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1、 i BS 1552 : 1995 Contents Page Committees responsibleInside front cover Forewordii Specification 1Scope1 2Normative references1 3Definitions1 4Materials1 5Design2 6Manufacture3 7Connections3 8Leak tightness3 9Nominal flow rate3 10Mechanical performance3 11Endurance3 12Fire resistance4 13Operational
2、 data4 14Marking4 Annexes A(informative) Examples of application5 B(normative) Test methods7 C(informative) Equivalent gas rate10 Tables 1Minimum torque to unscrew niting nuts2 2Torque and bending moment values3 Figures A.1 Typical examples of applications5 B.1Paint scratch test apparatus8 List of r
3、eferencesInside back cover BS 1552 : 1995 ii Foreword This British Standard has been prepared under the direction of the Engineering Sector Board and covers valves outside the scope of prEN 331 which is being prepared by CEN/TC 236. It supersedes BS 1552 : 1989, which is withdrawn. Its scope differs
4、 from that of BS 1552 : 1989, as it covers only open bottomed taper plug valves. Compliance with a British Standard does not of itself confer immunity from legal obligations. BS 1552 : 1995 1 1)1 mbar = 100 N/m2 = 100 Pa. Specification 1 Scope This British Standard specifies the requirements and met
5、hods of test for the design and performance of manually operated open bottomed taper plug valves, operating at a declared working pressure of up to 200 mbar1)on 1st, 2nd and 3rd family gases. Valve sizes covered are up to and including size R2 and a maximum bore of 50 mm or equivalent free area. 2 N
6、ormative references This British Standard incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition
7、cited applies: any subsequent amendments to or revisions of the cited publication apply to this British Standard only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 3 Definitions
8、For the purposes of this British Standard the following definitions apply. 3.1 valve A device which admits or closes the gas flow by movement of a closure member. NOTE. A valve is termed manually operated if the operation can be directly performed by the user. 3.2 open bottomed taper plug valve A va
9、lve with a taper plug closure member and open bottomed body. NOTE. Examples of applications are given in annex A and are illustrated in figure A.1. 3.3 closure member The moving part of the valve that effects opening and closing. 3.4 declared flow rate The flow rate, at the fully open position, decl
10、ared by the manufacturer, using air at a pressure differential across the valve of 1.0 mbar. NOTE 1. Air at standard density and pressure has a relative density of 1. NOTE 2. A method of calculating the equivalent gas rate is given in annex C. 4 Materials 4.1 Body, closure member and its retaining p
11、arts The body, closure member and its retaining parts shall be made of a metallic material with a melting point in excess of 425 C. Zinc alloys shall not be used for these components. 4.2 Zinc alloys Where zinc alloys are used for components other than those specified in 4.1, the following condition
12、s shall apply. a) The alloys shall conform to the specification of alloy A given in BS 1004. b) The castings shall be manufactured in accordance with BS 5338. c) The parts shall not be subjected to a temperature higher than 80 C. 4.3 Corrosion resistance 4.3.1 General For all parts of the valve, cor
13、rosion resistance shall be achieved either by the use of corrosion-resistant materials or by means of a protective coating, e.g. paint. Sealing surfaces of the valve shall be made from corrosion-resistant materials. No part of the valve shall corrode to an extent that would affect its safe and corre
14、ct operation. Conformity shall be checked in accordance with 4.3.2 and 4.3.3. 4.3.2 Scratch resistance Those parts of the valve that are coated for protection and not solely for decoration shall be tested as specified in B.1, both before and after the humidity tests specified in B.2. There shall be
15、no penetration of the protective coating by the ball. 4.3.3 Resistance to humidity Following the test in B.2 the valve shall conform to the following. a) No part of the valve shall show signs of undue corrosion, and coated surfaces shall not show signs of bubbling or blistering when viewed with the
16、naked eye. b) Those parts of the valve, the corrosion of which could adversely affect the continued safe working of the valve, shall not show any signs of corrosion. BS 1552 : 1995 2 4.4 Operation at low temperature Where a valve is declared to operate at a temperature below 0 C, it shall conform to
17、 clause 8 and 10.1 after having been maintained at the declared minimum temperature, with inlet and outlet parts open to atmosphere, for 24 h. 4.5 Accelerated ageing Following the accelerated ageing test given in B.3, the valve shall conform to clause 8 and 10.1 at (205) C. 5 Design 5.1 Set position
18、s When a valve is set to any specific position it shall remain there. 5.2 Handles Except in the case of nursery union cocks, the handle or lever shall be securely attached. There shall be provision to enable the installer to remove and replace the handle or lever using commercially available tools.
