Section 2 Materials and Welding

201. Materials

1. The materials used for hull construction and equipment are to comply with the requirements in Pt 2, Ch 1, of Rules for the Classification of Steel Ships, unless other specified.

2. Where materials other than those specified in rules are used, their use and the corresponding scan- tlings are to be specially approved by the Society.

3. Where high tensile steels are used for hull construction, the drawings showing their scope and loca- tion together with their type and scantlings, must have Society approval.

4. Steel used for hull construction is to comply with the requirements in Pt 3, Ch 1, Sec 4. of

Rules for the Classification of Steel Ships.

202. Welding

1. Welding is to be in accordance

2. Welding structures are to be

Classification of Steel Ships.

with Pt 2, Ch 2.

in accordance with Pt 3, Ch 1, Sec 5. of Rules for the

203. Corrosion protection

1. All steel surfaces, except in oil tanks for craft use, are to be protected against corrosion by suit- able paint or other effective coating. Inner bottoms and decks for dry cargoes shall be specially considered.

2. For other materials, such as propellers, provisions are to be made to avoid galvanic corrosion.

3. Coating specifications, including antifouling, are to state details concerning :

(1) Metal surface cleaning and treatment before application of primer coat.

(2) The system for build-up of coating with individual coats.

(3) Curing time and overcoating intervals.

(4) Acceptable temperatures of air and metal surfaces.

(5) Acceptable dryness/humidity conditions during above operations.

(6) Thickness of individual and final coatings.

4. Coatings

(1) Before coating, the metal surface is to be properly treated by blast cleaning.

(2) Shop primer applied over areas which will subsequently be welded, shall have no detrimental effect on the finished welds.

(3) Coatings are to be compatible with previously applied shop primer. Primer or intermediate coat- ing which have been exposed for some time must be cleaned before application of the next

coat.

5. Provisions to avoid galvanic corrosion

(1) Acceptable provisions are either one of or a combinations of the following.

(A) Coating of exposed surfaces by moisture.

(B) Electrical insulation of different metals.

(C) Cathodic protection.

(2) In addition to the coating, external cathodic protection of steel hulls can be obtained with alu- minium or zinc sacrificial anodes or impressed current.

(3) If an impressed current system is applied, precautions must be taken to avoid overprotection by

means of anode screen and overprotection alarm.

6. Specification and documents of cathodic protection

(1) Specifications of cathodic protection systems are to state details as follows.

(A) Areas to be protected.

(B) Current density demand.

(C) Anode material and manufacturer.

(D) Anode weight, distribution and total number.

(E) Service life of anode.

(2) The designed service life of the cathodic protection system is normally to be for at least 5 years.

7. Deck composition

Deck composition is subject to type approval. It is to be of an elastic, non-hygroscopic material. Deck compositions for application in cargo areas are to be suitably reinforced.