API RP 577 provides guidance to the API authorized inspector on welding inspection as encountered with fabrication and repair of refinery and chemical plant equipment and piping. Common welding processes, welding procedures, welder qualifications, metallurgical effects from welding, and inspection techniques are described to aid the inspector in fulfilling their role implementing API 510, API 570, API Std 653 and API RP 582. The level of learning and training obtained from this document is not a replacement for the training and experience required to be an American Welding Society (AWS) Certified Welding Inspector (CWI).

Welding inspection is a critical part of an overall weld quality assurance program. Welding inspection includes much more than just the non-destructive examination of the completed weld. Other important issues include review of specifications, joint design, cleaning procedures, and welding procedures. Welder qualification should be performed to help ensure that the weldment performs properly in service.