Mss Sp-134-2012

MSS SP-134-2012

Valves for Cryogenic Service, including Requirements for Body/Bonnet Extensions

Standard Practice Developed and Approved by the Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. 127 Park Street, NE Vienna, Virginia 22180-4602 Phone: (703) 281-6613 Fax: (703) 281-6671 E-mail: [email protected]

MSS

®

www.mss-hq.org

MSS

STANDARD PRACTICE

SP-134

This MSS Standard Practice was developed under the consensus of the MSS Technical Committee 114 and the MSS Coordinating Committee. The content of this Standard Practice is the resulting efforts of competent and experienced volunteers to provide an effective, clear, and non-exclusive standard that will benefit the industry as a whole. This MSS Standard Practice describes minimal requirements and is intended as a basis for common practice by the manufacturer, the user, and the general public. The existence of an MSS Standard Practice does not in itself preclude the manufacture, sale, or use of products not conforming to the Standard Practice. Mandatory conformance to this Standard Practice is established only by reference in other documents such as a code, specification, sales contract, or public law, as applicable. MSS has no power, nor does it undertake, to enforce or certify compliance with this document. Any certification or other statement of compliance with the requirements of this Standard Practice shall not be attributable to MSS and is solely the responsibility of the certifier or maker of the statement. “Unless indicated otherwise within this MSS Standard Practice, other standards documents referenced to herein are identified by the date of issue that was applicable to this Standard Practice at the date of approval of this MSS Standard Practice (see Annex B). This Standard Practice shall remain silent on the validity of those other standards of prior or subsequent dates of issue even though applicable provisions may not have changed.” By publication of this Standard Practice, no position is taken with respect to the validity of any potential claim(s) or of any patent rights in connection therewith. MSS shall not be held responsible for identifying any patent rights. Users are expressly advised that determination of patent rights and the risk of infringement of such rights are entirely their responsibility. In this Standard Practice, all text, notes, annexes, tables, figures, and references are construed to be essential to the understanding of the message of the standard, and are considered normative unless indicated as “supplemental”. All appendices, if included, that appear in this document are construed as “supplemental”. Note that supplemental information does not include mandatory requirements. U.S. customary units in this Standard Practice are the standard; (SI) metric units are for reference only. This document has been substantially revised from the previous 2010 edition. It is suggested that if the user is interested in knowing what changes have been made, that direct page by page comparison should be made of this document and that of the previous edition. Non-toleranced dimensions in this Standard Practice are nominal and, unless otherwise specified, shall be considered “for reference only”. Excerpts of this Standard Practice may be quoted with permission. Credit lines should read ‘Extracted from MSS SP-134-2012 with permission of the publisher, Manufacturers Standardization Society of the Valve and Fittings Industry'. Reproduction and/or electronic transmission or dissemination is prohibited under copyright convention unless written permission is granted by the Manufacturers Standardization Society of the Valve and Fittings Industry Inc. All rights reserved. Originally Approved: February 2005 Originally Published: July 2006 Current Edition Approved: December 2011 Current Edition Published: May 2012 MSS is a registered trademark of Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Copyright © 2012 by Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. Printed in U.S.A.

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TABLE OF CONTENTS SECTION 1 2 3 4 5 6 7 8 9 10 11

PAGE

SCOPE ..................................................................................................................................................... 1 DEFINITIONS ........................................................................................................................................ 1 CLASS/SIZE DESIGNATION ............................................................................................................... 2 MATERIALS .......................................................................................................................................... 2 DESIGN .................................................................................................................................................. 2 GATE AND GLOBE VALVES .............................................................................................................. 3 BALL & BUTTERFLY VALVES .......................................................................................................... 4 EXTENSION LENGTH .......................................................................................................................... 4 FABRICATION ...................................................................................................................................... 4 PRODUCTION PRESSURE TESTING ................................................................................................. 4 LOW TEMPERATURE CRYOGENIC TESTING ................................................................................ 5

TABLE 1 2 A1 A2

Body/Bonnet Extension Length, U.S. Customary Units ......................................................................... 6 Body/Bonnet Extension Length, SI Metric Units .................................................................................... 6 Allowable Seat Leakage Rates for Cryogenic Closure Tests ................................................................ 14 Helium Test Pressures ........................................................................................................................... 14

FIGURE 1 2 3 4 A1

Typical Outside Screw and Yoke Cryogenic Globe Valve ..................................................................... 7 Typical Outside Screw and Yoke Cryogenic Gate Valve ....................................................................... 8 Typical Cryogenic Ball Valve ................................................................................................................. 9 Typical Cryogenic Butterfly Valve ....................................................................................................... 10 Typical Test Set-Up ............................................................................................................................... 14

ANNEX A Low Temperature Cryogenic Testing .................................................................................................... 11 B Referenced Standards and Applicable Dates ......................................................................................... 15 APPENDIX X1 Guidance for Stem Strength Calculations .............................................................................................. 16

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VALVES FOR CRYOGENIC SERVICE, INCLUDING REQUIREMENTS FOR BODY/BONNET EXTENSIONS 1. SCOPE 2. DEFINITIONS

1.1 This Standard Practice covers requirements for material, design, dimensions, fabrication, non-destructive examination and pressure testing of stainless steel and other alloy cryogenic service valves with body/bonnet extensions. Requirements for check valves for cryogenic service, which may not require body/bonnet extensions, are also covered. This Standard Practice applies to cryogenic gate, globe, butterfly, ball, and check valves, and may be used in conjunction with other valve-specific standards; including the following identified in this Standard Practice as a parent standard:

2.1 General Definitions given in MSS SP96 apply to this Standard Practice. 2.2 Cryogenics The science of materials at extremely low temperatures. 2.3 Cryogenic Fluid A gas that can be changed to a liquid by removal of heat by refrigeration methods to a temperature at -100 °F (-73 °C) or lower. 2.4 Cryogenic Temperature For this Standard Practice a temperature range of -100°F (-73 °C) to -425 °F (-254 °C) is cryogenic.

