BS 6683-1985 Guide to installation and use of valves《阀门安装和使用指南》.pdf

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1、BRITISH STANDARD BS 6683:1985 Incorporating Amendment No. 1 Guide to Installation and use of valves UDC 621.646.005BS6683:1985 This British Standard, having been prepared under the directionof the Piping Systems Components Standards Committee, was published underthe authority of the BoardofBSI and c

2、omes intoeffecton 31October 1985 BSI 06-1999 The following BSI references relate to the work on this standard: Committee reference PSE/7 Draft for comment 84/72775 DC ISBN 0 580 14746 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Pip

3、ing Systems Components Standards Committee (PSE/-) to Technical Committee PSE/7, 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

4、 British Chemical Engineering Contractors Association British Compressed Gases Association British Foundry Association British Gas Corporation British Maritime Technology British Shipbuilders British Valve Manufacturers Association Ltd. Copper Development Association Copper Tube Fittings Manufacture

5、rs Association Electricity Supply Industry in England and Wales Energy Industries Council Engineering Equipment and Materials Users Association GAMBICA (BEAMA Ltd.) General Council of British Shipping Greater London Council Health and Safety Executive Institute of British Foundrymen Institution of C

6、hemical Engineers Institution of Gas Engineers Institution of Mechanical Engineers Institution of Water Engineers and Scientists Society of British Gas Industries Steel Casting Research and Trade Association Water Authorities Association Water Companies Association Amendments issued since publicatio

7、n Amd. No. Date of issue Comments 6604 April 1991 Indicated by a sideline in the marginBS6683:1985 BSI 06-1999 i Contents Page Committees responsible Inside front cover Foreword ii Section 1. General 1.1 Scope 1 Section 2. Service and environmental considerations 2.1 Fluid 2 2.2 Pressure-temperature

8、 rating 2 2.3 Layout and siting 2 2.4 Bending strength 2 2.5 Fire-tested 2 2.6 Pressure surge and cycling 3 2.7 Throttling 3 2.8 Flow coefficients 3 2.9 Effects of temperature 3 2.10 Trapped pressure 4 2.11 Corrosion 4 2.12 Stem sealing 4 2.13 Cryogenic services 4 2.14 Operating effort 4 2.15 Vibrat

9、ion 4 Section 3. Storage and handling 3.1 General 5 3.2 Handling 5 3.3 Storage 5 Section 4. Installation 4.1 General 6 4.2 Inspection 6 4.3 Threaded valve/pipe assembly 6 4.4 Flanged joint assembly 7 4.5 Weld joint assembly 7 4.6 Testing and adjustment 7 Section 5. Operation and maintenance 5.1 Gene

10、ral 9 5.2 Operation of manual valves 9 5.3 Operation of power actuated valves 10 5.4 Quarter turn valves 10 5.5 Noise 10 5.6 Maintenance 10 Publications referred to Inside back coverBS6683:1985 ii BSI 06-1999 Foreword This British Standard has been prepared under the direction of the Piping Systems

11、Components Standards Committee. Since the incorrect use of valve types may result in operating problems which adversely affect system safety and efficiency, the valve industry recognizes that it will benefit all concerned if information can be made conveniently available to those responsible for ins

12、talling and using valves to help them avoid such problems. Valves are of many types and are used in a wide variety of service conditions. Having correctly selected a valve, its satisfactory performance depends on proper packing and protection during handling and storage, installation and operation,

13、and adequate maintenance. This standard presents information which should help users to avoid the most obvious causes of trouble. The standard does not include requirements but is intended to make the user more aware of the problems that can arise. Advice regarding a particular application should be

14、 obtained from the manufacturer of the valve. It has not been possible to include every consideration related to the satisfactory use of valves, and, especially in abnormal or unusual circumstances, the possible need for other considerations and precautions should be recognized. Observance of the re

15、commendations and precautions given in this standard will provide increased assurance of satisfactory valve performance. It is intended that this standard should be used in conjunction with the appropriate valve product standards (see 1.1). In addition, this standard may be used to provide guidance

