Maximum SMYS for pipe if a fillet welded patch is installed?

Maximum SMYS for pipe if a fillet welded patch is installed?

• A. 50,000 psi
• B. 30,000 psi
• C. 40,000 psi
• D. 60,000 psi

Answer: (C)

When a fillet welded patch is installed, the weld area becomes the control point for strength because welds and the heat-affected zone can behave differently from the base metal. To account for these potential weaknesses and to provide a conservative design margin, the allowable specified minimum yield strength is reduced to a safe, common value of 40,000 psi. This ensures the patch and its welds won’t govern the pipe’s strength more than the intended design, even under fluctuating loads and long-term service. In other words, the patch introduces conditions that justify a lower SMYS than the pipe material’s base strength, so 40,000 psi is the appropriately conservative limit.

When a fillet welded patch is installed, the weld area becomes the control point for strength because welds and the heat-affected zone can behave differently from the base metal. To account for these potential weaknesses and to provide a conservative design margin, the allowable specified minimum yield strength is reduced to a safe, common value of 40,000 psi. This ensures the patch and its welds won’t govern the pipe’s strength more than the intended design, even under fluctuating loads and long-term service.

In other words, the patch introduces conditions that justify a lower SMYS than the pipe material’s base strength, so 40,000 psi is the appropriately conservative limit.