MESC Specification - FKM

MESC ADDITIONAL REQUIREMENT Revision: 04-Mar-2005.

SPE 77/101 Page 1 of 13

.

STEEL GATE, GLOBE AND CHECK VALVES TO ISO 15761.

INTRODUCTION

(Intro-duction)

The purpose of this MESC additional requirement is to establish requirements for steel wedge gate and globe valves (both including bellows-sealed types) and check valves in nominal sizes DN 100 and smaller, designed to ISO 15761 with flanged, butt welding or threaded ends in carbon steel, low alloy and high alloy steels, nickel alloy and nickel/copper alloy. The ISO 15761 general construction and design requirements parallels those specified in API 602.

Note: ISO-15761 supersedes BS-5352, because BS-5352 is inactive/withdrawn.

1. (1) SCOPE

1.1 This specification applies to:

-wedge gate valves, with outside screw and yoke, rising stem, bolted or welded bonnet and bolted gland;

-wedge gate valves, with inside screw, rising stem and hand wheel, bolted or welded bonnet and gland;

-globe valves, with outside threaded stems; -globe valves with inside threaded stems; -bellows stem sealed gate and globe valves and -check valves (standard pattern and Y pattern) with disk, high lifting piston or ball closure element.

The applicable nominal pressures are PN 20, 50, 110, 130 and 260 and equivalent nominal class ratings 150, 300, 600, 800 and 1500.

1.2 This specification gives amendments / supplements to standard ISO 15761 with the purpose of compliance with Shell group requirements.

1.3 Clauses of ISO 15761 which are not amended by this specification shall remain valid as written.

1.4 This specification shall be considered to be part of the valve buying description, when referred to in a MESC description and / or requisition.

1.5 The numbers in brackets at the section headings refer to the relevant sections in ISO 15761.

2. (2) NORMATIVE REFERENCES

In addition to the normative references specified in ISO 15761 in this specification, reference is made to the following publications:

NOTE: Unless specifically designated by date, the latest edition of each publication shall be used, together with any amendments/supplements/revisions thereto.

API 6FA Specification for fire test for valves.

API 598 (8th edition, May-2004)

Valve inspection and testing

API 602 Compact steel gate valves flanged, threaded, welding and


SPE 77/101 Page 2 of 13

.

extended-body ends.

ASME VIII DIV.1 ASME boiler and pressure vessel code, Section VIII, Division 1: Rules for construction of pressure vessels.

ASME B 16.25 Butt-welding ends.

ASME B 31.3 Process piping.

BS 6755 2 (withdrawn)

Testing of valves, part 2: Specification for fire type testing requirements.

EN 1127-1 Potentially explosive atmospheres Explosion protection Part 1: Basic concepts and methodology.

EN 12874 Flame blow-out fuses performance requirements, test procedure and usage restrictions.

EN 13463-1 Non-electrical equipment for use in potentially explosive atmospheres - Part 1: Basic concepts and methodology.

PrEN 13463-5 (2003-05)

Non-electrical equipment for use in potentially explosive atmospheres Part 5: Protection by design safety.

European Directive 97/23/EC

Pressure Equipment Directive (PED)

European Directive 94/9/EC

Equipment and protective systems intended for use in potentially explosive atmospheres.

ISO 10497 Testing of valves: fire type testing requirements.

ISO 15761 (1st edition 15-12-2002)

Steel gate, globe and check valves, for sizes DN100 and smaller, for the petroleum and natural gas industries.

NACE MR 0175 (Edition 2002)

Standard material requirements; Metals for sulphide stress cracking and stress corrosion cracking resistance in sour oilfield environments.

3. (3) TERMS AND DEFINITIONS

3.1. (3) See ISO 15761

4 (4) (B3)

PRESSURE / TEMPERATURE RATINGS - BODY, BONNET, COVER & BELLOWS ASSEMBLY

4.1 (4.1.1) The rating shall be calculated in accordance with the appropriate class, as specified in ASME B16.5 or ASME B16.34 and shall fulfill the most severe design conditions.

4.2 For double seated valves which are subject to temperature changes and consequent expansion of the medium the Principal shall specify in the purchase order that the cavity of these valves shall be provided with a pressure relief device (see also SPE 77/200 section 3.3.1 and SPE 77/209 section 3.4). This requirement is to avoid excessive pressure build-up in the cavity of double seated valves, where the medium (volatile liquid) may be trapped.


