For preheat and PWHT, the heated zone must extend beyond the edge of the weld by at least:

For preheat and PWHT, the heated zone must extend beyond the edge of the weld by at least:

• A. 1 inch
• B. 2 inches
• C. 0.5 inch
• D. 3 inches

Answer: (A)

When you perform preheat and PWHT, the heated zone must cover not just the weld itself but also extend into the surrounding base metal. The minimum distance is one inch beyond the weld edge. This ensures the heat reaches the heat-affected zone and remains long enough to bring the adjacent metal up to the required treatment temperature. Heating into the surrounding metal helps smooth the temperature gradient at the weld toe, reducing residual stresses and lowering the risk of brittle fracture or hydrogen-induced cracking on cooling. The one-inch extension is the default minimum to guarantee adequate heat penetration around the weld, though longer extensions may be needed for thicker sections or different materials to achieve the same metallurgical benefits.

When you perform preheat and PWHT, the heated zone must cover not just the weld itself but also extend into the surrounding base metal. The minimum distance is one inch beyond the weld edge. This ensures the heat reaches the heat-affected zone and remains long enough to bring the adjacent metal up to the required treatment temperature. Heating into the surrounding metal helps smooth the temperature gradient at the weld toe, reducing residual stresses and lowering the risk of brittle fracture or hydrogen-induced cracking on cooling. The one-inch extension is the default minimum to guarantee adequate heat penetration around the weld, though longer extensions may be needed for thicker sections or different materials to achieve the same metallurgical benefits.