ISO 15734:2001

Ships and marine technology - Hydrostatic release units

This International Standard specifies performance and testing requirements for hydrostatic release units used in conjunction with float-free lifesaving appliances including inflatable liferafts and Emergency Position Indicating Radio Beacons (EPIRB 's). Hydrostatic release units which comply with this International Standard and which have been formally approved by the cognizant Maritime Safety Administration may be considered to comply with the 1974 Safety Of Life At Sea Convention (SOLAS 74) and the IMO Life-Saving Appliances Code, as amended.

Navires et technologie maritime — Dispositifs de largage hydrostatique

General Information

• Status: Published
• Publication Date: 30-May-2001
• ICS: 47.020.99 - Other standards related to shipbuilding and marine structures
• ICS: 47.080 - Small craft
• Technical Committee: ISO/TC 8/SC 1 - Maritime safety
• Drafting Committee: ISO/TC 8/SC 1/WG 1 - Lifesaving appliances and arrangements
• Current Stage: 9093 - International Standard confirmed

Overview

ISO 15734:2001 specifies performance and testing requirements for hydrostatic release units (HRUs) used with float‑free lifesaving appliances such as inflatable liferafts and EPIRBs. HRUs that comply with this standard and are formally approved by the relevant Maritime Safety Administration may be considered to meet the requirements of SOLAS 1974 and the IMO Life‑Saving Appliances (LSA) Code. The standard covers construction, marking, servicing, prototype and production testing, installation inspection and weak‑link requirements.

Key topics and technical requirements

• Scope: Performance and testing for HRUs for liferafts and Emergency Position Indicating Radio Beacons (EPIRBs).
• Construction & materials:
  • Corrosion‑resistant materials compatible with seawater, oil and detergents.
  • Drains to prevent water accumulation in the hydrostatic chamber.
  • Operability over air temperature −30 °C to +65 °C and seawater −1 °C to +30 °C.
  • Automatic release at a depth of not more than 4 m; no premature release from surface wash‑over.
• Markings & documentation:
  • Permanent marking of manufacturer, type, serial number, manufacture date and capacity limits; expiry marking for disposable types.
  • Operating and maintenance instructions and a servicing record plate for annual service units.
• Weak link:
  • Materials resistant to corrosion; cordage ends whipped/heat treated or wire ends secured with thimbles and ferrules.
  • Tensile‑break strength between 1.8 kN and 2.6 kN.
• Prototype tests (sequence includes):
  • Corrosion resistance: salt spray per ISO 9227 (5% NaCl, +35 °C for 160 h).
  • Temperature cycling: alternating half‑cycles at −30 °C and +65 °C.
  • Submergence & manual release: release between 1.5 m and 4 m depth; inspection for degradation.
  • Strength test: tensile load (minimum 10 kN for 30 min, increased to 15 kN for liferafts approved for >25 persons).
  • Membrane tests: cold flexing and heat exposure; resistance to oil, seawater and detergents.
• Production tests:
  • Visual/dimensional sampling and submergence tests for reusable and disposable units; sample rejection criteria apply.
  • Weak‑link lot testing: minimum five samples; all must break within the specified 1.8–2.6 kN range.
• Installation:
  • Must be removable for servicing, not permanently secured; allow release without tools; weak link must not become part of painter until raft floats free.

Applications and who uses ISO 15734:2001

• Manufacturers of HRUs, liferafts and EPIRBs use the standard to design, test and certify equipment.
• Shipowners and operators reference it when procuring lifesaving appliances to ensure SOLAS/IMO compliance.
• Classification societies, flag state authorities and maritime inspectors use it for type approval and installation checks.
• Marine equipment suppliers, shipyards and third‑party test labs rely on the specified prototype and production test methods.
• Practical uses: product development, conformity assessment, routine production quality control, installation guidance, and maintenance/servicing protocols.

