July 2009
Examiners’ Report NEBOSH International Diploma in Occupational Health and Safety (Unit IC)
Examiners’ Report NEBOSH INTERNATIONAL DIPLOMA IN OCCUPATIONAL HEALTH AND SAFETY Unit IC – International workplace and work equipment safety JULY 2009
CONTENTS
Introduction
2
General comments
3
Comments on individual questions
4
© 2009 NEBOSH, Dominus Way, Meridian Business Park, Leicester LE19 1QW tel: 0116 263 4700
fax: 0116 282 4000
email:
[email protected]
website: www.nebosh.org.uk
The National Examination Board in Occupational Safety and Health is a registered charity, number 1010444 T(s):exrpts/J/J-C0907
EXTERNAL
DW/DA/REW
Introduction
NEBOSH (The National Examination Board in Occupational Safety and Health) was formed in 1979 as an independent examining board and awarding body with charitable status. We offer a comprehensive range of globally-recognised, vocationally-related qualifications designed to meet the health, safety, environmental and risk management needs of all places of work in both the private and public sectors. Courses leading to NEBOSH qualifications attract over 25,000 candidates annually and are offered by over 400 course providers in 65 countries around the world. Our qualifications are recognised by the relevant professional membership bodies including the Institution of Occupational Safety and Health (IOSH) and the International Institute of Risk and Safety Management (IIRSM). NEBOSH is an awarding body to be recognised and regulated by the UK regulatory authorities: • • •
The Office of the Qualifications and Examinations Regulator (Ofqual) in England The Department for Children, Education, Lifelong Learning and Skills (DCELLS) in Wales The Council for the Curriculum, Examinations and Assessment (CCEA) in Northern Ireland
NEBOSH follows the “GCSE, GCE, VCE, GNVQ and AEA Code of Practice 2007/8” published by the regulatory authorities in relation to examination setting and marking (available at the Ofqual website www.ofqual.gov.uk). While not obliged to adhere to this code, NEBOSH regards it as best practice to do so. Candidates’ scripts are marked by a team of Examiners appointed by NEBOSH on the basis of their qualifications and experience. The standard of the qualification is determined by NEBOSH, which is overseen by the NEBOSH Council comprising nominees from, amongst others, the Health and Safety Executive (HSE), the Department for Education and Skills (Df ES), the Confederation of British Industry (CBI), the Trades Union Congress (TUC) and the Institution of Occupational Safety and Health (IOSH). Representatives of course providers, from both the public and private sectors, are elected to the NEBOSH Council. This report on the Examination provides information on the performance of candidates which it is hoped will be useful to candidates and tutors in preparation for future examinations. It is intended to be constructive and informative and to promote better understanding of the syllabus content and the application of assessment criteria. © NEBOSH 2009
Any enquiries about this report publication should be addressed to: NEBOSH Dominus Way Meridian Business Park Leicester LE10 1QW Tel: 0116 263 4700 Fax: 0116 282 4000 Email:
[email protected]
2
EXTERNAL
General comments
Many candidates are well prepared for this unit assessment and provide comprehensive and relevant answers in response to the demands of the question paper. This includes the ability to demonstrate understanding of knowledge by applying it to workplace situations. There are always some candidates, however, who appear to be unprepared for the unit assessment and who show both a lack of knowledge of the syllabus content and a lack of understanding of how key concepts should be applied to workplace situations. In order to meet the pass standard for this assessment, acquisition of knowledge and understanding across the syllabus are prerequisites. However, candidates need to demonstrate their knowledge and understanding in answering the questions set. Referral of candidates in this unit is invariably because they are unable to write a full, well-informed answer to the question asked. Some candidates find it difficult to relate their learning to the questions and as a result offer responses reliant on recalled knowledge and conjecture and fail to demonstrate any degree of understanding. Candidates should prepare themselves for this vocational examination by ensuring their understanding, not rote-learning pre-prepared answers. Common pitfalls It is recognised that many candidates are well prepared for their assessments. However, recurrent issues, as outlined below, continue to prevent some candidates reaching their full potential in the assessment. −
Many candidates fail to apply the basic principles of examination technique and for some candidates this means the difference between a pass and a referral.
