1、BRITISH STANDARD BS 2837:1988 Specification for Steel links and strap assemblies for lifting attachments for packing cases UDC 621.86.06:621.798BS2837:1988 This British Standard, having been prepared under the direction of the Packaging and Freight Containers Standards Committee, was published under
2、 the authority of the Board of BSI and comes into effect on 31October 1988 BSI 08-1999 First published February 1957 First revision January 1970 Second revision October 1988 The following BSI references relate to the work on this standard: Committee reference PKM/553 Draft for comment 86/44617DC ISB
3、N 0 580 16671 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Packaging and Freight Containers Standards Committee (PKM/-) to Technical Committee PKM/553, upon which the following bodies were represented: British Fibreboard Packaging A
4、ssociation PIRA Timber Packaging and Pallet Confederation Timber Research and Development Association United Kingdom Tea Association The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Ports Association and the National Association of
5、 Ports Employers Health and Safety Executive Institute of Packaging Ministry of Defence Amendments issued since publication Amd. No. Date of issue CommentsBS2837:1988 BSI 08-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Rating 1 3 Material 1 4 Forms and dimen
6、sions 1 5 Bolts and nuts 3 6 Workmanship 3 7 Heat treatment of the links and quality marking 3 8 Proof loading 4 9 Marking 4 10 Manufacturers certificate (links) 4 Appendix A Examples of application of strap assemblies 5 Figure 1 Triangular link 1 Figure 2 Strap assembly (with intermittent welds) 2
7、Figure 3 Method of fitting strap assemblies: styles 1 and1A 6 Figure 4 Method of fitting strap assemblies: styles2 and2A 7 Figure 5 Placings of straps: styles1A and2A 8 Figure 6 Methods of fitting strap assemblies: styles3 and3A 8 Table 1 Triangular links 2 Table 2 Strap assembly and recommended loa
8、ding on four links and two links 3 Publications referred to Inside back coverBS2837:1988 ii BSI 08-1999 Foreword This revision of BS2837 has been prepared under the direction of the Packaging and Freight Containers Standards Committee. It supersedes BS2837:1970which is withdrawn. This revision makes
9、 changes to the material specifications for strap assemblies and increases the specified thicknesses as necessary to enable the assemblies to provide the required levels of performance. These changes have been made following investigations which confirmed that the materials previously specified were
10、 no longer available as steel stock in flat bar form. 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
11、obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1to8, 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
12、 the inside front cover.BS2837:1988 BSI 08-1999 1 1 Scope This British Standard specifies requirements for10classes of drop forged or welded triangular link and its associated strap assembly for use as lifting attachments for packing cases. This British Standard deals with that part of the strap ass
13、embly which contains the turnover forming the housing for the link. When lifting on four links, these assemblies are suitable for loads up to25tonnes. This British Standard also describes in Appendix A typical styles of attachment for strap assemblies. NOTEThe titles of the publications referred to
14、in this standard are listed on the inside back cover. 2 Rating 2.1 Links The links shall be rated according to the safe working loads given in Table 1. 2.2 Lifting on four links When lifting on four links, the safe working load of the combined strap assemblies shall not exceed the values given in co
15、lumn7of Table 2. 2.3 Lifting on two links Where the height of the packing case is materially the greatest dimension, a two-link assembly may be used; the safe working load of the strap assembly shall then not exceed the values given in column8of Table 2. 3 Material 3.1 Links The links shall be made
16、from wrought carbon manganese steel having the following chemical composition 1) : 3.2 Strap assemblies The strap assemblies shall be made from either: a) welding quality structural steel complying with grade50B of BS4360; or b) steel complying with grade43A of BS4360. 4 Forms and dimensions 4.1 Lin
17、ks The form of the links shall be in accordance with Figure 1and the dimensions, subject to the tolerances given in4.1.1 and 4.1.2, shall be in accordance with Table 1. 4.1.1 Tolerances on drop forged links. Tolerances on drop forged links shall be quality F as specified in BS4114. 4.1.2 Tolerances
18、on welded links. The internal dimensions of welded links shall be not less than the specified sizes and shall not exceed them by more than5 %. The size of the material in the finished link shall be not less than the nominal diameter, and shall not exceed the nominal diameter by more than0.8mm. 4.2 S