ASME B16.34, Valves – Flanged, Threaded, and Welding End

2.5 Cold Box An enclosure that insulates a set of equipment from the environment without the need for insulation of the individual components inside the cold box.

API 600, Steel Gate Valves – Flanged and Butt-welding Ends, Bolted Bonnets API 602, Steel Gate, Globe, and Check Valves for Sizes NPS 4 (DN 100) and Smaller for the Petroleum and Natural Gas Industries

2.6 Cold Box Extension A valve body/bonnet extension section that removes the operating mechanism of the valve outside the cold box and is required to be longer than a non-cold box extension.

API 603, Corrosion-resistant, Bolted Bonnet Gate Valves – Flanged and Buttwelding Ends

2.7 Non-Cold Box Extension A body/bonnet extension that is used for valves that are normally individually insulated.

API 608, Metal Ball Valves – Flanged, Threaded and Welding Ends API 609, Butterfly Valves: Double Flanged, Lug- and Wafer-type

2.8 Parent Valve Standard Endorses the ASME B16.34 construction requirements but has additional construction detail requirements exceeding or not addressed by ASME B16.34.

API 6D, Specification for Pipeline Valves (identical to ISO 14313) 1.2 The requirements in this Standard Practice are not intended to supersede or replace requirements of a parent valve standard.

2.9 Gas Column That portion of body/bonnet extension that allows for the formation of an insulating column of vapor.

1.3 This Standard Practice includes additional construction detail requirements specifically related to valves, including body/bonnet extensions essential for cryogenic applications.

2.10 Double Block and Bleed Valve Valve with two seating surfaces that when in the closed position, blocks flow from both valve ends when the cavity between the seating surfaces is vented through a bleed connection provided in the valve body.

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3. CLASS/SIZE DESIGNATION

The body/bonnet extension shall be constructed of the same ASME B16.34 Table 1 group material as the valve body group material or a similar ASME B16.34 group material with the same cryogenic material compatibility as the valve body.

3.1 Pressure Rating Designation Class, followed by a dimensional number, is the designation for pressure-temperature ratings. Standardized designations are as follows: Class

150 900

300 1500

400 2500

600 4500

4.3 Unless otherwise specified in the purchase order internal wetted parts shall be made of a material that is suitable for the specified cryogenic temperature and has a corrosion resistance that is comparable with the body material.

3.2 Size NPS indicates “Nominal Pipe Size” (U.S customary). A standard size identification number, not necessarily an actual dimension. The (SI) metric-based equivalent is called DN or Nominal Diameter/"diametre nominel". NPS is related to the reference DN (used in many international standards). The typical relationship is as follows: NPS

DN

1/4 3/8 1/2 3/4 1 11/4 11/2 2 21/2 3 4

8 10 15 20 25 32 40 50 65 80 100

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4.4 Packing and gasket materials in direct contact with the service fluid shall be capable of operating at temperatures from +150 °F (+65 °C) to the lowest cryogenic temperature of the service fluid specified in the purchase order. 4.5 When pipe or non-standard wall tube material is used for constructing body/bonnet extensions, the material shall be seamless. 5. DESIGN 5.1 The requirements of ASME B16.34, Section 2.1.6, shall be met for weld fabricated body/bonnet extensions. 5.2 Valves shall have a body/bonnet extension integrally cast/forged or consisting of a pipe or non-standard wall tube that distances the stem packing and valve operating mechanism from the cryogenic fluid in the valve body/bonnet extension that might otherwise damage or impair the function of these items. The body/bonnet extension shall be of sufficient length to provide an insulating gas column that prevents the packing area and operating mechanism from freezing.

For NPS ≥ 4, the related DN = 25 multiplied by the NPS number.

4. MATERIALS 4.1 Materials in contact with cryogenic fluid or exposed to cryogenic temperatures shall be suitable for use at the minimum temperature specified by the purchase order. ASME B31.3, Table A1 lists mechanical properties for materials at temperatures as low as -425 °F (-254 °C).

Check valves do not require extensions except when they are designed for stop-check service. Stop check valve extensions shall follow this Standard Practice rules for cryogenic globe valves.

4.2 Body, bonnet, body/bonnet extension, and pressure retaining bolting shall be of materials listed in ASME B 16.34, Table 1 and also listed in ASME B31.3, Table A1 for the cryogenic valve design temperature.

The purchaser shall provide the body/bonnet extension length when Table 1 or Table 2 extension lengths are not adequate.

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5.5.4 Valves with extended body/bonnets in cryogenic gas service shall be capable of operating in any stem orientation unless otherwise limited by the manufacturer.

5.2.1 The cast/forged extension, pipe or non-standard wall tube thickness shall take into account pressure stresses as well as operating torque, stem thrust and bending stresses induced by handwheels, gears and power actuators.

5.6 Valve Stems The design of globe, gate, and quarter-turn valves having extended stem lengths, as required by this Standard Practice, introduces stem buckling and angle of twist design inputs that shall be considered in the valve design.

5.2.2 The body/bonnet extension shall meet the minimum wall thickness requirements of ASME B16.34, Section 6.1.3, for the applicable pressure class of the valve body unless a greater wall thickness is specified by the parent valve specification. If the body/bonnet extension is made from a different ASME B16.34, Table 1, material than the valve body and has an ASME B16.34 pressure-temperature rating less than the valve body, then the extension thickness must be increased proportionately to meet the pressure-temperature rating of the body at all applicable temperatures.

Specifically for stem buckling design considerations, a number of different model equations, based on stem guiding end designs (fixed, pinned, or combination thereof), are available to the designer for consideration. For moderate length stems where combined compression/buckling failure mode may occur, there are many empirical equations that can be used. These multiple model and empirical equations are a deterrent to standardization of stem design methods.

5.3 Valves shall be designed for operating at temperatures from +150 °F (+65 °C) to the lowest cryogenic temperature of the service fluid.

