Section 3 Aluminium alloy castings

3.1.1 Provision is made in this Section for aluminium alloy castings intended for use in the construction of ships, ships for liquid chemicals and other marine structures and liquefied gas piping systems where the design temperature is not lower than minus 165°C. These materials should not be used for piping systems outside cargo tanks except for short lengths of pipes attached to the cargo tanks in which case fire-resisting insulation should be provided.

3.1.2 Castings are to be manufactured and tested in accordance with Chapters Ch 1 General Requirements and Ch 2 Testing Procedures for Metallic Materials and also with the requirements of this Section.

3.1.3 As an alternative to Ch 8, 3.1 Scope 3.1.2, castings which comply with National or proprietary specifications may be accepted provided that these specifications give reasonable equivalence to the requirements of this Section or are approved for a specific application. Generally, survey and certification are to be carried out in accordance with the requirements of Ch 1 General Requirements.

3.2.1 Castings are to be manufactured at foundries approved by LR.

3.3.1 All castings are to be free from surface or internal defects which would be prejudicial to their proper application in service.

3.4.1 The chemical composition of a sample from each cast is to comply with the requirements given in Table 8.3.1 Chemical composition , percentage. Suitable grain refining elements may be used at the discretion of the manufacturer. The content of such elements is to be reported in the ladle analysis.

3.4.2 Where it is proposed to use alloys not specified in Table 8.3.1 Chemical composition , percentage, details of the chemical composition, heat treatment and mechanical properties are to be submitted for approval.

3.4.3 When a cast is wholly prepared from ingots for which an analysis is already available, and provided that no significant alloy additions are made during melting, the ingot maker's certified analysis can be accepted subject to occasional checks as required by the Surveyor.

3.5.1 Castings are to be supplied in the following conditions:

3.6.1 At least one tensile specimen is to be tested from each cast and, where heat treatment is involved, for each heat treatment batch from each cast. Where continuous melting is employed, 500 kg of fettled castings may be regarded as a cast.

3.6.2 The test samples are to be separately cast in moulds made from the same type of material as used for the castings. These moulds should conform to National Standards.

3.6.3 The method and procedures for the identification of the test specimens, and the castings they represent, are to be agreed with the Surveyor. The identification marks are to be maintained during the preparation of test specimens.

3.6.4 Where castings are supplied in the heat treated condition, the test samples are to be heat treated together with the castings which they represent prior to testing.

3.6.5 The results of all tensile tests are to comply with the appropriate requirements given in Table 8.3.2 Minimum mechanical properties for acceptance purposes of sand-cast and investment cast reference test pieces and/or Table 8.3.3 Minimum mechanical properties for acceptance purposes of chill-cast reference test pieces.

3.6.6 Where the results of a test do not comply with the requirements, the re-test procedure detailed in Ch 2, 1.4 Re-testing procedures is to be applied. Where castings are to be used in the heat treated condition, the re-test sample must have been heat treated together with the castings it represents.

3.7.1 All castings are to be cleaned and adequately prepared for inspection.

3.7.2 The accuracy and verification of dimensions are the responsibility of the manufacturer, unless otherwise agreed.

3.7.3 Before acceptance, all castings are to be presented to the Surveyor for visual examination.

3.8.1 At the discretion of the Surveyor, small surface blemishes may be removed by local grinding.

3.8.2 Where appropriate, repair by welding may be accepted at the discretion of the Surveyor. Such repair is to be made in accordance with an approved procedure.

3.9.1 Where required by the relevant Rules, castings are to be pressure tested before final acceptance. Unless otherwise agreed, these tests are to be carried out in the presence and to the satisfaction of the Surveyor.

3.10.1 The manufacturer is to adopt a system of identification as per the requirements of Ch 1, 4.8 Identification of materials, which will enable all finished castings to be traced to the original cast and the Surveyor is to be given full facilities for tracing the castings when required.

3.10.2 All castings which have been tested and inspected with satisfactory results are to be clearly marked with the following details:

1. Identification number, cast number or other markings which will enable the full history of the casting to be traced.

2. LR or Clasifications Register and the abbreviated name of LR's local office.

3. Personal stamp of the Surveyor responsible for the inspection.

4. Test pressure where applicable.

5. Date of final inspection.

3.10.3 Where small castings are manufactured in large numbers, modified arrangements for identification may be specially agreed with the Surveyor.

3.11.1 A LR certificate is to be issued (see Ch 1, 3.1 General) giving the following particulars for each casting or batch of castings which have been accepted:

1. Purchaser's name and order number.

2. Description of castings and alloy type.

3. Identification number.

4. Ingot or cast analysis.

5. General details of heat treatment, where applicable.

6. Results of mechanical tests.

7. Test pressure, where applicable.