[www.staffempire.com]-MSS SP-117-2006 Bellows Seals for Globe and Gate Valves.pdf

MSS SP-117-2006 www.mss-hq.org Standard Practice Developed and Approved by the Manufacturers Standardization Society of the Valve and Fittings Industry,Inc.127 Park Street,NE Vienna,Virginia 22180 Phone:(703)281-6613 Fax:(703)281-6671 e-mail:infomss.hq.org Bellows Seals for Globe and Gate Valves MSS Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MSS STANDARD PRACTICE SP-117 iThis 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 result of the efforts of competent and concerned volunteers to provide an effective,clear,and non-exclusive specification that will benefit the industry as a whole.This MSS Standard Practice 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 manufac-ture,sale,or use of products not conforming to the Standard Practice.Mandatory conformance is established only by reference in a code,specification,sales contract,or public law,as applicable.Unless otherwise specifically noted in this MSS SP,any standard referred to herein is identified by the date of issue that was applicable to the referenced standard(s)at the date of issue of this MSS SP.(See Annex B.)In this Standard Practice all notes,annexes,tables,and figures are construed to be essential to the understanding of the message of the standard,and are considered part of the text unless noted as supplemental.All appendi-ces appearing in this document are construed as supplemental.Supplemental information does not include mandatory requirements.Substantive changes in this 2006 edition are“flagged”by parallel bars as shown on the margins of this paragraph.The specific detail of the change may be determined by comparing the material flagged with that in the previous edition.Any part of this standard may be quoted.Credit lines should read extracted from MSS SP-117,2006 with permission of the publisher,the Manufacturers Standardization Society.Reproduction prohibited under copyright convention unless written permission is granted by the Manufacturers Standardization Society of the Valve and Fittings Industry Inc.Originally Approved April,1996 Copyright,1996 by Manufacturers Standardization Society of the Valve and Fittings Industry,Inc.Printed in U.S.A.Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-标准分享网 w w w.b z f x w.c o m 免费下载MSS STANDARD PRACTICE SP-117 iiTABLE OF CONTENTS SECTION PAGE 1 SCOPE.1 2 MARKING.1 3 DESIGN.1 4 INSPECTION AND TEST.3 5 SHIPPING INFORMATION.4 6 ORDERING INFORMATION.4 FIGURE 1 Typical Bellows Stem Seal Arrangement.5 ANNEX A Definitions.6 ANNEX B Referenced Standards and Applicable Dates.7 Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MSS STANDARD PRACTICE SP-117 1 Bellows Seals for Globe and Gate Valves 2.MARKING2.1 Valves utilizing bellows seals shall have a corrosion-resistant metal identification plate securely attached,giving the following information:a)Bellows seal per MSS SP-117 b)Bellows Material:(insert actual bellows material)Note:If the parent valve elevated pressure-tempera-ture rating is to be derated or service temperature limited due to bellows design limitations,any bellows rated limitations to the parent valve pressure-tempera-ture rating shall be marked as required by the parent valve specification.3.DESIGN3.1 General 3.1.1 The purpose of the bellows seal is to provide a metal barrier between the stem at its point of entry through the pressure boundary and the process fluid within the valve to eliminate stem leakage.The bellows seal is not intended to be a structural member of the valve nor is it considered to be the ultimate pressure containing mechanism of the valve.Thus,the bellows seal is to be designed in conjunction with and not as a substitute for the conventional pressure boundary components normally required.See Figure 1 for an example of a typical valve assembly with bellows seal.3.1.2 Because a conventional pressure boundary mechanism is available to act as the ultimate pressure containing mechanism,latitude is permitted in the design of bellows seals so long as they satisfy the performance and all other requirements of this Standard Practice.3.1.3 Except as specifically noted herein,the rules governing the design of all other valve components found in the parent valve specifications apply.1.SCOPE(1)1.1 This Standard Practice covers requirements for design,materials,fabrication,installation,qualification,examination,testing,and shipment of metal bellows and/or bellows assemblies to be installed in manual and automated on-off globe and gate valves.1.2 This Standard Practice is applicable to metal bellows used in conjunction with steel globe and gate valves which otherwise satisfy the requirements of standards such as API600/ISO10434,API602/ISO 15761,ASME B16.34 and API603.Such standards are referred to herein as the“parent”valve specifications.1.3 This Standard Practice does not apply to non-metallic bellows or bellows made of low melting point materials such as brass,phosphor-bronze,or similar materials.1.4 Except where specifically noted in the text of this Standard Practice,the requirements here are not intended to supersede or replace those requirements of the parent valve standard.This standard specifies additional requirements for those valves utilizing bellows seals.1.5 It is the responsibility of the bellows valve manufacturer to ensure compliance with this Standard Practice.