BS 6364-1984 阀门标准 Specification for Valves for cryogenic service.pdf

BRITISH STANDARD BS 63641984 Incorporating Amendments Nos. 1, 2 and 3 Specification for Valves for cryogenic service ICS 23.060.01 Licensed Copy Institute Of Technology Tallaght, Institute of Technology, Tue Aug 22 002712 BST 2006, Uncontrolled Copy, c BSI BS 63641984 This British Standard, having been prepared under the direction of the Mechanical Engineering Standards Committee, was published under the authority of the Board of BSI and comes into effect on 29 February 1984 BSI 05-1999 ISBN 0 580 13786 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Mechanical Engineering Standards Committee MEE/- to Technical Committee MEE/191 upon which the following bodies were represented Amalgamated Union of Engineering Workers Associated Offices Technical Committee Association of Bronze and Brass Founders Association of Hydraulic Equipment Manufacturers British Chemical Engineering Contractors Association British Compressed Gases Association British Gas Corporation British Ship Research Association British Shipbuilders British Valve Manufacturers Association Ltd. Copper Development Association Copper Tube Fittings Manufacturers’ Association Council of Ironfoundry Associations Electricity Supply Industry in England and Wales Energy Industries Council Engineering Equipment and Materials Users Association Gambica BEAMA General Council of British Shipping Greater London Council Health and Safety cutive Institution of Chemical Engineers Institution of Gas Engineers Institution of Mechanical Engineers Institution of Water Engineers and Scientists National Coal Board Society of British Gas Industries Steel Casting Research and Trade Association Water Companies Association Coopted members Amendments issued since publication Amd. No.Date of issueComments 6591April 1991 9431March 1997 10115September 1998 Indicated by a sideline in the margin Licensed Copy Institute Of Technology Tallaght, Institute of Technology, Tue Aug 22 002712 BST 2006, Uncontrolled Copy, c BSI w w w . b z f x w . c o m BS 63641984 BSI 05-1999i Contents Page Committees responsibleInside front cover Forewordii Section 1. General 1Scope1 2Definitions1 3General requirements1 Section 2. Design 4Requirements1 5Materials3 6Non-destructive testing3 7Repair of castings4 Section 3. Testing 8Pressure testing4 9Marking4 Appendix A Cryogenic test5 Appendix B Preferred materials7 Appendix C Ination to be supplied by purchaser8 Figure 1 Valve with extended bonnet/gland2 Figure 2 Typical arrangement of low temperature type test rig6 Table 1 Minimum gland extension length for cold box applications3 Table 2 Austenitic steels8 Table 3 Non-ferrous materials8 Publications referred toInside back cover Licensed Copy Institute Of Technology Tallaght, Institute of Technology, Tue Aug 22 002712 BST 2006, Uncontrolled Copy, c BSI w w w . b z f x w . c o m BS 63641984 ii BSI 05-1999 Foreword This British Standard has been prepared under the direction of the Mechanical Engineering Standards Committee. It is the first national standard for valves for cryogenic service but it is intended that it can only be used in conjunction with the appropriate valve product standard since the requirements and tests specified are additional to those specified in the valve product standards. 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 This document comprises a front cover, an inside front cover, pages i and ii, pages 1 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. Licensed Copy Institute Of Technology Tallaght, Institute of Technology, Tue Aug 22 002712 BST 2006, Uncontrolled Copy, c BSI w w w . b z f x w . c o m BS 63641984 BSI 05-19991 Section 1. General 1 Scope This British Standard specifies the requirements for the design, manufacture and testing of valves for cryogenic service. It is a requirement of this standard that the valves comply with the appropriate valve product British Standards, i.e. steel wedge gate valves BS 1414; steel check valves BS 1868; steel globe and globe stop and check valves BS 1873; steel ball valves BS 5351; steel wedge gate, globe and check valves DN 50 and smaller BS 5352; copper alloy globe, globe stop and check, check and gate valves BS 5154; testing of valves BS 6755; butterfly valves for general purposes BS 5155. The size range covered by this standard is DN 15 to a maximum nominal size appropriate to the above product standards, in the temperature range – 50 C to – 196 C, yet capable of operation at ambient conditions to allow for start-up and run-down. NOTE 1For marine applications where design temperatures are below – 165 C attention is drawn to the need to check requirements with the relevant Statutory Authority. Appendix C lists the ination to be supplied by the purchaser. 