19、trap assemblies The form of the strap assemblies shall be in accordance with Figure 2, and the dimensions of the cross sections shall be in accordance with Table 2, and appropriate to the material from which the assemblies are made (see BS4360). There shall be provision for not less than two bolts i
20、n the turnover of each strap assembly, and the distance from the bottom lower hole to the end of the turnover shall not exceed one quarter of the breadth of the strap. NOTEThe length of the turnover and the spacing of the bolts have not been specified as these dimensions vary with the type of case (
21、see Appendix A). Carbon Manganese Sulphur Phosphorus % min. % min. % max. % max. 0.25 0.70 0.050 0.050 % max. % max. 0.30 0.90 1) For further information in relation to this material, apply to Enquiry Section, BSI, Linford Wood, Milton Keynes MK14 6LE, enclosing a stamped addressed envelope for repl
22、y. Figure 1 Triangular linkBS2837:1988 2 BSI 08-1999 Table 1 Triangular links 1 2 3 4 5 6 7 8 9 Class Nominal size of link Internal breadth Internal length Internal radius at top Internal radius at bottom Safe working load Proof load Mass Force d B L r 1 r 2 mm mm mm mm mm tonnes tonnes kN A B C 10
23、12 14 67 67 67 67 67 67 25 25 25 8 8 8 0.32 0.5 0.8 0.64 1 1.6 6.18 9.81 15.69 D E F 19 22 26 93 93 93 115 115 115 38 38 38 14 14 14 1.25 2 3.2 2.5 4 6.4 24.5 39.2 62 G H J K 34 40 44 48 118 118 128 128 140 140 165 180 50 50 64 64 21 21 26 26 5 8 10 12.5 10 16 20 25 98 157 196 245 Figure 2 Strap ass
24、embly (with intermittent welds)BS2837:1988 BSI 08-1999 3 Table 2 Strap assembly and recommended loading on four links and two links 5 Bolts and nuts The bolts securing the strap assembly to the sides of the case shall be black cup square neck bolts complying with BS4933. The nuts shall comply with g
25、rade4of BS4190. 6 Workmanship 6.1 Links The links shall be produced by either of the following manufacturing processes: a) drop forging; or b) welding. The weld should be in either of the straight sloping parts and not in any of the radii nor in the lower straight part of the link. When the links ar
26、e welded, the weld shall be smoothly finished all round, and it is essential that porosity is avoided and that penetration and fusion take place throughout. Welded links shall be made by one of the following methods: a) electric resistance butt-welding; b) flash-butt welding; c) atomic-hydrogen weld
27、ing; d) inert gas shielded-arc welding. 6.2 Strap assemblies The strap assemblies shall be formed from straight bar by hot bending. The form of the bend housing the link shall be as shown in Figure 2and the working clearance for the link shall not exceed2mm. The turnover housing the link shall be we
28、lded along each side: the welds may be continuous, or intermittent at intervals that shall not exceed1.5 times the breadth of the strap. There shall be no welding along the bottom of the turnover (see Figure 2). Sharp corners on the exposed edges of the strap shall be removed. 7 Heat treatment of th
29、e links and quality marking 7.1 Heat treatment The links shall be subjected to one of the following heat treatments after all forging or welding operations: a) normalizing, i.e. heating to a temperature between860 C and890 C, followed by cooling in still air; b) hardening and tempering, i.e. heating
30、 to a temperature between860 C and890 C, followed by quenching in oil or water and tempering at a suitable temperature between550 C and660 C; 1 2 3 4 5 6 7 8 Class Nominal size of link Safe working load of link Strap Recommended maximum safe working load on four links Recommended maximum safe workin
31、g load on two links Breadth Thickness BS 4360 grade 50B a BS 4360 grade 43A a mm tonnes mm mm mm tonnes tonnes A B C 10 12 14 0.32 0.5 0.8 50 50 50 5 6 6 5 8 8 0.64 1 1.6 0.32 0.5 0.8 D E F 19 22 26 1.25 2 3.2 65 65 65 10 10 10 10 10 12 2.5 4 6.4 1.25 2 3.2 G H J 34 40 44 5 8 10 75 75 75 12 20 20 15
32、 20 25 10 16 20 5 8 10 K 48 12.5 75 25 25 12.5 Load reduction factor 0.5 0.5 NOTEThe load reduction factor makes an arbitrary allowance for angular loading on sling legs, assuming that in no circumstances will the included angle between any diagonally opposite legs exceed120 . Recommendations for th
33、e safe use of wire rope slings are given in BS6210. a See clause 3.BS2837:1988 4 BSI 08-1999 c) if necessary, an alternative heat treatment to a) or b) to ensure that links are in a uniform condition with links as previously treated. NOTEThis does not preclude the use of an alternative heat treatmen
34、t which will ensure that the links are in a uniform condition with links as previously treated. 7.2 Quality marking Each link shall be legibly and permanently marked on the side of the crown with the symbol “4” when normalized, and with the symbol “04” when hardened and tempered. The mark shall be e