SPE 77/101 Page 3 of 13

.

5. (5) DESIGN

5.1 (5.1) REFERENCE DESIGN

5.1.1 (5.1.1) The design shall be based on the most unfavourable pressure/temperature rating of the appropriate class.

5.1.2 (5.1.1) The valve body shall be designed to withstand loading, induced by the connected piping, without distortion of the internals affecting the free movement of the closure member and sealing performance.

5.1.3 (5.1.2) For valves made of nickel alloy, nickel / copper alloy ISO 15761 shall be guidance for design, marking inspection and testing.

5.1.4 (5.1.2 & Annex B)

GATE & GLOBE VALVES WITH BELLOWS STEM SEALS

5.1.4.1 (B.1) The application of bellows stem seals in gate and globe valves shall be limited to a nominal valve size of DN 100 maximum.

5.1.4.2 The valve manufacturer shall prove that the bellows of a standard bellows sealed on/off gate valve and globe valve will exceed a minimum life time of 3000 cycles by providing bellows fatigue testing records.

5.1.5 FIRE TESTED OR FIRE-SAFE DESIGN

5.1.5.1 Metal-seated valves shall be of a fire-safe design.

5.1.5.2 Soft seated valves shall be of a fire tested design.

NOTE: A fire-tested design is one which has successfully passed prototype fire testing. A fire-safe design is a design which by nature of its features/properties is capable of passing a fire test.

5.1.5.3 Fire testing and certification shall be in accordance with ISO 10497, taking into account the following additional requirements:

- The flame(s) shall not be in direct contact with, or close oriented to, the valve and temperature measuring devices.

- Number of leak tests for asymmetric valves: - One (in the non-preferred flow direction) for valves tested at 2 barg, - Two (in both flow directions) for valves tested at 75% of the rated pressure

5.1.5.4 Valves, which are previously, fire tested and certified in accordance with BS 6755 part 2 or API 6FA are acceptable.

5.1.5.5 The valve operating mechanisms shall be of a fire-safe design.

5.1.5.6 Qualification of untested similar valves of the same basic design and construction is as per ISO 10497 fire testing requirements.

5.2 (5.2) FLOW PASSAGEWAY

5.2.1 (5.2) See ISO 15761


SPE 77/101 Page 4 of 13

.

5.3 (5.3) WALL THICKNESS - BODY, BONNET, BELLOWS ENCLOSURE AND COVER

5.3.1 (5.3) The wall thickness shall be calculated in accordance with ISO 15761 (or ASME VIII division 1, UG-101 when applicable).

5.4 (5.4) (A.3)

VALVE BODY

5.4.1 (5.4.1) Forged bodies and body connectors shall be forged close to final shape.

5.4.2 Provisions for drain tapping are not allowed.

5.4.3 VALVE ENDS

5.4.3.1 (5.4.2) (tables 4, 5, A2 & A3)

Valves with Socket-Welding (SW) ends shall not be used.

5.4.3.2 (5.4.3) (table 5)

Threaded ends.

5.4.3.2.1 Valves with threaded ends shall not be used in hydro carbon services.

5.4.3.2.2 (5.4.3.2) (table A1)

Threaded ends shall be in accordance with ASME B1.20.1

5.4.3.3 (5.4.4) Flanged ends and body-bonnet joints.

5.4.3.3.1 (5.4.4.2) End flanges or stubs of nickel alloy, nickel / copper alloy valves shall be cast or forged integral with the body or body connector.

5.4.3.3.2 Flange calculations shall be in accordance with ASME B16.34 and ASME VIII, division 1, appendix 2 or appendix Y as applicable.

5.4.3.3.3 (5.4.4.3 & table 6)

Body end flanges shall be aligned to the design plane.

For valves executed with flanges to ASME B16.5 the maximum difference to the design plane (flange face misalignment) for an individual flange shall be1.8 mm / m.

5.4.3.3.4 (5.5.4) The surface finish of the nut bearing area at the back face of flanged valves shall be parallel to the flange face within 1 degree.

5.4.3.4 (5.4.5) Butt-welding ends

5.4.3.4.1 (5.4.5.2) The end-to-end dimensions for BW end valves are specified in the MESC buying descriptions.

5.4.4 (5.4.6) BODY SEATS

5.4.4.1 (5.4.6.1) Integral seat rings are preferred (instead of screwed-in, rolled-in or pressed-in seat rings).


SPE 77/101 Page 5 of 13

.

