1、BRITISH STANDARDBS 7438:1991Specification forSteel and copper alloy wafer check valves,single disk,spring-loaded typeBS 7438:1991This British Standard,having been prepared under the direction of the Piping Systems Components Standards Policy Committee,was published under the authority of the Standar
2、ds Board and comes into effect on 31 May 1991 BSI 08-1999The following BSI references relate to the work on this standard:Committee reference PSE/7Draft for comment 90/75853 DCISBN 0 580 19614 3Committees responsible for this British StandardThe preparation of this British Standard was entrusted by
3、the Piping Systems Components Standards Policy Committee(PSE/-)to Technical Committee PSE/7,upon which the following bodies were represented:Amalgamated Engineering UnionAssociation of Bronze and Brass FoundersAssociation of Building Component ManufacturersBritish Chemical Engineering Contractors As
4、sociationBritish Foundry AssociationBritish Gas plcBritish Maritime TechnologyBritish Plumbing Fittings Manufacturers AssociationBritish Valve and Actuator Manufacturers AssociationChartered Institution of Building Services EngineersCopper Development AssociationDepartment of the Environment(Propert
5、y Services Agency)Electricity Supply Industry in United KingdomEnergy Industries CouncilEngineering Equipment and Materials Users AssociationGAMBICA(BEAMA Ltd.)Health and Safety ExecutiveInstitute of British FoundrymenInstitution of Chemical EngineersInstitution of Gas EngineersInstitution of Mechan
6、ical EngineersInstitution of Water and Environmental ManagementLiquefied Petroleum Gas Industry Technical Association(UK)Pipeline Industries GuildSociety of British Gas IndustriesSociety of British Water IndustriesWater Companies AssociationWater Services Association of England and WalesWest Midland
7、s CBIAmendments issued since publicationAmd.No.DateCommentsw w w.b z f x w.c o mBS 7438:1991 BSI 08-1999iContentsPageCommittees responsibleInside front coverForewordiiSection 1.General1Scope12Definitions13Type14Nominal sizes15Nominal and Class pressure designations16Pressure/temperature ratings17Dim
8、ensions and tolerances2Section 2.Design and operation8Design49Operation4Section 3.Materials10Optional requirements511Body material512Disk,spring,spring retainer materials513Identification plates5Section 4.Testing14Production pressure testing615Test certificate6Section 5.Marking and packaging16Body m
9、arkings717Packaging7Appendix A Information to be supplied by the purchaser8Figure 1 Typical wafer check valve for use with PN flanges2Figure 2 Typical wafer check valve for use with Class designated flanges3Table 1 Dimensions and tolerances of wafer check valves for use with PN flanges(type A)2Table
10、 2 Dimensions and tolerances of wafer check valves for use with Class designated flanges(type B)3Publication(s)referred toInside back coverw w w.b z f x w.c o mBS 7438:1991ii BSI 08-1999ForewordThis British Standard has been prepared under the direction of the Piping Systems Components Standards Pol
11、icy Committee and at the time of publication of this British Standard no corresponding international standard exists.Face-to-face dimensions comply with DIN 3202 and tolerances comply with BS 5155.Body outside diameters for wafer check valves for use with Class designated flanges are consistent with
12、 the dimensions of centring ring outside diameters of Table 1 of BS 3381:1989 and those for use with PN flanges are consistent with the dimensions of centring ring outside diameters of Table 1 of BS 4865-2:1989.Product certification.Users of this British Standard are advised to consider the desirabi
13、lity of third party certification of product conformity with this British Standard based on testing and continuing surveillance,which may be coupled with assessment of a suppliers quality systems against the appropriate Part of BS 5750.Enquiries as to the availability of third party certification sc
14、hemes will be forwarded by BSI to the Association of Certification Bodies.If a third party certification scheme does not already exist,users should consider approaching an appropriate body from the list of Association members.A British Standard does not purport to include all the necessary provision
15、s of a contract.Users of British Standards are responsible for their correct application.Compliance with a British Standard does not of itself confer immunity from legal obligations.Summary of pagesThis document comprises a front cover,an inside front cover,pages i and ii,pages 1 to 8,an inside back
16、 cover and a back cover.This standard has been updated(see copyright date)and may have had amendments incorporated.This will be indicated in the amendment table on the inside front cover.w w w.b z f x w.c o mBS 7438:1991 BSI 08-19991Section 1.General1 ScopeThis British Standard specifies requirement
