.

(n)

Rotor condition.

(o)

Bearing fits on shaft.

(p)

Bearing fits in housings.

(q)

Bearing housing fits on frame.

(r)

Rotor retaining ring crack testing.

(s)

Rotor slot wedge crack testing.

(t)

Rotor cage integrity (crack detection).

(u)

Shaft forging and end-ring integrity (ultrasonic, dye penetrant, magnetic particle, as appropriate), solid cylindrical rotors.

(v)

Shaft, spider, rim and through-bolt integrity (hydro machines).

(w)

Winding condition.

(x)

Fretting at winding, core, core/frame junction.

(y)

Loosening of end-winding supports and bracing system.

(z)

Stator—rotor air gaps.

(aa) Signs of electrical corona and tracking. (bb) Flashover. (cc) Single phasing. (dd) Surge damage. (ee) Cooler gaskets erosion marks on the heat exchangers. (ff)

Burn damage between core plate dovetails and dovetail beams.

(gg) Insulation resistances of bearings, couplings, pedestals and shaft seals (where insulated). (hh) Insulation integrity of up-shaft leads, radial connectors and slip rings (solid cylindrical rotors). (ii)

Insulation integrity of winding connectors, leads, and terminals.

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Dielectric loss angle (DLA) (tan delta) testing of terminal bushings (high voltage machines).

(kk) Gas-tightness of up-shaft leads and radial connectors (hydrogen cooled machines). (ll)

Core insulation integrity (power flux test, low flux test), before and after winding removal.

(mm) Diagnosis of the cause of the machine failure. (nn) For water-cooled motors de-scale the water jacket and conduct volumetric, pressure, flow and wall thickness tests to ensure compliance with certification/approval documentation. NOTE: In the event that a rewind is required for an Ex ‘e’ motor, the manufacturer’s original winding data is required or a full locked rotor test is required to ensure compliance to the ‘tE’ time.

5.5.5 Rewinding Before undertaking a rewind the following information is necessary: (a)

Type of winding, e.g. single layer, double layer.

(b)

Winding diagram.

(c)

Number of conductors per slot and parallel paths per phase.

(d)

Interface connections.

(e)

Conductor size.

(f)

Insulation system, including varnish specification.

(g)

Resistance per phase or between terminals.

NOTE: Winding data should be available from the manufacturer or the certified holder. The whole of the winding should be restored to the original condition, except that partial winding replacement may be possible on larger equipment. A partial winding replacement should only be undertaken after reference to the equipment manufacturer or the appropriate certification/approval authority.

5.5.6 Removal of windings The process for softening the impregnating varnish of damaged windings with solvents, before stripping, is acceptable. The application of heat in a controlled manner, via a temperature controlled burn-out oven, is acceptable provided that the operation is carried out with caution so it will not adversely affect the insulation between the laminations of magnetic parts. If in doubt, the advice of the equipment manufacturer should be sought regarding the inter-laminar insulation material used in a rotating machine classified as utilising the increased safety technique. An increase in core loss resulting from degradation of inter-laminar insulation can significantly affect the motor operation or cause the temperature class to be exceeded. As part of the motor rewind process the service facility should conduct a core-loss test following the removal of windings. Burn out ovens should be equipped with accurate temperature control and monitoring systems. They should also be fitted with water spray devices that activate automatically in the event of an over temperature alarm or ignition within the oven. 5.5.7 Before winding (a)

Casing and frame weld quality (certification) (welder qualification, if necessary).

(b)

Frame and mounting integrity (weld integrity, crack detection, distortion).

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(c)

Shaft straightness.

(d)

Shaft forging and end-ring integrity (ultrasonic, dye penetrant, magnetic particle, as appropriate), solid cylindrical rotors.

(e)

Shaft, spider, rim and through bolt integrity (hydro machines).

(f)

Core insulation integrity (power flux test, low flux test, acceptance criterion for rewinding.

(g)

Core loss evaluation (refer to Clause 5.11).

(h)

Core lamination stack tightness tests (stators, rotors, hydro machine rotor rims), acceptance criterion for rewinding.

(i)

Winding material quality checks (to winding designer’s requirements).

(j)

Winding support components fits and dimensions (in overhangs and slots) to winding designer’s requirements. Winding connector, lead and terminal insulation integrity.

(k)

Bearing fits on shaft.

(l)

Bearing fits in housings.

(m)

Stator winding dielectric loss angle (DLA) (tan delta) tests on replacement bars and coils (HV windings only).

(n)

Stator winding partial discharge tests on individual bars and coils (HV windings only).

(o)

Stator winding dielectric tests with high voltage on each bar or coil (HV windings only).

5.6 ADDITIONAL NOTES FOR COPY WINDING The option for copy winding explosion-protected rotating machines may be considered when insufficient information is in the equipment’s verification dossier. Before any copy winding on motors is considered, it is expected that a competent person has verified what tests are required to maintain Ex compliance, and has confidence that the existing winding data is original. The first step in this would be a review of the verification dossier and equipment history, supplied by the owner/operator. A visual inspection of the winding, and comparison with the certification/approval data would then be undertaken. For example, during a standard motor winding, varnishing is found to be present, while the verification documents specify formed coils, with higher levels of insulation/varnish. Following the rewind of an Ex ‘e’ motor, a locked rotor test at full voltage would be a minimum expectation to determine and verify the tE (stall time). 5.7 AFTER WINDING The following tests and inspections should take place after the winding has been installed (a)

Winding material quality checks (to manufacturer’s or winding designer’s requirements).

(b)

Winding support components fits and dimensions (in overhangs and slots) to manufacturers requirements

(c)

Winding connector, lead and terminal insulation integrity.

(d)

Coil polarity checks. COPYRIGHT

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(e)

Rotor banding check.

(f)

Rotor cage continuity check.

(g)

Stator winding insulation tests.

(h)

d.c. leakage currents (form-wound coils or bars).

(i)

Insulation resistance and polarization index.

(j)

Dielectric tests at high voltage (according to IEC 60034-1).

(k)

Surge comparison test for inter-turn insulation (form-wound coils or bars).

(l)

Dielectric loss tangent (DLA) and tip up (form-wound coils or bars).

(m)

Partial discharge tests on form wound coils and bars and on random wound windings used on inverter fed supplies.

(n)

Discharge location test (ultrasonic or peak pulse probe) form-wound coils or bars.

(o)

Rotor winding insulation tests.

(p)

Insulation resistance and polarization index.

(q)

Dielectric tests at high voltage (according to IEC 60034-1).

(r)

Inter turn insulation tests.

(s)

Recurrent surge oscillograph (solid cylindrical rotors).

(t)

Impedance measurements (hydro and solid-cylindrical rotors).

(u)

Winding resistances (stator, wound rotors).

NOTE: Dielectric and inter-turn tests before vacuum/pressure impregnation are by agreement between the owner/operator and the service facility.

5.8 REPAIR OF ROTORS Rotors with faulty diecast aluminium cages should be completely replaced with new rotors obtained from the equipment manufacturer. Bar-wound cage rotors should be rewound using materials of equivalent specification. Particular care is necessary to ensure a tight fit if replacing conductors in a cage rotor. The same method used by the manufacturer to achieve the degree of slot tightness and end-ring connection should be used. 5.9 TEMPERATURE SENSORS In cases where additional auxiliary equipment is requested (e.g. anti-condensation heaters or temperature sensors) the manufacturer should be consulted to establish the feasibility of and the procedure for the proposed modification. Replacement or the retrofitting of temperature sensors or anti-condensation heaters should only be attached to existing windings after the correct procedure to undertake this task has been obtained from the manufacturer. 5.10 ENCLOSURES If minor damage to enclosures, terminal boxes and covers is to be repaired by welding or metal stitching, care should be taken to ensure that the integrity of the equipment is not impaired and, in particular, that it remains capable of maintaining the degree of protection.

