ISO 4778:2019

INTERNATIONAL ISO
STANDARD 4778
Second edition
2019-06
Round steel short link chains for
lifting purposes — Chain slings of
welded construction — Grade 8
Chaînes de levage en acier de section ronde à maillons courts —
Elingues en chaînes assemblées par soudure — Classe de qualité 8
Reference number
©
ISO 2019
© ISO 2019
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Published in Switzerland
ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 3
4.1 Chain sling . 3
4.2 Components . 4
4.2.1 Chain legs . 4
4.2.2 Master links . 4
4.2.3 Intermediate master links, joining links and end links . 4
4.2.4 Hooks . 5
4.2.5 Other forged components . 5
4.3 Working load limit (WLL) . 5
4.4 Mechanical requirements . 6
4.4.1 General. 6
4.4.2 Single leg chain sling. 7
4.4.3 Double leg chain sling . 8
4.4.4 Three and four leg chain sling . 9
5 Marking .10
5.1 General .10
5.2 Single leg chain sling .10
5.3 Double leg chain sling .11
5.4 Three and four leg chain sling.11
6 Manufacturer's certificate .11
7 Examples of chain slings .12
Annex A (informative) Bases for calculation .16
Annex B (informative) Correlations, grade 8 .20
Annex C (informative) Compatibility of chain slings to shank hooks .22
Annex D (informative) Information for the calculation of the nominal diameter of links .24
Bibliography .26
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
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.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 111, Round steel link chains, chain slings,
components and accessories, Subcommittee SC 1, Chains and chain slings.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
This second edition cancels and replaces the first edition (ISO 4778:1981), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— omission of grades 4 and 6;
— increased range of nominal diameters from 4 mm to 45 mm;
— modernization of the document structure and layout, following the structure already implemented
in the latest publications of ISO/TC 111/SC 1.
iv © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 4778:2019(E)
Round steel short link chains for lifting purposes — Chain
slings of welded construction — Grade 8
1 Scope
This document specifies the requirements, methods of rating and testing of single, double, three and
four leg welded chain slings of grade 8 using components such as sling chains according to ISO 3076
together with links according to ISO 16798, hooks according to ISO 7597 and forged components
according to ISO 8539.
NOTE 1 For special lifting purposes not covered by this document, additionally intermediate links can be
used, for example to connect components to each other having different working load limit.
The range of nominal diameter, d , covered by this document is from 4 mm to 45 mm.
n
Chain slings according to this document are for use in the temperature range –40 °C to +400 °C
according to ISO 3056.
NOTE 2 Concerning the use and maintenance of chain slings of grade 8, see ISO 3056.
Chain slings according to this document comply with the general conditions of acceptance of ISO 1834
and are used for symmetrically distributed loads only.
NOTE 3 For rating of chain slings with asymmetrically distributed loads, see ISO 3056.
This document does not apply to mechanically joined chain slings.
NOTE 4 For mechanically joined chain slings, see ISO 7593.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3076, Round steel short link chains for general lifting purposes — Medium tolerance sling chains for
chain slings — Grade 8
ISO 7597, Forged steel lifting hooks with latch, grade 8
ISO 8539, Forged steel lifting components for use with Grade 8 chain
ISO 16798, Links of Grade 8 for use with slings
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
nominal diameter
d
n
diameter of the sling chain used as a chain leg in a chain sling
Note 1 to entry: The nominal diameter of the chain slings is the nominal diameter of the sling chain used.
3.2
chain sling
assembly consisting of chain leg or chain legs joined to upper and lower terminal components for
attaching loads to be lifted to the hook of a crane or other lifting machine
Note 1 to entry: See Figures 5 to 8.
3.3
chain leg
component of a chain sling, consisting of a fixed number of identical chain links
3.4
upper terminal component
link or other device fitted through a joining link or links to the end of a chain leg or chain legs by means
of which it is attached to the hook of a crane or other lifting machine
Note 1 to entry: See Figures 5 to 8.
3.5
master link
parallel-sided link forming the upper terminal component
3.6
master link assembly
assembly consisting of a master link together with two intermediate master links
Note 1 to entry: See Figure 1.
Key
1 master link
2 intermediate master link
Figure 1 — Master link assembly
3.7
intermediate master link
parallel-sided link used to connect one or two chain legs to a master link
Note 1 to entry: See Figures 5 to 8.
2 © ISO 2019 – All rights reserved

3.8
joining link
parallel-sided link fitted to connect the chain leg to an upper or lower terminal component
Note 1 to entry: See Figures 5 to 8.
3.9
lower terminal component
end link, hook or other device fitted through a joining link to the end of a chain leg opposite to the upper
terminal component
Note 1 to entry: See Figures 5 to 8.
3.10
end link
parallel-sided link forming the lower terminal component
3.11
nominal reach
effective length of a chain leg, measured from the inside of the lower terminal component to the inside
of the upper terminal component
Note 1 to entry: See Figures 5 to 8.
3.12
working load limit
WLL
maximum mass which a chain sling is authorized to sustain in service
3.13
manufacturing proof force
MPF
force applied during manufacture to test sections of the chain sling
3.14
breaking force
BF
maximum force which the test sections of the chain withstands during the course of a static tensile test
to destruction
3.15
inclination angle
β
angle between the chain leg and the vertical, separated to the range from 0° up to and including 45° and
the range from 45° up to including 60°
3.16
test section
TS
individual section of the chain sling to be tested
4 Requirements
4.1 Chain sling
No one but the chain manufacturer, its licensee or an organization authorized by an appropriate
authority is allowed to weld, heat treat and test chain slings covered by thi
...