1、BRITISH STANDARD BS 7438:1991 Specification for Steel and copper alloy wafer check valves, single disk, spring-loaded typeBS7438:1991 This British Standard, having been prepared under the directionof the Piping Systems Components Standards Policy Committee, was published underthe authority of the St
2、andards Board and comes intoeffect on 31 May 1991 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference PSE/7 Draft for comment 90/75853 DC ISBN 0 580 19614 3 Committees responsible for this British Standard The preparation of this British Standard was ent
3、rusted by the Piping Systems Components Standards Policy Committee (PSE/-) to Technical Committee PSE/7, upon which the following bodies were represented: Amalgamated Engineering Union Association of Bronze and Brass Founders Association of Building Component Manufacturers British Chemical Engineeri
4、ng Contractors Association British Foundry Association British Gas plc British Maritime Technology British Plumbing Fittings Manufacturers Association British Valve and Actuator Manufacturers Association Chartered Institution of Building Services Engineers Copper Development Association Department o
5、f the Environment (Property Services Agency) Electricity Supply Industry in United Kingdom Energy Industries Council Engineering Equipment and Materials Users Association GAMBICA (BEAMA Ltd.) Health and Safety Executive Institute of British Foundrymen Institution of Chemical Engineers Institution of
6、 Gas Engineers Institution of Mechanical Engineers Institution of Water and Environmental Management Liquefied Petroleum Gas Industry Technical Association (UK) Pipeline Industries Guild Society of British Gas Industries Society of British Water Industries Water Companies Association Water Services
7、Association of England and Wales West Midlands CBI Amendments issued since publication Amd. No. Date CommentsBS7438:1991 BSI 08-1999 i Contents Page Committees responsible Inside front cover Foreword ii Section 1. General 1 Scope 1 2 Definitions 1 3 Type 1 4 Nominal sizes 1 5 Nominal and Class press
8、ure designations 1 6 Pressure/temperature ratings 1 7 Dimensions and tolerances 2 Section 2. Design and operation 8 Design 4 9 Operation 4 Section 3. Materials 10 Optional requirements 5 11 Body material 5 12 Disk, spring, spring retainer materials 5 13 Identification plates 5 Section 4. Testing 14
9、Production pressure testing 6 15 Test certificate 6 Section 5. Marking and packaging 16 Body markings 7 17 Packaging 7 Appendix A Information to be supplied by the purchaser 8 Figure 1 Typical wafer check valve for use with PN flanges 2 Figure 2 Typical wafer check valve for use with Class designate
10、d flanges 3 Table 1 Dimensions and tolerances of wafer check valves for use with PN flanges (type A) 2 Table 2 Dimensions and tolerances of wafer check valves for use with Class designated flanges (type B) 3 Publication(s) referred to Inside back coverBS7438:1991 ii BSI 08-1999 Foreword This British
11、 Standard has been prepared under the direction of the Piping Systems Components Standards Policy Committee and at the time of publication of this British Standard no corresponding international standard exists. Face-to-face dimensions comply with DIN3202 and tolerances comply with BS5155. Body outs
12、ide diameters for wafer check valves for use with Class designated flanges are consistent with the dimensions of centring ring outside diameters of Table 1 of BS3381:1989 and those for use with PN flanges are consistent with the dimensions of centring ring outside diameters of Table 1 of BS4865-2:19
13、89. Product certification. Users of this British Standard are advised to consider thedesirability of third party certification of product conformity with this BritishStandard based on testing and continuing surveillance, which may be coupled with assessment of a suppliers quality systems against the
14、 appropriate Part of BS 5750. Enquiries as to the availability of third party certification schemes 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 o
15、f Association members. A British Standard does not purport to include all the necessary provisions 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 pages T
16、his document comprises a front cover, an inside front cover, pages i and ii, pages1 to 8, an inside back 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.BS743
17、8:1991 BSI 08-1999 1 Section 1. General 1 Scope This British Standard specifies requirements 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 DN15 to DN100. NOTE 1To
18、 assist the purchaser, Appendix A lists information which should be supplied when ordering wafer check valves. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Standard, the following definitions app
19、ly. 2.1 wafer a valve primarily intended for clamping between pipe flanges using through bolting 2.2 face-to-face dimension the distance between two planes, perpendicular to the body axis located at the extremities of the body end ports 2.3 nominal size (DN) a numerical designation of size which is
20、common to all components in a piping system other than those components designated by outside diameter or by thread size. It is a convenient round number for reference purposes and it is normally only loosely related to manufacturing dimensions NOTE 1Nominal size is designated by the letters DN foll
21、owed by a number. NOTE 2This definition is identical with that given in ISO6708. 2.4 nominal pipe size (NPS) a designation 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 purpos
22、es and it is normally only loosely related to manufacturing dimensions NOTE 1Nominal pipe size is designated by the 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
23、number for reference purposes all the equipment of the same nominal size (DN) designated by the same PN number shall have compatible mating dimensions NOTE 1The maximum allowable working pressure depends on materials, design and working temperatures, and should be selected from the tables of pressur
24、e/temperature ratings given in the appropriate standards. NOTE 2Nominal pressure is designated by the letters PN followed by the appropriate reference number. NOTE 3This definition is identical with that given in ISO7268. 2.6 class a numerical designation for reference purposes NOTE 1The maximum all