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5.11 SPECIFIC TESTS APPLICABLE TO ROTATING MACHINES 5.11.1 General Depending on the scope of work to be undertaken, the repair facility should reach agreement with the owner/operator on the type of test that the repair facility undertakes as standard and what, if any, additional tests are required. It should also be noted that specific tests may be shown in the certification and therefore are a mandatory requirement to be undertaken. Typical tests are as follows: (a)

Insulation resistance.

(b)

Continuity.

(c)

Degree of protection—IP rating.

(d)

Core loss testing.

(e)

Full load test.

(f)

Temperature rise test.

(g)

Lock rotor test.

(h)

Vibration—base reading.

DLA, Partial Discharge testing, locked rotor and surge testing are destructive tests, to insulation and should only be conducted under strict supervision. 5.11.2 Core loss testing Stator core testing, often referred to a loop test, has proven effective in detecting shorted laminations in stator core iron. The test involves establishing a specific magnetising level in the core by energising loops of cable wound through the stator bore and around the outside of the frame. The circulating currents induced in the laminations will simulate core loss and heat up the stator iron. The approximate design core loss can be calculated from the core dimensions. The loop turns, required current and saturation point can then be calculated. The condition of the core can then be determined from the core temperature, input power and saturation point. The point-of-core saturation can be verified by use of a voltmeter connected to a separate loop of insulated wire passed through the core. The voltmeter reading can be plotted against the input current to the energising loop circuit to confirm saturation point. It is essential to monitor the core temperature at all points to detect any hot spots. Infra-red probes and thermographic devices are recommended for this. NOTES: 1

Hot spots in the back iron may need 20–30 min. of testing before they become evident on the surface of the core.

2

The core is going to become hot during this process.

Further information on core testing can be found in EASA publications. Core loss should always be verified prior to and after winding removal to ensure that— (a)

the inter-laminar insulation has not been damaged;

(b)

physical damage has not occurred to the core; and

(c)

acceptance criterion for rewinding is achieved.

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5.12 SPECIFIC REQUIREMENTS FOR REPORTING ON ROTATING MACHINES It is important to monitor the life cycle maintenance of machines operating in hazardous areas. This is to ensure that the machine maintains its hazardous protection technique at all times during operation. The information detailed in reports by repair facilities should be comprehensive and up-todate, since the information can and would be used to review possible reasons for any consistent non-warranty failures. 5.13 SPECIFIC REQUIREMENTS FOR PACKAGING AND DESPATCH OF ROTATING MACHINES One might think that once a machine has been overhauled and tested the job is complete, but not so. The correct packaging of rotating machines is also a very important factor that must be addressed to ensure that the equipment is received at the site in a usable condition. Typical steps to take during packaging include: (a)

Bearings should be locked to prevent brinelling, which will cause premature failure.

(b)

Terminal box gland entries are to be closed off to prevent the ingress of moisture in the event of inclement weather.

(c)

It is recommended that shaft locks be fitted as a mandatory requirement and that the machine should be packed in a manner that will minimise potential damage to any external component.

5.14 REINSTALLATION RECOMMENDATIONS FOR ROTATING MACHINES Factors to be considered during an installation include: (a)

Correct alignment.

(b)

Correct fitting of couplings.

(c)

Correct fittings of cables and appropriate glands.

(d)

Any additional advice given by the service facility.

(e)

Maintenance of IP and EX rating, i.e. unused gland entries are appropriately blanked.

(f)

Correct installation of monitoring equipment, i.e. vibration and RTDs.

(g)

Correct setting of protection equipment, i.e. overloads.

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SECT ION

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EX ‘d’ F L AMEPROOF EQU IPME NT

6.1 INTRODUCTION 6.1.1 General Flameproofing is an explosive-protection technique where the parts which can ignite an explosive atmosphere are placed within enclosures that can withstand the pressure developed during an internal ignition of an explosive mixture, and prevent the transmission of the explosion to the explosive atmosphere surrounding the enclosure. AS/NZS 60079.1 details the construction requirements for this equipment. The important aspects of the flameproof design guard against the following: (a)

Without suffering damage.

(b)

Without causing ignition.

6.1.2 Without suffering damage Substantial pressures can be generated due to an explosion within a flameproof enclosure. Typical pressures are in the range of 200–1000 kPA. It is most important that an enclosure can withstand the particular pressures that it may encounter in service. The pressure created by the explosion within the enclosure is released to the atmosphere so that the enclosure is not permanently deformed in a way that can impair the integrity of the enclosure. 6.1.3 Without causing ignition As the explosive pressure within an enclosure forces its way through the gaps in the enclosure, the explosion flame is carried with it. If the energy of the explosion is not reduced as it forces its way through the gaps, the explosion pressure front could have sufficient energy to ignite a surrounding explosive atmosphere. The gaps and joints in the enclosure are designed to act as energy sinks and reduce the level of energy in the accompanying explosion flame to below the level needed to ignite the surrounding explosive atmosphere. The specially designed gaps and joints in the enclosure are referred to as flamepaths. The first source of these flamepath dimensions is the certification/approval drawings. If not specified here then AS/NZS 60079.1 specifies the minimum requirements for the length of the flamepath and the allowable gaps or diametrical clearances. 6.1.4 Overhaul pre-requisites The overhaul of electrical equipment for use in hazardous areas is extremely important and should only be carried out under the guidance of a competent person. It is further recommended that any person working on equipment for use in hazardous areas has an understanding of the purpose and implications of the type of protection involved. Persons should have a minimum trade qualification and be proficient in the use of measuring tools, drawing evaluation and report writing with respect to flameproof equipment.

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6.1.5 Initial inspection The initial examination should ensure that: (a)

All protective access covers are removed and flameproof enclosures and/or covers are inspected as follows: (i)

Check that all marking plates/labels associated with certification/approval are securely in place and are complete and legible.

(ii)

Check for external and internal damage to the enclosure/case, including indications of heating, burning and spatter.

(iii) Check for indications of environmental penetration (dust, fluids) of the enclosure/case. (iv)

Where fitted (e.g. in Ex ‘e’ and ‘i’ equipment), check seals and O-rings for integrity.

(v)

Examine flamepaths for signs of pitting, damage and deviation from true plane surfaces.

(vi)

Examine flamepath lengths for compliance with minimum length, as specified by the certification/approval drawings. This includes ‘L’ and ‘l’.

(vii) Check all door and enclosure flanges’ thickness for compliance with the minimum allowable on the certification/approval drawings. If no minimum is specified on the certification/approval drawings, then refer to the guidelines in AS/NZS 3800. (viii) Examine all boltholes for hole depth, thread depth, thread form and condition, along with the correct amount of material behind blind holes, as specified by the certification/approval drawings. Where shrouds are fitted, check condition. (ix)

Examine all fasteners for correct length, thread form, tensile strength and head type, as specified by the certification/approval drawings. Note: It is accepted industry practice to replace all fasteners as part of standard overhaul scope of work.

