Which statement best describes the weld thickness when joining pipe to welded fittings?

• A. Twice the pipe wall thickness
• B. Half the pipe wall thickness
• C. Weld thickness equals the inside diameter of the pipe
• D. Equal to the pipe wall thickness

Answer: (D)

When joining pipe to welded fittings, the weld should be sized to match the pipe wall thickness. This keeps the joint’s strength and cross-sectional area consistent with the rest of the pipe, so the joint behaves like the pipe itself under pressure. A weld that is thinner would create a weaker point at the joint, increasing the risk of leakage or failure, while a weld thicker than the pipe wall doesn’t provide a meaningful strength gain and can complicate fabrication or inspection. Therefore, using a weld thickness equal to the pipe wall thickness ensures uniform performance and reliability of the standpipe system.