BS ISO 4778:2019 pdf download – Round steel short link chains for lifting purposes — Chain slings of welded construction — Grade 8
After proof loading, the difference between the longest and shortest chain legs of a multi-leg chain sling,when measured under a tension of 20 % of the working load limit, shall not exceed 10 mm for chain legs up to 2 m in length. For chain slings in excess of 2 m, the difference between the longest and shortest chain legs may be increased by 5 mm/m.
4.2 Components
4.2.1 Chain legs
Chain legs shall comply with ISO 3076.
4.2.2 Master links
Master links shall comply with ISO 16798.
The inside dimension and the cross-section of the material shall be such that:
a) the master link fits to a shank hook (e.g. according to ISO 17440; see Annex C);
b) the inside width of the master link is not less than 1,2 times the maximum width (see dimension b 2 in ISO 17440:2014, Figure A.1 and Table A.1) of the shank hook;
c) for chain slings with hooks as lower terminal components the inside dimensions and the crosssection are such as to allow the lower terminal component when not loaded to be hooked back into the master link while it is on the shank hook.
Master links may be of round or other suitable cross-section. But the cross-section of the material shall be chosen so that:
a) after proof loading (see 4.4.1) the master link does not show any significant permanent deformation;
b) the minimum total ultimate elongation at fracture is at least that of the sling chain.
NOTE A method of calculating the cross-section of master links is given in Annex D.
IMPORTANT — Egg- or pear-shaped links shall be designed to exclude unintended inverting.
4.2.3 Intermediate master links, joining links and end links
Intermediate master links, joining links and end links shall comply with ISO 16798 except for the clauses relating to link dimensions.
The internal dimensions of intermediate master links, joining links and end links shall be such that they ensure free articulation of the links.
The cross-section of the material shall be such that:
a) after proof loading (see 4.4.1) the intermediate master links, joining links and end links do not show any significant permanent deformation;
b) the minimum total ultimate elongation at fracture is at least that of the sling chain.
IMPORTANT — Egg- or pear-shaped links shall be designed to exclude unintended inverting.
4.2.4 Hooks
Forged steel lifting hooks with latch shall comply with ISO 7597 and shall be compatible with the sling chains according to ISO 3076.
Hooks not otherwise covered by this document shall comply with ISO 8539.
4.2.5 Other forged components
Other forged steel components, e.g. shackles, shall comply with ISO 8539 and shall be compatible with the sling chains according to ISO 3076.
4.3 Working load limit (WLL)
Table 1 gives values for the working load limit (WLL) calculated on the bases given in Annex A.
For the calculation of a working load limit (WLL) for angles other than specified, the indicated formulae shall be used in a corresponding manner. For this purpose, the value of the maximum angle of a range or the fixed inclination angle is inserted into the corresponding formula.
4.4 Mechanical requirements
4.4.1 General Chain slings according to this document shall comply with the mechanical requirements given in Table 2, 3 and 4 for the appropriate test sections. If the whole chain sling is heat treated, it shall be tested as an assembly by subjecting each test section to a value for the manufacturing proof force (MPF) at least equal to the value specified in Tables 2, 3 and 4, calculated on the bases given in Annex A. Subsequently, the chain sling shall be examined by a competent person. The manufacturer shall also verify that all components remain in accordance with the appropriate requirements of the component standards. If only the inserted links are heat treated, they shall be considered as a test section, as well as any parts of the chain sling affected by this heat treatment.
These sections shall then be subjected to a value for the manufacturing proof force (MPF) at least equal to the value specified in Tables 2, 3 and 4, calculated on the bases given in Annex A. Subsequently, the inserted links and any parts of the chain slings affected by heat treatment shall be examined by a competent person. The manufacturer shall also verify that all components remain in accordance with the appropriate requirements of the component standards. The manufacturer shall have records concerning the breaking test and bend test for every type and size of sling chain and link built into the complete chain sling.BS ISO 4778 pdf download.