k-304 TEMPERATURE MEASUREMENT CRITERIA

PDVSA ENGINEERING DESIGN MANUAL VOLUME 9–I ENGINEERING SPECIFICATION

PDVSA N°

TITULO

TEMPERATURE MEASUREMENT CRITERIA

K–304

2

OCT.02

Modified paragraph 17.5

5

N.L.

Y.K.

R.R.

1

JUN.01

General Revision

5

Y.K.

A.A.

E.C.

0

AUG.94

FOR APPROVAL

17

L.T.

E.J.

A.N.

REV.

FECHA

APPD.

APPD.

APPD.

Youhad Kerbaje

E PDVSA, 1983

DESCRIPCION DATE

OCT.02

PAG. REV. APPD.

Raúl Rivero

DATE

OCT.02

SPECIALISTS

ENGINEERING SPECIFICATION

PDVSA

PDVSA K–304 REVISION

DATE

2

OCT.02

TEMPERATURE MEASUREMENT CRITERIA

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INTRODUCTION 1.1

Purpose (Modify) The purpose of this document is to provide design criteria for the equipment selection, systems design, and installation of temperature instrumentation All guidelines of document K–300 “Introduction to PDVSA Instrumentation” shall also be explicitly followed. Since PDVSA has decided to adopt the PIP (Process Industry Practices) document PIP PCCTE001 ” Temperature Measurement Criteria ” as an integral part of the Engineering Design Manual (MID), the requirements in this document are additions or modifications to the PIP PCCTE001 and the section / paragraph numbers and the associated headings used in this document correspond to the ones used in PIP PCCTE001.

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REFERENCES 2.0

Petróleos de Venezuela Standards (PDVSA) (Add) PDVSA K–300 PDVSA K–369 PDVSA 90620.1.113

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Introduction to PDVSA Instrumentation Instrumentation QA/QC Temperature Measurement Guidelines

TECHNICAL REQUIREMENTS

3.1

Data (Modify)

3.1.1

3.3

The data set shall be electronic and hard copy format

Shutdown Service (Modify) Temperature elements in shutdown service shall be separate from elements in monitoring services and installed in separate thermowells.

4 4.4

THERMOWELLS Exception (3) (Modify) Before considering exception (3), special design fast response TW’s shall be considered. Exception (4) (Add) Downhole temperature sensors are not installed in TWs. Manufacturer’s special carrier is used.

ENGINEERING SPECIFICATION

PDVSA

TEMPERATURE MEASUREMENT CRITERIA

PDVSA K–304 REVISION

DATE

2

OCT.02

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(Add) Other TW bore sizes (1/2”, etc.), may be used for customized elements.

5 5.1

THERMOCOUPLE (Modify) Thermocouples (TCs) shall be in hard packed ceramic insulation (usually magnesium oxide). The choice of grounded or ungrounded TC’s shall depend on local practices and/or project requirements

5.4

(Modify) Modify according to modification in numeral 5.1.

6 6.8

RESISTANCE TEMPERATURE DETECTORS (Add) For refinery installations, RTD’s shall be considered as first option for control and emergency applications.

7 7.1

TEMPERATURE TRANSMITTERS (Modify) Pneumatic force balance 3–15 psig transmitters may be used subject to PDVSA approval.

7.5

(Add) Transmitters shall be used for remote control and emergency applications.

7.6

(Add) Transmitters shall have RFI and lightning/surge protection.

8

STAND ALONE ELECTRONIC INDICATORS AND CONTROLLERS

8

(ADD) Add “and controllers”

ENGINEERING SPECIFICATION

PDVSA

TEMPERATURE MEASUREMENT CRITERIA

PDVSA K–304 REVISION

DATE

2

OCT.02

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(MODIFY) Stand alone electronic indicators and controllers devices (that receive a temperature element as a direct input) shall have the following characteristics:

10 FILLED AND MECHANICAL THERMAL SYSTEMS 10.2

(Add) Refer to Section 13 for temperature switches.

11 INSTALLATION REQUIREMENTS 11.6

(Add) Downhole temperature sensors shall be installed following manufacturer installation procedure.