(x)

Inspect all windows to ensure that the fixing medium is sound and serviceable, and that the lens is not damaged (look for cracking, scouring, impacts and other deterioration). If guards are fitted, also check their condition.

(xi)

Assess all push button/switch operators and measure the worst case. They should also be checked to ensure correct securing method.

(xii) Remove and inspect spigot glands associated with electric motor junction boxes to assist in future motor change-out. (xiii) Check all hand-hole and inspection covers and their corresponding threaded holes for thread pitch, thread engagement, thread wear and locking devices. (xiv) Check all interlocking mechanisms for signs of wear. Cover interlocks and all mechanically actuated electrical interlocks forming part of the enclosure interlocking system should be checked individually and collectively for freedom from action and correct sequence of operation. (b)

All electrical equipment associated with flameproof equipment should be tested and inspected, as follows: (i)

Check all electrical equipment for correct mounting.

(ii)

Carry out insulation testing on all electrical circuits, low voltage and above.

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(iii) Check all cables for damage, including all machine cables and their associated cable protection hoses, etc. (iv)

Check all connections for signs of corrosion or heating.

(v)

Check all protection devices (whether operated thermally, electrically or by pressure) for correct settings, and where test facilities are incorporated within the machine, correct operation should also be verified. Consideration should be given to the calibration, testing and verification of all primary protective devices, tripping values and operating times. NOTE: This may require removal of protective devices and off-site verification.

(vi)

Check all earth connection resistance, including ensuring that any resistance is less than 1 Ω between the earth connection and the machine frame.

(vii) Insulation resistance of transformers, operating at low voltage and above, should be checked between primary and secondary windings and windings to frame and core. (viii) Check all contactor mechanical interlocks for correct operation.

(c)

(ix)

Check all insulation to ensure it is clean and sound and no signs of overheating or cracking are evident.

(x)

Check all insulation for appropriateness, ensuring no polycarbonates are within the vicinity of potential points of arcing.

Rotating machinery should be subjected to basic checks to establish continued operability as follows: (i)

Insulation test.

(ii)

Voltage drop.

(iii) Free rotation. (iv)

Functional.

(v)

Overload tests.

(d)

Where the equipment incorporates a number of explosive-protection techniques, check that the installation complies with the relevant certification/approval documents or appropriate Standard, or both. These components should be checked for damage and should be within the recommended intervals for overhaul.

(e)

On completion of the inspection, the competent person should produce a comprehensive report and record, taking into account the results of the pre-overhaul audit or review including: (i)

The serial number and condition of each item examined.

(ii)

A list of parts and components supplied but not examined, and the reason for their omission.

(iii) All items that require overhaul. (iv)

Details of any components that do not comply with the relevant requirements of AS/NZS 3800 or the certification/approval drawings. Rectification work required to ensure safety should be highlighted and brought to the attention of the owner/operator.

NOTES: 1

The certification/approval documents are the primary inspection criteria. Design standards should not be used where certification/approval documents are available.

2

A typical report form is included in Appendix C. COPYRIGHT

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6.2 OVERHAUL It is essential to establish a scope of work for the repair and overhaul that is to be accepted by the owner/operator before commencing any work. Equipment should be received into the repair facility, externally inspected, photographs taken and electrical tests conducted, if applicable, prior to commencing to dismantle. Once the equipment has been fully dismantled and cleaned a full inspection of all components, measurements for compliance and repair procedures established are carried out and documented for issue to the owner/operator. The repair facility must insist that the owner/operator provide a copy of the certification/approval documentation for the equipment, together with history of previous overhauls, repairs or failures. Repair facilities cannot rely on drawings or documents they may have from some other overhaul of similar equipment, because some small changes may have been applied under a supplementary certificate. 6.3 REPAIR Where the work includes machining to flameproof surfaces, certification and approval will not be considered invalidated provided that the cumulative effect of such machining does not— (a)

reduce the flanges below the minimums where the minimum dimension of the thickness of flanges is detailed in the certification/approval drawings;

(b)

reduce the flange thickness more than 12.5% for internal flanges and 7.5% for external flanges, if nominal-only dimensions are detailed in the certification/approval drawings for the thickness of flanges;

(c)

alter the volume of the enclosure (without internal parts) by more than 0.5%;

(d)

reduce the length of any flamepath whether plain or threaded; or

(e)

result in any deviation to the requirements of the relevant Standards.

Where any flamepath was originally grooved to relieve internal pressure, the grooving should be machined out and eliminated. This will not be regarded as a modification provided that the conditions required in Items (a), (b), (c) and (e) are satisfied and where explosion pressure tests are carried out in order to determine the new explosion pressure test figure and to verify flamepaths. After repair, the procedures in Clause 6.1.4 should be followed. 6.4 RECLAMATION Refer generally to Clause 3.13 covering mechanical repair processes. Metal spraying on flamepath flanges and spigots in considered an inappropriate practice. 6.5 CATEGORIES OF REPAIR The level of reclamation work completed on flameproof equipment needs to be categorised into major or minor repairs. It is the competent person’s role to categorize the repairs. Major repairs include any repair involving thread replacement, rebuilding flamepaths, structural welding or any action that brings the enclosure integrity into doubt. These must be classified as a major repair and be verified by pressure test. Minor repairs are simple in nature, such as hinge replacements (where minimal heat is applied to the body of the enclosure) or a window lens replacement, etc.

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6.6 CHECKS AND REPORTING 6.6.1 General The safe use of electrical equipment in hazardous areas may depend on other factors besides use of flameproof enclosures, such as the following: (a)

Because the flameproof technique depends on operation of the equipment within its rating, means should be provided to prevent overloading of the equipment and for power-interrupting devices, to ensure that the rated breaking capacity or temperature level is not exceeded. The consequences of a destructive short-circuit within the equipment should be guarded against by providing the means to achieve automatic interruption of the short circuit elsewhere before the risk of destroying the enclosure supervenes.

(b)

Because the flameproof technique depends on maintenance of the structure in its designed condition, it is essential that due attention is paid to this condition at all times, and that corrosion, deformation or wear of parts be remedied before any design openings or gaps in the enclosure have enlarged beyond the limits shown in Figure 6.2.

6.6.2 Flameproof motors Electric motors, generators and machinery with rotating shafts require separate consideration for flameproof classification. Clearances and tolerances normally provided for ball, roller or sleeve bearings in motors do not provide safe flameproof gap dimensions. To overcome this difficulty, special glands or labyrinths have been designed to provide a flameproof path along the shaft; at times, this applies to the drive shaft bearing only, if the rear-end bearing carrier and end cover have flameproof dimensions. In all cases, however, the flamepath bush or labyrinth should always be checked for damage or excess tolerances. 6.6.3 Maximum surface temperature The maximum operating external surface temperature for flameproof equipment should not exceed 150°C for Group I equipment and an appropriate value from AS/NZS 60079.0 for Group II and Group III equipment. The maximum permissible surface temperature for equipment or parts of equipment external to the enclosure should be determined by— (a)

danger of ignition of the explosive gas/air mixture and its ignition temperature;

(b)

danger of ignition of combustible dust deposited on a heated surface; and

(c)

the thermal stability of the materials used.

