k-332

 ENGINEERING DESIGN MANUAL VOLUME 9–I ENGINEERING SPECIFICATION SPECIFICATION

PDVSA N

°

CONTROL CONT ROL VALVES ALVES

K–332

0 REV.

AUG.94

FOR APPROVAL

DATE

APPD.BY Eliecer Jiménez

 PDVSA,

1983

TITLE

DESCRIPTION DATE

8

L.T.

E.J.

A.N.

PAG.

REV.

APPD.

APPD.

DATE

AUG.94

AUG.94 APPD.BY Alejandro Newski

ESPECIALISTAS

ENGINEERING SPECIFICATION

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CONTROL VALVES

PDVSA K –332 REVISI ON

DATE

0

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Page Menú Principal

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Index Page

1 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

2 CODES, STANDARDS AND PRACTICES . . . . . . . . . . . . . . . . . . . .

3

3 DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

4 DESIGN REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Control Valve Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Valve Trim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Positioners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electro – Pneumatic Convertors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Handwheels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solenoid Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Limit Switches and Valve Position Transmitters . . . . . . . . . . . . . . . . . . . . . . Volume Boosters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Air Lock Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Self Acting Regulating Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3 5 5 6 6 6 7 7 7 7 8 8 8

5 SPECIFICATION FORMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8

6 INSTALLATION AND COMMISSIONING . . . . . . . . . . . . . . . . . . . . . .

8

7 Q.A. / Q.C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8


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FOREWORD

This document is the result of several years ’ work by engineers in the petroleum industry of Venezuela (PDVSA). The recommendations presented in this publication are not intended to supersede applicable laws and regulations. Users of this recommended practice are reminded that no publication of this type can be complete, nor, can any written document, be substituted for qualifed engineering analysis. Suggested revisions are invited and should be submitted to:

The manager PDVSA Engineering Standards, C/O INTEVEP – TENA División, Apartado 76343 Caracas – 1070A Venezuela


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SCOPE This section covers PDVSA requirements for the design, specification, installation and commissioning of control valves. All guidelines of the introduction specification K – 300 shall also be explicitly followed. These specifications also serve for valves used on emergency shut off services but attention is drawn to paragraph 4.1.12 with respect to their use.

2

CODES, STANDARDS AND PRACTICES A.N.S.I. B16.104 A.P.I. RP – 550 F.C.I. 70 – 2 I.S.A. R.P.75.01 to 75.16 I.S.A. N.A.C.E.

3

Manual on refinery instrument installation Valves calculations Standards for control valves Handbook of control valves.

DEFINITIONS All definitions are listed in specificatio n K – 300.

4

DESIGN REQUIREMENTS

4.1

General

4.1.1

The control valves shall be air operated.

4.1.2

The body shall be 1 – inch, carbon steel, flanged 300 lbs. A.N.S.I. minimum except for line sizes smaller than 1 – inch in which case the appropriate line size body shall be used. The valve trim shall be 316 stainless steel minimum.

4.1.3

Globe or eccentric rotary plug type valves shall be considered the first option. The type of internals viz single seat, double seat, cage, Lo – dB, stellited, etc., shall be carefully selected to suit the particular application.

4.1.4

Ball, flangeless eccentric rotary, flangeless butterfly based on 60 maximum opening, angle, etc. type, of valve shall be used depending on the particular application subject to PDVSA approval.

4.1.5

The control valve shall be sized taking into account the minimum, normal and maximum operating conditions. The finally selected item shall ensure that the valve operates between 17 and 90 percent opening in accordance with I.S.A. – S75.11. The valve shall also operate without any cavitation and produce a noise level less than 85 dB.

4.1.6

Valves on hydrogen sulfide and other toxic ambience conditions shall conform to the appropriate N.A.C.E. specifications.

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4.1.7

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The control valve shall be single seated in tight shut off services. The valve leakage class shall be as per ANSI B16.104/FCI standard 70 – 2. An extract from the standard is listed below. The seating shall be soft seat or metal to metal to suit the process operating conditions.