(1)This Standard Practice is not intended for valves developed for and predominantly used in instrument piping systems.Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-标准分享网 w w w.b z f x w.c o m 免费下载MSS STANDARD PRACTICE SP-117 23.2 Pressure-Temperature Ratings 3.2.1 The Pressure-Temperature ratings of ASME B16.34 or other parent specification for the pressure class and body material of the valve apply as well to the bellows seal.The bellows shall with-stand the parent valve class full 1000F rating.The valve manufacturer may choose to derate the bellows seal to some lower pressure rating at elevated temperatures than the pressure-temperature rating of the parent valve.The manufacturer may also apply an elevated temperature limitation due to the bellows limitations.The valve manufacturer shall provide published rating to end user when a derated pressure-temperature rating applies.3.3 Materials 3.3.1 Bellows seal material shall be selected so that the maximum temperature is below the creep range.3.3.2 Acceptable bellows materials are:a)Stainless Steel,Types 321,316L-ASTM A 240/A 312 b)Stainless Steel,Types 304 and 304L-ASTM A 240/A 312 c)Stainless Steel,Type 347-ASTM A 240/A 312 d)Alloy 600-ASTM B 168/B 167 e)Alloy 625-ASTM B 443 f)Alloy 718-ASTM B 670 g)Alloy 400-ASTM B 127/B 165 h)Alloy C22-ASTM B 575/B 622 i)Alloy C276-ASTM B 575/B 622 Other materials may be used with the concurrence of the purchaser.3.3.3 Acceptable materials for the bellows end fittings,including rings,caps or flanges if utilized are:a)Stainless Steel,Types 321,316L-ASTM A 276/A 479 b)Stainless Steel,Types 304 and 304L-ASTMA 276/A 479 c)Stainless Steel,Type 347-ASTM A 276/A 479 d)Alloy 600-ASTM B 564 e)Alloy 625-ASTM B 446 f)Alloy 718-ASTM B 637 g)Alloy 400-ASTM B 164/B 564 h)Alloy C22-ASTM B 574 i)Alloy C276-ASTM B 574 Other materials may be used with the concurrence of the purchaser.3.3.4 The bellows,bellows end fittings and final attachment point such as the stem shall be weld com-patible and have no negative effect on the bellows corrosion resistance.3.3.5 The bellows material shall be free of weld repair.3.4 Bellows Fabrication 3.4.1 The bellows may be constructed by forming individual convolutions from butt welded tube or drawn tube or by welding a series of formed disks together at both the outside diameter and the inside diameter of the individual disks.Forming may be accomplished either mechanically of hydraulically or any other suitable manufacturing method.The bellows type shall be in accordance with the parent valve specification.3.4.2 Precautions must be taken in the fabrication of multi-ply bellows to prevent moisture or other cont-amination between the plies.3.4.3 Bellows may be welded together in series to accommodate the stroke requirements of the valve.Mechanical connections between bellows are not permitted.3.4.4 Appropriate design features must be included to prevent squirm(buckling)of the bellows and to prevent localized contact between the bellows convolutions,valve body and stem which could lead to accelerated wear and premature failure.Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MSS STANDARD PRACTICE SP-117 33.4.5 Material certification of conformance for the bellows and end fittings is required to be furnished by the bellows manufacturer for each shipment if requested by the customer.Material certification should also be required for the end fittings of the bellows when furnished by the manufacturer.3.5 Stem/Disk or Moving Connection 3.5.1 The bellows,or a ring welded to the end of the bellows at the moving end,shall be attached to the disk/stem of moving componenet be welding.A mecha-nical connection between the stem/disk or moving component and the bellows is not permitted.3.5.2 The bellows shall not be subjected to torsional loads associated with operating the valve.3.6 Fixed Connection 3.6.1 The bellows fixed end shall be welded to the body,the bonnet or to a flange clamped or welded between the body and the bonnet.A mechanical connection to the bellows is not permitted.If welded to the valve body,this weld must be cut in order to perform maintenance of the valve seat.3.7 Bellows Compression-Extension 3.7.1 