Appendix X1 is offered as a guideline for stem design, which may be used by manufacturers that subscribe to the models and empirical equations used in the Appendix.

5.4 The pressure rating of the valve at service temperatures below -20 °F (-29 °C) shall not exceed the ASME B16.34 pressure rating at -20 °F (-29 °C) to 100 °F (38 °C) for the applicable valve body material and appropriate Class designation. 5.5

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5.6.1 Stem calculations are a requirement of this Standard Practice and the manufacturer shall utilize the guidance of Appendix XI or other stem model derivatives to arrive at such calculations.

Body/Bonnet Extensions

5.5.1 Body/Bonnet Extensions should be used primarily for temperatures colder than -100 °F (-73 °C). When specified by the purchaser this Standard Practice may also be used for valves with body/bonnet extensions for low temperature applications for temperatures warmer than -100 °F (-73 °C).

6. GATE & GLOBE VALVES 6.1 Gate valves shall be provided with a means for allowing any pressure increase in the body/bonnet extension cavity to be vented to the high pressure side of the closed obturator, such as a vent hole on the higher pressure side of the wedge, unless otherwise specified in the purchase order.

5.5.2 Stem to extension tube diametrical clearance should be minimized to help reduce convective heat losses.

Double block and bleed valves shall be vented using some form of a pressure relief device that does not violate the dual seating requirement of the valve.

5.5.3 For cold box applications, valves with extended body/bonnets shall be capable of operating with the stem oriented from 150 to 900 above the horizontal plane.

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6.2 A flow arrow indicating flow direction for uni-directional valves shall be cast, stamped, or etched on the valve body.

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8.3 Non-cold box valve dimensions are for those valves with body/bonnet extensions for valves in cryogenic gas or liquid service, with the orientations of Sections 5.5.3 or 5.5.4 as applicable.

Alternatively, a flow arrow tag may be attached by welding to the valve body.

9. FABRICATION

6.3 Backseats, when utilized, may be at the bottom or at the top of the body/bonnet extension. Backseats provided at the bottom of a bonnet extension may cause excessive increase of extension cavity pressure. Valves with bottom backseats shall be designed with a provision to protect from excessive cavity pressure buildup.

9.1 Valves fabricated by welding shall be done in accordance with ASME B16.34, Section 2.1.6. 9.2 Welding procedures, welders, and welding operators, shall be qualified under the provisions of ASME Boiler and Pressure Vessel Code, Section VIII, Division 1. Welding requirements of the parent standard shall be met when specified in the purchase order.

7. BALL & BUTTERFLY VALVES 7.1 Ball valves shall be provided with a provision to vent the body and bonnet extension cavity to the upstream side of the closed ball, either by drilling a bleed hole in the ball or by other means of protection against over-pressurization of the body/bonnet extension cavity.

9.3 The weld configuration of the bonnet extension tube to body/bonnet connections may be full penetration Vee groove, partial penetration Vee groove or fillet type. Full strength threaded joints with seal welds can also be used.

Double block and bleed valves shall be vented using some form of a pressure relief device that does not violate the dual seating requirement of the valve.

9.4 Non-destructive examination of welds shall be performed per ASME Boiler and Pressure Vessel Code, Section VIII, Division 1 to achieve a joint efficiency as required by ASME B16.34, Section 2.1.6.

7.2 A flow arrow indicating flow direction shall be cast, stamped, or etched on the valve body. Alternatively, an arrow tag may be attached by welding to the valve body. For bidirectional ball valves, including block and bleed, a flow arrow indicating flow direction is not required.

Weld quality requirements of the parent standard shall be met when specified in the purchase order. 10. PRODUCTION PRESSURE TESTING 10.1 Prior to testing, each valve shall be cleaned and degreased as specified in the purchase order.

8. EXTENSION LENGTH 8.1 Minimum extension lengths for rising stem gate/globe valves and for quarter-turn valves shall be per Tables 1 and 2, unless otherwise specified in the purchase order.

10.2 Each valve shall be shell and closure tested as required by ASME B16.34. Each valve shall be tested in accordance with the parent standard when specified in the purchase order.

8.2 Cold box valve dimensions are for valves with body/bonnet extensions on valves in cryogenic liquid/vapor service, which have installation orientation restrictions. See Section 5.5.3.

10.3 Following ASME B16.34 final testing, each valve shall be dried of all water test solution trapped in the valve.

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10.4 Each fabricated body/bonnet extension shall be subjected to a supplemental pneumatic testing with inert gas at 80-100 psig (5.5-6.9 barg) for a minimum duration of 60 seconds. No visible bubble leakage is allowed through welds or the pressure boundary as determined by testing under water, with an applied foaming solution, or with a mass leak detection device. 11. LOW TEMPERATURE CRYOGENIC TESTING 11.1 Cryogenic qualification or production testing, when specified for an item or a sample of an item by the purchase order or agreement between purchaser and manufacturer, shall be performed per the requirements of Annex A.

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TABLE 1 Body/Bonnet Extension Length, U.S. Customary Units

Dimensions are in inches. Rising-Stem Valves Quarter-turn Valves Size (NPS) Cold Box Non-Cold Box Cold Box Non-Cold Box 1/2 17 12 16 7.5 3/4 17 12 16 7.5 1 17 12 16 7.5 1 1 /2 21 14 20 8.5 2 21 16 20 10 3 24 18 22 13 4 26 22 24 14 6 30 24 24 17 8 34 27 26 18 10 40 32 28 25 12 45 36 32 28 Dimensions – Centerline of valve to top of stuffing box. See Section 8 and Figures 1, 2, 3, and 4.

TABLE 2 Body/Bonnet Extension Length, SI (Metric) Units Size (DN) 15 20 25 40 50 80 100 150 200 250 300

Rising-Stem Valves Cold Box Non-Cold Box 425 300 425 300 425 300 500 350 500 400 600 450 650 550 750 600 900 700 1000 800 1150 900

Dimensions – Centerline of valve to top of stuffing box. See Section 8 and Figures 1, 2, 3, and 4.