5.4.4.2 (5.4.6.2) If screwed-in, rolled-in or pressed-in seat rings are used they shall be properly secured (see 5.12).

5.4.4.3 For globe valves an integral seat ring shall be used when the needle disk is integral with the stem.

5.4.4.4 (5.7.6) (5.4.6.2)

BACK SEATS (FOR GATE AND GLOBE VALVES)

5.4.4.4.1 (5.7.6) (5.4.6.2)

Rolled / pressed-in or screwed-in back seat bushings are only acceptable when additionally secured against loosening (see 5.12).

5.5 (5.5) VALVE BONNET OR COVER

5.5.1 (5.5.1) Screwed/threaded body/cover connections shall not be used.

5.5.2 (5.5.3) Spiral wound gaskets for the body/cover connection shall be fully confined or provided with outer/inner guide rings.

5.5.3 (5.5.5) In order to maintain a uniform pitch distance and bolt loading body / bonnet flanges shall preferably be kept circular. Oval flanges are only acceptable in class 150 valves. Square flanges body-bonnet designs shall not be used.

5.6 CLOSURE MEMBERS (ORTURATORS)

5.6.1 (5.6.2) Gate valve wedge

5.6.1.1 (5.6.2.2) A gate valve wedge with a button-form connection for the stem is not acceptable.

5.6.2 (5.6.3) Globe valve disk

5.6.2.1 (5.6.3.2) The disk to stem retaining design clearances shall allow for proper seating.

5.6.2.2 (5.8.2) When the disk is attached by a disk nut the nut shall be secured to the disk (ref. 5.12).

5.6.3 (5.6.4) Closure members of check valves (standard and Y patterns)

5.6.3.1 (5.6.4.1) The closure member in piston type check valves and ball type check valves may be assisted by Inconel X750 springs to ensure positive shut-off at low differential pressures and in case the process fluid is highly viscous.

5.6.3.2 (5.6.4.1) The piston of piston type check valves shall be of the high lifting design. This design ensures that in open position of the valve, the piston is not having any effect on the flow of the process fluid.

5.7 (5.7) STEM (FOR GATE AND GLOBE VALVES)

5.7.1 (5.7.3) (5.7.5)

Stem head: The stem head shall be forged to shape. The stem and stem head may be machined from forged or hot drawn bars/billets, provided manufacturer/supplier supplies proof by UT that the steel has a re-crystallised random grain structure free from striations inherent in rolled products.


SPE 77/101 Page 6 of 13

.

5.7.2 The combined stresses due to side load and operating torque shall be less than the maximum allowable stresses specified in ASME VIII div. 1.

5.7.3 (5.7.2) The design shall take into account a safety margin based on the maximum output torque of the operating mechanism.

5.7.4 The weakest point of the stem shall always be outside the valve. To ensure the smallest cross sectional area of the stem and stem head provide adequate strength to operate the valve at the most severe design conditions as per appropriate class. It shall withstand the maximum side loads and operating torque needed to seal and to operate against the maximum class differential pressure (applied to one or both sides of the valve, whichever case needs the highest torque). The manufacturer shall be able to demonstrate the adequacy of the stem design by calculations and proving stem pull tests. These combined stresses shall not exceed the maximum allowable stresses specified in ASME section II Part D.

5.7.5 (5.7.2) Stem sections shall be cylindrical, within a tolerance of +/- 0.05 mm length.

5.7.6 (5.7.2) The stem shall be straight within a tolerance of +/- 1 mm per 1000 mm length.

5.7.7 (5.7.3) The stem shall have a maximum surface roughness (Ra) of 0.8 micrometers and free from any defects.

5.7.8 (5.6.2.3 & Table 8)

Wear travel: The stem projection outside the yoke sleeve of the top of the stem on a closed valve shall be within 2 mm (minimum) and 10 mm (maximum).

5.7.9 (5.7.7) STEM RETENTION (ANTI BLOW-OUT)

5.7.9.1 (5.7.5) The anti blow-out stem/body configuration shall be capable of withstanding the full internal pressure of the valve as per appropriate class.

5.7.9.2 The stem retainer ring or collar shall be integral with the stem.

5.7.9.3 The stem retention shall be designed as an axial bearing, unless a bearing has been incorporated in a different manner.

5.8 (5.8) Stem nut or stem bushing.

