Section 3 Materials and Weldings

301. General

1. Materials are to be suitable for the purpose intended and for the processes applied, e.g. welding, and are to meet the requirements stated below. Materials for which no special requirements are stated in this section are subject to recognized standards.

2. The manufacturing, processing and testing of materials are to be in accordance with Pt for the Classification of Steel Ships.

2 of Rules

302. Approved materials

1. Rolled or forged steels and steel castings with guaranteed ductility and toughness are normally to be used for pressure hull fabrication. Steel plates, profiles and bars are to be made of fine grained special steels which comply with 303. and conform to recognized standards or manufacturer's speci-

fications which have been examined and approved hulls are listed in Table 1.5.1

by the Society. Approved materials for pressure

Table 1.5.1 Approved materials for pressure hulls

Type	Grade of materials	Material standards or specification
Plate	Special fine grained steel and rolled steel plates of grade DH 32/36, or EH 32/36	Manufacturer's specification Pt 2, Ch 1, 301. of Rules for the Classification of Steel Ships or Recognized standard
Profiles and bars	General purpose shipbuilding and structural steels, provided these are killed, also fine grained structural steels	Pt 2, Ch 1, 301. of Rules for the Classification of Steel Ships or Recognized standard
Pipes	Seamless and welded ferritic steel pipes	Pt 2, Ch 1, Sec 4 of Rules for the Classification of Steel Ships or Recognized standard
Forgings	Forgings for boilers, tanks and pipings	Pt 2, Ch 1, Sec 6 of Rules for the Classification of Steel Ships or Recognized standard
Castings	Castings for boilers, pressure vessels and pipings	Pt 2, Ch 1, Sec 5 of Rules for the Classification of Steel Ships or Recognized standard
Bolts and nuts	Unalloyed and alloyed steel bar	Recognized standard
View-ports	Acrylic and other approved materials	Separately provided Guidances

2. Materials other than those mentioned in Par 1, e.g. austenitic stainless steels, may be used pro- vided they have been proved to be suitable for the intended application. If no recognized standards are available, the relevant specifications are to be submitted to the Society for examination and approval. The use of brittle materials such as grey cast iron is not permitted.

3. Viewports constituting part of the pressure hull are to be made of acrylic plastic and are to meet the requirements separately provided by the Society.

303. Special requirements applicable to materials for pressure hulls

1. Ductility

All metals are to possess sufficient ductility (in terms of the elongation measured by tensile test).

The

elongation at fracture is to conform to the values stated in the standard or material specifica-

tion and shall not be less than 16 %.

2. Impact energy

Steel grades are to conform to the impact energy values measured by notched bar impact test stat- ed in the standard or material specification. In addition, plates are to possess an impact energy of at least 30 J measured on ISO V-notch transverse specimens at a test temperature corresponding to the plate thickness in accordance with Table 1.5.2 Steel profiles and bars welded direct to the pressure hull, e.g. reinforcing rings or stiffeners, are to possess an impact energy of at least 27 J measured in ISO V-notch longitudinal specimens at a test temperature of 0°C

Table 1.5.2 Test temperature for notched bar

Thickness (mm)	Test Temp (°C)
20 or less	0
21 ~ 40	-20
41 ~ 60	-40
Exceeding 60	by agreement with the Society

3. Freedom from defects

Internal or surface defections regarded to harmful for usage are not permitted.

4. Proof of characteristics

Proof of the characteristics of materials used forpressure hulls is to be supplied in the form of ma- terials test certificates according to recognized standard. The type of certificate required for the product concerned is to be submitted to the Society and approved.

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