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Dimensions are in millimeters. Quarter-turn Valves Cold Box Non-Cold Box 400 200 400 200 400 200 500 225 500 250 550 300 600 350 600 425 650 450 700 600 800 700

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PART NAMES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

Handwheel Nut Identification Plate Handwheel Stem Nut Gland Gland Bolting Yoke Packing Stem Bonnet Extension Bonnet Bolting Bonnet Gasket Disc Nut Disc Body

FIGURE 1 Typical Outside Screw and Yoke Cryogenic Globe Valve (For Illustration Only) 7

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PART NAMES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.

Handwheel Nut Identification Plate Handwheel Stem Nut Gland Bolting Gland Packing Stem Bonnet Extension Bonnet Bolting Bonnet Gasket Seat Ring Gate Body

FIGURE 2 Typical Outside Screw and Yoke Cryogenic Gate Valve (For Illustration Only) 8

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PART NAMES 1. 2. 4. 5. 6. 7. 9. 11. 12. 13. 15. 16. 19. 33. 46. 55. 56. 63. 90.

FIGURE 3 Typical Cryogenic Ball Valve (For Illustration Only) 9

Body Bonnet Stem Ball Thrust Washer Stem Bushing Seat Packing Flange Gland Bushing Packing Ring Stud Nut Gasket Handle Spring Bushing Hex Head Caps Screw Packing Washer Extension

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PART NAMES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

FIGURE 4 Typical Cryogenic Butterfly Valve (For Illustration Only) 10

Gear Actuator Handwheel Handwheel Pin Mounting Bracket Mounting Bolt Upper Journal Bearing Packing Housing Extension Stem Stop Bearing Thrust/Journal Bearing Disk Body Packing Stud Packing Bolt Packing Follower

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ANNEX A Low Temperature Cryogenic Testing A1. CRYOGENIC VALVE TEST FLUIDS

A3. TEST EQUIPMENT

A1.1 Cryogenic valves constructed of materials suitable for use in temperatures in the -150 °F to -425 °F (-100 °C to -255 °C) range (examples: Group 2 and Group 3 materials of ASME B16.34) and requiring qualification or production testing by the purchase order shall be tested using liquid nitrogen as the immersion and cool down test fluid.

A3.1 The valve to be tested to Section A1.1 requirements shall be supported in an insulated stainless steel tank. The ends of the valve shall be blanked off with stainless steel blank flanges, plugs, or plates, to contain pressure during the test. Small diameter 18-8 or copper tubing shall be connected to each end of the valve. Tank, flange, plugs, plates, and fittings used for testing shall be 18-8 austenitic stainless steel compatible with liquid nitrogen at -320 °F (-195 °C).

A1.2 Cryogenic valves constructed of alloy steel materials suitable for use in the -100°F to -150 °F (-73 °C to -100 °C) range (examples: A352 LC2 and A352 LC3, Group 1 materials of ASME B16.34) and requiring qualification or production testing by the purchase order shall be tested using a immersion liquid acceptable for the cryogenic temperature (examples: heat transfer fluid or ethylene glycol), which shall be cooled by control flow through coils of liquid nitrogen or mechanical refrigeration or by addition of cooling media directly to the immersion fluid. Alternately the valve body may be cooled in a closed insulated box using nitrogen vapors or mechanical refrigeration methods without the use of an immersion liquid.

Similar requirements apply for valves tested to Section A1.2 requirements except materials for flanges, plugs, tubing or plates may be made of a material meeting the test temperature requirements. During testing, gate, globe, ball and butterfly stem orientation shall be vertical. Check valves (piston, ball, swing, dual plate, etc.) may be tested in either vertical or horizontal disc position except for gravity closure check valves, which shall be tested in a vertical disc position. A3.2 At least one (1) thermocouple shall be attached to the valve body. A second thermocouple shall be attached to the valve packing area. A third thermocouple shall be attached to the outlet of the pressure tubing. The packing and pressure tubing thermocouples should be insulated from direct exposure to the liquid nitrogen to avoid false readings. See Figure A1 for typical test set-up.

A2. PRELIMINARY TEST PREPARATIONS A2.1 The valve or valves shall be pre-tested in accordance with parent valve standard at ambient temperature. A2.2 The valve or valves shall be purged with clean dry nitrogen or air to remove any remaining moisture. A2.3 Unless otherwise agreed with the purchaser, testing shall be conducted on 10% (minimum of one piece) of each valve type, class, and size contained on the purchase order.

A4. PURGING A4.1 Gate and globe valves shall be partially opened and ball and butterfly valves shall be fully opened prior to immersion in liquid nitrogen per Section A1.1 or other media per Section A1.2.

A2.4 All instruments (flow meters, pressure gauges, torque wrenches, etc.) shall be calibrated. Helium sniffing devices shall be calibrated as per the instrument manufacturer’s recommendation. 11

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A4.2 A helium low pressure (15 psig min.) (1 barg min.) shall be maintained in the valve during immersion with a purge started as cooldown progresses.

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A4.6.4 The maximum allowable leakage rates shall not exceed those as listed in Table A1. A4.6.5 Repeat the sequence described in Sections A4.6.1 through A4.6.4 on each seat for bi-directional valves.

A4.3 The valve shall be lowered into an insulated tank and liquid nitrogen, per Section A1.1 or other media per Section A1.2, shall be allowed to fill the insulated tank around the valve, to a level approximately 1 in. (25.4 mm) above the body/bonnet bolting or body/bonnet welded connection.

A4.7 High Pressure Seat Test A4.7.1 Following the low pressure seat test and with valve in the open position, gradually increase the helium pressure until the pressure reaches 80 psig (5.5 barg), then close the valve and continue pressurization until the valve reaches the test pressure listed in Table A2. The valve shall be closed for a minimum of ten minutes to stabilize the pressure.

A4.4 After the valve has stabilized at the test temperature, the helium purge shall be turned off and the valve cycled open and closed three (3) times. A4.5 To safeguard against inaccurate readings during testing, the helium purge flow through the valve prior to subsequent pressurization shall be verified to be zero.

