Before the joint is assembled, to remove any sources of contamination, clean a ____ inch wide or wider band, both inside and outside of the pipe.

• A. One and a half
• B. One half
• C. One
• D. Two

Answer: (C)

Contaminants around the joint can cause porosity and poor fusion in a GTAW weld, so the area near the joint must be thoroughly cleaned. Cleaning a band at least one inch wide around the joint, on both the inside and outside of the pipe, ensures that all potential oils, grease, oxides, and dirt in the heat-affected zone are removed before assembly. This prevents those contaminants from being drawn into the weld as the pipe pieces come together and heat is applied. A wider band can be used if there’s heavy contamination, but the minimum standard is one inch to reliably prepare the joint without removing unnecessary material. Use proper cleaning methods and recheck cleanliness before assembly.