16、for the installation and use of valves not covered by product standards. Sections of this standard have been based on MSSSP92 “Valve user guide” by kind permission of the Manufacturers Standardization Society of the Valves and Fittings Industry Incorporated. A British Standard does not purport to in

17、clude 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, pag

18、es i and ii, pages1to12, 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.BS6683:1985 BSI 06-1999 1 Section 1. General 1.1 Scope This British St

19、andard provides important guidance on the handling, storage, installation, and operation and maintenance of valves. This standard applies to the installation and use of valves complying with the following valve product standards: NOTEThe titles of the publications referred to in this standard are li

20、sted on the inside back cover. BS 1414 BS 5152 BS 5157 BS 5351 BS 1868 BS 5153 BS 5158 BS 5352 BS 1873 BS 5154 BS 5159 BS 5353 BS 5150 BS 5155 BS 5160 BS 6364 BS 5151 BS 5156 BS 5163BS6683:1985 2 BSI 06-1999 Section 2. Service and environmental considerations 2.1 Fluid Since a fluid can take many fo

21、rms, careful consideration should be given to the properties of the fluid to be handled in order that the valves and materials chosen will adequately withstand the corrosive, erosive or other nature of the fluid. Attention is also drawn to the effect of materials on the fluid(s) to be conveyed. Flui

22、ds may be classed as gases, vapours, liquids, fluidized solids or solids in suspension and each class presents its own handling problem. The problems are determined by the fluidity, particle size, viscosity, velocity, pressure, temperature, etc.of the fluid and whether the state remains constant thr

23、oughout the system. A liquid, for example, may flash into a gas due to the pressure drop across a valve and mixtures of fairly innocuous liquids may cause severe corrosion problems when combined and heated. Other problems which have to be considered are the osmotic or penetrating properties of the f

24、luid. Erosion is mainly dependent upon the velocity and particle size and hardness, and small changes in these can materially affect the choice of a suitable material. 2.2 Pressure-temperature rating The pressure-temperature rating of the valve should be consistent with the service conditions and in

25、 accordance with the appropriate valve product standard. If system testing will subject the valve to pressure in excess of its working pressure rating, the intended testing pressure and a statement explaining whether the test pressure is through the open valve or is a differential pressure across th

26、e closed valve should be included in the enquiry and/or order for a valve. 2.3 Layout and siting It is necessary at the design stage to consider where and how the valve will be located. Valves should be provided with adequate supports, where necessary; this is especially important if the pipework is

27、 constructed from plastics materials. Valves should be accessible for operation, adjustment, maintenance and repair. Generally, it is preferable for valves to be mounted with the stem in the vertical position. In a branch system, consideration should be given to the possibility of removing single va

28、lves for overhaul without having to shut down the whole system. Easy removal and replacement of important valves should be ensured and isolating valves fitted at appropriate locations. Check valves should be carefully installed; some are only suitable for horizontal pipe systems, others only for ver

29、tical pipe systems whilst some are suitable for both horizontal and vertical pipe systems. In addition, check valves should not be located immediately downstream from pipe elbows, because turbulence in the flowing fluid may cause disk motion and excessive wear. 2.4 Bending strength Pipe systems are

30、subject to mechanical constraints at support points, rigid nozzles, anchors, etc. Cold springing at assembly and system temperature changes, together with gravity, possible inertia loads, landslides, non-uniform subsidence in buried lines, etc., may all potentially affect the bending moment at vario

31、us points in the system. Valves are subjected to the bending moments in the adjacent pipe in addition to normal pressure loadings. It is therefore recommended design practice to avoid locating valves at points of large bending moments. In many cases, normal valve design practice results in a body st

32、rength greater than the strength of the adjoining pipe, providing inherent protection against valve damage. In other cases, conditions may increase the possibility of harmful valve body deformation. The following are examples of possible problems: a) reduced-bore type valves, made by providing enlar

33、ged ends on smaller basic valves; b) cast iron valves installed in steel piping; c) where the pipe may be stiffer and stronger than the valves; d) rigidly bonded linings, e.g. glass lining. If there is reason for concern regarding possible high bending moments, valve designs having inherent body ben