−
In some instances, candidates are failing because they do not attempt all the required questions or are failing to provide complete answers. Candidates are advised to always attempt an answer to a compulsory question, even when the mind goes blank. Applying basic health and safety management principles can generate credit worthy points.
−
Some candidates fail to answer the question set and instead provide information that may be relevant to the topic but is irrelevant to the question and cannot therefore be awarded marks.
−
Many candidates fail to apply the command words (also known as action verbs, eg describe, outline, etc). Command words are the instructions that guide the candidate on the depth of answer required. If, for instance, a question asks the candidate to ‘describe’ something, then few marks will be awarded to an answer that is an outline.
−
Some candidates fail to separate their answers into the different sub-sections of the questions. These candidates could gain marks for the different sections if they clearly indicated which part of the question they were answering (by using the numbering from the question in their answer, for example). Structuring their answers to address the different parts of the question can also help in logically drawing out the points to be made in response.
−
Candidates need to plan their time effectively. Some candidates fail to make good use of their time and give excessive detail in some answers leaving insufficient time to address all of the questions.
−
Candidates should also be aware that Examiners cannot award marks if handwriting is illegible.
3
EXTERNAL
UNIT IC – International workplace and work equipment safety
Section A – all questions compulsory Question 1
Outline the precautions that should be taken when construction work is to take place under or near overhead power lines that will remain live during the work.
(10)
In answering this question, candidates would have done well to have structured their responses round the key elements described in HSE Guidance Note GS6. The initial precaution to be considered would have been the possibility of rerouting the cables but if this was not possible then the local electricity supply company would need to be approached for advice on the precautions to be taken. This would include advice on the maximum working heights and horizontal distances permitted near the overhead lines. The next step would be to establish the maximum height and vertical reach of plant to be used on site including those of sub contractors and those which could penetrate the safe distances would have to have physical limiting equipment fitted. Safe routes where plant could travel and operate would have to be marked, barriers and solid goal posts erected which would need to be monitored on a regular basis to ensure they remained intact and in place, and appropriate warning signs displayed. Non-conductive equipment, for example wooden ladders, would have to be used on site. Workers and sub contractors should be briefed on the hazards associated with the work and the safe systems of work to be followed and drivers of visiting vehicles would also have to be instructed on the routes to be followed. Procedures for dealing with an emergency would be necessary and information on these procedures would again have to be passed on to workers. Finally a high level of supervision would have to be provided to ensure that there was strict adherence with the precautionary measures that had been put in place. Answers were generally to a reasonable standard though some candidates treated it as an electricity, rather than a construction, question and wrote of the precautionary measures to be taken to deal with the possible presence of buried cables. If marks were lost it was because candidates produced a list rather than the outline that was required.
4
EXTERNAL
Question 2
In 1974 a plant in Flixborough, United Kingdom, producing highly flammable pressurised gas developed a leak on the fifth of six reactors. In order to continue production the fifth reactor was removed from service and a bypass assembly then installed between the fourth and sixth reactor. The bypass assembly subsequently ruptured and an unconfined vapour cloud explosion followed. (a)
(b)
Describe the mechanism for an unconfined vapour cloud explosion.
(3)
Outline the technical failings that contributed to this major accident.
(7)
The incident at Flixborough occurred following the uncontrolled release of a gas, cyclohexane, from a temporary pipeline which had been used to bypass a reactor taken out of service for repair. On release the gas formed a flammable mixture in air within explosive limits and the large vapour cloud either immediately came across a source of ignition or travelled some distance to find one where it was quickly detonated causing rapid flame propagation. In answering part (b), candidates should have descrined the absence of a professionally qualified mechanical engineer on site to oversee the modification between the fourth and fifth reactor. The plant modification took place without a full assessment being made of the potential consequences of its installation. There was an absence of drawings for the proposed modification, no reference was made to any recognised standard, the constructed assembly was of unknown strength and flow and pressure calculations were undertaken on a straight bypass line and not a dog leg as subsequently fitted. Pneumatic tests that were carried out were for leak testing and not in order to assess the strength of the assembly. There was apparently no appreciation that the pressurised assembly would be subject to a turning moment, imposing lateral shear forces on the bellows nor an appreciation of a hydraulic thrust on them and consequently no calculations were undertaken for the dog leg line or the bellows to withstand these strains. No reference was made to the Designer’s guide so that bellows were used out of line without adequate support, and insufficient support provided for the newly installed pipe work under working conditions. Finally and in short, those concerned with the design, construction and lay out of the modification did not consider the potential for a major disaster to occur instantaneously. Answers provided for this part of the question were particularly disappointing. Some candidates described what happened rather than why it happened and some appeared unfamiliar with Flixborough.
