(a) Repairs to boilers or pressure vessels in service may be performed by welding provided the welding meets the applicable requirements of part 57 of this subchapter.(b) No repairs by welding must be made except temporary emergency repairs without prior approval of the Officer in Charge, Marine Inspection. Emergency repairs must be replaced with permanent repairs meeting the requirements of this subchapter when the vessel returns to a port in which an Officer in Charge, Marine Inspection, is located.(c) Repair welding of power boilers not meeting the requirements of subpart 52.05 of this subchapter is prohibited.(d) Only welded repairs as specified in this subchapter are permitted on boilers and pressure vessels. The welding repairs allowed by this subpart apply only to boilers and pressure vessels fabricated of carbon steel. Welding repairs to boilers and pressure vessels fabricated of alloy steel will be given special consideration by the Commandant. Such other method of repairs by means of welding not covered in this subchapter must be referred to the Commandant.