34、ding strength weakness should be carefully evaluated. 2.5 Fire-tested The term fire-tested is intended to replace the previous misleading term of fire-safe. A fire-tested valve indicates that prototype valves of a certain design, materials and manufacturer have been tested in accordance with a speci

35、fied test, such as given in Appendix A of BS6755-2:1987. Such a test demonstrates that during the fire test the leakage from the stem, body joint and cover was not in excess of that specified and that after fire testing, with the valve closed, the seat leakage was not in excess of that specified.BS6

36、683:1985 BSI 06-1999 3 2.6 Pressure surge and cycling Closure of a valve in a flowing fluid line causes the velocity of the fluid to be reduced to zero. If the fluid is a relatively incompressible liquid, the inertia of the upstream column produces at the valve a pressure surge whose magnitude is in

37、versely proportional to the time required for closure. The surge pressure is also proportional to the length of the upstream fluid column and the fluid velocity prior to closure initiation. If the application involves a long upstream line, a long downstream line, a high fluid velocity and/or rapid c

38、losure, singly or in any combination, the possibility of unacceptable pressure surge should be investigated. This is particularly applicable where power operation is required as this usually enables faster operation to be achieved than is normal with manual operation, and this could increase the pre

39、ssure surge, resulting in the actuator being unable to operate the valve. In the case of check valve closure on flow reversal, it can be considered that velocity cut-off is instantaneous. Pressure surge may consequently be very high, depending on the velocity of the reverse flow at the instant of cl

40、osure and, again, the length of the fluid column. Applications of check valves in liquid lines should always be evaluated for possible surge (water hammer) problems. Check valves are actuated by the flow or pressure of the line fluid. Problems involving excessive wear of internal parts or noisy oper

41、ation can result from the use of check valves which are not fully opened by the normally sustained flow or from the pulsing or instability of such flow. Applications involving gas or steam flow may be complicated by an energy transfer phenomenon which can cause valve cycling even under steady flow c

42、onditions. Such cycling may cause rapid wear and premature valve failure or malfunction. In liquid lines, valve cycling is not normally a problem unless the flow itself is cycling, as at the discharge of a reciprocating pump. In all cases, the preferred sizing of check valves is such that at normal

43、sustained flow, the valve closure element will be held against its stop in the fully open position. 2.7 Throttling Control of flow or pressure may involve very severe fluid turbulence and to get the best performance from a valve used for control it is important that it is correctly sized, having reg

44、ard to the conditions of the flowing media. Reference should therefore be made to the manufacturer for confirmation of the methods of calculation used. If, for example, the control valve chosen is too large, it will be only open by a small amount which will result in poor flow control, blockage, dew

45、atering effects or vibration causing damage. Depending upon the type of fluid, whether liquid or gas, and the pressure drop across the valve, fluid energy conversion equivalent to the output of a large pump or boiler may be required in the valve. Such energy conversion may be the source of high inte

46、nsity noise. In throttling of a gas, e.g. steam or air, the noise may be produced principally by shock waves as the flow breaks the sound barrier. In liquids, a major source of noise is cavitation, or more specifically the collapse of cavitation vapour bubbles as the fluid static pressure recovers d

47、ownstream. The noise in an ordinary water tap is an example of low level cavitation noise. If examination of the flow data suggests the probability of a noise problem, then advice should be sought from the manufacturer. In cases where cavitation is especially heavy and/or continuous for extended per

48、iods, the possibility of mechanical damage should be evaluated. 2.8 Flow coefficients It is often convenient, particularly with control valves, to be able to express the relationship between pressure drop and flow rate through a valve by a coefficient. In many parts of the world, including the UK an

49、d the USA, the flow coefficient in most general use is Cv. However, testing methods can vary and this should be borne in mind when comparing the performance of valves on the basis of Cv values. 2.9 Effects of temperature A condition of non-uniform temperature in pipework may impose significant thermal stresses or distortion, with possible adverse effects on valve performance. In applications involving frequent temperature cycling, the possibility of thermal stress fatigue should be considered. Practical problems can result from failure to anticipate temperature effects. An ex