ISO 4779:2021

Chain components for lifting purposes - Forged eye hook with point and latch - Grade 4, stainless steel, solution annealed

This document specifies the requirements for forged eye hooks with point and latch of grade 4 from stainless steel and solution annealed for use preferably as a component in chain slings of welded construction of grade 4 from stainless steel and solution annealed. IMPORTANT - For other applications, e.g. steel wire rope slings or textile slings, it is important that the hook design is checked to ensure its fitness for a safe use. NOTE 1 The grade for the hook according to this document is taken from the grade of the sling chain according to ISO 1835. Both (sling chains and hooks) have identical scopes and values for the working load limit, WLL, according to Table 2 and values for the mechanical requirements according to Table 3. Thus, the direct correlation of hooks to the sling chain is given by the WLL and especially the code system on the product body itself. The grade of the hook does not define any values of the tensile strength of the hook material. For further information, see Annex B. The range of the nominal diameter, dn, of the associated sling chain according to ISO 1835 is from 4 mm to 22 mm. Hooks according to this document are for use in the temperature range –100 °C to +400 °C. These hooks are solution annealed in the finished condition and can therefore be used without restrictions with regard to the corrosion resistance of the steels according to 5.1. NOTE 2 The term “eye hook with point and latch” is taken from ISO 1837:2003, Figure 5.

Éléments de chaînes de levage — Crochets de levage forgés en acier à bec et à œil — Grade 4, acier inoxydable, recuit d’homogénéisation

General Information

• Status: Published
• Publication Date: 18-Aug-2021
• ICS: 53.020.30 - Accessories for lifting equipment
• Technical Committee: ISO/TC 111/SC 3 - Components and accessories
• Drafting Committee: ISO/TC 111/SC 3 - Components and accessories
• Current Stage: 6060 - International Standard published
• Start Date: 19-Aug-2021
• Due Date: 06-Jan-2022
• Completion Date: 19-Aug-2021

Relations

• Revises: ISO 4779:1986 - Forged steel lifting hooks with point and eye for use with steel chains of grade M(4)
• Effective Date: 11-Nov-2017

Overview

ISO 4779:2021 specifies requirements for forged eye hooks with point and latch - Grade 4, stainless steel, solution annealed, intended primarily as components in welded chain slings (grade 4). The standard covers material, manufacture, heat treatment, dimensions, mechanical properties, testing, marking and certificates for hooks matched to round steel sling chains with nominal diameters from 4 mm to 22 mm. Hooks manufactured to ISO 4779 are suitable for service temperatures from –100 °C to +400 °C and are solution annealed to ensure corrosion resistance.

Keywords: ISO 4779:2021, forged eye hook, grade 4, stainless steel, solution annealed, lifting chain components, working load limit (WLL).

Key topics and requirements

• Scope and application: Hooks are intended preferably for welded chain slings of grade 4; alternative uses (wire rope or textile slings) require design verification for safe use.
• Material: Austenitic stainless steels with molybdenum and resistance to intergranular corrosion (e.g., X6CrNiMoTi17-12-2 / 1.4571 / S31635) are specified.
• Manufacture and heat treatment:
  • Drop-forged in one piece, free from harmful surface defects.
  • Solution annealed (approx. 1 020 °C to 1 120 °C) and rapidly cooled; surface pickling/passivation required after heat treatment.
• Dimensions and designation: Dimension limits are given (Table 1) and calculation bases are in Annex A. Hooks are designated by nominal chain diameter and grade (e.g., 10-4).
• Mechanical properties & WLL: Working Load Limit (WLL) values correspond directly to the sling chain grade per ISO 1835; mechanical test requirements (test force, elongation, breaking force, deformation) are specified.
• Testing & inspection: Type, manufacturing and end tests include dimensional checks, surface/penetrant tests, tensile testing and inspection criteria; personnel qualification and test certification are required.
• Marking & documentation: Product body coding and certificates (type test and manufacturer’s) are required for traceability.

