All TWI Inspectors are certified through testing to the discipline which certified. Additional certifications include American Petroleum Institute (API)
API 510 – Covers maintenance inspections, repair, alteration, and re-rating procedures for pressure vessels used by petroleum and chemical process industries.

API 570 – Performs visual, baseline and in-service corrosion inspections on piping systems.

API 653 – Specific inspection requirements and techniques that apply to above ground storage tanks.

Inspectors through the API Individual certification program, and American Welding Society (AWS) certified weld inspectors.