A4.7.2 The valve body and packing helium test temperatures shall be recorded. The leaking gas temperature shall be measured by test outlet tubing thermocouple (see Section A3.2) and recorded. After five minutes, the detected leakage rate shall be recorded and then converted to an actual leakage rate, as applicable, by multiplying the detected leakage rate by a correction factor in accordance with the Boyle-Charles rule. This calculation shall correct the measured leakage to standard conditions of 14.7 psig (1.01 barg) at 60 °F (15.6 °C).

A4.6 Low Pressure Seat Test A4.6.1 The valve shall be pressurized with 80 psig (5.5 barg) helium in the open position. A4.6.2 The valve shall be closed for a minimum of ten minutes to stabilize the test pressure. A4.6.3 The valve body and packing test temperatures shall be recorded. The leaking gas temperature shall be measured by test outlet tubing thermocouple (see Section A3.2) and recorded. After five minutes, the detected leakage rate shall be recorded and then converted to an actual leakage rate, as applicable, by multiplying the detected leakage rate by correcting factor in accordance with the Boyle-Charles rule. This calculation shall correct the measured leakage to standard conditions of 14.7 psig (1.01 barg) at 60 °F (15.6 °C).

Alternately an electronic mass flow leakage device may be used and when calibrated to standard conditions the temperature need not be recorded nor the correction factor be applied. The standard conditions leak rate shall be recorded. A4.7.3 The maximum allowable leakage rates shall not exceed those listed in Table A1. A4.7.4 Repeat the test sequence as described in Sections A4.7.1 through A4.7.3 on each seat for bi-directional valves.

Alternately, an electronic mass flow leakage device may be used and when calibrated to standard conditions the temperature need not be recorded nor the correction factor be applied. The standard conditions leak rate shall be recorded.

A4.8 Shell Test A4.8.1 Shell test leakage shall be measured with a sniffing device sensitive only to helium. 12

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STANDARD PRACTICE A4.8.2 Shell test shall be performed while the valve is still at cryogenic temperatures from previous seat testing.

A4.10.5 When testing with an inert gas, each valve shell shall be subjected to a 200 psig (13.8 barg) pressure test for a minimum duration of 10 minutes. No visible bubble leakage is allowed through the pressure boundary as determined by testing under water, or with an applied foaming solution.

A4.8.3 Valve shall be partially opened and pressurized to a test pressure of 200 psig (13.8 barg) minimum. A4.8.4 After the shell pressure has stabilized, the valve shall be lifted from the liquid nitrogen for access by the heliumsniffing device.

A4.10.6 If the stem packing shows signs of leakage and requires adjustment, the pressure shall be bled off, the packing tightened and the valve re-pressurized for ten minutes before resuming the test.

A4.8.5 Any sustained leakage in excess of 1 x 10-4 std cc/sec or 50 PPM (v) shall be cause for rejection during a minimum 10 second sniffing duration.

A5. CORRECTIVE ACTION Valves, which fail to meet the test requirements of this Annex, shall be reviewed for root cause, corrective action taken, and re-tested. Any corrective action modifications made on the test valve shall also be made on the balance of valves represented by the test valve.

A4.8.6 Packing leakage that can be corrected by packing adjustment shall not be cause for rejection. A4.9 Ambient Low Pressure Seat Test A4.9.1 Remove valve from test apparatus and allow valve to warm up to ambient temperature.

A6. TEST REPORT The test report shall include the valve information, tester’s name, and date of test, temperatures, pressures, and durations. Pressure-temperature charts shall be provided, as required by a purchase order.

A4.9.2 Perform a low pressure seat test using 80 psig (5.5 barg) nitrogen gas. Repeat test on opposite seat for bi-directional valves. A4.9.3 Acceptable leakage rate shall be in accordance with parent valve testing standard. A4.10

Ambient Shell Test

A4.10.1 With the valve half open, and ports sealed, pressurize the valve with 200 psig (13.8 barg) helium or other inert gas. A4.10.2 Shell test pressure maintained for ten minutes.

shall

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be

A4.10.3 When utilizing a sniffing device, which is sensitive only to helium, the entire body, bonnet and gasket area shall be examined. A4.10.4 At any time during the test, a sustained reading of greater than 1 x 10-4 std cc/sec or 50 PPM (v) shall be cause for rejection during a minimum 10 second sniffing duration. 13

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STANDARD PRACTICE TABLE A2 Helium Test Pressures

TABLE A1 Allowable Helium Seat Leakage Rates for Cryogenic Closure Tests Allowable Leakage (scc/minute/NPS) Seat Test

Gate, Globe, Butterfly, Ball

Class

Size*

150

Metal Seat

Low pressure seat Test (80 psig)

25

50

100

High pressure Seat test for Class 150, 300 & 600 (Table A2)

75

150

300

High pressure seat Test for Class 800, 900 & 1500 (Table A2)

100

200

400

High pressure Seat Test ** (psig)

(barg)

< NPS 24

230

15.8

300

< NPS 24

600

41.4

600

< NPS 18

1200

82.7

800

< NPS 8

1600

110.3

900

< NPS 8

1800

124.1

1500

< NPS 6

1800

124.1

Check

Soft Seat

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*Test pressures for larger size valves shall be limited to 300 psig (20 barg). **Test pressures for butt-weld valves tested with a test fixture, shall be limited to 200 psig (14 barg).