19、5.3 Wall thickness The wall thickness from any gasway to atmosphere or to any holes connected to atmosphere shall be not less than 1 mm. 5.4 Dismantling in service There shall be ready access to the plug for servicing, using tools which are readily available commercially, and the valve shall be so c
20、onstructed that incorrect assembly is both difficult and obvious when tested in accordance with B.4. The valve shall conform to 8.1 following the serviceability test. 5.5 Assembly 5.5.1 Niting washers shall be flat. 5.5.2 The washer seating of the body shall be machined square with the axis of the b
21、ore. NOTE. The moving parts should adjusted to give a smooth action without unevenness. 5.5.3 The screwed portion of the plug which projects beyond the nut securing the niting washer shall not be burred over. The nut shall be a spanner-tight fit over the whole length of the spigot and shall conform
22、to 5.5.5. 5.5.4 When tested in accordance with B.5, the minimum torque to unscrew the niting nut shall be not less than given in table 1. Table 1. Minimum torque to unscrew niting nuts Nominal size of valveTorque Nm 0.17 0.34 0.62 ?0.90 11.25 11.70 14.10 27.90 5.5.5 It shall not be possible to loose
23、n the fastener without the use of a tool. 5.6 Operation Meter controls for use in domestic applications shall close from the fully open position in a quarter turn. For 1st and 2nd family gas installations there shall be provision for locking the valve in the OFF position. For other single outlet val
24、ves which are operated by a rotating closure member, the valve shall close in a clockwise direction. If the rotation from open to close is a quarter turn and if the manual actuator is detachable, the end of the closure member shall have a raised or recessed line to indicate direction of gas flow. If
25、 more than a quarter turn is required to close the valve, the closing direction shall be indicated. 5.7 Open and closed positions The fully open and closed positions of valves shall be clearly recognizable and the closed position(s) shall be limited by a fixed non-adjustable stop(s). For valves whic
26、h are operated by a lever or handle, the lever or handle shall be arranged such that it is: a) at right angles to the direction of the outlet flow for the closed position; and b) parallel with the direction of the outlet flow for the open position. 5.8 Compensation for wear 5.8.1 Valves shall be des
27、igned to compensate for wear (see figure A.1). 5.8.2 Valves for use with 3rd family gases shall have a means for providing compensation for wear, e.g. spring loading, without the need for manual adjustment. BS 1552 : 1995 3 6 Manufacture All components of valves shall be of sound manufacture, free f
28、rom burrs and clean, e.g. free from swarf and core sand. They shall also be free from sharp edges and corners which could cause damage, injury or incorrect operation. 7 Connections 7.1 Only commercially available tools shall be required for making connections. 7.2 Where valves are provided with thre
29、aded connections, these connections shall conform to: a) BS 21; b) designation G of BS 2779; c) BS 746 for the outlet of meter control valves. 7.3 Compression fittings shall conform to BS 864 : Part 2 or BS 2051 : Part 2. Non-symmetrical olives shall not be used. 7.4 Flange connections shall conform
30、 to the manufacturers specification. 7.5 Capillary joints shall conform to BS 864 : Part 2 or BS 2051 : Part 2. 8 Leak tightness 8.1 General The valve shall be leak tight and shall be considered to be so if it meets the requirements of 8.2 and 8.3 at an internal air pressure of 300 mbar. 8.2 Externa
31、l leak tightness When tested in accordance with B.6, the leakage rate shall not exceed 20 cm3/h. 8.3 Internal leak tightness When tested in accordance with B.7, the leakage rate shall not exceed 20 cm3/h. 9 Nominal flow rate When measured in accordance with B.8, the corrected flow shall be not less
32、than the declared flow rate, for a differential pressure of 1 mbar. 10 Mechanical performance 10.1 Ease of operation When tested in accordance with B.9, the maximum and minimum torque applied to operate the valve shall be within the limits declared by the manufacturer. 10.2 Mechanical strength The v
33、alve shall remain functional when tested as specified in B.10 and B.11 using the values given in table 2. The leakage rates given in clause 8 shall not be exceeded and there shall be no distortion or cracking. When a control has provision for mounting, e.g. fixing lugs, tapped holes or pressed steel
34、 fixing brackets, this fitting shall be used to hold the control while the mechanical strength tests are carried out. Spanner flats, if provided, shall be used to hold the control when carrying out the test described in B.10. Table 2. Torque and bending moment values Nominal inlet sizeTorqueBending