25、owable working pressure depends on materials, design and design temperature and should be selected from the table of pressure/temperature ratings given in the appropriate standards. NOTE 2Class is designated by the word Class followed by the appropriate reference number. 3 Type Wafer valves shall ha
26、ve 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 (see7.1); b) type B for use with Class designated flanges (see7.2). 4 Nominal sizes Valves shall be of the following nominal sizes (DN) or nominal pipe sizes (NPS
27、): NOTENon-preferred sizes are shown in parentheses. 5 Nominal and Class pressure designations 5.1 Nominal pressure (PN) designations The nominal pressure (PN) designations for valves specified by nominal size (DN) shall be as follows: PN6, PN10, PN16, PN25, PN40. 5.2 Class pressure designations The
28、 Class pressure designations for valves specified by nominal pipe size (NPS) shall be as follows: Class 150, Class 300. 6 Pressure/temperature ratings Pressure/temperature ratings shall be as specified in BS4504-3.1 and BS4504-3.3 for type A valves, or BS1560-3.1 and BS1560-3.3 for type B valves. NO
29、TE 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 material of the seat. DN 15 20 25 (32) 40 50 (65) 80 100 NPS “ # 1 (1!) 1“ 2 (2“) 3 4BS7438:1991 2 BSI 08-1999 7 Dimensions and tole
30、rances 7.1 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 given inTable 1. Table 1 Dimensions and tolerances of wafer check valves for use with PN flanges (type A) Figure 1 Typical wafe
31、r check valve for usewith PN flanges Nominal size of valve Face-to-face dimension L 1 Body outside diameter D o Max. port diameter D i Body diameter D x Flange thickness T DN NPS PN 10 PN 16 PN 25 PN 40 PN 6 in mm mm mm mm mm mm mm 15 “ 16 53 53 45 29 38 4 20 # 19 63 63 55 36 45 4 25 1 22 73 73 65 4
32、4.5 55 5 (32) (1!) 28 84 84 78 55 68 5 40 1“ 31.5 94 94 88 66 79 5 50 2 40 109 109 98 77 93 8 (65) 2“ 46 129 129 118 98.5 113 8 80 3 50 144 144 134 112 128 8 100 4 60 164 170 154 130.5 148 9 +0 0.8 +0 0.8 +0 0.8 BS7438:1991 BSI 08-1999 3 7.2 Dimensions and tolerances of wafer check valves for use wi
33、th 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 check valve for usewith
34、Class designated flanges Nominal size of valve Face-to-face dimension L 1 Body outside diameter D o Max. port diameter D i DN NPS Class 150 Class 300 in mm mm mm mm 15 “ 25 47.6 54 23 20 # 31.5 57.2 66.7 28 25 1 35.5 66.7 73 34 (32) (1!) 40 76.2 82.6 44 40 1“ 45 85.7 95.3 50 50 2 56 104.8 111.1 61 (
35、65) (2“) 63 123.8 130.2 76 80 3 71 136.5 149.2 92 100 4 80 174.6 181.0 112 +0 0.8 +0 0.8 BS7438:1991 4 BSI 08-1999 Section 2. Design and operation 8 Design 8.1 General Bodies shall be of the wafer style and of one piece construction. 8.2 Face-to-face dimensions Face-to-face dimensions shall be as gi
36、ven inTable 1 and Table 2, as appropriate. NOTEThe dimensions are in accordance with DIN3202, sheet3, series K4 and series K5 for Table 1 and Table 2, respectively. 8.3 Seat The valve seat shall be integral with the body. 8.4 Guides The body shall contain a minimum of four disk guides. The guides sh
37、all be integral with, or welded to, the body. 8.5 Disk The 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 (see10.4 and Appendix A). 8.6 Spring The spring shall be of helical form with close
38、d ends. 8.7 Spring retainer The spring retainer shall: a) 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.
39、The retainer shall not be fastened to the body by use of screws. NOTEA typical method of assembly of the retainer to the body is by engaging slots in the disk guides. 8.8 Valves for potable water When used under the conditions for which they are designated, non-metallic products in contact with or l
40、ikely to come into contact with potable water shall comply with the requirements of BS6920-1:1990. 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
41、 Details of the Scheme are obtainable from the Water Research Centre 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
42、are considered free from adverse health effects for the purposes of compliance 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, 4
43、3 Marsham Street, London SW1 3PY. 9 Operation The valve shall automatically check 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.BS7438
44、1991 BSI 08-1999 5 Section 3. Materials 10 Optional requirements 10.1 General If the purchaser does not indicate his wish to implement any of the options included in10.2 and10.3 at the time of the enquiry and order, the manufacturer shall comply with clause11 and12. 10.2 Body material The material
45、used for the body shall be selected by the purchaser. 10.3 Disk, spring, spring retainer material The material used for the disk, spring and spring retainer shall be selected by the purchaser. 10.4 Resilient seats When resilient seats are required, the purchaser shall specify his requirements to the
46、 manufacturer (see8.5 and Appendix A). NOTEThe materials of resilient seats are not specified in this standard. 11 Body material If the purchaser wishes to take up the optional requirements given in clause10, such requirements shall be specified and documented at the time of the enquiry and/or order
47、 In the absence of such information, the manufacturer shall supply in accordance with the following. The material used for the body shall be one of the following: a) 12% chromium steel complying with BS1503 or 13% chromium steel complying with BS 1504; b) austenitic steel type 316 complying with BS
48、4504-3.1 or BS1560-3.1; c) copper alloy complying with BS4504-3.3 or BS1560-3.3. 12 Disk, spring, spring retainer materials If the purchaser wishes to take up the optional requirements given in clause10, such requirements shall be specified and documented at the time of the enquiry and/or order. In
49、the absence of such information, the manufacturer shall supply in accordance with the following. The material used for the disk, spring and spring retainer shall be an austenitic steel type316 complying with BS4504-3.1 or BS1560-3.1. 13 Identification plates Identification plate material and its attachment, where these are supplied, shall be corrosion resistant.BS7438:1991 6 BSI 08-1999 Section 4. Testing 14 Production pressure testing 14.1 General Valves shall be pressure tested in accordance with BS6755-1. 14.2 Seat test leakage rates