The glow temperature of certain types of combustible dust is known to be within the range 150°C to 170°C. Also the temperature of a surface in contact with combustible dust can be raised significantly owing to the effect of reduced heat dissipation. This temperature increase can lead to exothermic reaction due to oxidation of the combustible dust. Therefore, combustible dust should not be allowed to build up on any equipment surface. Equipment design makes provision for heat radiation, e.g. cooling fins and water jackets, therefore any obstruction to the heat transfer medium should be removed to keep the surface temperature as low as possible. 6.6.4 Fixing bolts, studs and nuts To ensure the safety of equipment, broken or missing fasteners should be replaced with identical fasteners and not with just any bolt selected at random.

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Stud or bolt holes that could pass into the flameproof enclosure should always be blind holes, with a thickness of metal at the bottom of the hole of not less than 3 mm or one-third of the hole diameter, whichever is the greater. If, for reasons of construction, holes have to penetrate the enclosure’s walls, they should be plugged for not less than 6 mm or the diameter of the hole, whichever is the greater, by a screwed plug complying with thread pitch requirements, which is permanently fixed in place. Permanently attached studs should be screwed in place and securely fixed. No washers (plain or lock) should be placed under bolt heads, screw heads or nuts unless they form part of the original approval. For coal mines, bolt heads, nuts and the like used on flameproof equipment and enclosures should be suitably shrouded or designed (e.g. button or pyramid head bolts), so that they can only be loosened and removed with the aid of a special tool. A pyramid or buttonheaded bolt should only be used if the surface around the hole has been spot machined to ensure that the axis of the bolt is normal to the surface. Where replacement bolts are used, they should be of the same type, diameter, pitch and length, and at least the same tensile strength. Any broken or damaged attachment, which could affect the flameproof properties of an enclosure, should be replaced with a part that does not void the current certification. For Group II equipment, shrouding is no longer a requirement however for Group 1 enclosures, shrouding is still a requirement. 6.6.5 Breathing devices Where used, breathing devices should be regarded as component parts of the enclosure and should maintain the explosion-protection properties of the enclosure and comply with the requirements specified for the approval of such devices. The testing of breathing devices should be at the direction of the relevant regulatory authority. 6.6.6 Flamepaths 6.6.6.1 Surface finish When running a fingernail across the flamepath a tactile indication of surface finish is revealed. The level of finish is critical and must be maintained should remachining of the flamepath be required at any time. A more scientific analysis can be achieved using a RUGO gauge. 6.6.6.2 Flamepath— straightness/deviation Tests of joint surfaces using straightedges are illustrated in the Figure 6.1 below.

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Straightedge /position A

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300 mm

300 mm

Straightedge /position B

Straightedge/position A - No deviation Straightedge/position B - No deviation 150 mm

150 mm 150 mm

Flamepath flange

150 mm

300 mm Straightedge /position C

Straightedge/position C - Deviation

Straightedge across flamepath Deviation

NOTE: Use of straightedges to determine flange deviation: (a)

All measuring devices are to be calibrated as per the quality management system.

(b)

Straightedges should be 300 mm long.

(c)

The straightedge is to be used over the full length of the flange in approximate 150 mm increments.

(d)

The straightedge should be used in such a way that the worst case deviation of the flange can be detected. If a flange is longer than 300 mm and a 300 mm straightedge is used, care should be taken not to use discrete steps of 300 mm for measurement, or else excessive deviations may not be detected as demonstrated in straightedge position C.

The deviation over any 300 mm length of flange should not exceed one half of the flamepath gap as specified in AS/NZS 60079.1. The intent of this practice is to detect imperfections in flanges that can result in a flamepath gap greater than that specified in AS/NZS 60079.1 when the flamepath flanges are bolted together. A longer straightedge should be used over openings or un-machined surfaces to ensure that opposite flanges are on the same plane. Although this Figure shows a method of carrying out this test, there is no one specific method of determining the deviation; methods will vary from enclosure to enclosure and length of straightedge. Whatever method is used the main aim is to detect the possibility of excessive flamepath gaps and all measurements should be made with this in mind.

FIGURE 6.1 TESTS OF JOINT SURFACES

6.6.6.3 Flamepath length and gap dimension Flamepath lengths and gaps dimension positions are shown in Figure 6.2

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L

C D1

D2

Flange

L = length of flamepath C = clearance between flameproof faces when flanges have been tightened D 1 and D 2 = depth of corrosion or surface indentation in each face

FIGURE 6.2 FLAMEPATH AND GAP DIMENSION

6.6.6.4 Corrosion or surface indentation tolerances Maximum allowable depth of corrosion or surface indentation is shown in Figure 6.3

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NOTE: Example is for Group I only. DIMENSIONS IN MILLIMETRES

FIGURE 6.3 MAXIMUM ALLOWABLE DEPTH OF CORROSION OR SURFACE INDENTATION ON THE FLAMEPROOF FACES OF AN ENCLOSURE

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6.6.6.5 Checks on circular flanges, spigots and holes This Section indicates the checks to be performed on circular flanges, spigots and holes using inside and outside micrometers and dial gauges. These checks should be carried out in accordance with Figures 6.4, 6.5 and 6.6.

FIGURE 6.4 DIAMETRAL CHECK

FIGURE 6.5 FLANGE FLATNESS AND SPIGOT DEPTH CHECK

FIGURE 6.6 END COVER FLATNESS, DIAMETRAL AND SPIGOT DEPTH CHECK

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6.6.6.6 Guidance for repaired/overhauled

measurement

tolerances

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in

flameproof

equipment

when

The values shown in Tables 6.1 and 6.2 are an indication only of what the gaps would become for a reduction to 80% of the maximum allowable diametral gap, and to 40% of the maximum allowable gap for a flange. If achievable, these reduced gaps may enable prolonging the use of equipment in injurious environments. However, regular inspection should be carried out to determine the condition of the gaps in flamepaths, in all flameproof enclosures. The values shown for diametral clearances do not take into account any bore tolerances or eccentricities for bearings, bearing housing and the like. 6.6.6.7 Shafts with rolling-element bearings—Limits for radial clearance The limits stated in AS 2380.2 are as follows: Minimum radial clearance, k— (a)

for Groups I, IIA and IIB ...................................................................... 0.075 mm; or

(b)

for Group IIC ............................................................................................. 0.05 mm.

Maximum radial clearance m not greater than two thirds of the maximum allowed diametral gap. NOTE: For rods, spindles and shafts the maximum diametral gap is the maximum diametral clearance.

6.6.6.8 Values corresponding to 80% of the maximum allowable diametral gap These values are given in Table 6.1.

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TABLE 6.1 GUIDANCE FOR TOLERANCES FOR SHAFTS WITH ROLLING-ELEMENT BEARINGS Parameters

m (not > than 2/3 gap)

Maximum allowable diametral gaps

Diametral gaps at 80% of maximum allowance

Value for Groups I, IIA and IIB, using minimum flamepath, in accordance with AS/NZS 60079.1

Values for Group IIC, using minimum flamepath, in accordance with AS/NZS 60079.1

V ≤1000

1000 < V ≤ 2000

V > 2000

V ≤ 100

100 < V ≤ 500

500 750 mm Pilot Cond

Copper Repairs

Earth Cond Earth Screen Power Cond Pilot Cond

Splice

Earth Cond Earth Screen Armour Power Cond Pilot Cond

Re-insulate

Earth Cond Semi Cond Earth Screen Power Cond Full Splice Distance From End A Cable Repairer Vulcaniser No. Cable Internal Condition: 1 2 3 4 5 6 7 8 9 New

Repair Hardness:.....................................................