Valve Class

Maximum Leakage rate

IV

0.01 % of rated valve capacity

V

5 x 10 – 4 ml per minute of water per inch of orifice diameter per psi differential (5 x 10 – 12 m3 per second of water per mm of orifice diameter per bar differential)

VI

4

Nominal Port Diameter Milimeters

Inches

ml per minute

Bubbles per minute

25

1

0.15

1

38

1 1/2

0.30

2

51

2

0.45

3

64

2 1/2

0.60

4

76

3

0.90

6

102

4

1.70

11

152

6

4.00

27

203

8

6.75

45

4.1.8

The speed of response of the valve shall be carefully examined to ensure compliance with the particular application requirements. For eg. valves in compressor surge system; tanker and other pipeline loading systems are required to complete their full travel in 1 to 5 seconds. However caution must be exercised in determining the full open to full close duration to ensure that there are no occurrences of surge pressures due to sudden valve closures.

4.1.9

Valves with liners on body and trims with vulcanised liners shall be subject to careful analysis and PDVSA approval.

4.1.10

By – pass valves shall only be installed after a “HAZOP” study has been performed. Block valves and by – pass manifold shall be in accordance with I.S.A. standard RP 75.06.

4.1.11

Three way control valves shall be used, subject to PDVSA approval.

4.1.12

Valves used on emergency shut off service applications shall be dedicated solely to that service only and shall not be used for normal process control purposes.


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4.2

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Control Valve Body

4.2.1

Control valve body material shall conform to the pipe line specification in which they are installed. Carbon steel shall be the minimum. The end connections shall conform with the respective piping specification – RF, RTJ, flat face, etc.

4.2.2

Extended Bonnets shall be provided on fluid operating temperatures above 230 C or below 0 C. °

°

4.2.3

Bellows seal bonnets shall be provided on all toxic and hazardous fluids and also when it is necessary to ensure no leakage to atmosphere along the stem in order to comply with E.P.A. emission regulations.

4.2.4

The use of angle valves shall kept to a minimum and are subject to PDVSA approval.

4.2.5

The use of welded end connections and items on hydrogen, hydrogen sulfide, cryogenic, pipeline services, etc., shall be subject to careful analysis and PDVSA approval.

4.2.6

Screwed end connections shall only be used on non – hazardous fluids operating below 50 C and 50 P.S.I.G. (3.5 kg/cm 2) and body sizes below 1 – inch. °

4.3

Valve Trim

4.3.1

The valve C.V. shall be calculated in accordance with equations in ISA standard S 75.01.

4.3.2

The trim type viz. Single or double seat, low noise, cage, soft seat, cavitation – free, etc., shall be selected to suit the particular application.

4.3.3

The valve characteristic viz. equal percentage, linear, on – off, etc., shall be selected to suit the particular application and process operating data.

4.3.4

The ISA handbook shall be used for selection guidance.

4.3.5

Where the selected valve does not comply with requirements of paragraph 4.1.5 consideration shall be given to increase the available pressure drop and as a last resort to installation of two valves in parallel, one large and one small with split range operation.

4.3.6

Butterfly valves shall be sized on maximum 60 operation.

4.3.7

The valve plug shall be solid. The trim material shall be 316 stainless steel minimum. Other materials shall be used to suit the fluid erosion and corrosion properties. Stellite or harder trim material shall be used on:

°

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Flashing fluids Fluids with entrained solids Pressure drops over 14 kg/cm 2 G. (200 P.S.I.G).


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4.4

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Packing TEFLON shall be used for fluid temperatures upto 230 C. °

GRAFOIL containing zinc corrosion inhibitor shall be used for all higher temperatures.

4.5

Actuators

4.5.1

The actuator shall be corrosion resistant to marine and any other specified toxic ambience.

4.5.2

Pneumatic diaphragm or piston type actuator shall be used to ensure that the valve: a.

Operates correctly under all specified operating conditions

b.

Withstands a pressure drop equal to the maximum upstream pressure

c.

Speed of response complies with the process operational requirements.

4.5.3

The shaft stem shall be solid and linked positively to the valve plug. Shaft thrust bearings shall be provided as necessary to ensure smooth operation.

4.5.4

The use of electro – hydraulic, electric, hydraulic or digital actuators on special applications are subject to PDVSA approval.