Applications and users

• Primary users: lifting equipment manufacturers, chain-sling fabricators, forging shops, QA/inspection teams, procurement/specification engineers, and lifting/safety officers.
• Practical applications: Components for chain slings used in material handling, offshore, chemical and food industries where corrosion resistance and high temperature performance are required.
• Practical notes: Always verify hook compatibility (geometry, WLL, attachment type) when substituting between sling types; rely on the product code/WLL for direct correlation to chain grade.

Related standards

• ISO 1835 - Round steel short link chains for lifting (Grade 4)
• ISO 1837 - Lifting hooks - Nomenclature
• ISO 16143-2 - Stainless steels - Corrosion-resistant semi-finished products
• ISO 3452-1, ISO 7500-1, ISO 8539, ISO 13385-1, EN 10228-2 - referenced for testing, NDT and calibration

For specification or procurement, reference ISO 4779:2021 to ensure forged eye hooks meet recognized international requirements for safety, corrosion resistance and traceability.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 4779
Second edition
2021-08
Chain components for lifting
purposes — Forged eye hook with
point and latch — Grade 4, stainless
steel, solution annealed
Éléments de chaînes de levage — Crochets de levage forgés en acier à
bec et à œil — Grade 4, acier inoxydable, recuit d’homogénéisation
Reference number
©
ISO 2021
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
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below or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: [phone]
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Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Dimensions and designation . 2
4.1 Dimensions . 2
4.2 Designation . 3
5 Requirements . 4
5.1 Material . 4
5.2 Manufacture . 4
5.3 Heat treatment . 4
5.4 Dimensions . 4
5.5 Working load limit, WLL . 5
5.6 Mechanical properties . 5
5.6.1 General. 5
5.6.2 Test force, F . 6
T
5.6.3 Elongation at test force . . 6
5.6.4 Breaking force, F . 6
B
5.6.5 Deformation . 6
5.7 Surface condition . 6
6 Tests . 6
6.1 Qualification of personnel . 6
6.2 Type tests . 6
6.2.1 General. 6
6.2.2 Dimension test . 6
6.2.3 Surface test. 7
6.2.4 Tensile test . 7
6.3 Manufacturing examination . 8
6.4 End tests . 8
6.4.1 General. 8
6.4.2 Size of lot . . 8
6.4.3 Sampling. 8
6.4.4 Dimension test . 8
6.4.5 Tensile test . 8
7 Marking . 9
8 Certificates . 9
8.1 Type test certificate . 9
8.2 Manufacturer's certificate .10
9 Instructions for use .10
10 Environmental issues .10
Annex A (informative) Bases for the calculation.11
Annex B (informative) Conversion sling chains/chain components .14
Bibliography .15
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
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electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
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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URL: www .iso .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 3, Components and accessories.
This second edition cancels and replaces the first edition (ISO 4779:1986), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— limitation of the materials used to stainless steels;
— corresponding adaptation of the alloy elements and heat treatment;
— reduction of the sizes, corresponding to the related nominal chain sizes;
— including detailed formulae base for calculation of dimensions, working load limits and mechanical
requirements in Annex A.
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.
iv © ISO 2021 – All rights reserved