Customer Contract Review By: .............................................................................................. Brand MM Joy Macey Other Res CR Bolted Other Tags Voltage Amps

Replug Assemble D, CandC CandC Repair Paint Fit Tags

End A ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )

( ( ( ( ( ( (

) ) ) ) ) ) )

End B ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )

( ( ( ( ( ( (

) ) ) ) ) ) )

Date: .....................................

Plug Parts: End A:...............................

Plug Parts: End B: ..............................

.............................................................

............................................................

.............................................................

............................................................

.............................................................

............................................................

.............................................................

............................................................

.............................................................

............................................................

.............................................................

............................................................

.............................................................

............................................................

.............................................................

............................................................

.............................................................

............................................................

.............................................................

............................................................

Paint Cable:......................................... by: ........... metres

Colour:..................

Plug Repairer: ...................................................................................................... Comments:........................................................................................................... Cable Despatched:............................................................................................... Final Insp by: ...........................................

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TYPICAL PRESSURISED TRANSFORMER OVERHAUL INSPECTION FORM TYPICAL PRESSURISED TRANSFORMER OVERHAUL INSPECTION REPORT Customer Order No: Transformer Description Component Description Component Location Drawing Numbers Previous O/Haul Reference EXTERNAL EXAMINATION Flange examined for Ex.d Compliance Condition of Cooling Fins Condition of Tap Changer Cover Pressure Monitoring Equipment Gate Valves etc.

Contact Job No: TXF Plant No: Certification No: Results

Compliance Document

Pass

Fail

Pass

Fail

INTERNAL EXAMINATION Internal of Tank for signs of moisture and corrosion HV Bushings LV Bushings Core and Coils All Connections ELECTRICAL TESTING HV Winding Resistance LV Winding Resistance

A Ohms A Ohms Ambient Temperature Degrees Centigrade HV Insulation to Frame A Megohms LV Insulation to Frame A Megohms HV Insulation to LV A Megohms HV Test to 2380.6; High Voltage test for 1 minute LV Test to 2380.6; High Voltage test for 1 minute Repeat HV Test to A Frame Megohms Repeat LV Test to A Frame Megohms Repeat HV Test to LV A Megohms Temperature Monitoring Device

B Ohms B Ohms

C Ohms C Ohms

B Megohms B Megohms B Megohms

C Megohms C Megohms C Megohms

B Megohms B Megohms B Megohms

C Megohms C Megohms C Megohms

Certification/approval drawing no(s).: .............................................................................................. Remarks: ....................................................................................................................................... I ____ confirm that the above equipment has been [repaired/overhauled/altered] (delete as appropriate) in accordance with the relevant requirements of standard [AS/NZS 3800/other] (identify specific documents). Subject to the remarks above, the equipment conforms to the [certification documents/equipment standards] (identify specific documents) and has been marked as required by the relevant overhaul standard. This report has been recorded in the logbook of the service facility. ........................................................... Signature of competent person Identification no.:.....................

Date: ................

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TYPICAL PRE-OVERHAUL AUDIT REPORT SHEET As Per Requirements of AS/NZS 2290.1 Category Ex.d/Ex.e Gas Group CH4 NOTE: Circle the relevant requirement Machine type:

Plant No.

Customer

Order No.

Date of Last Overhaul

Job No.

Mines Overhaul period

Date of Audit

Previous Audit date

Next Audit*/Overhaul * Due

Previous Audit Cert No.

DESCRIPTION

EQUIPMENT: ................................

EQUIPMENT INSPECTED Comments/deterioration notes including hand-hole cover threads SERIAL No. Any Items that show deterioration should show up here

PLANT No....................

JOB No. .........................

The flameproof enclosures have been inspected in accordance with AS/NZS 2290.1 and have been found to comply with the approval conditions. This inspection covered all accessible components. Cable glands, lens, etc. were not dismantled and inspected NOTE: Motors Are not Subject to Pre-overhaul audit and must be changed out at nominated dates. Recommendations: Date next Audit:..............................................................

Inspected by: .....................................................................

Date next AS3800 overhaul: ............................................

Date: .................................................................................

Competency No.: ............................................................

Signature: ..........................................................................

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EQUIPMENT NOT INSPECTED (motors, I.S Equipment, Glands, lens These Items must be tested at normal inspection periods DESCRIPTION

SERIAL No.

COMMENTS/Audit Dates on Motors

CIRCUIT BREAKER and OVERLOAD TESTS (Units May need to be removed to a test facility or substituted) CIRCUIT BREAKER CB*********** CB************* CB************** TYPE EXTERNAL CONDITION INTERNAL CONDITION CONTACT TIPS

CIRCUIT BREAKER SETTINGS

% CURRENT

INJECTION TESTS CURRENT TEST CURRENT SETTINGS AMPS AMPS

TRIP TIME SECONDS

FINAL CHECKS TESTED TO TRIP CURVES

□

PASS

□

FAIL

C/BREAKER OPERATION

□

PASS

□

FAIL

CLEANED EXTERNAL AND INTERNAL

□

PASS

□

FAIL

C/BREAKER SETTINGS ARE RETURNED TO ORIGINAL

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OVERLOAD TYPE

O/L***********

O/L*************

O/L**************

EXTERNAL CONDITION INTERNAL CONDITION CT RATIO OVERLOAD SETTINGS INJECTION TESTS CURRENT TEST CURRENT SETTINGS AMPS AMPS

% CURRENT

TRIP TIME SECONDS

FINAL CHECKS TESTED TO TRIP CURVES

□

PASS

□

FAIL

OVERLOAD OPERATION

□

PASS

□

FAIL

PHASE IMBALANCE

□

PASS

□

FAIL

OVERLOAD SETTINGS ARE RETURNED TO ORIGINAL EQUIPMENT USED FOR TEST EQUIPMENT NO. and DESCRIPTION: CALIBRATION DUE DATE:

DIMENSIONAL CHECKS

ITEM

DESCRIPTION

LOCATED

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ORIGINAL RESULTS of Maximum Out of Plane or clearance

THESE RESULTS of Maximum Out of Plane or clearance

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EARTHING CONTINUITY CHECKS TESTS FROM MAIN RECEPTACLE EARTH TO ALL EARTH POINTS MAXIMUM RESISTANCE FOUND

□

Previous Reading

PASS

□

FAIL

Current reading

Comments:

TESTS OF TRANSFORMERS PRIMARY TO SECONDARY WINDINGS and to EARTH and to CORE Transformer ID

Primary to Secondary

Primary to Earth

Primary to Core

Secondary to Earth

Secondary to Core

Comments/any signs of heating or cracking

TEST EQUIPMENT USED Equipment No. and description

Calibration due

INTERLOCK TESTS ELECTRICAL INTERLOCKS TESTED MECHANICAL INTERLOCKS TESTED RESULTS Comments:

□

PASS

□

FAIL

RESULTS

□

PASS

□

FAIL

Comments:

FASTENER CHECKS (to correct size length and tensile strength) FASENERS CHECKED SIZES LENGTH TENSILE STRENGTH

Comments

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ANY GENERAL COMMENTS ABOUT THE EQUIPMENT CONDITION

Name of Authorised Person: .................................

Verified by:.........................................................

Competency No.: .................................................

Competency No.:................................................

Signature: ...........................................................

Signature: ..........................................................

Date:...................................................................

Date: .................................................................

