Hi Mangesh
Generally if repairs are made to the base metal, then the requirements of the material specification needs to be met. (Assuming the defect was inherent in the material from the mill.) Most material specifications will give guidance on allowable weld repairs to the material, although ASTM A516 is not one. (In some instances, the material spec will not weld repairs.)
If the repair to the material is due to some damage being introduced during fabrication, then first see what the material specification asks for. If this does not give guidance, then you need to perform repairs and NDT based on the design conditions and the most likely defect that could be present after the repair. Mostly UT and surface (MPI; DPI) comes to mind. For some design conditions, repair may not be a tolerable answer, then you may have to cut out and replace.
Hope that helps.
Regards
Niekie