INTERNATIONAL STANDARD ISO 4779:2021(E)
Chain components for lifting purposes — Forged eye hook
with point and latch — Grade 4, stainless steel, solution
annealed
1 Scope
This document specifies the requirements for forged eye hooks with point and latch of grade 4 from
stainless steel and solution annealed for use preferably as a component in chain slings of welded
construction of grade 4 from stainless steel and solution annealed.
IMPORTANT — For other applications, e.g. steel wire rope slings or textile slings, it is important
that the hook design is checked to ensure its fitness for a safe use.
NOTE 1 The grade for the hook according to this document is taken from the grade of the sling chain according
to ISO 1835. Both (sling chains and hooks) have identical scopes and values for the working load limit, WLL,
according to Table 2 and values for the mechanical requirements according to Table 3. Thus, the direct correlation
of hooks to the sling chain is given by the WLL and especially the code system on the product body itself. The
grade of the hook does not define any values of the tensile strength of the hook material. For further information,
see Annex B.
The range of the nominal diameter, d , of the associated sling chain according to ISO 1835 is from 4 mm
n
to 22 mm.
Hooks according to this document are for use in the temperature range –100 °C to +400 °C.
These hooks are solution annealed in the finished condition and can therefore be used without
restrictions with regard to the corrosion resistance of the steels according to 5.1.
NOTE 2 The term “eye hook with point and latch” is taken from ISO 1837:2003, Figure 5.
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 1835, Round steel short link chains for lifting purposes — Medium tolerance sling chains — Grade 4,
stainless steel
ISO 1837, Lifting hooks — Nomenclature
ISO 3452-1, Non-destructive testing — Penetrant testing — Part 1: General principles
ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and verification of the force-measuring system
ISO 8539, Forged steel lifting components for use with Grade 8 chain
ISO 13385-1, Geometrical product specifications (GPS) — Dimensional measuring equipment — Part 1:
Design and metrological characteristics of callipers
ISO 16143-2, Stainless steels for general purposes — Part 2: Corrosion-resistant semi-finished products,
bars, rods and sections
EN 10228-2, Non-destructive testing of steel forgings - Part 2: Penetrant testing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1837, ISO 8539 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
nominal size
combination of numerical values without units for designation and ordering purposes, which indicates
the nominal diameter of the associated round steel link chain and the grade of the forged component
EXAMPLE 10-4
3.2
test force
F
T
force applied to the hook during the tensile test
4 Dimensions and designation
4.1 Dimensions
The bases for calculation of the values for the dimension limits listed in Table 1 are given in Annex A.
The corresponding dimension letters are shown in Figure 1. The specified values are absolute limits.
The geometry of the hook is not specified in detail. Therefore, Figure 1 specifies only where the
dimension values according to Table 1 are measured.
2 © ISO 2021 – All rights reserved

Key
A bar diameter D seat diameter L inner length
B point hight E eye dimension M outer length, see 5.6.3
C throat opening H seat hight W seat width
Figure 1 — Dimensions of hooks
Preferred nominal sizes are given in Table 1, column 1. Other nominal sizes may be used, provided the
corresponding dimensions are calculated in accordance with Annex A.
Table 1 — Dimension limits
Dimensions in millimetres
1 2 3 4 5 6 7 8 9 10
A B C C D E H L W
Nominal
size
max min min max min min max max max
4 - 4 10 12 11 14 15 10 17 62 12
6 - 4 15 17 16 21 22 15 26 93 17
8 - 4 21 23 22 27 30 20 34 124 23
10 - 4 26 29 27 35 38 25 44 157 29
13 - 4 33 38 35 45 49 33 56 202 38
16 - 4 41 47 43 55 60 40 69 248 46
18 - 4 46 52 48 61 67 45 77 277 52
20 - 4 51 58 54 69 75 50 86 311 58
22 - 4 56 64 59 75 82 55 94 340 64
4.2 Designation
The designation of the hook shall be in accordance with the general format given in Figure 2.
Figure 2 — General format
5 Requirements
5.1 Material
The steel used shall be austenitic stainless steels with molybdenum and shall be resistant against
intergranular corrosion.
NOTE 1 For example the steel with the ISO name X6CrNiMoTi17-12-2 respectively with the ISO number 4571
316-35-I according to ISO 15510.
NOTE 2 The resistance against pitting corrosion will be increased by alloying with molybdenum.
After solution annealing, intergranular corrosion is unlikely at a service temperature of +400 °C and
with an extra low carbon content of the steel. T
...