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CIRCUIT BREAKER TEST REPORT JOB No.:

SERIAL No.:

CUSTOMER:

INSP. DATE:

VOLTAGE:

DESCRIPTION:

All Items must be filled in or crossed N/A to conform with QA requirements Circuit breakers MUST be returned to the original settings after testing unless advised otherwise INITIAL INSPECTION CIRCUIT BREAKER TYPE:

CB***********

CB*************

CB**************

EXTERNAL CONDITION: INTERNAL CONDITION: CONTACT TIPS: CIRCUIT BREAKER SETTINGS: INJECTION TESTS % CURRENT

CURRENT SETTINGS AMPS

TEST CURRENT AMPS

TRIP TIME SECONDS

FINAL CHECKS

□ □ □

TESTED TO TRIP CURVES: C/BREAKER OPERATION: CLEANED EXTERNAL AND INTERNAL:

PASS PASS PASS

C/BREAKER SETTINGS ARE RETURNED TO ORIGINAL: EQUIPMENT USED FOR TEST EQUIPMENT NO. AND DESCRIPTION:

CALIBRATION DUE DATE:

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FAIL FAIL FAIL

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COMMENTS:

Name of Authorised Person:...................................

Verified by:........................................................

Competency No.: ...................................................

Competency No.:...............................................

Signature: .............................................................

Signature: .........................................................

Date:.....................................................................

Date: ................................................................

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CURRENT TRANSFORMER TEST SHEET

JOB NO.:

SERIAL NO.:

CUSTOMER:

INSP. DATE:

MODEL No.:

ACCURACY CLASS:

RATIO:

ACCURACY:

CT TYPE: TEST CURRENT: TEST AMPS: OUTPUT AMPS:

PHASE A:

PHASE B (IF APPLICABLE):

TESTED BY:

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PHASE C (IF APPLICABLE):

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EARTH LEAKAGE TRIP TIME TESTS

Job No.:

Order No.:

Date:

Customer:

Tested by:

Customer Contact:

Location Description: Circuit Name: Relay Name: Sensitivity (mA):

Delay (mS):

Set:

Set:

Value:

Value:

Test:

Test:

Trip:

Avg:

(ma)

No.:

Time (mS)

(mS)

1 2 3 Circuit Name: Relay Name: Sensitivity (mA):

Delay (mS):

Set:

Set:

Value:

Value:

Test:

Test:

Trip:

Avg:

(ma)

No.:

Time (mS)

(mS)

1 2 3 Circuit Name: Relay Name: Sensitivity (mA):

Delay (mS):

Set:

Set:

Value:

Value:

Test:

Test:

Trip:

Avg:

(ma)

No.:

Time (mS)

(mS)

1 2 3 Test Equipment: Comments:

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OVERLOAD RELAY TEST REPORT JOB No.:

SERIAL No.:

CUSTOMER:

INSP. DATE:

VOLTAGE:

DESCRIPTION:

All Items must be filled in or crossed N/A to conform with QA requirements Overloads MUST be returned to the original settings after testing unless advised otherwise INITIAL INSPECTION CIRCUIT BREAKER TYPE:

CB***********

CB*************

CB**************

EXTERNAL CONDITION: INTERNAL CONDITION: CT RATIO: OVERLOAD SETTINGS: INJECTION TESTS % CURRENT

CURRENT SETTINGS AMPS

TEST CURRENT AMPS

TRIP TIME SECONDS

FINAL CHECKS

□ □ □

TESTED TO TRIP CURVES: OVERLOAD OPERATION: PHASE IMBALANCE:

PASS PASS PASS

OVERLOAD SETTINGS ARE RETURNED TO ORIGINAL: EQUIPMENT USED FOR TEST EQUIPMENT NO. AND DESCRIPTION:

CALIBRATION DUE DATE:

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COMMENTS:

Name of Authorised Person:...................................

Verified by:........................................................

Competency No.: ...................................................

Competency No.:...............................................

Signature: .............................................................

Signature: .........................................................

Date:.....................................................................

Date: ................................................................

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PROTECTION RELAY REPORT

Job No.:

Order No.:

Date:

Customer:

Tested By:

Customer Contact:

Location: Description: Relay Details

Over-current

Earth fault

Serial number:

(R)

(E/F)

Serial number:

(W)

(E/F)

Serial number:

(B)

(E/F)

Make: Model Number: Type (Inverse, Ext. Inverse ttc): C.T ratio:

Phase/Earth fault testing (1A/5A): Current Setting (plug) –A: Time Setting (multiplier): Instantaneous setting –A: Calculated pick up current –A: Calculated Trip current at 2x test –A: Calculated Trip current at 5x test –A: Calculated Trip current at 10x test – A: Calculated earth fault trip current –A: Calculated inst. trip current –A: Breaker trips: TEST RESULTS: PHASE

PICK (AMPS)

UP OPERATING TIME (SECONDS) 2x

5x

TEST EQUIPMENT USED:

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INST SETTINGS TRIPS AT (A)

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CURRENT INJECTION TESTING Adjust the check the trip times at various points over the range of the circuit breaker and plot them on the results graph Note: There should be sufficient check points so that a true representation of the curves is able to be interpreted

Current injection tester

Load

Overload

S O L I D - S TAT E OV E R C U R R E N T R E L AYS

90 80 70 60 50

T I M E - C U R R E N T C H A R AC T E R I S T I C S

40 18 0 0

30 20

600

10 9 8 7 6 5

300

4

10 9 8 7 6

1 0.9 0.8 0 .7 0.6

60

5 4 3

0.5

30

0.4

2

0.3

0.2

1 0 .1 0.09 0.08 0 . 07 0.06

6

0.05

3

5 4

0.04 2

0.03 0.02

200

50

40

60 70 80 90 10 0

30

20

6 7 8 9 10

5

4

3

0 . 01

2

1

0.5 0.6 0 .7 0.8 0.9 0 .1

TIME IN SECONDS

2

CYC L E S

3

C U R R E N T I N M U LT I P L E S O F S E T T I N G T Y P E 51l I N V E R S E

FIGURE C1 USING THE CURRENT INJECTOR TESTER

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WARNING: USING HIGH VOLTAGE OR HIGH CURRENT DEVICES HAS ITS ASSOCIATED DANGERS OF ELECTRIC SHOCK. WHEN ANY EQUIPMENT IS INSTALLED, FOR THE PURPOSES OF TESTING, IT IS HIGHLY RECOMMENDED THAT OH&S ISSUES FOR THE SAFETY OF THE OPERATORS OF THE DEVICES AND ANY BYSTANDERS BE ADDRESSED TO ENSURE THAT PERSONS ARE NOT INJURED BY THE EQUIPMENT. SEE PLANT SAFETY IN YOUR OH&S REGULATIONS.

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APPENDIX D

HISTORICAL INFORMATION RELATING TO EQUIPMENT APPROVAL SCHEMES D1 GENERAL Because of the clear risks associated with mining, specific Acts and regulations were developed for this industry. It was only later that the need for explosion-protected electrical equipment in non-mining applications became apparent. In Australia, therefore, two separate regimes of regulation developed— (a)

equipment for use in coal mines and regulated by the various state coal mining Acts; and

(b)

equipment for use in areas other than coal mines and covered by AS/NZS 3000 (wiring rules).