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 apply. 2.1 nominal size DN a numerical designation of size which is common to all components in a piping system other than components designated by outside diameters or by thread size. It is a convenient round number for reference purposes and is only loosely related to manufacturing dimensions NOTE 1It is designated by DN followed by a number. NOTE 2This definition is in accordance with ISO 6708. 2.2 nominal pressure PN a numerical designation relating to pressure that is a convenient round number for reference purposes it is intended that all equipment of the same nominal size DN designated by the same PN number shall have the same mating dimensions appropriate to the type of end connections the permissible working pressure depends upon materials, design and working temperature and has to be selected from the pressure/temperature rating tables in corresponding standards NOTE 1It is designated by PN followed by a number. NOTE 2This definition is in accordance with ISO 7268. 3 General requirements Valves shall comply with the appropriate standards listed in clause 1 in addition to clauses 4 to 9 of this standard. Section 2. Design 4 Requirements 4.1 Valves shall be supplied with extended bonnets/glands see Figure 1. The length of the extension shall be sufficient to maintain the stem packing at a temperature high enough to permit operation within the normal temperature range of the packing material. 4.2 Valves on gas service shall be capable of operation with the valve stem at or above the horizontal position. 4.3 Valves in liquid service other than cold box applications shall be capable of operation with the valve stem at or above 45 above the horizontal position. 4.4 For cold box applications, valves shall be suitable for use with the valve stem at or above 15 above the horizontal position and in addition the minimum gland extension length as shown in Figure 1 shall be as given in Table 1. NOTEIf any special length of gland extension is required by the purchaser he should state this see Appendix C. 4.5 For applications other than cold box applications the minimum gland extension length shall be 250 mm see Figure 1. 4.6 Valves shall be designed to relieve pressures above normal working pressure that may build up in trapped cavities due to thermal expansion or evaporation of liquid. NOTEFor ball and gate valves this requirement can be met by the provision of a pressure relief hole or passage or other means, e.g. pressure relieving seats, to relieve pressure in the bonnet and body cavities to the upstream side of the valve. The means adopted will be determined by the manufacturer unless the purchaser rcises his option in accordance with Appendix C. Licensed Copy Institute Of Technology Tallaght, Institute of Technology, Tue Aug 22 002712 BST 2006, Uncontrolled Copy, c BSI w w w . b z f x w . c o m BS 63641984 2 BSI 05-1999 Figure 1 Valve with extended bonnet/gland Licensed Copy Institute Of Technology Tallaght, Institute of Technology, Tue Aug 22 002712 BST 2006, Uncontrolled Copy, c BSI w w w . b z f x w . c o m BS 63641984 BSI 05-19993 Table 1 Minimum gland extension length for cold box applications 4.7 Where valves, by design, are unidirectional in operation, the flow direction shall be clearly indicated either on and integral with the body of the valve or on a plate securely attached to the body of the valve. In the design of such valves, measures shall be taken to prevent incorrect assembly. 4.8 Valve bonnets shall be bolted, welded or union type. Union type bonnets shall only be used on valves DN 50 and below, or for marine applications DN 40 and below, and the union nut shall be locked to the body. The use of screwed bonnets shall not be permitted. NOTEGasket materials for bolted bonnets are outside the scope of this standard see Appendix C. 4.9 For steel valves, fabricated gland extensions shall be constructed from a single length of seamless tube butt-welded to the bonnet and gland housing. 4.10 For high pressure bronze or copper alloy valves of PN 100 rating or greater, the extension tube shall be screwed into the bonnet prior to silver soldering. 4.11 The clearance between the valve stem and gland extension bore shall be designed to minimize convection heat losses. The wall thickness of the extension shall be minimized, compatible with the rating of the valve and mechanical strength requirements in order to reduce conduction heat losses. 