Question 3
(a)
(b)
Outline the purpose of non-destructive testing (NDT) on items of plant.
(2)
Outline the principles, benefits and limitations of the following NDT techniques: (i)
dye penetrant;
(4)
(ii)
radiography.
(4)
The purpose of non-destructive testing (NDT) is to check for faults such as cracks in components before they develop into total failure without affecting the integrity of the component.
5
EXTERNAL
In answering part (b) of the question, candidates were expected to outline that the use of the dye penetrant technique makes cracks visible as dye penetrates into them. It is a relatively cheap and simple operation but it does not detect sub-surface faults, is not totally reliable, interpretation of the indications may be difficult, there is a possible element of toxicity involved and there is no permanent record available of the results of the test. With radiography, x-rays or gamma rays are used to penetrate the item to leave an image on film. Any defects are shown up by the differences in the intensity of the radiation striking the film. The benefits of this technique are that it detects internal defects and produces a permanent record of the test. However, the operation is time consuming, expensive and requires bulky equipment and skilled radiographers. Additionally, there is a danger of radiation exposure. In general answers to this question were to a good standard.
Question 4
A scaffolder is lowering scaffold poles from the third floor of a scaffold assembly to a colleague below using a pulley wheel and rope. Next to the scaffold tower there is a shop entrance. The scaffolder on the ground floor places the scaffold poles horizontally onto the back of a lorry parked on a busy road. The scaffolders have already received information, instruction, training and suitable supervision. Outline the additional practical measures that could minimise the risk of injury to the scaffolders and others that may be affected by this activity.
(10)
The first option would be to investigate the possibility of using an alternative means of lifting such as a crane. If this was not possible then there would be a need to ensure that the pulley wheel and rope were in good condition and had been subjected to the required statutory inspections and that the safe working load of the equipment was not exceeded. The workmen would need to adopt the correct slinging techniques and rigging on the scaffold poles and use guide ropes where necessary. Toe boards and handrails would need to be fitted on the upper platform to protect both the scaffolder on that floor and the public below while belts or lanyards should also be worn by the workman on the upper floor as fall protection. Attention should be given to nearby hazards such as obstructions and power lines and signs and barriers erected at ground floor level to prevent public access to the lowering area. There could be a danger from passing traffic and the placing of cones would help to prevent a collision with the lorry. Finally both workmen should be provided with and wear high visible clothing, gloves and head protection. Whilst there were a number of reasonable answers provided for this question, there were a few who considered it to be predominantly a question dealing with scaffolding and wrote about ensuring that it was correctly constructed and was in no danger of falling over.
6
EXTERNAL
Question 5
As Health, Safety and Environment Manager at a hazardous installation you are responsible for emergency planning. The site is regulated under the International Labour Organisation (ILO) Code of Practice ‘Prevention of Major Industrial Accidents’ 1991. In the event of an uncontrolled release: (a)
outline the need for emergency planning;
(3)
(b)
outline the general emergency planning measures that should be taken by the competent authorities in association with the works management of the installation.
(7)
For part (a), candidates should have outlined, that in the event of an uncontrolled release, there would be a need for emergency planning to localise the release and if possible, contain it; and to minimise the harmful effects of the release on people, property and the environment both inside and outside the installation by the use of safety systems, alarm systems and the emergency services. Clear and well defined plans should be made available for quick and effective use and where emergency equipment and manpower are limited, provision should be made for mutual assistance from neighbouring industrial activities. For part (b), general emergency planning measures that should be taken by the competent authorities include the need: to establish arrangements for an on-site emergency plan which should be drawn up by the management of the installation; to establish arrangements for an off-site emergency plan to be drawn up by the local authority in conjunction with the installation’s management, which should be prepared following consultation with various bodies such as the fire and police authorities and the hospital and ambulance services and which should be consistent with the on-site emergency plan; to ensure that regular rehearsals were carried out in order to keep the off-site plan in a state of readiness and also to ensure that information on safety was provided to members of the general public. Many candidates found this question challenging, in particular the second part with a number concentrating on legal requirements including those contained in the COMAH Regulations. Examiners gained the impression that candidates provided answers for the question they had anticipated and had practised rather than the one that actually appeared on the question paper.
