ISO 21130:2019

INTERNATIONAL ISO
STANDARD 21130
First edition
2019-04
Ships and marine technology — Major
components of emergency towing
arrangements
Navires et technologie maritime — Principaux éléments des
dispositifs de remorquage d'urgence
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Technical requirements . 2
4.1 Major components of ETA . 2
4.2 Design arrangement of ETA . 2
4.3 Design and manufacturing requirements for major components . 3
4.3.1 Minimum strength requirement for ETA components . 3
4.3.2 Strength requirement for other parts . 3
4.3.3 Bow ETA . 3
4.3.4 Stern ETA . 5
5 Test method . 7
5.1 Bow ETA . 7
5.1.1 Prototype strength test for the bow ETA . 7
5.1.2 Fairlead . 7
5.1.3 Chain stopper . 7
5.1.4 Chafing chain . 8
5.1.5 Pedestal roller . 8
5.2 Stern ETA . . 8
5.2.1 Strength test for the stern ETA . 8
5.2.2 Fairlead . 8
5.2.3 Towing rope . 8
5.2.4 Stopper ring . 9
5.2.5 Strong point . 9
5.2.6 Storage container for the pick-up gear . 9
5.2.7 Storage winch . 9
5.3 Function test . 9
Annex A (informative) Type and dimensions of a fairlead .10
Annex B (informative) Chemical composition and mechanical properties of steel barsfor
ship anchor chains .11
Annex C (informative) Types and dimensions of chafing chains .12
Annex D (informative) Types and dimensions of chain stoppers .14
Annex E (informative) Type and dimensions of a towing rope .17
Annex F (informative) Types and dimensions of fairleads/strong points .18
Bibliography .19
Foreword
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This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology,
Subcommittee SC 4, Outfitting and deck machinery.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 21130:2019(E)
Ships and marine technology — Major components of
emergency towing arrangements
1 Scope
This document specifies the technical requirements, test methods, inspection rules and markings for
major components of emergency towing arrangements (ETA) provided for tankers, gas carriers (LPG,
LNG, etc.) and chemical vessels no less than 20 000 deadweight tonnes (DWT).
It is only applicable to emergency towing arrangements as defined in 3.1.
NOTE For any other applications, such as for mooring at a single point mooring (SPM) facility, the appropriate
standards need to be referred to.
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 3808, Road vehicles — Unscreened high-voltage ignition cables — General specifications, test methods
and requirements
ISO 4306-1, Cranes — Vocabulary — Part 1: General
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4306-1, ISO 3808 and the
following 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
emergency towing arrangement
ETA
system equipped on tankers, gas carriers and chemical vessels, used to tow the vessel in an emergency
such as mechanical failure or lack of power
Note 1 to entry: The International Maritime Organization (IMO) requires that tankers, gas carriers and chemical
vessels of not less than 20 000 DWT and constructed since Jan 1, 1996, be provided with emergency towing
arrangements installed on both the bow and the stern.
3.2
safe working load
SWL
maximum permissible load determined after the equipment has been tested according to the relevant
regulations
3.3
ultimate strength
certified minimum breaking load of a wire rope, chafing chain, shackle, etc.
Note 1 to entry: In the case of equipment such as chain stoppers, fairleads, etc., it can be defined as the load that
will cause a general failure of the structure or its attachment to the deck.
3.4
classification society
institution that establishes and maintains technical standards for the construction and operation of
ships and offshore facilities
4 Technical requirements
4.1 Major components of ETA
The major components of ETA are listed in Table 1 with their installation requirements.
Table 1 — ETA major components and installation requirements
Bow ETA Stern ETA Strength requirements
Component
(not preconfigured) (preconfigured) (see 4.3.1)
Pick-up gear Optional Required —
Towing rope Optional Required Required
Determined according to
Chafing chain Required Required
the design
Fairlead Required Required Required
Strong point Required Required Required
Determined according to
Pedestal rollers Required —
the design
4.2 Design arrangement of ETA
4.2.1 A typical arrangement of bow ETA is shown in Figure 1.
Key
1 pedestal rollers 3 fairlead 5 centreline of the chain
2 chain stopper 4 chafing chain 6 bulwark
NOTE The centreline of the chain is parallel to the deck.
Figure 1 — Typical arrangement of bow ETA
2 © ISO 2019 – All rights reserved

4.2.2 A typical arrangement of stern ETA is shown in Figure 2.
Key
1 pick-up gear 3 fairlead 5 storage winch
2 towing rope 4 strong point 6 stern
Figure 2 — Typical arrangement of stern ETA
4.3 Design and manufacturing requirements for major components
4.3.1 Minimum strength requirement for ETA components
The minimum strength requirement for ETA components under stress during the towing operation is
given in Table 2.
Table 2 — Minimum strength requirement
Working strength Ultimate strength
Ship size
kN kN
20 000 tones ≤ DWT < 50 000 tonnes 1 000 2 000
50 000 tonnes ≤ DWT 2 000 4 000
The strength should be sufficient for all relevant angles of the towline, i.e. up to 90° from the ship's
centreline to the port and starboard and 30° vertical downwards.
4.3.2 Strength requirement for other parts
Other parts shall have sufficient strength to withstand the load to which they may be subjected in
towing operations.
4.3.3 Bow ETA
4.3.3.1 Fairlead
a) The fairlead shall be of a closed type, with the opening dimensions of at least 600 mm in width and
450 mm in height.
b) The fairlead should be capable of supporting the stre
...