5.8.1 (5.8) Shall be in compliance with ISO 15761

5.9 (5.9) (table 10)

PACKING, STUFFING BOX AND GLAND (FOR GATE AND GLOBE VALVES)

5.9.1 Packing.

5.9.1.1 The installed valve stuffing box packing materials for top and bottom rings and intermediate rings shall be in compliance with the valve data/requisition sheet and/or MESC buying specification. The installed packing types shall comply with the requirements and properties listed in SPE 85/200 for those packing types.


SPE 77/101 Page 7 of 13

.

5.9.1.2 (5.9.4) Number of packing rings per set: - five rings for Class 150 to 800; - six rings for Class 900 to 2500.

5.9.1.3 (5.9.4) Other stem sealing-packing arrangements, as per the manufacturers standard, might be acceptable, provided manufacturer/supplier supplies proof of previous approval by Shell for proposed arrangement.

5.9.2 Stuffing box packing chamber.

5.9.2.1 (table 10) The dimensions of a stuffing box shall be based on square section packing.

5.9.2.2 A spacer ring at the bottom of the stuffing box is acceptable.

5.9.2.3 A lantern ring shall not be used.

5.9.3 Gland (follower).

5.9.3.1 (5.9.3) The gland shall be adjustable.

5.9.3.2 (5.9.3) Threaded glands shall not be used.

5.9.3.3 (5.9.3) The gland (follower) shall be installed such that it passes the edge of the stuffing box by minimum 2 mm prior to compression of the packing rings.

5.9.4 Diametrical clearances / tolerances

5.9.4.1 The manufacturer shall determine the tolerances by means of calculations, taking into account material expansion at upper design temperature.

5.9.4.2 The maximum diametrical clearance between the stuffing box diameter and the outside diameter of the gland (follower) and/or spacer ring shall be half the actual diametrical clearance between the inside diameter of the gland (follower) and the stem diameter.

5.9.4.3 (table 9) The maximum diametrical clearances between the stem and stuffing box bottom bore and spacer ring, the stem and inside diameter of the gland (follower), shall be 0.8 mm at the upper design temperature.

5.9.4.4 (table 9) The maximum diametrical clearance between the stem and the inside of the packing rings shall be 0.2 mm, between the inside diameter of the stuffing box and the outside diameter of the packing ring 0.1 mm.

5.10 (ISO 10434 / API 600 ANNEX B - POS 24)

YOKE (FOR GATE AND GLOBE VALVES)

5.10.1 For all valve sizes the yoke shall have provisions for an extended stem.

5.10.2 A screwed-on yoke shall be properly secured (see 5.12).

5.10.3 (5.8.2) If the yoke sleeve is retained to the yoke by means of a nut, the nut shall be secured.

5.10.4 If the yoke sleeve is a screwed-in type with collar then the collar shall be secured.


SPE 77/101 Page 8 of 13

.

5.11 (5.11) HAND WHEEL

5.11.1 (5.11.1) The diameter of the hand wheel shall not exceed 300 mm.

5.12 SECURING AND LOCKING

5.12.1 (5.4.6.2) Positive securing of separate removable valve parts against loosening shall primarily be done by means of seal or tack welding.

5.12.2 When valve parts are made from different materials or when materials are non weld able or not acceptable for welding, other methods of locking may be: -locking ring -retaining strips or tabs; -screws with close fit thread.

If retaining strips or tabs are used, the strip or tab area shall not reduce the projected valve bore with more than 5%.

5.12.3 Spring tension pins are not allowed for locking of internals.

6. (6) MATERIALS

6.1 (6.1, tables 11 & 12)

Trim materials

6.1.1 (6.1.1) The trim materials to be used are specified in the MESC buying descriptions.

6.2 (6.2) (table 13)

Materials other than trim

6.2.1 All internal parts other than seals and gaskets shall be metallic.

6.2.2 Materials for internal retaining components shall be of a material equivalent to that of the stem material.

6.2.3 Bolting and other valve components shall not be galvanized or cadmium plated.

6.2.4 The manufacturer shall list the material specifications for all valve parts.


1.

2.

SPE 77/101 Page 9 of 13

.

6.3 (6.2.3) (table 11)

WELDING AND HARD FACINGS

6.3.1 (6.2.3) All welding shall be performed in accordance with ASME B 31.3.

The manufacturer shall specify all welds that are considered part of the design of a production part and shall also describe the requirements for the intended weld.

Post-weld heat treatment shall be in accordance with the applicable qualified WPS. Welds may be locally post-weld heat-treated. The manufacturer shall specify procedures for the use of local post-weld heat treatment.

