Here is the ANSI standard referenced by OSHA- ANSI B56.1-1969 . This may or may not be revised by now and not yet adopted by OSHA.
OSHA States
1910.178(a)(4)
Modifications and additions which affect capacity and safe operation shall not be performed by the customer or user without manufacturers prior written approval. Capacity, operation, and maintenance instruction plates, tags, or decals shall be changed accordingly.
So the manufacturer would be the best place to start if you are intending to maintain compliance during repair. If NEW then the applicable ANSI standard should reference welding.