1、BRITISH STANDARD BS 6129-1: 1981 Code of practice for The selection and application of bellows expansion joints for use in pressure systems Part 1: Metallic bellows expansion joints UDC 621.643.43BS6129-1:1981 This British Standard, having been prepared under the directionof the Pressure VesselStand
2、ards Committee, waspublished under the authorityof the Executive Boardand comes into effect on 31July1981 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference PVE/13 Draft for comment 77/79382 DC ISBN 0 580 12122 4 Cooperating organizations The Pressure V
3、essel Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following: Associated Offices Technical Committee* Association of Shell Boilermakers British Chemical Engineering Contractors Association British Compressed Gases Association Bri
4、tish Gas Corporation* British Insurance (Atomic Energy) Committee British Steel Industry Chemical Industries Association Department of Trade (Marine Division) Engineering Equipment Users Association* Health and Safety Executive* Institution of Chemical Engineers Institution of Gas Engineers Institut
5、ion of Mechanical Engineers* Lloyds Register of Shipping Oil Companies Materials Association* Process Plant Association* United Kingdom Atomic Energy Authority University of Manchester. Institute of Science and Technology Water-tube Boilermakers Association* Welding Institute The organizations marke
6、d with an asterisk in the above list, together with the following, were directly represented on the Technical Committee entrusted with the preparation of this British Standard: High Pressure Pipework Consultative Committee Ministry of Defence Individual expert Amendments issued since publication Amd
7、. No. Date of issue CommentsBS6129-1:1981 BSI 08-1999 i Contents Page Cooperating organizations Inside front cover Foreword iii 1 Scope 1 2 References 1 3 Terms and definitions 1 3.1 Nominal size (DN) 1 3.2 Movement 1 3.3 Expansion joints 1 3.4 Effective area 2 3.5 Expansion joint components 2 3.6 A
8、ssociated equipment 3 4 Materials for convolution manufacture and precautions to avoid corrosion in service 4 4.1 General considerations affecting the choice of material for the convolutions of a bellows expansion joint 4 4.2 Precautions during storage, installation and use to avoid damage due to co
9、rrosion 5 4.3 Typical materials used in the fabrication of bellows convolutions 6 5 Application and use of expansion joints 7 5.1 General 7 5.2 Thermal expansion of various pipe materials 7 5.3 Unrestrained expansion joints 7 5.4 Restrained expansion joints 9 5.5 Special service conditions 10 6 Defi
10、nition of design conditions and working conditions and classification of inspection procedures 10 6.1 General 10 6.2 Design conditions 11 6.3 Working conditions 11 6.4 Classification of inspection procedures 11 7 Information to be provided by the purchaser and the manufacturer 12 7.1 Information to
11、be provided by the purchaser 12 7.2 Information to be provided by the manufacturer 12 8 Pre-installation inspection and testing 13 8.1 General 13 8.2 Class I 13 8.3 Class II 16 8.4 Class III 17 9 Identification, protection, packing, transportation and installation 17 9.1 Identification 17 9.2 Protec
12、tion 17 9.3 Packing and transportation 17 9.4 Installation 18 10 Testing of systems containing expansion joints 19 10.1 General 19 10.2 Cases where a standard pressure test, in accordance with 10.1.5, on a system including expansion joints is not reasonably practicable 20 11 Guide for maintenance of
13、 expansion joints after installation 20BS6129-1:1981 ii BSI 08-1999 Page 11.1 General 20 11.2 Inspection after first full movement 20 11.3 Periodic inspection after an agreed interval of time 20 11.4 Accessibility 21 12 Modifications to pressure systems incorporating expansion joints 21 12.1 General
14、 21 12.2 Examples of modifications hazardous to systems containing all types of expansion joints 21 12.3 Examples of modifications particularly hazardous to systems containing unrestrained axial expansion joints 21 12.4 Examples of modifications particularly hazardous to systems containing restraine
15、d expansion joints 21 13 Certification 21 Figure 1 Typical system using unrestrained expansion joint 22 Figure 2 Examples of unsafe practice in a system using unrestrained expansion joints 22 Figure 3 Diagrammatic explanation of cold pull of unrestrained expansion joint 22 Figure 4 Typical system us
16、ing a tied double expansion joint with hinged-end tie-bars 23 Figure 5 Typical system using a tied double expansion joint with spherical-ended tie-bars 23 Figure 6 Typical system using two single gimbal expansion joints 24 Figure 7 Typical system using one single hinged expansion joint and two singl
