DNV DNVGL-CP-0081 PDF

This CP gives a description of the procedures and requirements related to documentation, design and type testing applicable for TA of synthetic bushing materials for rudder bearings and propeller shafts.

This CP does not set the design requirements for synthetic bushing materials for rudder bearings and propeller shafts. TA is based on compliance with design requirements given in the rules and/or other regulations and standards. The CP describes the applicable requirements and how to document compliance with the requirements in order to obtain a TA certificate for the equipment. This includes, where relevant, technical requirements for how the type tests shall be performed.

The type approval certificate will cover one grade of the actual product with the possibility to include variants.

For synthetic bushing materials this means:

grade: one chemical composition, with our without reinforcements

variants: various dimensions

Synthetic bushing materials using different chemical compositions, resins, fibres, filler material etc. are considered to be different grades.

The Society's type approval for a synthetic bushing material is divided into four different main levels based on the bushing material’s capability to withstand surface pressure in operational condition:

5.5 N/mm² = type testing according to Sec.2 Table 1 and Sec.2 Table 2.

7.5 N/mm² = type testing according to the general scheme: Sec.2 Table 1, plus testing of swell (dry/ wet/dry/wet cycles) and wear testing at increased pressure: Sec.2 Table 3.

10 N/mm² = type testing according to the general scheme: Sec.2 Table 1, plus testing of swell (dry/ wet dry/wet cycles) and wear testing at increased pressure: Sec.2 Table 3. Additionally, satisfactory service experience from rudder bearing application in minimum 2.5 years (at minimum 5.5 N/mm²) in at least two different vessels classed with the Society shall be documented.

Type approvals issued for surface pressures above 5.5 N/mm² will be issued with a statement that area of application will be evaluated during approval of certified products if the surface pressure exceeds 5.5 N/mm².

Further, a maximum surface pressure of 10 N/mm² will be subject to evaluation w.r.t. service experience etc. in connection with renewal of a certificate.

The type approval will normally only cover water and/or oil lubrication, however, for self-lubricating materials that have documented good performance in lubricated systems for several years it will be possible to apply for an approval covering also non-lubrication (see Sec.2 [5]).

The Society's type approval for a synthetic propeller shaft bearing material is given for pressure up to 0.6 MPa (6 bar).

The type approval certificate is normally limited to one manufacturer at one production site, however, other arrangements may be agreed upon with the Society.

Type tests as specified in Sec.2 [3], shall be carried out and verified in one of the following ways:

at a DNV GL laboratory

 at an accredited and recognized testing laboratory or a laboratory accepted by the Society

at the manufacturer’s premises in the presence of a surveyor.

The type test results shall be submitted to the Society in form of a test report according to ISO 17025 and the additional requirements of the relevant test standard for evaluation.