Section 3 Materials
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Naval Ships, January 2023 - Volume 2 Machinery and Engineering Systems - Part 3 Transmission Systems - Chapter 2 Shafting Systems - Section 3 Materials

Section 3 Materials

Parent topic: Chapter 2 Shafting Systems

3.1 Materials for shafts

3.1.1 Components are to be manufactured and tested in accordance with the requirements of the Rules for the Manufacture, Testing and Certification of Materials (hereinafter referred to as the Rules for Materials).

3.1.2 The specified minimum tensile strength of forgings for shafts is to be selected within the following general limits:

  1. Carbon and carbon-manganese steel – 400 to 760 N/mm2 (41 to 77,5 kgf/mm2). See also Vol 2, Pt 3, Ch 2, 4.4 Screwshafts and tube shafts 4.4.1.

  2. Alloy steel – not exceeding 800 N/mm2 (82 kgf/mm2) and for other forgings not exceeding 1100 N/mm2.

3.1.3 Where it is proposed to use alloy steel, details of the chemical composition, heat treatment and mechanical properties are to be submitted for approval.

3.1.4 Where shafts may experience vibratory stresses close to the permissible stresses for transient operation, the materials are to have a specified minimum tensile strength of 500 N/mm2 (51 kgf/mm2).

3.1.5 Where materials with greater specified or actual tensile strengths than the limitations given above are used, reduced shaft dimensions or higher permissible vibration stresses are not acceptable when derived from the formulae used in Vol 2, Pt 3, Ch 2, 4.2 Intermediate shafts, Vol 2, Pt 3, Ch 2, 4.4 Screwshafts and tube shafts and Vol 2, Pt 5, Ch 1, 3.2 Limiting stress in propulsion shafting unless, for intermediate shafts only, it is verified that the materials exhibit a similar fatigue life to conventional steels through compliance with the requirements in Vol 2, Pt 3, Ch 2, 6 Approval of alloy steel used for intermediate shaft material.

3.1.6 Unprotected screwshafts and tubeshafts exposed to sea-water are, in general, to be manufactured from corrosion resistant ferrous or non-ferrous material, such as those indicated in Table 2.4.1 Provisional 'A' value for use in unprotected screwshaft formula

3.1.7 In the selection of materials for shafts, keys, locking nuts etc. consideration is to be given to their compatibility with the proposed propeller material.

3.1.8 Where shafts are manufactured from composite material the process is to be approved.

3.2 Shaft bearing materials

3.2.1 Shaft bearings fitted in sternbushes and shaft bossings in ‘A’ and ‘P’ brackets are to be constructed from an approved material and effectively secured to prevent rotational and axial movement in the sterntube(s) and sternbush(es).

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