Both applications fell generally within the ambit of occupational health and safety (OHS); an area that was retained by the states to regulate at Federation. Each state and territory enacted relevant Acts of parliament with associated regulations. Each Act and regulation was tailored to the specific needs and nuances of the industry within the enacting state at the time of assent. Not surprisingly, the content of each Act and regulation was different and, even when similar, the implementation and enforcement of the requirements were not nationally consistent. Each state supporting an underground mining industry operated a system of equipment approval. With the increasing standardisation of mining equipment and the need to hold a single approval for equipment nationwide, by the 1950s, the need for the regulatory authorities to participate in a national certification/approval scheme emerged. A series of equipment certification/approval schemes developed, run in parallel with approval schemes managed by state authorities. These certification/approval schemes relied on national and international Standards. As global equipment supply became more common, Australia adopted the requirements of international Standards, including adopting internationally accepted conformity assessment schemes. It has only been since 1990 that efforts have been made to establish an encompassing approach to the management of electrical equipment for hazardous areas. Because repair and overhaul activities are usually applied to equipment that has been in service, sometimes for many years, this Appendix will summarise the operation of a number of now superseded schemes. D2 STATE AUTHORITY APPROVALS D2.1 History In NSW, regulation of electrical equipment in mines has involved approval of various types since the first Act in 1908. In the early years, the British system of equipment approval was accepted and implemented without relying on Australian input. To serve local manufacturers and demand, in the 1950s the testing laboratory of the Sydney County Council started testing and issuing certificates for flameproof equipment. In the 1960s, the NSW and Queensland Departments of Mines started testing laboratories in support of their flameproof approval systems. The NSW Department of Mines started intrinsic safety testing in NSW, before the Sydney County Council laboratory took on this work*.

* Lloyd, 2nd conference of the IEE ‘Electrical Safety in Hazardous Environments’ December 1975. COPYRIGHT

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As late as 1975, the NSW Department of Mines would not allow Ex ‘e’, Ex ‘q’ or Ex ‘m’ in NSW coal mines. The NSW Department of Mineral Resources continued to issue approvals and supplementary approvals for equipment intended for use in NSW coal mines until 2006. This system offered a highly adaptable approach, suited to the ‘every mine unique’ industry structure in vogue at that time. D2.2 Overview A NSW Mines Department approval consists of attesting formally that a specified item of electrical apparatus (i.e. electrical appliance, machine, fitting) conforms to the requirements of the Chief Inspector of Coal Mines. These requirements may take the form of Australian or other Standards either in whole or part. Approval does not necessarily mean compliance with a Standard. All approvals have conditions or recommendations regarding use of the equipment. For equipment that only has NSW MDA approval it is essential that the drawings identified on the approval documents are used in the overhaul, repair or modification processes. The use of Standards only is not sufficient because the approved equipment may not comply with the Standard and alternative risk controls may be identified on the approval documentation (including drawings). Therefore, it is essential that equipment that only has an approval is checked for compliance with the approval documentation (including drawings). D2.3 Handling changes The approvals system typically allowed for incremental changes to equipment through the issuance of supplementary approvals. Over time, equipment could be progressively modified until many supplementary approvals were issued for a particular product family, although for any particular item of equipment a limited number of supplementary approvals may be relevant. Care should be exercised to— (a)

ensure that details of all supplementary approvals are held before an overhaul is commenced; and

(b)

ensure that all relevant supplementary approvals are identified in statements of conformity arising from an overhaul.

D3 P/3 APPROVALS COMMITTEE (1960–1987) D3.1 History During the 1960s, Standards Australia set up an approvals-type scheme for Ex equipment other than that used in mines, referred to in later years as the P/3 Scheme, as it operated under the direction of the Standards Australia P/3 Committee, Certification of ExplosionProtection Electrical Equipment. This Committee comprised representatives from state electrical and mining regulatory authorities. It was responsible for considering applications for certification and for authorising the issue of certificates of compliance or statements of opinion. It also advised regulatory authorities and industry on matters relating to the application of Australian Standards to electrical equipment or use in hazardous areas. D3.2 Overview Under the scheme the Committee met every two months to consider applications using test reports and (in most instances) samples to arrive at a decision to approve equipment for use. The decisions made in this Committee were based on the judgment of the Committee. Often some discretion was applied and equipment approved by the committee may not have been checked for full compliance with the then Standards. This was addressed by an evolutionary change, described in following sections. COPYRIGHT

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Committee P/3 administered the certification of explosion-protected electrical equipment from 1986. Between 1960–1986, different designations were used for the Committee. Standards applicable to the explosion-protected area are prepared by Committees EL/14 Electrical Equipment in Hazardous Areas, and EL/23 Electrical Equipment in Coal Mines. D4 P/3 AUSEx SCHEME (1987–1993) Between 1987 and 1993, the P/3 Committee continued its activities, but allowed for two paths: an approval path as outlined above, or a certification path in which the committee certified that a sample of the equipment, and the manufacturer’s drawings, complied fully with the requirements of the relevant Australian Standards. Reference: [SAI Ex Workshop notes, 2001] D5 AUSEx SCHEME 1993–2003 D5.1 History and overview In 1993 the AUS Ex scheme was introduced. This was managed by Standards Committee P/8 and administered by Quality Assurance Services (QAS) in accordance with MP 69 Explosion protected electrical equipment—Certification scheme—Policy. The scheme sought to demonstrate compliance of electrical equipment through measurement of key dimensions, a range of type tests and submission of relevant documentation. The sample was considered a realisation of a design (or type), which was approved if the sample was found to be compliant. This scheme certified that both the sample of the equipment and the manufacturer’s drawings complied fully with the requirements of the relevant Australian Standards. [SAI Ex Workshop notes, 2001]. Certificates of conformance were issued on the basis of a type test only, with no assurance regarding continued conformance during production, i.e. product quality assurance. The applicant undertook to ensure that, in production, every item would comply with the drawings specified in the certificate, and that production models would be identical to the model submitted for testing and examination, complying with relevant Australian, New Zealand or Joint Standards. [MP 69:1993 Clause 2.4] While there was the scope for manufacturers to voluntarily fulfil defined requirements leading to the application of an Ex mark, this was not generally taken up by Australian industry. Certificates of conformance that were issued had a limited validity of 10 years. This was applicable to the manufacturer, not the owner/operator. Since certificates of conformity were issued as late as December 2003, manufacturers are able to continue to manufacture in accordance with the AUS Ex scheme until December 2013. Related documents included Q7133:1993, Application procedures for Ex mark and Q7134:1994, Application procedures for Australian Ex certificate of conformity. D5.2 Documentation AUS Ex-approved equipment is required to be labelled with: (a)

The manufacturer’s name.

(b)

Name or symbol of the certifying authority.

(c)

Certificate reference.

(d)

The letter ‘X’, where appropriate.

NOTE: Where certification conditions apply AUS Ex certificates include an ‘X’, e.g. AUSEx 99998 X COPYRIGHT

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In some situations the certificates include a ‘U’, indicating that only components (rather than a complete assembly) have been covered by the certification. D6 ANZEx SCHEME 2001 Internationally IECEE was moving towards establishing the IECEx scheme, which was to be an implementation of an ISO Type 5 Certification System (sometimes referred to as Full Certification) based on the ISO/IEC Conformity Assessment Committee (CASCO) System 5 specification. In anticipation of this development, the P/8 Committee revised the AUSEx Scheme to include surveillance of manufacturers. This revised scheme, known as the ANZEx Scheme, is managed by Standards Committee P-008 and administered by SAI Global in accordance with MP-87, Australian/New Zealand certification scheme for explosion-protected electrical equipment (ANZEx Scheme)—Basic rules and procedures. In general the ANZEx Scheme— (a)

certifies that both the sample of the equipment and the manufacturer’s drawings comply fully with the requirements of the relevant Standards;

(b)

certifies that the manufacturer has a quality system that ensures that the manufacturer will be able to manufacture the items as they were certified; and

(c)

includes surveillance of the manufacturer’s factories to confirm that the manufacture is in accordance with the certification [SAI Ex Workshop notes, 2001].