Appropriate means shall be included in the valve design by the valve manufacturer to prevent compression or extension of the bellows beyond that qualified by the cycle life test.3.8 Bellows Cycle Life 3.8.1 A cycle is defined as fully open to fully closed to fully open.The bellows design shall be qualification tested in accordance with the following table unless otherwise agreed to by the valve manufacturer and end user:Valve Size Minimum Cycle LifeUp to and including Class 800 valves Gate Globe 4”1,000 2,000 Above Class 800 valves 4”1,000 1,000 3.8.2 The suitability of the bellows assembly design shall be demonstrated by means of prototype tests upon representative samples per 4.1.3.9 Bellows Welding 3.9.1 All welding of the bellows and bellows attachment welds must be performed by qualified operators using qualified procedures.All welding qualifications shall be per ASME Boiler and Pressure Vessel Code-Section IX.3.9.2 Bellows welds and bellows attachment welds,if not attached directly to the valve body or bonnet,are excluded from heat treat requirements of the parent specifications.4.INSPECTION AND TEST4.1 Bellows Design and Qualification Testing 4.1.1 The bellows assembly shall be cycle life tested either by cycling in an assembled valve without packing,or in a test rig which replicates the actual installation including the clearance,stroke,loading,pressure and wear couples of the parent valve.When required by the parent valve specification,an optional high temperature test shall be performed as designated in API602/ISO15761.4.1.2 Any variation that constitutes a change in basic design parameters that affect cycle life of the bellows will require requalification by cycle testing(e.g.change in bellow supplier,material specification,number of plies,wall thickness or diameter).A change in overall length or number of convolutions may not require requalification provided that the percentage of bellows movement in both compression and extension is the same or less than that of originally qualified bellows where:Mc=(L1 Lc)x 100/L1 Me=(Le L1)x 100/L1 Where:Mc is the percent of movement in compression L1 is the live length Lc is the compressed length Me is the percent of movement in extension Le is the extended length Copyright MSS Provided by IHS under license with MSSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-标准分享网 w w w.b z f x w.c o m 免费下载MSS STANDARD PRACTICE SP-117 45.SHIPPING INFORMATION5.1 Protection/Marking 5.1.1 Each bellows assembly must be cleaned and packaged to prevent internal moisture or contaimination.5.1.2 Each bellows assembly shall be individually packaged to prevent damage in handling or in transit.5.1.3 Each bellows assembly,if practical,shall be marked to insure proper identification of the material.If it is impractical to mark each assembly,each package must be so marked.6.ORDERING INFORMATION6.1 If the valve manufacturer needs a bellows seal that deviates from this Standard Practice,it is the valve manufacturers responsibility to clearly define such deviation and to furnish information to permit the bellows manufacturer to complete the order.6.2 If no exceptions are to be taken to this Stan-dard Practice,the purchase order need only make reference to MSS SP-117 and specify the following items:a)Valve size b)Pressure class or pressure temperature rating c)Materials and traceability d)Required travel or stroke e)Valve type Globe or Gate f)Packaging requirements g)Bellows fabrication method h)Inspection by valve manufacturer 4.1.3 After welding bellows to fittings and prior to qualification testing,each bellows assembly shall be Helium leak tested and exhibit no detectable leakage using an instrument with sensitivity of 10-6 cc/sec He.4.1.4 Prior to cycle testing each bellows assembly shall be hydrostatic pressure tested at 1.5 times the 1000 F valve design pressure.Each bellows assembly shall be fixed at the length where the valve is in the open position as required at normal valve shell test.The pressure shall be applied on the same side as the valve is designed to operate in service.Water used for testing of stainless stell bellows assemblies shall contain less than 100 ppm chlorides.4.1.5 The frequency of cycling shall take into consideration excessive heat which may be generated by abnormally fast cycling.In no case shall the frequency of cycling exceed one cycle per second.4.1.6 Cycling shall be carried out at ambient temperature and at the 1000F rated pressure of the bellows.The pressure shall be applied in a manner to simulate normal valve shell tests.4.1.7 A minimum of three bellows of each basic design and material selected at random from those produced using the standard production manufacturing processes shall by cycled to achieve the appropriate minimum cycle life requireme