Section 3 Specific requirements for fabricated steel sections

3.1.1 Fabricated steel sections are items used in place of rolled sections and as such will not be regarded as subassemblies. Products regarded as sub-assemblies are subject to requirements of welded construction specified in Ch 13, 2 Specific requirements for ship hull structure and machinery.

3.1.2 The requirements for structural steel sections are based on these being manufactured from flat products by automatic welding and intended for use in the construction of ships and other marine structures.

3.1.3 Fabricated steel sections are to be manufactured in accordance with the requirements of this Section and the general requirements of Ch 13, 1 General welding requirements.

3.1.4 In all cases, sections are to be manufactured at works, which have been assessed and approved in accordance with Materials and Qualification Procedures for Ships, Book J, MQPS Procedure 12-1.

3.2.1 Products are to conform dimensionally to the provisions of an acceptable National or International Standard.

3.2.2 The minimum throat thickness of fillet welds is to be determined from:

Throat thickness = 0,34t but not to be taken as less than 3 mm

3.2.3 Where a welding procedure using deep penetration welding is used (see Ch 11 Approval of Welding Consumables, ‘p’ and ‘T’ welding techniques) the minimum leg length required will be specially considered provided the requirements of Ch 13, 2.9 Fillet welds 2.9.2 are complied with.

3.2.4 Unless agreed otherwise, the leg length of the weld is to be not less than 1,4 times the specified throat thickness.

3.3.1 Every finished item is to be clearly marked by the manufacturer in at least one place with the following particulars:

1. The manufacturer’s name or trade mark.

2. Identification mark for the grade of steel.

3. Identification number and/or initials which will enable the full history of the item to be traced.

4. Where required by the purchaser, the order number or other identification mark.

5. The letters ‘LR'.

6. The Surveyor’s personal stamp.

The above particulars, but excluding the manufacturer’s name or trade mark where this is embossed on finished products, are to be encircled with paint or otherwise marked so as to be easily recognisable.

3.3.2 In the event of any material bearing LR’s brand failing to comply with the test requirements, the brand is to be removed or unmistakably defaced, see also Ch 1, 4.7 Rectification of defective material.

3.4.1 For cut edges that are to remain unwelded, it is to be demonstrated that the plate preparation procedures used are able to achieve edges that are free from cracks or other deleterious imperfections.

3.4.2 Where assembly jigs and devices are used to bring the web into contact with the flanges and hold these in place during welding, means are to be provided to ensure that the degree of contact is maintained until welding is complete.

3.4.3 Welding procedures are to be established for the welding of all joints including weld repairs and are to be approved in accordance with Ch 12 Welding Qualifications. Welders are to be approved in accordance with Ch 12 Welding Qualifications, and qualification records are to be available to the Surveyor.

3.4.4 The welding consumables used are to be approved in accordance with Ch 11 Approval of Welding Consumables and are to be suitable for the type of joint and grade of steel as described in Ch 13, 2.2 Welding consumables. For joining steel of different tensile strengths, the consumables are to be suitable for the tensile strength of the component considered in the determination of weld size.

3.4.5 The application of pre-heat and the use of low hydrogen welding consumables are to be in accordance with the requirements of Ch 13, 2.2 Welding consumables.

3.4.6 Welding is to be double continuous fillet welding or full penetration welding as specified in the approved plans.

3.4.7 Where deep penetration welding is used, the requirements of Ch 13, 2.9 Fillet welds 2.9.2 are to be complied with.

3.5.1 Surface inspection and verification of dimensions are the responsibility of the manufacturer and are to be carried out on all materials prior to despatch. Acceptance by the Surveyor of material later found to be defective does not absolve the manufacturer from this responsibility.

3.5.2 The Surveyor will carry out checks to ensure that the weld size and profile are in accordance with the manufacturing specification and the manufacturer’s Quality Control Procedures.

3.5.3 The manufacturer is to examine the welds by magnetic particle or dye penetrant methods. The length examined is to be 200 mm at each end, for each length cut for delivery.

3.5.4 If cracks are revealed, these are to be reported to the Surveyor and the whole of the length is to be examined by magnetic particle or dye penetrant methods. Corrective action in respect of the manufacturing process, and repairs are to be as indicated in the manufacturers’ Quality Control Manual.

3.5.5 The weld defect is not to exceed the acceptance levels given in Table 13.2.5 Acceptance criteria for visual testing, magnetic particle and liquid penetrant testing.

3.6.1 One production batch test is required for every 500 m of fabricated section manufactured, or fraction thereof. From each batch test, two samples are to be removed, one from near the beginning of the production run and one from near the end. From each of these test samples one macro specimen and one fracture test specimen are to be taken.

3.6.2 The macro specimens are to be prepared and etched to demonstrate freedom from unacceptable defects and that the weld penetration is in accordance with the manufacturing specification. The fracture specimens are to be broken, one for each side of the fillet welds and the fractured surfaces examined for compliance with the requirements of Table 13.2.6 Acceptance criteria for radiographic testing.

3.6.3 Where the welding procedure used has employed the deep penetration technique, the amount of root penetration is to be measured on the macro specimen and is not to be less than that demonstrated during welding procedure approval testing.

3.6.4 For the purposes of this Section, a batch is to consist of products of only one size and grade of material.

3.7.1 Each test certificate is to include the following particulars:

1. Purchaser’s name and order number.

2. Where known, the contract number for which the material is intended.

3. Address to which material is despatched.

4. Description and dimensions of the product.

5. Specification or grade of the steel.

6. Identification number and/or initials.

7. Cast number and chemical composition of ladle samples of constituent plates.

8. Mechanical test results of constituent plates.

9. Condition of supply when other than as-rolled.

10. Make and brand of welding consumables.

3.7.2 Test certificates or shipping statements may be signed by the Surveyor, provided the documentation requirements of Ch 13, 1.17 Certification are satisfied. The following form of declaration will be accepted if stamped or printed on each test certificate or shipping statement with the name of the works and signed by an authorised representative of the manufacturer: ‘We hereby certify that the material has been made by an approved procedure in accordance with the Rules for the Manufacture, Testing and Certification of Materials, July 2022'.

3.7.3 The manufacturer is to maintain records by which sources of material can be identified together with the results of all inspections and tests.