However, provision remains for an ISO Type 1 (Type test) Scheme to cover ‘one off’ situations, which may lead to the issue of a restricted type test certificate. The ANZEx Scheme establishes certification bodies that are (on the basis of suitable evidence, principally reports from approved testing laboratories and manufacturer’s documentation) able to issue certificates of conformity for electrical equipment. These certification bodies are required to conduct periodic surveillance on manufacturers holding a ‘certificate of conformity’ for electrical products. The certificate of conformity provides distinctive third-party confirmation of a manufacturer’s claimed compliance to the relevant Standards and that product is manufactured under the ANZEx quality management system requirements. Applications for amendments to certificates for non-expired AUS Ex certificates are exempt, since such certificates were issued under the previous phase of the ANZEx scheme and have a 10-year life from issue date. D7 HANDLING CHANGES Certification bodies are able to amend a certificate of conformity at the request of the holder of the original certificate of conformity. Amendments to certificates of conformity are generally issued to cover the following: (a)

A modification to certified equipment.

(b)

An extension to certified equipment in the form of a new model or a new option.

(c)

A change in one or more of the components which form part of the certified equipment.

(d)

A change of catalogue or part number.

(e)

A change of brand or trade name.

(f)

A change in name or address of the certificate of conformity holder.

(g)

A change of name or location of manufacturer.

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In use, modifications to equipment may be of three types: (i)

Modifications within certification.

(ii)

Modifications not within certification. In this case the equipment no longer complies with the original certification and that an application for new certification should be made. Should the owner/operator not wish to proceed with re-certification, the apparatus is no longer suitable for use in a hazardous area and the Ex marking is to be removed from the apparatus.

(iii) Modification by competent person assessment, Ex ‘d’ protection only, can be considered providing the requirements of AS/NZS 3800 are met. Because of the role and responsibilities of the certificate holder, modification demands consultation and provision of suitable advice to the certificate holder. Some modifications may mean the equipment no longer complies with the original certification. Examples of modifications requiring competent person assessment may include the following: (A)

A modification to the equipment such as the addition, omission or relocation of hinge supports mounts and glands.

(B)

Replacement of internal electrical equipment by an engineering equivalent such as power contactors, overloads, control and monitoring apparatus.

(C)

Alterations to the layout form or function of the internal electrical arrangement under certain restrictions detailed in AS/NZS 3800.

D8 RELEVANT INTERNATIONAL SCHEMES D8.1 UK Testing of flameproof equipment in the UK commenced in 1924 at Sheffield University. Certificates of compliance were issued and the scheme was taken over by an industry group before becoming the responsibility of the mining regulator*. In July 1967, the HQ Acceptance Scheme was launched. In this scheme drawings of all equipment were examined and the manufacturer gave an undertaking that the equipment manufactured would be in accordance with the provided drawings. The UK regulator also operated a system where workshops were authorised and the proposed overhaul/rectification process was to be approved by a government inspector before it was performed. D8.2 IECEx Formed in response to a 1991 international survey, the IECEx Scheme is operated in accordance with IECEE 04 Rules and procedures of the scheme of the IECEE for certification of Standards for electrical equipment for explosive atmospheres (first published March 1995) and the more recently published IECEx 01 Basic rules of the IECEx scheme, and IECEx 02 Rules of procedure of the IECEx scheme (published October 1999). The IECEx Scheme: (a)

Certifies that both the sample of the equipment and the manufacturer’s drawings comply fully with the requirements of the relevant [IEC] Standards.

(b)

Certifies that the manufacturer has a quality system that ensures that the manufacturer will be able to manufacture the items as they were certified.

(c)

Includes surveillance of the manufacturer’s factories to confirm that the manufacture is in accordance with the certification.

* A V Jones and R P Tarkenter, Electrical technology in Mining: the dawn of a new age, Peter Peregrinus Ltd 1992 COPYRIGHT

195

HB 239:2011

APPENDIX E

HISTORICAL INFORMATION RELATING TO SERVICE FACILITY APPROVAL SCHEMES There are various authorities in Australia and New Zealand concerned with the safety of electrical installations in hazardous areas. These include the electrical regulatory authorities, mine regulators, OHS regulators and the insurance industry. Where there is a potential for an explosive atmosphere, or the risk of an explosion from an electrical source of ignition, one of the key risk controls is the use of explosion-protected electrical equipment. As the consequences of an explosion at a mine or other industrial facility can be catastrophic (numerous deaths and injuries), it has been accepted that a high degree of confidence in the explosion-protected properties of electrical equipment should be maintained. This high degree of confidence has been established through published Standards, competent independent facilities to assess the design against the Standard (Ex test labs) and competent independent recognition of the design and testing through certification or approval (AUS Ex, ANZEx, IECEx, MDA approval). However, the certification or approval of equipment only encompasses the design part of the life cycle. The selection, installation, inspection, use and maintenance of the equipment has been covered by published Standards such as AS/NZS 2381, IEC 60079.14 and 17 and AS/NZS 2290 (for coal mines). The only parts of the life cycle not covered were overhaul, repair and modification. The Australian coal mining industry recognized the importance of these elements of the life cycle and developed a coal-mine-specific Standard, AS 2290.2, for the overhaul and repair of explosion-protected equipment for coal mines (Group I). To support this Standard, the NSW mining regulator implemented a program of ‘approved Ex service facilities’ in the late 1970s—early 1980s, where facilities that overhauled and repaired explosion-protected equipment for NSW coal mines had to have facilities (including premises and tools), and competencies to conduct the overhaul and repair work in accordance with AS 2290.2. This program included the competent persons programme, where individuals had their knowledge of the repair, overhaul and modification of Ex equipment assessed by oral and/or written examinations. During the mid-to-late 1980s the NSW mining regulator reviewed the requirements for Ex service facilities approval and introduced requirements for the implementation of certified quality management systems. Throughout the 1990s, AS 2290.2 evolved into AS/NZS 3800 and encompassed both Group I and Group II industries. At the same time non-regulatory bodies such as NATA and SAI Global began providing accreditation/certification services for facilities that overhauled and repaired Ex equipment. National competency Standards were also established for hazardous area electrical equipment. With all of this, mining regulators have recognized the need to fully embrace the equipment certification and Ex service facilities recognition capabilities available. It is now recognized that the infrastructure is in place and is mature enough to consolidate the recognition of Ex service facilities that repair, overhaul or modify hazardous area equipment. It is due to this set of circumstances that the Joint Policy Committee, P-008, endorsed the inclusion of Ex service facilities and their recognition within its scope of activities. As a result owner/operators can have a high degree of confidence in the explosion-protected properties of hazardous area equipment that they purchase, or have overhauled, repaired or modified where the equipment certification schemes and Ex service facilities recognition schemes are used. It is also recognized that the IECEx Scheme has been expanded to encompass Ex service facilities. As such it is envisaged that, as this scheme and the IECEx Scheme evolve, there will be close alignment between the two. COPYRIGHT

HB 239:2011

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NOTES

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