17、s for the pressure/temperature ratings,dimensions,design,materials,testing and marking of steel and copper alloy wafer check valves,single disk,spring-loaded type in nominal sizes DN 15 to DN 100.NOTE 1To assist the purchaser,Appendix A lists information which should be supplied when ordering wafer
18、check valves.NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover.2 DefinitionsFor the purposes of this British Standard,the following definitions apply.2.1 wafera valve primarily intended for clamping between pipe flanges using through bolting2.2 fac
19、e-to-face dimensionthe distance between two planes,perpendicular to the body axis located at the extremities of the body end ports2.3 nominal size(DN)a numerical designation of size which is common to all components in a piping system other than those components designated by outside diameter or by
20、thread size.It is a convenient round number for reference purposes and it is normally only loosely related to manufacturing dimensionsNOTE 1Nominal size is designated by the letters DN followed by a number.NOTE 2This definition is identical with that given in ISO 6708.2.4 nominal pipe size(NPS)a des
21、ignation of size in inches which is common to all components in a piping system other than those components designated by outside diameter.It is a convenient number for reference purposes and it is normally only loosely related to manufacturing dimensionsNOTE 1Nominal pipe size is designated by the
22、letters NPS followed by a number.NOTE 2NPS is used only in association with the“Class”rating system.2.5 nominal pressure(PN)a numerical designation which is a convenient rounded number for reference purposesall the equipment of the same nominal size(DN)designated by the same PN number shall have com
23、patible mating dimensionsNOTE 1The maximum allowable working pressure depends on materials,design and working temperatures,and should be selected from the tables of pressure/temperature ratings given in the appropriate standards.NOTE 2Nominal pressure is designated by the letters PN followed by the
24、appropriate reference number.NOTE 3This definition is identical with that given in ISO 7268.2.6 classa numerical designation for reference purposesNOTE 1The maximum allowable working pressure depends on materials,design and design temperature and should be selected from the table of pressure/tempera
25、ture ratings given in the appropriate standards.NOTE 2Class is designated by the word Class followed by the appropriate reference number.3 TypeWafer valves shall have a single disk,be spring-loaded,have metal or resilient seatings and shall be one of the following:a)type A for use with PN flanges(se
26、e 7.1);b)type B for use with Class designated flanges(see 7.2).4 Nominal sizesValves shall be of the following nominal sizes(DN)or nominal pipe sizes(NPS):NOTENon-preferred sizes are shown in parentheses.5 Nominal and Class pressure designations5.1 Nominal pressure(PN)designationsThe nominal pressur
27、e(PN)designations for valves specified by nominal size(DN)shall be as follows:PN6,PN10,PN16,PN25,PN40.5.2 Class pressure designationsThe Class pressure designations for valves specified by nominal pipe size(NPS)shall be as follows:Class 150,Class 300.6 Pressure/temperature ratingsPressure/temperatur
28、e ratings shall be as specified in BS 4504-3.1 and BS 4504-3.3 for type A valves,or BS 1560-3.1 and BS 1560-3.3 for type B valves.NOTE 1For metal seated valves the temperatures will be restricted by the material of the spring.NOTE 2For resilient seated valves temperatures will be restricted by the m
29、aterial of the seat.DN15 20 25(32)4050(65)80 100NPS#1(1!)12(2)34w w w.b z f x w.c o mBS 7438:19912 BSI 08-19997 Dimensions and tolerances7.1 Dimensions and tolerances of wafer check valves for use with PN flanges(type A)Dimensions of valve bodies shown in Figure 1 for use with PN flanges shall be as
30、 given in Table 1.Table 1 Dimensions and tolerances of wafer check valves for use with PN flanges(type A)Figure 1 Typical wafer check valve for use with PN flangesNominal size of valveFace-to-face dimensionL 1Body outside diameter DoMax.port diameter DiBody diameter DxFlange thickness TDNNPSPN 10PN
31、16PN 25PN 40PN 6inmmmmmmmmmmmmmm15165353452938420#19636355364542512273736544.5555(32)(1!)288484785568540131.594948866795502401091099877938(65)24612912911898.51138803501441441341121288100460164170154130.51489+00.8+00.8+00.8w w w.b z f x w.c o mBS 7438:1991 BSI 08-199937.2 Dimensions and tolerances of
32、 wafer check valves for use with Class designated flanges(type B)Dimensions of valve bodies shown in Figure 2 for use with Class designated flanges shall be as given in Table 2.Table 2 Dimensions and tolerances of wafer check valves for use with Class designated flanges(type B)Figure 2 Typical wafer
33、 check valve for use with Class designated flangesNominal size of valveFace-to-face dimension L 1Body outside diameter DoMax.port diameter DiDNNPSClass 150Class 300inmmmmmmmm152547.6542320#31.557.266.72825135.566.77334(32)(1!)4076.282.6444014585.795.35050256104.8111.161(65)(2)63123.8130.27680371136.
