Reg. 559, Reg. 560

Types of welded shell seams

Reg. 560

Repairs to welded seams

a)	Any repair to a weld carried out by the manufacturer shall first be agreed to by the Inspecting Authority.
b)	Where defects are distributed over the whole length of the seam the total length of the portions which may be cut out from any one longitudinal or circumferential seam to remove all defects shall not exceed 15 per cent of the total length of the seam. When, however, the defects are all located in a single continuous length which may be cut out to remove all defects shall not exceed 10 per cent of the total length of the seam. Circumferential seams:- Where the length of weld metal cut out for repair in a circumferential seam exceeds the amount stated above the whole of the weld metal shall be removed and the seam re-welded. Representative tests for a rewelded circumferential seam shall be provided when required by the Inspecting Authority. Longitudinal seams:- Where the length of weld metal cut out for repair in any longitudinal seam exceeds the amount stated above, or the weld metal in any other way fails to comply with the requirements specified, the whole of the weld metal shall be removed and the seam re-welded, provided that the original test plates are treated similarly or new plates of the same thickness as the joint and of similar quality of material are attached to the ends of the seam and re-welded with it. In either case the plates are to be tested in accordance with the appropriate provision of regulation 561 and the requirements for heat-treatment to be in accordance with regulation 562.
c)	Defect shall be cut out by chipping, machining or other approved methods.
d)	Whenever a defective part has been cut out, the Inspecting Authority shall be notified so that, if necessary, an examination may be made before re-welding.
e)	In the case of Class I boilers all repaired areas shall be subjected to radiographic examination.
f)	The boilers shall be heat-treated on completion of all welded repairs.