The base material and weld shall retain the minimum mechanical property requirements after post-weld heat-treatment. The manufacturer shall specify the methods to assure these mechanical properties and record the results as part of the PQR.

Notes:

Material selection and PWHT requirements should be based upon the potential damage mechanisms anticipated or experienced in service and the severity of the process environment, i.e. Susceptibility to: - Sulphide Stress Corrosion (SSC) cracking - Alkaline Stress Corrosion (ASCC) cracking - Hydrogen blistering, Hydrogen induced cracking (HIC) and Stress orientated hydrogen induced cracking (SOHIC) - Carbonate cracking (as experienced in sour water)

Potential mechanisms are not exclusive, i.e. if there is more than one mechanism active, the materials and PWHT requirements may have to be combined to address the severity of more than one environment. For example, should an application exist where a high severity for hydrogen blistering, HIC, SOHIC and carbonate cracking are present, the requirements for materials and PWHT shall be combined.

6.3.2 Other welding, including weld overlay and tack welding, shall be performed in accordance with procedures, and by welders, qualified in accordance with ASME IX. For valves of welded construction the manufacturer shall meet the additional requirements specified by the Principal (e.g. local or national regulations). When the MESC buying description specifies sour service the weld metal and heat effected zone of all valve welds, including tack welds, shall satisfy the requirements of NACE MR0175.

6.3.3 Hard facings, applied through welding, shall have a minimum finished thickness of 1.0 mm (ref. ISO 15761 section 5.4.6.1).

6.3.4 Spray and fused and D-gun deposit layers are acceptable, provided manufacturer/supplier supplies proof of previous approval by Shell for proposed method.

6.3.5 13 Cr and austenitic stainless steel deposit welding on carbon steel base material, without a buffer layer, is not acceptable, unless. manufacturer/supplier supplies proof of previous approval by Shell for proposed welding method.

6.3.6 Internal valve parts of a martensitic (13 Cr) material shall not be tack welded.


SPE 77/101 Page 10 of 13

.

7. (7, B8) MARKING

7.1 (7.1) Each valve shall be marked with the identification code number as specified in the relevant MESC description. The marking shall be applied by die-stamping one flange rim or, for welding end or threaded ends valves, the valve body.

7.2 (6.1, 7.4 & Table 11)

Hard-facing trim combination number (CN) shall be identified. For Combination Numbers not listed in tables 11 and 12 a manufacturer's code may be used.

7.3 (7.2) Body / cover castings and forging shall have the charge or heat number and heat treatment batch cast or stamped in the material.

7.4 (7.2) Stamping shall be done by means of a low-stress die stamp or alternatively in a low-stress area.

7.5 (7.2.2) In case it is physically impossible to apply the required marking, it may be acceptable to apply electrochemical etching or marking on a durable, securely affixed metal tag.

7.6 (7) The PED replaces existing pressure equipment legislation in European countries, is mandated by European law (European Directive: 97/23/EC).

Valves supplied to end users in European member states and countries in the European Free Trade Association (EFTA) area shall demonstrate full compliance with the Pressure Equipment Directive (PED) and be marked with the following 1) : - CE marking, - PED fluid group 2) . - PED conformity assessment module applied.

Notes: 1. The above requirements are applicable only for valves falling in Conformity Assessment Categories I, II, III and IV. 2. Determination of fluid group according to directive 67/548/EEC.

- Year of manufacture.


SPE 77/101 Page 11 of 13

.

8. (8, B5, B7) TESTING AND INSPECTION

8.1 (8.1, B7, C3)

PRESSURE TESTING

8.1.1 (8.1.1.2, B.7.3 & C.3.2.2)

For carbon steel valves and low alloy steel valves the hydrostatic test fluid shall be potable water with a chloride content of maximum 200 mg/kg. Austenitic and duplex stainless steel valves and valves made of 9% nickel alloy shall be hydrostatic tested with potable water with a chloride content of 50 mg/kg or less. These valves shall be flushed with condensate or de-mineralized water (chloride content of 2 mg/kg maximum) immediately after the hydro test. All valves shall be drained immediately after the test and shall be thoroughly dried immediately after draining.

8.1.2 (8.1.2.3 & table 14)

Minimum test durations for hydrostatic or pneumatic testing shall comply with:

Nominal valve size DN

Shell body test (8.1.2)

Seat test metal seated valves (table 15)

Seat test for elastomeric or polymeric seated valves.