34、5149.292100480174.6181.0112+00.8+00.8w w w.b z f x w.c o mBS 7438:19914 BSI 08-1999Section 2.Design and operation8 Design8.1 GeneralBodies shall be of the wafer style and of one piece construction.8.2 Face-to-face dimensionsFace-to-face dimensions shall be as given in Table 1 and Table 2,as appropri
35、ate.NOTEThe dimensions are in accordance with DIN 3202,sheet 3,series K4 and series K5 for Table 1 and Table 2,respectively.8.3 SeatThe valve seat shall be integral with the body.8.4 GuidesThe body shall contain a minimum of four disk guides.The guides shall be integral with,or welded to,the body.8.
36、5 DiskThe disk shall be supplied with an integral seating surface.NOTEWhen specified by the purchaser,the disk or body may be fitted with a resilient seating surface(see 10.4 and Appendix A).8.6 SpringThe spring shall be of helical form with closed ends.8.7 Spring retainerThe spring retainer shall:a
37、)locate the end of the spring;b)totally enclose the whole of the spring in its compressed state;c)act as a stop for the disk in the fully open position.After assembly to the body,the spring retainer shall be securely locked in position.The retainer shall not be fastened to the body by use of screws.
38、NOTEA typical method of assembly of the retainer to the body is by engaging slots in the disk guides.8.8 Valves for potable waterWhen used under the conditions for which they are designated,non-metallic products in contact with or likely to come into contact with potable water shall comply with the
39、requirements of BS 6920-1:1990.NOTE 1Non-metallic products for installation and use in the United Kingdom which are verified and listed under the UK Water Fittings Byelaws Scheme are deemed to satisfy the requirements of this clause.Details of the Scheme are obtainable from the Water Research Centre
40、 Byelaws Advisory Service,660 Ajax Avenue,Slough SL1 4BG.Non-metallic products approved by the Department of the Environment Committee on Chemicals and Materials of Construction for use in Public Water Supply and Swimming Pools are considered free from adverse health effects for the purposes of comp
41、liance with this clause.NOTE 2A list of approved chemicals and materials and details of the approvals scheme is available from the Secretary of the Committee at the Department of the Environment,Water Division,Romney House,43 Marsham Street,London SW1 3PY.9 OperationThe valve shall automatically che
42、ck reverse flow when installed in any attitude.NOTEValve opening pressures and data relating to flow and pressure loss are outside the scope of this standard.Details should be obtained from the valve manufacturer.w w w.b z f x w.c o mBS 7438:1991 BSI 08-19995Section 3.Materials10 Optional requiremen
43、ts10.1 GeneralIf the purchaser does not indicate his wish to implement any of the options included in 10.2 and 10.3 at the time of the enquiry and order,the manufacturer shall comply with clause 11 and 12.10.2 Body materialThe material used for the body shall be selected by the purchaser.10.3 Disk,s
44、pring,spring retainer materialThe material used for the disk,spring and spring retainer shall be selected by the purchaser.10.4 Resilient seatsWhen resilient seats are required,the purchaser shall specify his requirements to the manufacturer(see 8.5 and Appendix A).NOTEThe materials of resilient sea
45、ts are not specified in this standard.11 Body materialIf the purchaser wishes to take up the optional requirements given in clause 10,such requirements shall be specified and documented at the time of the enquiry and/or order.In the absence of such information,the manufacturer shall supply in accord
46、ance with the following.The material used for the body shall be one of the following:a)12%chromium steel complying with BS 1503 or 13%chromium steel complying with BS 1504;b)austenitic steel type 316 complying with BS 4504-3.1 or BS 1560-3.1;c)copper alloy complying with BS 4504-3.3 or BS 1560-3.3.1
47、2 Disk,spring,spring retainer materialsIf the purchaser wishes to take up the optional requirements given in clause 10,such requirements shall be specified and documented at the time of the enquiry and/or order.In the absence of such information,the manufacturer shall supply in accordance with the f
48、ollowing.The material used for the disk,spring and spring retainer shall be an austenitic steel type 316 complying with BS 4504-3.1 or BS 1560-3.1.13 Identification platesIdentification plate material and its attachment,where these are supplied,shall be corrosion resistant.w w w.b z f x w.c o mBS 74
49、38:19916 BSI 08-1999Section 4.Testing14 Production pressure testing14.1 GeneralValves shall be pressure tested in accordance with BS 6755-1.14.2 Seat test leakage ratesThe maximum permissible seat test leakage rates shall be as follows:a)metal to metal seats,rate D;b)resilient seats,rate A.14.3 Test
50、 durationsThe minimum durations of the tests shall be as follows:a)hydrostatic tests,60 s;b)pneumatic tests,DN 15 to DN 40,15 s;DN 50 to DN 1 000,60 s.15 Test certificateIf required,the manufacturer shall supply a certificate stating that the valves have been tested in accordance with this standard