Section 9 Friction stir welding requirements for aluminium alloys
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules for the Manufacture, Testing and Certification of Materials, July 2022 - Chapter 13 Requirements for Welded Construction - Section 9 Friction stir welding requirements for aluminium alloys

Section 9 Friction stir welding requirements for aluminium alloys

Parent topic: Chapter 13 Requirements for Welded Construction

9.1 Scope

9.1.1 The requirements of this Section apply to the application of FSW during construction.

9.1.2 Prior to welding, the friction stir welding equipment is to have been demonstrated as being suitable for use.

9.1.3 Qualified welding procedures that have been approved by LR are required. Procedures to ISO 25239-4 that are endorsed by another Classification Society may be accepted if they are to the satisfaction of the attending Surveyor.

9.1.4 Welding operators are to be qualified to ISO 25239-3 standard. Where qualifications have been certified by another Classification Society, acceptance of the qualifications will be subject to document review and demonstration of knowledge of the FSW process and function of the FSW installation.

9.2 Production quality control

9.2.1 The general requirements for quality control are specified in ISO 25239-5.

9.2.2 Unless otherwise specified in relevant parts of the Rules, the following production tests will be required.

9.2.3 A production test is required when there is a change in procedure, a change in tooling, after equipment repairs or modifications, after deviation from optimum parameters are detected, when defects are identified by non-destructive testing, after continuous welding of every 100 m length during a single shift and with a maximum interval between procedure tests of 8 hours. For butt welds the production tests are to consist of 100 per cent visual examination, two face bend tests, two root bend tests and one macro section. For thicknesses exceeding 12 mm, sets of face and bend tests may be replaced by side bend tests. For test assembly, see Figure 13.9.1 Production test assembly for Friction Stir Welds. The production tests for other joint geometry are to be agreed between the Surveyor and the fabricator.

Figure 13.9.1 Production test assembly for Friction Stir Welds

9.2.4 As an automated process, all essential variables are to be recorded by the FSW system. The welding operator is responsible for ensuring that the system continues to produce welds that are in compliance with the qualified procedure. Surveyors are to be informed when the system exceeds the operating parameters. Surveyors are periodically to review the welding records.

9.2.5 Production welds are to be subject to 100 per cent visual examination by the fabricator and be subject to random checking by the Surveyor.

9.2.6 Surface and volumetric NDE testing is to be conducted on production welds at a frequency of two per welded panel or one every 100 m of weld, whichever is the greater.

9.2.7 Assessment of imperfections is to be in accordance with ISO 25239-5 Annex A and the requirements of Table 13.8.3 Radiographic acceptance criteria for internal imperfections of aluminium.

9.3 Repair

9.3.1 All defective welds are to be reported to the Surveyor.

9.3.2 The manufacturer is to have an approved procedure for the repair of defective welds.

9.3.3 Weld repairs are to be conducted by qualified welders or welding operators in accordance with qualified weld procedures. Welding procedures and welders/operators are to be qualified in accordance with the requirements of Ch 12 Welding Qualifications as appropriate to the welding process used for the weld repair.

9.3.4 All repairs are to be subject to 100 per cent visual, surface and volumetric NDE.

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