Related standards

• ISO 9227 (salt spray corrosion testing)
• SOLAS 1974 and IMO Life‑Saving Appliances (LSA) Code (for regulatory compliance)

Keywords: ISO 15734:2001, hydrostatic release units, liferaft HRU, EPIRB, SOLAS compliance, IMO LSA Code, marine safety testing, corrosion resistance, submergence test, weak link strength.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15734
First edition
2001-06-01
Ships and marine technology — Hydrostatic
release units
Navires et technologie maritime — Dispositifs de largage hydrostatique
Reference number
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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 committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 15734 was prepared by Technical Committee ISO/TC 8, Ships and marine technology,
Subcommittee SC 1, Lifesaving and fire protection.
©
ISO 2001 – All rights reserved iii

INTERNATIONAL STANDARD ISO 15734:2001(E)
Ships and marine technology — Hydrostatic release units
1 Scope
This International Standard specifies performance and testing requirements for hydrostatic release units used in
conjunction with float-free lifesaving appliances including inflatable liferafts and Emergency Position Indicating Radio
Beacons (EPIRB 's). Hydrostatic release units which comply with this International Standard and which have been
formally approved by the cognizant Maritime Safety Administration may be considered to comply with the 1974
Safety Of Life At Sea Convention (SOLAS 74) and the IMO Life-Saving Appliances Code, as amended.
2 Normative reference
The following normative document contains provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent edition of the normative document indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain
registers of currently valid International Standards.
ISO 9227:1990, Corrosion tests in artificial atmospheres — Salt spray tests.
3 General requirements
3.1 Construction
A hydrostatic release unit used in the float-free arrangements of a survival craft or EPIRB shall be so constructed that
— the materials used are compatible so as to prevent malfunction of the unit; particular care shall be taken to
ensure that metallic-coated parts are not used where damage to the coating from contact with other parts could
adversely affect the functioning of the unit,
— it has drains to prevent the accumulation of water in the hydrostatic chamber when the unit is in its normal
position,
— each structural part connected to the painter system has a strength not less than that required by the painter,
— it can readily be removed for replacement or annual servicing,
— materials and components shall be corrosion-resistant and not affected by seawater, oil or detergents,
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— it can function properly throughout an air temperature range of− 30 C to + 65 C,
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— it can function properly throughout a seawater temperature range of− 1 C to + 30 C,
— it can automatically release the float-free lifesaving appliance at a depth of not more than 4m, and
— it cannot release prematurely when seawater washes over the unit.
3.2 Markings
The unit shall be marked permanently on its exterior with
— its manufacturer, type, and serial number,
— a means of identifying its date of manufacture,
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ISO 2001 – All rights reserved 1

— the maximum-capacity liferaft with which the unit may be used, if the unit has such a limitation, and
— a means of indelibly marking its date of expiry, if it is of the disposable type.
3.3 Servicing record plate
If the unit is of a type which requires annual servicing, it shall be provided with a permanently attached plate to
maintain a record of servicing.
3.4 Operating and maintenance instructions
Operating and maintenance instructions and information shall be provided in a clear and concise form in the
appropriate language or languages and shall include the following:
— general description of the unit;
— installation instructions;
— any on-board maintenance requirements;
— servicing requirements.
3.5 Weak link
3.5.1 Materials
A weak link used in conjunction with a hydrostatic release unit in a float-free arrangement shall
— be made from a material which is corrosion-resistant and not affected by seawater, oil or detergent,
— have the ends either whipped or heat treated, when made of cordage, and
— have each end looped around a thimble and secured with a locking ferrule, when made from a flexible wire.
3.5.2 Strength
A weak link used in conjunction with a hydrostatic release unit in a float-free arrangement of an inflatable liferaft shall
be of sufficient strength to
— pull the painter out of the liferaft container,
— operate the liferaft inflation system, and
— break under a tensile force of between 1,8 kN and 2,6 kN.
4 Prototype tests
4.1 Technical tests
4.1.1 Testing sequence
At least two prototype hydrostatic release units shall be tested in the sequence listed below. No parts may be
renewed or repaired between the tests.
a) Corrosion-resistance test (4.1.2).
b) Temperature cycling test (4.1.3).
c) Submergence and manual release test (4.1.4).
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2 ISO 2001 – All rights reserved

d) Strength test (4.1.5).
e) Membrane-material technical tests (4.1.6).
4.1.2 Corrosion resistance test
The hydrostatic release units shall be exposed to a salt water spray test (5% sodium chloride solution) in accordance
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with ISO 9227, at a temperature of + 35 C� 3 C for 160 h without interruption. After completion, the hydrostatic
release units shall show no corrosion which could affect their efficient functioning, and shall
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