Question 6
(a)
Give the meaning of the term ‘confined space’.
(2)
(b)
Outline the factors that should be considered to ensure that emergency rescue arrangements for confined space work are suitable and sufficient.
(8)
An acceptable answer to part (a) of the question would have been that a “confined space” is any enclosed or partially enclosed place such as a chamber, tank, vat, silo, pit, trench, pipe, sewer or flue or other similar space in which, by virtue of its enclosed nature, there arises a reasonably foreseeable specified risk such as a lack of oxygen or the possibility of drowning in free flowing solids.
7
EXTERNAL
Part (b) required an outline of the specific factors that would have to be considered in ensuring that arrangements for emergency rescue from a confined space were suitable and sufficient. The factors would relate to the nature of the confined space, the risks identified and how an emergency rescue might take place and could include methods of raising the alarm to advise those outside to initiate rescue procedures; the type of equipment such as life lines, lifting equipment and breathing apparatus that would be required; the means provided for emergency access/egress; the precautions taken to protect rescuers from the risks to health and safety identified in the assessment; the identification of plant in the vicinity that may need to be shut down during an emergency rescue; the number and competence of those who would be involved in the rescue; precautions taken to counter the possibility of fire such as the provision of fire extinguishers; means provided for contacting public emergency services and supplying them with relevant information; the availability of first aid assistance until the arrival of professional medical help and the provision of training or refresher training for persons likely to be involved in emergency rescue procedures. There were some vague definitions of a confined space given in answer to part (a), while a number of candidates did not read the second part of the question with sufficient care and outlined the normal control measures that should be put in place when carrying out work in a confined space.
Section B – three from five questions to be attempted Question 7
As a Health and Safety Officer you are asked to give advice to a lift supervisor regarding a proposed lifting operation. The lift requires the use of two cranes working together (a tandem lift). Outline the elements of a safe system of work you would expect to see in order that the lift may be conducted safely.
(20)
A prime requirement would be that the proposed lifting operation should be planned by a competent person and be closely supervised in accordance with the level of risk involved. A risk assessment would need to be carried out which should address matters such as the weight, shape and centre of gravity of the loads and the availability of lifting points; the positioning of the cranes and any available resting places for the loads; the number of times the lifting operation will be carried out; the availability of the correct lifting equipment together with the availability of test certificates and reports of statutory examination for the cranes; the precautions taken to cordon off the area for the lift and the environment in which the lifting equipment will be used and the likely weather conditions. The cranes will have to be positioned using outriggers and jacks to ensure stability, and sited on firm ground away from trench work or other excavations and overhead and underground services. The lift should be under the control of a competent person with knowledge of and training and experience in carrying out a tandem lift. Crane drivers and banksmen would have to be competent and there would need to be an effective means of communication between them using standard methods of signalling, Calculations should be carried out by a competent person to decide whether the cranes would need to be de-rated and the lift should be carried out in such a way that the agreed individual safe working load of either crane is not exceeded. This was a popular question which produced a good standard of response although candidates failed to gain marks by producing lists rather than outlines.
8
EXTERNAL
Question 8
A factory manufactures upholstery using fabrics and plastic pellets. These raw materials are delivered to a warehouse. The fabrics and plastic pellets are machined to form furniture coverings and cushions. The plastic pellets have been sprayed with flame retardant. The finished product is then stored in a despatch warehouse prior to distribution. The movement of goods around the premises is carried out by Liquid Petroleum Gas (LPG) fuelled forklift trucks. The company is located on the outskirts of a small town and employs 230 people. Outline the range of factors that must be addressed to ensure a suitable and sufficient fire risk assessment is made for the premises.