FIGURE A1 Typical Test Set-Up

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ANNEX B Referenced Standards and Applicable Dates This Annex is an integral part of this Standard Practice and is placed after the main text for convenience. Standard Name

Description

ASME; ASME/ANSI B16.34-2009 B31.3-2010 BPVC-VIII, Div. 1-2010

Valves – Flanged, Threaded, and Welding End; w/ Supplement (2010) Process Piping Boiler and Pressure Vessel Code, Section VIII, Division 1, Rules for Construction of Pressure Vessels; w/ Addenda Reprint (2011)

API; ANSI/API 6D-2008 (ISO 14313:2007)

600-2009 602-2009 603-2007 608-2008 609-2009

Specification for Pipeline Valves; w/ Addendum 1 (2009) and Addendum 2 (2011), Errata 1 (2008), Errata 2 (2008), Errata 3 (2009), Errata 4 (2010), Errata 5 (2010), and Errata 6 (2011) (Identical to ISO 14313:2007, Petroleum and Natural Gas Industries Pipeline Transportation Systems) Steel Gate Valves – Flanged and Butt-welding Ends, Bolted Bonnets; w/ Errata 1 (2009) Steel Gate, Globe, and Check Valves for Sizes NPS 4 (DN 100) and Smaller for the Petroleum and Natural Gas Industries Corrosion-resistant, Bolted Bonnet Gate Valves – Flanged and Butt-welding Ends Metal Ball Valves – Flanged, Threaded and Welding Ends Butterfly Valves: Double Flanged, Lug- and Wafer-type

MSS SP-96-2011

Guidelines on Terminology for Valves and Fittings

The following organizations appear in the above list: ANSI

American National Standards Institute, Inc. 25 West 43rd Street, Fourth Floor New York, NY 10036-7406

ASME

American Society of Mechanical Engineers (ASME International) Three Park Avenue New York, NY 10016-5990

API

American Petroleum Institute 1220 L Street, NW Washington, D.C. 20005-4070

ISO

International Organization for Standardization 1, ch. de la Voie-Creuse, Case postal 56 CH-1211 Geneva 20, Switzerland

MSS

Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. 127 Park Street, NE Vienna, VA 22180-4602 15

MSS

STANDARD PRACTICE

SP-134

APPENDIX X1 Guidance for Stem Strength Calculations This Appendix is supplementary and does not include mandatory requirements. X1.1 Valve Stems X1.1.1 Gate and globe valve stems shall have an area and length to diameter (or radius of gyration) ratio that precludes compression stress yield failure or elastic buckling while under compressive loading. Section 8.1 establishes a minimum extension length dimension that impacts on the stem’s length/diameter (or radius of gyration) ratio. X1.1.2 The following equations shall be used to determine the critical slenderness ratio of globe or gate valve stems:

L 2CE =π r Sy

Equation #1

Or for round solid stems with r = d/4

L π = d 4

2CE Sy

Equation #2

Where: L/r = slenderness ratio for stems made from various stem cross section geometries, L/d = slenderness ratio for stems made from round bar, L

= unsupported length of a uniformly straight stem span between the upper stem guide and stem-to-disc interface (see Figures 1 and 2),

d

= stem diameter,

r

= minimum radius of gyration for stem cross section, where r =

E

= modulus of elasticity of the stem material,

Sy

= yield strength of stem material,

I

= minimum moment of inertia about axis of bending through stem’s transverse area centroid,

A

= area of stem’s traverse area,

C

= constant depending on the valve stem end support conditions.

I/A,

Suggested C = 2 for a stem of a globe or gate valve that has a stem guided disc/gate. Suggested C = 4 for a stem of a globe or gate valve that has a body guided disc/gate. Other C’s may be used at manufacturer’s option if representative of the design of their stem end supports.

16

MSS

STANDARD PRACTICE

SP-134

APPENDIX X1 (continued) Guidance for Stem Strength Calculations X1.1.3 Using the physical dimensions of the stem intended to be used in the globe or gate valve the stem’s actual L/r or L/d ratio shall be determined. The actual ratio shall be compared with that determined by calculation from Equation #1 or Equation #2. If the actual stem L/r or L/d ratio is greater than that determined by Equation #1 or Equation #2 the potential failure mode is buckling. Use the methods in Section X1.1.4.1 to calculate the critical load and safe load requirements. If the actual stem L/r or L/d ratio is less than that determined by Equation #1 or Equation #2, the potential failure mode is combined compression/buckling. Use the methods in Section X1.1.4.2 to calculate the critical load and safe load requirements. X1.1.4 Critical and Safe Load Calculations X1.1.4.1 If the stem’s actual L/d or L/r is greater than that calculated by Equation #1 or Equation #2 the stem’s failure mode would be buckling. The stem’s critical load to cause buckling and safe operating closing force shall be calculated using Equation #3 and Equation #4:

Fc =

Cπ 2 EA (L / r )2

Equation #3 (Euler’s Equation)

Or for round solid stems with r = d/4

Fc =

Cπ 2 EA 16( L / d ) 2

Equation #4 (Euler’s Equation for Round Stems)

Where: Fc = critical load to cause buckling. Other symbols are as defined in Section X1.1.2. The Safe Stem Load shall incorporate a factor of safety and be calculated as follows:

FS =

Fc N

Equation #5

Where: Fs = safe stem force, Fc

= critical load to cause buckling as determined from Equation #3 or Equation #4,

N

= factor of safety, commonly used = 2.

If the actual closing stem force is less than the critical as determined by Equations #3 or Equation #4 the stem will be acceptable for use and not expected to fail by buckling, but an appropriate factor of safety shall be applied by Equation #5 to insure a safe load determination. If the actual stem load is greater than the critical load (Fc), than the stem’s cross sectional dimensions shall be increased. Equation #3 or Equation #4 can be used to determine the stem required cross section dimensions. Stem dimensional changes will change the stem’s L/r or L/d ratio, which may move the critical load (Fc) calculations to the Section X1.1.4.2 method.