35、moment Pipe thread or maximum bore Tube outside diameter mmmmNmNm 61525 86 and82035 1010 and 123570 151550105 ?202285225 12528125340 132160475 140200610 2502501100 11 Endurance 11.1 Valves selected for an endurance test shall be in a new condition. They shall be checked for conformity to clauses 8 a
36、nd 9 and 10.1 before being subjected to the endurance test. Two valves shall be subjected to an endurance test comprising the cycling test and static test specified in B.12, after which they shall still conform to clauses 8 and 9 and 10.1. 11.2 A valve that is declared to operate below 0 C shall con
37、form to 4.4 after having successfully completed the endurance test required by 11.1. 11.3 Following the endurance test required by 11.1 and 11.2, as appropriate, the valve shall conform to 5.5.4 and 5.5.5. BS 1552 : 1995 4 12 Fire resistance Meter controls and other valves which are declared to be f
38、ire resistant shall not melt nor show any sign of deformation during the test specified in B.13, and the total leakage, i.e. let-by and soundness, from each valve shall not exceed 0.14 m3/h at an internal air pressure of 50 mbar. After cooling to room temperature, the total leakage shall remain with
39、in this limit. It shall then be possible to close the open valve by use of the handle or a commercially available spanner or wrench, and the total leakage through the closed valve shall not exceed 0.14 m3/h. 13 Operational data The manufacturer shall state: a) the working temperature range of the bo
40、dy for which the valve has been designed; b) the gas family or families for which the valve is suitable; c) the declared flow rate and differential pressure; d) the working life of the valve (minimum 300 cycles); e) working gas pressure range (in mbar); f) materials specification including lubricant
41、s; g) operating torque (minimum and maximum); h) whether the valve is fire resistant; i) overall dimensions and connections, and, where applicable, details of flanges; j) direction of flow. 14 Marking 14.1 Each valve shall be marked with the manufacturers name or trade mark and date code. 14.2 Valve
42、s that are designed for uni-directional operation shall be marked with the direction of flow, unless this is obvious. 14.3 All marking shall be easily visible and indelible. Conformity shall be checked by ensuring that the marking remains legible and secure subsequent to the tests specified in B.3 a
43、nd B.12 (accelerated ageing test and endurance). 14.4 Each consignment shall contain the operational data given in 13a, 13b, and 13e. 5 BS 1552 : 1995 Union cock: drop fanUnion cock: rigid fan Nursery union cockUnion cock: diamond head Figure A.1. Typical examples of applications Annexes Annex A (in
44、formative) Examples of application NOTE. The following examples of application are illustrated in figure A.1. A.1 Meter control cock A meter control cock is intended for use on the service pipe to a meter. The inlet end is screwed internally with an RCthread of appropriate size conforming to BS 21.
45、The outlet end embodies a union boss threaded in accordance with BS 746. The range of sizes is from in to 2 in. A.2 Main cock A main cock is intended for use as a control valve on pipe lines. One end is screwed internally and the other end screwed externally, each in accordance with BS 21. The range
46、 of sizes is from in to 2 in. A.3 Union cock A union cock is intended for use as a control valve on pipe lines. The inlet end is screwed internally and the outlet end embodies a union with either internal or external threads, in each case in accordance with BS 21 . The range of sizes is from in to 1
47、 in. A.4 Nursery union cock A nursery union cock is the same as a union cock, but with shrouding and a detachable key. The sizes are in and in. BS 1552 : 1995 6 Meter control cock with washered union Main cockEnlarged view showing protrusion of plug beyond taper bore in body Meter control cock or ma
48、in cock with tapping for locking screw Figure A.1. Typical examples of applications (concluded) BS 1552 : 1995 9 B.10.3 Flared compression connections Using a short length of steel tube with a flared end, apply the torque specified in table 2 according to the largest tube that can be used with the n
49、ut and proceed as described in B.10.1. Discount any deformation of the cone seating or mating surfaces that is consistent with the torque applied. B.10.4 Flanged connections Connect the appropriate mating flange, with the test pipe attached, to the valve inlet and/or outlet as applicable. Apply the test torque as described in B.10.1. B.10.5 Union connections Replace the nut and liner with a one-piece test connection and replace any non-metallic seal with a soft copper seal. Screw the test piece onto the valve and proceed as described in B.10.1. B.11 Bending