35、nclosed in a circle. NOTERecommended maximum sizes of stamp are as follows: classes A and B: 3.5 mm; classes C, D, E: 5 mm; classes F, G, H, J, K: 6.5 mm. 8 Proof loading Each link shall, after manufacture and subsequent heat treatment, be subjected by the manufacturer to a proof load not less than
36、twice the safe working load (see Table 1), which it shall withstand without showing any visible permanent set. The straight portion of the lower face of the link shall be uniformly loaded during the application of the proof load. After proof loading each link shall be thoroughly examined by a compet
37、ent person and shall show no visible flaw or defect. 9 Marking Each link shall, after testing, be permanently and legibly stamped on one of the sides with the safe working load given in Table 1, and also with marks or symbols which will allow identification with the manufacturers certificate of test
38、 and examination. Such stamping shall not be near a weld and shall be in such a position as to be visible after assembly. The stamps used shall have a concave surface and the indentation shall be neither too sharp nor excessive in depth. NOTEFor recommended maximum sizes of stamp, see the note to7.2
39、. 10 Manufacturers certificate (links) The manufacturer shall provide a certificate with every consignment of links giving the following information for each one: a) distinguishing mark (to enable the particular link to be identified); b) class (see Table 1); c) safe working load of one link (see Ta
40、ble 1); d) heat treatment (i.e. normalized or hardened and tempered). The certificate shall declare that the links comply in all aspects with BS2837 2) . It shall also state the address of the testing establishment and the status of the signatory. 2) Marking BS2837on or in relation to a product repr
41、esents a manufacturers declaration of conformity, i.e. a claim by or on behalf of the manufacturer that the product meets the requirements of the standard. The accuracy of the claim is therefore solely the responsibility of the person making the claim. Such a declaration is not to be confused with t
42、hird party certification of conformity, which may also be desirable.BS2837:1988 BSI 08-1999 5 Appendix A Examples of application of strap assemblies A.1 Methods of attachment The decision as to the best method of attaching strap assemblies will depend upon a number of factors, such as the type and c
43、onstruction of the case, the type of equipment being packed and the method of securing it in the case, and upon the facilities at the packers works. It is, therefore, not practicable to give specific guidance on this subject, but Figure 3, Figure 4, Figure 5and Figure 6illustrate examples of commonl
44、y used methods. They should not be regarded as definite recommendations as there are many other methods that may be more appropriate to particular circumstances. A.2 Styles A.2.1 Styles 1 and 1A, and styles 2 and 2A A.2.1.1 General. Styles1 and1A (see Figure 3) and styles2and2A (see Figure 4) are su
45、itable for export packing and, in conjunction with suitable bolts and a suitable case, are generally confined to loads not exceeding6tonnes and25tonnes respectively. When the straps are fitted to sheath type cases, only one bolt should pass through the top frame member in order to avoid unnecessary
46、weakening of this member where the maximum strength is needed. The turnover should be of sufficient length to house a second bolt clear of the top frame member. When designing the case it is essential that a compression member (top bearer) be placed at the position of the top of the strap. The strap
47、 assemblies should be recessed into the skids of the wooden cases. The depth of the recesses should be twice the thickness of the strap and should be taken into account in determining the depth of the skids to prevent weakness at the point of recessing. The straps should be attached to the sides of
48、the case by means of black cup square neck bolts (see clause5), the nuts being on the outside. It is not considered necessary to use bolts and nuts for the part of the strap in contact with the underside of the case. Where necessary, spring washers complying with type A of BS4464should be fitted und
49、er the nuts. A.2.1.2 Placing of straps. There can be no hard and fast rule for the placing of the straps on account of the diverse shapes of cases, and of the possibility that the centre of gravity of the load will not be in the centre of the case. It is important, however, to ensure that the straps are placed in the most favourable positions in relation to the centre of gravity of the load so that when the case is being lifted it will remain in a horizontal position with equal load distribution on the legs of the sling and on each strap asse