4.5.5

The fail position of the actuator on the loss of actuating medium fluid viz. air, hydraulic or electric shall be carefully evaluated and specified to ensure safe operating condition of the plant and/or equipment.

4.6

Positioners

4.6.1

All valves shall be fitted with pneumatic positioners. Electro – pneumatic positioners shall be used on all applications where the positioner operation is not affected by line vibrations. Exceptions are on – off valves and certain flow or liquid pressure loops where the added positioner gain could lead to instability. These exceptions are subject to PDVSA approval.

4.6.2

The input signal shall be 3 to 15 P.S.I.G. The output shall suit the selected actuator.

4.6.3

Positioners shall be complete with bypass, input, output and air supply gauges and an air filter set.

4.6.4

The positioner and all accessories shall be corrosion resistant to marine atmosphere. The tubing between positioner and actuator shall be P.V.C. covered 316 stainless steel.


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4.7

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Electro – Pneumatic Convertors

4.7.1

When specified they shall be suitable for specified 4 – 20 or 4 – 12 or 12 – 20, m.A. D.C. input operation. The output shall be 3 – 15 P.S.I.G. The convertor shall be certified intrinsically safe.

4.7.2

The convertor and all accessories shall be corrosion resistant to marine atmosphere.

4.7.3

The convertor shall be mounted on a suitable vibration free bracket.

4.8

Handwheels

4.8.1

These shall be supplied when specified. They shall be declutchable type with a clear indication of the neutral position.

4.8.2

The handwheel mechanism shall not increase frictional load of the actuator and operable even against the specified maximum differential pressure.

4.8.3

Clutch/linkage mechanisms on rotary valves shall be designed such that the control of the valve position is not lost when engaging the handwheel.

4.8.4

Hand wheel shall be specified only after a ‘‘HAZOP’’ study has been performed.

4.9

Solenoid Valves

4.9.1

When specified they shall be installed in the output tubing between the positioner and the valve actuator.

4.9.2

They shall be 3 – way, 1/4” N.P.T.F. 316 stainless steel body type with resilient seats and 24 volts D.C hermetically potted coil suitable for operation at 50 C ambient temperature. They shall be suitable for operation in intrinsically safe circuits and provided with a manual reset lever when specified. °

4.9.3

4.10

If an airlock valve is specified for the system the solenoid valve shall be installed between the air lock valve and the actuator.

Limit Switches and Valve Position Transmitters

4.10.1

When specified they shall be linked directly to the valve stem.

4.10.2

The limit switches shall be snap acting hermetically sealed micro – switch and rated for operation at 1 amp. at 24 volts D.C.

4.10.3

The transmitter output shall be 4 to 20 m.A. D.C.

4.10.4

All electrical items shall be certified for use in intrinsically safe circuits and corrosion resistant to marine atmosphere.


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4.11

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Volume Boosters

4.11.1

Volume boosters shall be installed, when necessary to increase speed of response of the control valve.

4.11.2

The booster shall be installed in the output tubing between the positioner and the valve actuator.

4.12

Air Lock Valves

4.12.1

When specified the air lock valve shall be installed between the positioner and the actuator.

4.12.2

The air supply for the lock valve shall be the same as for the valve positioner.

4.12.3

The item shall be corrosion resistant to marine atmosphere and the setting shall be tamper – proof.

4.13

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Self Acting Regulating Valves

4.13.1

They shall be used on inert services such as water, air or nitrogen and noncritical services such as fuel gas to pilot burners.

4.13.2

All actuators shall be capable of withstanding the maximum specified upstream pressure.

4.13.3

Body and trim shall conform with guidelines in this specification.

SPECIFICATION FORMS FORM No.

TITLE

20.50

Control valves

20.50X

On/off valves with positive closure

20.51

Self acting pressure regulator

20.52

Self acting temperature regulator

The forms are included at the end of this specification.

6

INSTALLATION AND COMMISSIONING All installation and commissioning shall be performed in accordance with project drawings and specifications.

7

Q.A. / Q.C. All items shall conform with the procedures in specification K – 369.

k-332

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