17

MSS

STANDARD PRACTICE

SP-134

APPENDIX X1 (continued) Guidance for Stem Strength Calculations X1.1.4.2 If the stem’s actual L/r or L/d ratio is less than that calculated from Equation #1 or Equation #2 the stem stress failure mode would be based on combined compression/buckling. The stem’s critical load and safe operating closing force shall be calculated using Equations #6 or #7 and #8:

 S y ( L / r )2  Fcr = S y A 1 −  4Cπ 2 E 

   

Equation #6 (J. B. Johnson Formulae)

Or for round solid stems

 4 S y ( L / d )2  Fcr = S y A 1 −  Cπ 2 E 

   

Equation #7 (J.B. Johnson Formulae for Round Stems)

Where: Fcr = critical load to cause combined compression/buckling stem failure, Other symbols are as defined in Section X1.1.2. The safe stem load shall be calculated as follows:

Fs =

Fcr N

Equation #8

Where: Fs = safe stem force, N

= factor of safety, commonly used = 2.

If the actual closing stem force is less than the safe stem force determined by Equation #6 or Equation #7 the stem will be acceptable for use and not expected to fail by combined compression/buckling stress. If the actual stem load is greater than the critical load (Fc) than the stem’s cross sectional dimensions shall be increased. Equation #6 or Equation #7 can be used to determine the stem required cross section dimensions. Increased stem dimensional changes will change the stem’s L/r or L/d ratio, but for moderate length stems, the method of Section X1.1.4.2 can be used to validate final stem design. X1.1.4.3 For stem unsupported spans that fit other column end restraint models, the manufacturer may develop L/r or L/d equations for determination of the critical load and safe load incorporating a suggested factor of safety (N) equal to two (2). For stems not of uniform diameter, the manufacturer shall execute more extensive calculations or tests to assure that stem buckling or combined compression/buckling is prevented. X1.1.5 Extended stems in quarter-turn valves shall be proportioned so that, under torsional loading, the stem torque is limited by the stem angle of twist and as a result also limited by the critical shear stress of the stem material. Stem diameters and stem lengths shall be proportioned such that maximum applied torque meets the requirements of Sections X1.1.6 and X1.1.7.

18

MSS

STANDARD PRACTICE

SP-134

APPENDIX X1 (continued) Guidance for Stem Strength Calculations X1.1.6 Quarter-turn valve stem length and diameter combinations that limit stem torsional deflection or angle of twist to π/90 radians (2-degrees) as determined by the following equation: π TL θ = GJ ≤ 90

Equation #9

Where: θ = angle of twist, radians, T

= maximum stem design torque,

L

= length of stem from point of torque application to obturator attachment (see Figures 3 and 4),

G = modulus of rigidity = E/2(1+μ), E

= modulus of elasticity of the stem material,

μ

= Poisson’s ratio,

J

= polar moment of inertia of round stem.

X1.1.7 The stem torque shall not be greater than that which could cause the stem material to exceed its shear stress limit at the outer fiber as calculated by the following:

TS ≤

πd S3τ max 16 N

Equation #10 (for Solid Round Stem)

Where: Ts = the manufacturer’s designated maximum stem torque, τmax = the stem material shear stress limit, ds = the stem diameter, N

= 2, a factor of safety.

X1.1.8 Valves with soft seats or a soft closing member insert to be used with flammable vapors or liquids shall be designed in such a way that there is electric continuity between the body and stem of the valve. Such a design must be qualified by testing the maximum electrical resistance, which shall not exceed 10 ohms across the discharge path. To test for continuity, a new dry valve shall be cycled at least five times, and the resistance measured using a DC power source not exceeding 12 volts. X1.1.9 Valves in flammable fluid service shall be of fire-safe design, and in case the valve is equipped with soft-seats or a soft-closing member, the design shall be successfully fire tested as per API 607, “Fire Test for Quarter-turn Valves and Valves Equipped with Nonmetallic Seats”.

19

TITLE SP-6-2012 SP-9-2008 SP-25-2008 SP-42-2009 SP-43-2008 SP-44-2010 SP-45-2003 SP-51-2012 SP-53-1999 SP-54-1999 SP-55-2011 SP-58-2009 SP-60-2012 SP-61-2009 SP-65-2012 SP-67-2011 SP-68-2011 SP-69-2003 SP-70-2011 SP-71-2011 SP-72-2010a SP-75-2008 SP-78-2011 SP-79-2011 SP-80-2008 SP-81-2006a SP-83-2006 SP-85-2011 SP-86-2009 SP-87-1991 SP-88-2010 SP-91-2009 SP-92-2012 SP-93-2008 SP-94-2008 SP-95-2006 SP-96-2011 SP-97-2012 SP-98-2012 SP-99-2010 SP-100-2009 SP-101-1989 SP-102-1989 SP-104-2012 SP-105-2010 SP-106-2012 SP-108-2012 SP-109-2012 SP-110-2010 SP-111-2012 SP-112-2010 SP-113-2012 SP-114-2007 SP-115-2010 SP-116-2011 SP-117-2011 SP-118-2007 SP-119-2010 SP-120-2011 SP-121-2006 SP-122-2012 SP-123-1998 SP-124-2012 SP-125-2010 SP-126-2007 SP-127-2001 SP-128-2012 SP-129-2003 SP-130-2003 SP-131-2010 SP-132-2010 SP-133-2010 SP-134-2012 SP-135-2010 SP-136-2007 SP-137-2007 SP-138-2009 SP-139-2010 SP-140-2012 SP-141-2012 SP-142-2012 SP-143-2012