4.12 Valve stems shall be of one-piece construction except for end entry ball valves, in which case the valve design shall be such that the valve stem cannot be blown out of the body in the event of the gland being removed while the valve is under pressure. Rising stem valves with renewable gland packing that incorporate a back seat shall have the back seat located in the region of the gland. Gland designs incorporating lantern rings and screwed plugs in the gland body shall not be used. 4.13 Globe valves shall have tapered or conical discs. The use of flat seated discs shall not be permitted. 4.14 The maximum force required to operate the valves manually under service conditions, when applied at the rim of the handwheel or lever, shall not exceed 350 N, except for valve seating and unseating only, when it shall be permissible for this value to be increased to 500 N. Where reduction gearing is provided, it shall be suitable for operation at ambient temperature. 4.15 Valves for flammable service shall be designed to ensure electrical continuity to prevent build-up of static electricity. 5 Materials NOTEThe specification of materials and gland packing is outside the scope of this standard owing to the variety of materials for the temperature range of operation, but Appendix B gives the preferred austenitic steels and non-ferrous materials that may be used. 5.1 Bolting materials shall be selected from those listed in BS 4882. NOTENote that on first cooling below ambient temperature and down to – 196 C, some austenitic steels increase slightly in size owing to a permanent metallurgical change. This may result, for example, in bolts relaxing their pre-load the first time they are cooled. The manufacturer/user should take account of this in selecting the steels used. 5.2 Valves shall have metal/metal or soft seats see Appendix C. Soft seats shall be backed by a secondary metal seat. Virgin PTFE shall be supported in such a way as to prevent cold flow. 5.3 The valve trim materials selected shall be such as to avoid the effects of galling seizure or binding caused by frequent operation at cryogenic temperatures. 6 Non-destructive testing 6.1 Examination of welds. Butt welded joints on fabricated sections of valves shall be fully radiographed and shall comply with 5.7 of BS 55001988. 6.2 Examination of castings 6.2.1 If weld ends are to be radiographed they shall meet a minimum radiographic standard for a distance of 25 mm from the machined weld preparations, and shall be as specified for class 1 in BS 5998. TypeGland extension length min. for nominal size DN 152025385080100150200250300350400450500 mmmmmmmmmmmmmmmmmmmmmmmmmmmmmm Globe Gate Ball Butterfly 500 500 500 500 500 500 500 500 500 600 600 600 600 600 600 700 700 700 700 700 700 700 700 750 700 750 900 700 850 1 000 750 850 1 100 800 1 200 850 1 300 850 1 400 900 1 500 950 Licensed Copy Institute Of Technology Tallaght, Institute of Technology, Tue Aug 22 002712 BST 2006, Uncontrolled Copy, c BSI w w w . b z f x w . c o m BS 63641984 4 BSI 05-1999 NOTEFurther non-destructive examination of castings in relation to quality, if required, should be in accordance with BS 5998. 6.2.2 The of radiographic examination of castings shall be in accordance with BS 4080. Radiographic records shall be retained for a period of at least 5 years by the manufacturer. 7 Repair of castings Weld repair of castings shall be to the standards of acceptability in accordance with the quality level specified in BS 5998. Section 3. Testing 8 Pressure testing 8.1 Shell strength test 8.1.1 The valve body and bonnet shall be subjected to a hydrostatic or pneumatic test. Hydrostatic testing shall be carried out as described in the appropriate standards given in clause 1. For stainless steel valves, the chloride content of the water for hydrostatic tests shall not exceed 30 p.p.m. Pneumatic tests shall be at the full test pressure specified in the appropriate valve product standard. WARNING. Attention is drawn to the hazardous nature of pneumatic testing. 8.1.2 For shell tests, discs and wedges, if fitted, shall be in the open position and ball valves shall be in the half-open position. 8.1.3 After hydrostatic shell testing, the component parts of the valve shall be thoroughly cleaned and degreased. 8.2 Shell leak test. After the hydrostatic or pneumatic strength test, body and bonnet joints and glands of valves shall be soap or immersion-under-water tested using dry oil-free air or nitrogen at the full seat rating of the valve. The stem shall be free to turn at this pressure. During the test duration specified in Appendix B of BS 6755-11986, there shall be no visible leakage. 8.3 Seat leak test 8.3.1 Valve seats shall be tested with dry oil-free air or inert gas at the full seat rating or for ball valves at 6.9 bar1 Valve shut-off shall be achieved by the normal s of operation and duration of tests shall be in accordance with BS 6755-1. 8.3.2 For valves having metal-to-metal seats, the maximum permitted leaka