17、e gimbal expansion joints 24 Figure 8 Typical systems using single hinged expansion joints 25 Figure 9 Examples of unsafe practice in systems using gimbal expansion joints 26 Figure 10 Examples of cold pull in a piping system with restrained expansion joints 27 Figure 11 Systems using a pressure-bal
18、anced expansion joint 28 Table 1 Classification of inspection procedures 12 Publications referred to Inside back coverBS6129-1:1981 BSI 08-1999 iii Foreword This British Standard has been prepared under the direction of the Pressure Vessel Standards Committee. Although there is a large amount of wel
19、l established useful data on the use of bellows expansion joints this is contained either within manufacturing companies or publications originating outside the United Kingdom. Industry, user organizations, inspecting authorities and other interested parties have therefore combined to prepare a new
20、code of practice to give guidance on the application and use of expansion joints in pressure systems. This is the first Part of the code and deals with metallic bellows expansion joints; Part2 will deal with non-metallic bellows expansion joints. A British Standard does not purport to include all th
21、e 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 to iv,
22、pages1to 28, 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.iv blankBS6129-1:1981 BSI 08-1999 1 1 Scope This British Standard gives informatio
23、n and recommendations on the selection, application and testing of metallic bellows expansion joints for use in pressure systems. 2 References The titles of the standards publications referred to in this code are listed on the inside back cover. 3 Terms and definitions For the purposes of this code
24、the following terms and definitions apply. 3.1 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 re
25、lated to manufacturing dimensions 3.2 movement The various dimensional changes which an expansion joint is required to absorb, such as those resulting from thermal changes in a piping system. 3.2.1 axial compression the dimensional shortening of an expansion joint along its longitudinal axis. Axial
26、compression has been referred to as axial movement or compression 3.2.2 axial extension the dimensional lengthening of an expansion joint along its longitudinal axis. Axial extension has been referred to as axial movement, elongation or extension NOTEAxial compression and extension are sometimes ref
27、erred to as minus and plus respectively but this designation is non-preferred and is, in any case, to be used only in addition to and not instead of a clear statement describing axial movement in terms of compression or extension. 3.2.3 lateral deflection the relative displacement of the two ends of
28、 an expansion joint perpendicular to its longitudinal axis. This has been referred to as lateral offset, lateral movement, parallel misalignment, direct shear, or transverse movement 3.2.4 angular rotation the relative angular displacement of the two ends of the expansion joint so as to displace the
29、 longitudinal axis of the expansion joint from its initial straight line position into a circular arc. This has been referred to as angular or rotational movement 3.2.5 rated movement the maximum amount of movement (axial extension, axial compression, lateral deflection, angular rotation, or any com
30、bination thereof) which an expansion joint is capable of absorbing. This rating may be different for each size, type and make of expansion joint and is established by the manufacturer 3.2.6 cyclic life the minimum number of cycles of movement at the specified conditions which an expansion joint is d
31、esigned to withstand without failure 3.3 expansion joints Devices containing one or more bellows used to absorb dimensional changes, such as those caused by thermal expansion or contraction of a pipeline, duct or vessel. 3.3.1 single expansion joint the simplest form of expansion joint, of single be
32、llows construction, designed to absorb all of the movement of the section in which it is installed. The most common example is that of a single bellows designed to absorb axial movements only. This is often referred to as an axial expansion joint 3.3.2 single gimbal expansion joint an expansion join
33、t containing one bellows and designed to permit angular rotation in any plane by the use of two pairs of hinges affixed to a common floating gimbal ring. The gimbal ring, hinges and pins are designed to restrain the thrust of the expansion joint due to internal pressure and extraneous forces, where
34、applicable 3.3.3 single hinged expansion joint an expansion joint containing one bellows and designed to permit angular rotation in one plane only by the use of a pair of pins through hinge plates attached to the expansion joint ends. The hinges and hinge pins are designed to restrain the thrust of
