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PDVSA N TITLE

REV. DATE DESCRIPTION PAG. REV. APPD. APPD.

APPD.BY DATEDATE

VOLUME 9I

E PDVSA, 1983

K302 FLOW INSTRUMENTATION

FOR APPROVAL

Alexis Arvalo Enrique CarmonaJAN. 01 JAN.01

ENGINEERING SPECIFICATION

AUG.94

JAN.01 Y. K.

L.T.

1

0

GENERAL REVISION 4

32

A. A.

E.J.

E. C.

A.N.

ENGINEERING DESIGN MANUAL

SPECIALISTS

APPD.BY

PDVSA
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PDVSA K302

Men Principal Indice manual Indice volumen Indice norma

PDVSA

1 INTRODUCTION

1.1 Purpose (Modification)

The purpose of this engineering specification is to provide designers and vendorswith requirements for the design, specification, installation and commissioning offlow instrumentation. All guidelines of the introduction specification PDVSAK300 shall also be explicitly followed.

Since PDVSA has decided to adopt the PIP (Process Industry Practices)document: PCCFL001 Flow Measurement Criteria as an integral part of theEngineering Design Manual (MID), the requirements in this document areadditions or modifications to the PCCFL001 and the section/paragraph numbers

and the associated headings used in this document correspond to the ones usedin PCCFL001.

1.2 Scope (Addition)

Restriction flow elements and flow switches are included in this specification.

Gas or liquid hydrocarbon flow measurement systems for custody transfer or fiscalpurposes shall comply with special design, specification, installation, calibrationand commissioning requirements stated on API and regulations defined byVenezuelan Government Energy Office: Ministerio de Energa y Minas.

2 REFERENCES

2.1 Petrleos de Venezuela Specifications (PDVSA) (Addition)

PDVSA K300 Introduction to PDVSA Instrumentation

PDVSA K369 Instrumentation QA/QC

2.2 (Addition)

ISO 5168 Measurement of Fluid Flow Evaluation of Uncertainties shall beconsidered as an integral part of this Practice.

4 GENERAL REQUIREMENTS

4.1.1 (Modification)

b. Calculation for sizing of concentric, squareedged orifice meters shall conformto ISO 5167.

c. Nozzle, venturi, and other differential pressure device calculations shallconform to ISO 5167.
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Orifice bore required dimension shall be calculated to the nearest 1 mm (1/16inch), and differential pressure ranges in 25 mm H2O (1 inch H2O), increments.Whenever possible, differential pressure calibration ranges of 1250, 2500, 3750and 5000 mm H2O (50, 100, 150, 200 and 250 inches H2O), are preferred.


The instrument ranges and scales shall be according to plant criteria unlessotherwise specified in the project specification.


Each flow metering application shall be reviewed carefully and the requiredmeasurement uncertainties shall be classified as listed below during the designstage.

Note that listed uncertainties correspond to the combined expanded uncertaintyfor 95% confidence level of the total measurement equation, as defined in NISTtechnical note 1297, Guidelines for Evaluating and Expressing the Uncertainty ofNIST Measurement Results.

Total measurement equation corresponds to all the elements of the measurementsystem that contribute error terms: flow elements, flow, pressure, temperatureand analytical sensors, transmitters and receivers, calibration procedures andcalculations, manual compensations, etc. Refer to ISO/TR 5168, Measurementof Fluid Flow Evaluation of Uncertainties, and API MPMS, Ch. 14, Sc.3, Part 1General Equations and Uncertainty Guidelines, for further clarification of theseterms and methods of calculation of uncertainties.

Measurement classification Uncertainties

1 LESS THAN 1.0%

2 BETWEEN 1% AND 2.0%

3 > 2.0%

All measurements of fluids for custody transfer or fiscal purpose shall be class 1,exceptions require PDVSA approval (i.e.: very inexpensive raw materials).

All other measurements are class 3 except those identified as class 1 or 2 byproject specifications in order to perform efficiency calculations of process plantor rotating equipment, leak detection or mass balance calculations.


Any piping element which modifies flow profile shall be located a minimum of 5nominal pipe diameters downstream of the meter.
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The use of flow straighteners shall conform to ISO 5167, section 6.3.

4.3 (Modification)

Winterproofing is not required in Venezuela.

4.6.1 (Modify last sentence)

Square root operation may be performed either in the smart transmitter or the DCSwhen using the digital mode.

4.7 (Addition) Flow Switches4.7.1 Flow switching shall be effected by means of a dedicated flow measuring device

with analog or pulse signal, processed in a central control room receiver, wherethe switching signal is generated electronically.

4.7.2 Alternatively, flow switching may be effected as follows (previous PDVSAapproval):

S By means of paddle or thermal type direct flow switches.

S As a secondary function of a local flow indicator/totalizer.

S As a secondary functional configuration of a smart type flow transmitter.

4.7.3 Flow switching specification and design shall follow project or site specificpractices and specifications.

4.7.4 The maximum number of independent switching contacts actuated by one flowswitch or meter shall be two.

4.7.5 For safety applications flow switches shall be dedicated. Installations sharing oneflow element with dual sensors one for indication, one for safety and separatelycased transmitter electronics require PDVSA approval. For additionalinformation, refer to PDVSA K336, Safety Instrumented Systems.

5 SPECIFIC REQUIREMENTS

5.1.1 (Addition)

Ring type joint orifice flanges shall be used only in ratings Class 900 and up, inaccordance with ANSI B16.36.


Orifice plates shall be fabricated according to ISO 5167.
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Meter tube pipe and orifice flange internal dimensional tolerances shall be inaccordance with ISO 5167.

5.1.15 (Addition)

Table 2 only applies for class 3 measurements and requires PDVSA approval.


Tap connections shall be installed according to ISO 5167.


Minimum straight run pipe length requirements shall conform to ISO 5167.


Classical venturis shall be fabricated according to ISO 5167.

5.5 (Addition)

The use of integral orifice requires PDVSA approval.

5.8.6 (Addition)

Most petroleum hydrocarbons have insufficient conductivity to be measured with

a magnetic flowmeter. Therefore, use in petroleum industry applications is limitedto certain water, acids, emulsions, and other conductive liquids.


Scales for purge metersshall read according to plant criteria unless otherwisespecified in the project specification.

6 (Addition)QUALITY ASSURANCE/QUALITY CONTROLRefer to PDVSA Specification K369
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