Section 13 Flexible hoses

13.1.1 A flexible hose assembly is a short length of metallic or non-metallic hose normally with prefabricated end fittings ready for installation.

13.1.2 For the purpose of approval for the applications in Vol 2, Pt 7, Ch 1, 13.2 Applications, details of the materials and construction of the hoses, and the method of attaching the end fittings together with evidence of satisfactory prototype testing, are to be submitted for consideration. The materials used in the construction of flexible hoses are to be suitable for the intended purposes.

13.1.3 Hose clamps and similar types of end attachments are not be used for flexible hoses in piping systems for steam, flammable media, starting air systems or for sea-water systems where failure may result in flooding. In other piping systems, the use of hose clamps may be accepted where the working pressure is less than 5 bar and provided that there are two clamps at each end connection.

13.1.4 Flexible hoses are to be limited to a length necessary to provide for relative movement between fixed and flexibly mounted items of machinery/equipment or systems.

13.1.5 Flexible hoses are not to be used to compensate for misalignment between sections of piping.

13.1.6 Flexible hose assemblies are not to be installed where they may be subjected to torsional deformation (twisting) under normal operating conditions.

13.1.7 The number of flexible hoses in piping systems mentioned in this section is to be kept to a minimum and to be limited for the purpose stated in Vol 2, Pt 7, Ch 1, 13.2 Applications 13.2.1.

13.1.8 Where flexible hoses are intended for use in piping systems conveying flammable fluids, they are not to be installed in close proximity to hot surfaces, electrical installations or other sources of ignition. The risk of ignition due to failure of the hose assembly and subsequent release of fluids is to be mitigated as far as practicable by the use of screens or other suitable protection.

13.1.9 Flexible hoses are to be installed in clearly visible and readily accessible locations.

13.1.10 The installation of flexible hose assemblies is to be in accordance with the manufacturer's instructions and use limitations with particular attention to the following:

1. Orientation.

2. End connection support (where necessary).

3. Avoidance of hose contact that could cause rubbing and abrasion.

4. Minimum bend radii.

13.1.11 Flexible hoses are to be permanently marked by the manufacturer with the following details:

1. Hose manufacturer's name or trademark.

2. Date of manufacture (month/year).

3. Designation type reference.

4. Nominal diameter.

5. Pressure rating.

6. Temperature rating.

Where a flexible hose assembly is made up of items from different manufacturers, the components are to be clearly identified and traceable to evidence of prototype testing. See Vol 2, Pt 1, Ch 3, 4.18 Electromagnetic hazards regarding requirements for a flexible hose register.

13.2.1 Short joining lengths of flexible hoses complying with the requirements of this Section may be used, where necessary, to accommodate relative movement between various items of machinery connected to permanent piping systems. The requirements of this Section may also be applied to temporarily-connected flexible hoses or hoses of portable equipment.

13.2.2 Rubber or plastics hoses, with integral cotton or similar braid reinforcement, may be used in fresh and seawater cooling systems. In the case of sea-water systems, where failure of the hoses could give rise to the danger of flooding, the hoses are to be suitably enclosed, as indicated in Vol 2, Pt 7, Ch 1, 14.2 Applications 14.2.4.

13.2.3 Rubber hoses, with single, double or more closely woven integral wire braid or other suitable material reinforcement, or convoluted metal pipes with wire braid protection, may be used in bilge, ballast, compressed air, fresh water, sea-water, fuel oil, lubricating oil, Class III steam, hydraulic and thermal oil systems. Flexible hoses of plastics materials for the same purposes, such as Teflon or Nylon, which are unable to be reinforced by incorporating closely woven integral wire braid are to have suitable material reinforcement as far as practicable. Where rubber or plastics hoses are used for fuel oil supply to burners, the hoses are to have external wire braid protection in addition to the integral wire braid. Flexible hoses for use in steam systems are to be of metallic construction.

13.2.4 Flexible hoses are not to be used in high pressure fuel oil injection systems.

13.2.5 The requirements in this Section for flexible hose assemblies are not applicable to hoses intended to be used in fixed fire extinguishing systems.

13.2.6 Short lengths of flexible hoses may be used for acoustic attenuation where agreed by LR. The use of hoses for such applications is to be kept to a minimum.

13.3.1 Flexible hose assemblies are to be designed and constructed in accordance with recognised National or International Standards acceptable to LR.

13.3.2 Flexible hoses are to be complete with approved end fittings in accordance with manufacturer's specification. End connections which do not have flanges are to comply with Vol 2, Pt 7, Ch 1, 5.2 Flange connections as applicable and each type of hose/fitting combination is to be subject to prototype testing to the same standard as that required by the hose with particular reference to pressure and impulse tests.

13.3.3 Flexible hose assemblies intended for installation in piping systems where pressure pulses and/or high levels of vibration are expected to occur in service, are to be designed for the maximum expected impulse peak pressure and forces due to vibration. The tests required by Vol 2, Pt 7, Ch 1, 13.4 Testing are to take into consideration the maximum anticipated in-service pressures, vibration frequencies and forces due to installation.

13.3.4 Flexible hose assemblies constructed of non-metallic materials intended for installation in piping systems for flammable media, and sea-water systems where failure may result in flooding, are to be of fire-resistant type. Fire resistance is to be demonstrated by testing to ISO 15540 and ISO 15541.

13.3.5 Flexible hose assemblies are to be suitable for the intended location and application, taking into consideration ambient conditions, compatibility with fluids under working pressure and temperature conditions consistent with the manufacturer's instructions and any other applicable requirements in the Rules.

13.4.1 Acceptance of flexible hose assemblies is subject to satisfactory prototype testing of a representative hose assembly. Prototype test programmes for flexible hose assemblies are to be submitted by the manufacturer and are to be sufficiently detailed to demonstrate performance in accordance with the specified standards.

13.4.2 For a particular hose type complete with end fittings, the tests, as applicable, are to be carried out on different nominal diameters for pressure, burst, impulse and fire resistance in accordance with the requirements of the relevant standard. The following standards are to be used as applicable:

• ISO 6802 – Rubber and plastics hoses and hose assemblies with wire reinforcements – Hydraulic impulse test with flexing.
• ISO 6803 – Rubber or plastics hoses and hose assemblies – Hydraulic pressure impulse test without flexing.
• ISO 15540 – Ships and marine technology – Fire resistance of hose assemblies – Test methods.
• ISO 15541 – Ships and marine technology – Fire resistance of hose assemblies – Requirements for test bench.
• ISO 10380 – Pipework – Corrugated metal hoses and hose assemblies.

Other standards may be accepted where agreed by LR.

13.4.3 All flexible hose assemblies are to be satisfactorily prototype burst tested to an International Standard* to demonstrate they are able to withstand a pressure of not less than four times the design pressure without indication of failure or leakage.