35、the expansion joint due to internal pressure and extraneous forces, where applicableBS6129-1:1981 2 BSI 08-1999 3.3.4 pressure balanced expansion joint an expansion joint designed to absorb axial movement and/or lateral deflection while restraining the pressure thrust by means of tie rods interconne
36、cting the flow bellows with an opposed bellows also subjected to line pressure. A pressure balanced expansion joint sometimes contains two bellows in the flow section separated by a common connector, to permit greater lateral movement 3.3.5 externally pressurized expansion joint an expansion joint d
37、esigned so that the pressure acts on the outer surface of the bellows. This form of construction is often used where it is necessary periodically to completely drain the fluid within the system 3.3.6 double expansion joint An expansion joint consisting of two bellows separated by a short connecting
38、tube used to accommodate larger movements than are possible with single expansion joints. 3.3.6.1 untied double expansion joint a double expansion joint capable of absorbing combinations of axial, lateral and angular movement. For this reason this type of expansion joint is sometimes referred to as
39、a universal expansion joint 3.3.6.2 tied double expansion joint a double expansion joint in which the pressure thrust is carried by external or internal ties across the bellows. These ties may be in the form of hinged or spherical ended bars attached to opposite ends of the unit or in the form of in
40、dividual hinges or gimbal rings spanning each bellows. Because of these ties the units are only capable of absorbing lateral and/or angular movements. Depending on the construction, tied double units may be referred to as articulated, double hinged or double gimbal expansion joints two tie bars are
41、designed to allow limited angular rotation in one plane; three or more tie-bars prevent this rotation 3.3.7 internally guided expansion joint an expansion joint designed so that axial guidance is provided within the expansion joint by means of heavy internal sleeves which may incorporate bearing rin
42、gs 3.4 effective area the cross-sectional area of the bellows over which the pressure is assumed to act, which is used for the calculation of axial thrust 3.5 Expansion joint components The following are part of, or are used in connection with, expansion joints. 3.5.1 bellows the flexible element of
43、 an expansion joint, consisting of one or more convolutions and the end cuffs, if any 3.5.2 convolution the smallest flexible unit of a bellows. The total movement capacity of a bellows is proportional to the number of convolutions 3.5.3 cuffs the straight, unconvoluted portions at the ends of the b
44、ellows. They are sometimes referred to as tangents or tails 3.5.4 weld ends the ends of an expansion joint equipped with pipe suitably bevelled for welding to adjacent equipment or piping 3.5.5 flanged ends the ends of an expansion joint equipped with flanges for the purpose of bolting the expansion
45、 joint to the mating flanges of adjacent equipment or piping 3.5.6 internal sleeve a device which shields the convolutions from direct contact with the flow of fluid. This device has also been referred to as a liner, telescoping sleeve or baffle sleeve 3.5.7 cover a device used to provide limited pr
46、otection of the exterior surface of the bellows of an expansion joint from foreign objects or mechanical damage. It is sometimes referred to as a shroud or external sleeve 3.5.8 root reinforcing rings devices fitting snugly in the roots of the convolutions to reinforce the bellows against internal p
47、ressure. Root reinforcing rings are fabricated from tubing or solid round bars of carbon steel, stainless steel, or other suitable alloysBS6129-1:1981 BSI 08-1999 3 3.5.9 reinforcing collars devices used to reinforce the cuffs of bellows 3.5.10 equalizing rings rings, usually T-shaped in cross secti
48、on, used to distribute movement equally between the convolutions of the bellows. They are usually designed to act as reinforcing rings 3.5.11 tie rods devices, usually in the form of rods or bars, attached to the expansion joint assembly, whose primary function is to restrain the pressure thrust or
49、pull due to internal pressure or vacuum. Tie rods may be designed to provide the features of control rods 3.5.12 control rods devices, usually in the form of rods or bars, attached to the expansion joint assembly, whose function is to distribute the movement between the two bellows of an untied double expansion joint. These devices are not designed to restrain bellows pressure thrust 3.5.13 purge connections connections, usually installed at the sealed end of each internal sleeve of an expansion joint for the purpose of injecting a liquid or gas betw