Listing of MSS Standard Practices (as of May, 2012) Standard Finishes for Contact Faces of Pipe Flanges and Connecting-End Flanges of Valves and Fittings Spot Facing for Bronze, Iron and Steel Flanges Standard Marking System for Valves, Fittings, Flanges, and Unions Corrosion Resistant Gate, Globe, Angle and Check Valves with Flanged and Butt Weld Ends (Classes 150, 300 & 600) Wrought and Fabricated Butt-Welding Fittings for Low Pressure, Corrosion Resistant Applications (Incl. 2010 Errata Sheet) Steel Pipeline Flanges (incl. 2011 Errata Sheet) (R 2008) Bypass and Drain Connections Class 150LW Corrosion Resistant Flanges and Cast Flanged Fittings (R 2007) Quality Standard for Steel Castings and Forgings for Valves, Flanges, and Fittings and Other Piping Components – Magnetic Particle Examination Method (R 2007) Quality Standard for Steel Castings and Forgings for Valves, Flanges, and Fittings and Other Piping Components – Radiographic Examination Method Quality Standard for Steel Castings for Valves, Flanges, Fittings, and Other Piping Components – Visual Method for Evaluation of Surface Irregularities (ANSI-approved American National Standard) Pipe Hangers and Supports – Materials, Design, Manufacture, Selection, Application, and Installation (incorporates content of SP-69, 77, 89, and 90) (ANSI-approved American National Standard) Connecting Flange Joints between Tapping Sleeves and Tapping Valves Pressure Testing of Valves High Pressure Chemical Industry Flanges and Threaded Stubs for Use with Lens Gaskets Butterfly Valves High Pressure Butterfly Valves with Offset Design Pipe Hangers and Supports – Selection and Application (ANSI-approved American National Standard) Gray Iron Gate Valves, Flanged and Threaded Ends Gray Iron Swing Check Valves, Flanged and Threaded Ends Ball Valves with Flanged or Butt-Welding Ends for General Service Specification for High-Test, Wrought, Butt-Welding Fittings Gray Iron Plug Valves, Flanged and Threaded Ends Socket Welding Reducer Inserts Bronze Gate, Globe, Angle, and Check Valves Stainless Steel, Bonnetless, Flanged Knife Gate Valves Class 3000 Steel Pipe Unions Socket Welding and Threaded Gray Iron Globe & Angle Valves, Flanged and Threaded Ends Guidelines for Metric Data in Standards for Valves, Flanges, Fittings, and Actuators (Incl. 2011 Errata Sheet) (R 1996 – Reinstated 2011) Factory-Made Butt-Welding Fittings for Class I Nuclear Piping Applications Diaphragm Valves Guidelines for Manual Operation of Valves MSS Valve User Guide Quality Standard for Steel Castings and Forgings for Valves, Flanges, Fittings, and Other Piping Components – Liquid Penetrant Examination Method Quality Standard for Ferritic and Martensitic Steel Castings for Valves, Flanges, Fittings, and Other Piping Components – Ultrasonic Examination Method Swage(d) Nipples and Bull Plugs Guidelines on Terminology for Valves and Fittings Integrally Reinforced Forged Branch Outlet Fittings – Socket Welding, Threaded, and Buttwelding Ends Protective Coatings for the Interior of Valves, Hydrants, and Fittings Instrument Valves Qualification Requirements for Elastomer Diaphragms for Nuclear Service Diaphragm Valves (R 2001) Part-Turn Valve Actuator Attachment – Flange and Driving Component Dimensions and Performance Characteristics (R 2001) Multi-Turn Valve Actuator Attachment – Flange and Driving Component Dimensions and Performance Characteristics Wrought Copper Solder-Joint Pressure Fittings Instrument Valves for Code Applications Cast Copper Alloy Flanges and Flanged Fittings: Class 125, 150, and 300 Resilient-Seated Cast Iron Eccentric Plug Valves Welded-Fabricated Copper Solder-Joint Pressure Fittings Ball Valves Threaded, Socket-Welding, Solder Joint, Grooved and Flared Ends (incl. 2010 Errata Sheet) Gray-Iron and Ductile-Iron Tapping Sleeves Quality Standard for Evaluation of Cast Surface Finishes – Visual and Tactile Method. This SP must be used with a 10-surface, three dimensional Cast Surface Comparator, which is a necessary part of the standard. Additional Comparators available separately. Connecting Joints between Tapping Machines and Tapping Valves Corrosion Resistant Pipe Fittings Threaded and Socket Welding Class 150 and 1000 (ANSI-approved American National Standard) Excess Flow Valves, 1¼ NPS and Smaller, for Fuel Gas Service Service-Line Valves and Fittings for Drinking Water Systems Bellows Seals for Globe and Gate Valves Compact Steel Globe & Check Valves – Flanged, Flangeless, Threaded & Welding Ends (Chemical & Petroleum Refinery Service) Factory-Made Wrought Belled End Pipe Fittings for Socket-Welding Flexible Graphite Packing System for Rising Stem Valves – Design Requirements Qualification Testing Methods for Stem Packing for Rising Stem Steel Valves Plastic Industrial Ball Valves (R 2006) Non-Ferrous Threaded and Solder-Joint Unions for Use with Copper Water Tube Fabricated Tapping Sleeves Gray Iron and Ductile Iron In-Line, Spring-Loaded, Center-Guided Check Valves Steel In-Line Spring-Assisted Center Guided Check Valves Bracing for Piping Systems Seismic-Wind-Dynamic Design, Selection, Application Ductile Iron Gate Valves (R 2007) Copper-Nickel Socket-Welding Fittings and Unions Bellows Seals for Instrument Valves Metallic Manually Operated Gas Distribution Valves Compression Packing Systems for Instrument Valves Excess Flow Valves for Low Pressure Fuel Gas Appliances Valves for Cryogenic Service, including Requirements for Body/Bonnet Extensions High Pressure Knife Gate Valves Ductile Iron Swing Check Valves Quality Standard for Positive Material Identification of Metal Valves, Flanges, Fittings, and Other Piping Components Quality Standard Practice for Oxygen Cleaning of Valves & Fittings Copper Alloy Gate, Globe, Angle, and Check Valves for Low Pressure/Low Temperature Plumbing Applications Quality Standard Practice for Preparation of Valves and Fittings for Silicone-Free Service Multi-Turn and Check Valve Modifications Excess Flow Valves for Fuel Gas Service, NPS 1½ through 12 Live-Loaded Valve Stem Packing Systems

(R YEAR) Indicates year reaffirmed • Price List Available Upon Request • MSS is an ANSI-accredited American National Standards developer

Manufacturers Standardization Society of the Valve and Fittings Industry, Inc. 127 Park Street, NE, Vienna, VA 22180-4620 • (703) 281-6613 • Fax # (703) 281-6671 MSS SP-134-2012