12 RADIATION PYROMETERS (NEW SECTION) 12.1

Infrared and other non–contact devices shall be specified for special applications subject to PDVSA approval.

13 TEMPERATURE SWITCHES (NEW SECTION) 13.1

The primary element shall be filled system or bimetallic type.

13.2

Direct acting temperature switches shall be used on non–critical alarm applications. Other uses require PDVSA approval.

13.3

The number of switches directly connected to process elements shall be a minimum. PDVSA prefers temperature transmitter for switching.

13.4

Field mounted switches shall be weatherproof, corrosion resistant according to ambient conditions. The switch housing shall conform to the appropriate area classification.

13.5

The switches shall be micro type rated for 5 Amp at 24 volts D.C. Unless other wise specified by PDVSA.

13.6

All switches shall have a scale to indicate switch setting. Trip setting shall be tamper proof.

13.7

The switch shall be single pole double throw (S.P.D.T.) type as a minimum.

ENGINEERING SPECIFICATION

PDVSA

PDVSA K–304 REVISION

DATE

2

OCT.02

TEMPERATURE MEASUREMENT CRITERIA

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The maximum number of independent switches actuated by one temperature element shall be two.

14 MULTIPLEXER (NEW SECTION) 14.1

For Multiplexer refer to API 5.5.1 section 5, numeral 5.3.6.3.

15 SPECIFICATION FORMS (NEW SECTION) Refer to ISA S 20.

16 DEFINITIONS (NEW SECTION) All definitions are listed in the appendix of PDVSA standard K–300.

17 SELECTION AND SPECIFICATION (NEW SECTION) 17.1

General The selection and specification of all instruments for process applications, utilities, etc. shall be done in accordance with the following procedure: S Define measurement options and decide upon the optimum for the application. S Select the manufacturers and types of instruments from the ”List of Selected Instrument Vendors” as prepared by PDVSA representative. S Select the accuracy and range of the instrument to suit the process requirements.

17.2

Principles of Selection The following items shall be defined for instrument selection: S Instrument purpose (indication, control, transmitter, etc.). S Process conditions, such as fluid phase, viscosity, corrosiveness, erosiveness, toxicity, temperature, pressure, etc., under normal and abnormal conditions. S Environmental conditions, electrical area classification and mechanical integrity (piping class, vibration, etc). S Ranges and accuracy classes shall be selected according to the process data sheets. S Calibration facilities, possible cross contamination of process fluids and the need to wash before removal (purge, flush and disposal) shall be identified as these will influence the instrument selection for the process condition (normal, abnormal, start–up and shut–down). S Maintenance aspects such as access, ease of installation, calibration and removal and remote of self–diagnostic features shall be considered.

ENGINEERING SPECIFICATION

PDVSA

TEMPERATURE MEASUREMENT CRITERIA

PDVSA K–304 REVISION

DATE

2

OCT.02

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Units of Measurement The instrument ranges and scales shall be according to the plant criteria unless otherwise specified in the project specification.

17.4

Selection of Ranges S The selected range shall be such that the normal operating condition is approximately at mid scale and that the maximum process operating pressure does not exceed 80% of the range of the indicating instrument or self acting regulator. S The instrument shall have over range protection 50% greater than the maximum operating temperature without suffering any damage. S Instruments exposed to vacuum shall have under–range protection to full vacuum.

17.5

General Design Requirements S Field mounted temperature indicating, recording instrument, switch, transmitter, transducer and controller shall have wall / yoke mounting cases with bottom connections. S Instrument air supply and transmission connections shall be 1/4’’ NPT. The electrical connection shall be 1/2” NPT.F. S The temperature indicating pointers shall be adjustable with a micrometer type screw. S Panel mounted temperature indicating, recording instrument, switch, transmitter, transducer and controller shall have flush mounting cases with rear connections. S Blind temperature controllers shall not be used. S The thermowell process connection shall be 1” NPT.M. or ’’flanged consistent with the piping or vessel specification and connection”. Flange size shall be 11/2” minimum.

18 QUALITY ASSURANCE / QUALITY CONTROL Refer to PDVSA K–369 for QA / QC directives.

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