(20)
There are a number of factors to be considered in carrying out a suitable and sufficient fire risk assessment of the premises described in the scenario and they may be grouped under the general headings of fuels, ignition sources, people issues, preventive actions, mitigating actions, means of escape and management systems. Factors connected with fuels which would have to be addressed include the LPG for the fork lift trucks, the flammable covers and untreated fillings and structural issues such as the materials of construction of the premises themselves. Ignition sources would include those connected with the use of electricity including the likely presence of static, friction from machinery which may not be adequately maintained, “illegal” smoking by personnel, the controls (or lack of them) introduced for maintenance which might include hot work, and the possibility of arson. As for people issues, attention would have to be given to the number of persons to be evacuated in the event of a fire including visitors and contractors with the needs of disabled workers being particularly addressed. Preventive actions would include compartmentalisation for higher risk areas such as the plastics and LPG stores with the latter being segregated, bunded and provided with a fixed sprinkler system; fixed protection systems in warehouses and an adequate supply of water and/of foam; the use of fire resistant cover materials; minimising the amount of stock kept on the premises and ensuring a good standard of housekeeping with facilities provided for the segregation of waste. Mitigating actions would be concerned with the sufficiency and appropriate nature of the fire fighting equipment together with its location, smoke venting of warehouses and the provision of access for emergency services. The assessment would need to give particular attention to the means of escape and there would have to be assurance that these were continually maintained and that fire doors were correctly specified. Attention would have to be given to travel distances including multi-storey considerations, the provision of normal and emergency signage and emergency lighting together with refuges for subsequent evacuation and the provision of assembly points in a place of safety. Finally the assessment would have to consider the management systems introduced for the maintenance and testing of fire precautions and mitigation equipment, the carrying out of fire drills and the training given to workers both in evacuation procedures and the use of fire fighting equipment. Several candidates wrote about generic fire control measures and did not deal with the potential hazards involved in the operations carried out in the premises described in the question. A few limited their answers to the problems associated with the use of LPG fuelled trucks.
9
EXTERNAL
Question 9
A plastics injection moulding machine is supplied to your workplace. Outline the moulding machine’s features that you would have expected to have been addressed in order to demonstrate that the machine is safe.
(20)
Features that should have been addressed to demonstrate the safety of the plastics injection moulding machine could have been outlined under the headings of general features, and those dealing with controls, protection against mechanical hazards, protection against other hazards, maintenance and indicators. Successful candidates structured their answers under these headings. The general features of the machine include the safety integration principles such as the control hierarchy applied, foreseeable abnormal use and ergonomics anthropometry; the prevention of danger to the user from the materials used in the construction of the machine or products created during its use such as coolants; the lighting provided which gives adequate visibility without causing dazzle or producing stroboscopic effects; and the handling and installation of the machine so that sharp edges are avoided and the machine is fitted with eyebolts. With regard to controls and control systems, their safety and reliability should be addressed to ensure they can withstand the rigours of normal use and take account of errors in logic; that control devices are visible, identifiable, well positioned, logical and sufficiently robust; that there are adequate means for starting the machine by voluntary actuation except where an automated cycle is in operation and a stopping device is fitted which disengages power to the actuators and also an emergency stop which brings the machine to a halt quickly without creating additional risk; that a failure of the power supply and/or control circuit does not allow the machine to start unexpectedly and the protection devices remain effective, and that any interactive software fitted is user friendly. The features concerned with the protection against mechanical hazards which should have been addressed include the stability of the machine; the risk of break up during operation; the risks caused by falling or ejected objects; the variations in speeds and risks from moving parts which should be designed to avoid hazards or provided with protective devices; the choice and characteristics of guards and protective devices whether fixed, movable or adjustable; and issues arising from working at heights. Protection against other hazards would need consideration of electrical risks, those arising from fire and explosion, extremes of temperature, noise and vibration and the emission of dust and/or gases. As for maintenance, matters such as remote adjustment and lubrication, automatic cleaning, isolation, and means of access should have been addressed, while finally for indicators, issues which should have been considered include the provision of unambiguous and easily understood information and warning devices, the provision of instructions on the installation, use and maintenance of the machine and its marking, in particular the CE mark, its serial number and details of the manufacturer. This was not a popular question and was not well answered with some candidates only offering advice on how to use the machine safely.