Back seat test for gate and globe valves (8.1.5)

Up to and including DN100

60 S 60 S 60 S 60 S

8.1.3 When, due to temperature change, the applied pressure changes excessively the test duration timing shall begin after the pressure has stabilized.

8.2 (8.2) INSPECTION

8.2.1 The maximum operating forces and torques (BTO, RT, ETO, BTC, ETC) of metal seated valves shall be based on a differential pressure equal to 50% of the allowable (rated) cold working pressure of the valve body.

8.2.2 The maximum operating torque shall not exceed 350 Nm.


SPE 77/101 Page 12 of 13

.

8.3 POTENTIALLY EXPLOSIVE ATMOSPHERES (ATEX) CERTIFICATION

8.3.1 Regardless of whether or not a valve is used in, or in relation to, a potential explosive environment, or not, the manufacturer is under obligation to assess hazards of any kind which may occur through operation according to regulations but also through a rationally foreseeable misuse of his valve.

8.3.2 The manufacturer shall take appropriate measures and/or safety precautions and controls to minimize hazards risks.

8.3.3 The manufacturer shall carry out a risk assessment in accordance with European Council Directive 94/9/EC. The following standards may be used as guidance: EN 1127-1, EN 12874, EN 13463-1 and PrEN 13463-5.

8.3.4 For both non-electrically operated valves and electrically operated valves all ignition sources named in European Directive 94/9/EC shall be taken into consideration during the risk assessment.

8.3.5 Particular attention shall be paid to the following ignition sources: mechanically and/or electrically produced sparks, hot surfaces and electrostatic discharge.

8.3.6 The manufacturer shall be able to provide an EC certificate demonstrating that the valves Technical Construction File (TCF) is in compliance with the requirements of European Council Directive 94/9/EC Annex VIII section 3, module A.

9. DISCLAMERS

9.1 It is the responsibility of the manufacturer to assure that his product is fit for purpose and fully meets the design criteria specified in the MESC buying descriptions and MESC additional requirements specified in the purchase order.

9.2 The manufacturer shall immediately notify the Principal in writing should any conflict occur, error, omission or discrepancy appear in the provided information.

9.3 In case of conflict between the drawings and/or specifications and the industry codes and standards referenced in the purchase order the manufacturer shall present the differences to the Principals representative for resolution.


SPE 77/101 Page 13 of 13

.

10 (9, B9) PREPARATION FOR DESPATCH

10.1 The valve internals shall be thoroughly cleaned and dried and the surfaces shall be free from: - hydrostatic test fluids, - cleaning agents, - adhered scale, weld spatter, loose particles or fibres, - organic substances, e.g. grease, oil, paint and sealant.

10.2 (9.3) Surface treatments of pressure containing valve components to prevent corrosion during storage prior to and during manufacture with a single primer coat (maximum 25 microns thickness) or phosphate treatment is acceptable provided these preservations do not hide any porosity.

10.3 (9.3) Carbon and low alloy steel valves shall be painted or coated in accordance with the manufacturers standard.

10.4 (9.3) High alloy steel, nickel alloy and nickel / copper alloy valves shall not be painted, unless otherwise stated in the project specification and/or purchase order.

10.5 (9.4) Machined and threaded surfaces shall be coated with a easily removable rust protective fluid e.g. Shell ENSIS MD or equivalent.

10.6 (9.5) Valve body ends shall be covered with close fitting protectors (e.g. plastic caps) to protect the machined parts and prevent ingress of dirt and moisture for at least one year when stored outside.

10.7 (9.8) Prior dispatch/shipment valves shall be properly packaged to ensure protection against ingress of moisture, rainfall, (sea) water splash and dirt.

INTRODUCTIONThe purpose of this MESC additional requirement is to establish requirements for steel wedge gate and globe valves (both including bellows-sealed types) and check valves in nominal sizes DN 100 and smaller, designed to ISO 15761 with flanged, butt weldNORMATIVE REFERENCESThe application of bellows stem seals in gate and globe valves shall be limited to a nominal valve size of DN 100 maximum.The valve manufacturer shall prove that the bellows of a standard bellows sealed on/off gate valve and globe valve will exceed a minimum life time of 3000 cycles by providing bellows fatigue testing records.CLOSURE MEMBERS (ORTURATORS)Gate valve wedge

MARKINGTESTING AND INSPECTION

Documents

MESC Specification - FKM