10
EXTERNAL
Question 10
(a)
(b)
Describe the effects of a fire in a workplace on the following structural materials: (i)
steel;
(4)
(ii)
concrete;
(4)
(iii)
wood.
(4)
Outline the precautions that could be taken to prevent failure of these materials in the event of fire.
(8)
In answering part (a) of the question, candidates should have recognised that steel expands on heating, loses strength as the temperature rises and tends to deform and buckle. It regains strength on cooling but its properties may have changed. Concrete on the other hand exhibits limited expansion and has a tendency to spall and crack which can be exacerbated by the expansion of steel reinforcement within the concrete. The structural strength of concrete is lost on cooling and it loses structural integrity. As for wood, while thin sections will burn and promote fire, the charred surface of thicker structural members may act as an insulator to protect the inner timber. However, burning timber generates smoke and fumes and allows the surface propagation of fire. Some varieties of timber are more resistant to fire than others while large timbers generally tend to retain their structural integrity. Part (b) was concerned with the precautions that could be taken to prevent failure of the materials in the event of fire. Steel might be protected by the use of sprayed concrete or intumescent coatings, while for concrete, the selection of the type of mix to improve fire resistance and increasing the thickness of concrete between the external face and reinforcement bars would provide some protection. Failure of wood may be prevented by selecting fire resistant timber, increasing the thickness used to allow for a charring outer layer or impregnating it with fire retardant. Other general precautions include the provision of means such as compartmentalisation to prevent heat transfer through long steel members in the event of fire; automatic means of applying water to structural members should fire occur and the use of fire resistant surface claddings or flammable sacrificial cladding.
Question 11
As part of a water treatment system, a manufacturer is to install a plant suitable for the reception and storage of sulphuric acid and caustic soda, both of which will be delivered in road tankers. These substances are highly corrosive and can react violently together. Outline the safety provisions required for: (a)
the design;
(10)
(b)
the operation;
(6)
(c)
the maintenance of the proposed storage facility.
(4)
Candidates who divided the question into its component parts, ie design, operation and maintenance and dealt with the detail of these issues in turn achieved more success.
11
EXTERNAL
Under the design issues, it was expected that candidates would deal with the need for the storage tanks and pipe work to be constructed of suitable chemical resistant material; the design, positioning and marking of the delivery inlets to prevent connection being made to the wrong tank; the positioning of the storage tanks in separate bunds with the bunds being capable of holding the entire contents of the tanks plus 10%; the erection of hazard warning signs clearly identifying the contents of the tanks and the colour coding of pipe work; the fitting of level indicators and high level alarms to prevent overfilling; the provision of good vehicle access including a hard standing for tankers with facilities for spill containment; provision of earthing and bonding for the tanker, connection and hoses; measures to avoid the tanker being driven away whilst still connected and the provision of drench showers and eyewash stations and a good standard of lighting. Operational issues should have included the introduction of a safe system of work including emergency procedures to deal with spillages and the provision and maintenance of a contingency supply of neutralising and absorbent materials and water; providing training for the personnel involved including tanker drivers in the risks associated with the operation and the control measures to be followed and the provision of personal protective equipment such as chemical suits, chemical resistant gloves and full face protection. In outlining the issues connected with maintenance, candidates were expected to refer to the arrangements for the examination and testing of safety critical plant; the use of permit to work systems; the completion of the flushing out of tanks and pipe work and their isolation before the start of maintenance work; regular cleaning of the bunds and the provision of training to maintenance staff in emergency procedures. Answers provided for part (a) were generally better than those for the other two parts of the question. Some candidates provided very general responses without paying too much attention to the scenario described, whilst others dealt with it as a question on highly flammable liquids with the potential for a BLEVE or unconfined vapour cloud explosion.
12
EXTERNAL
The National Examination Board in Occupational Safety and Health Dominus Way Meridian Business Park Leicester LE19 1QW telephone +44 (0)116 2634700 fax +44 (0)116 2824000 email
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