What is the maximum stress allowed during a pressure test?

What is the maximum stress allowed during a pressure test?

• A. 100% of SMYS
• B. 90% of SMYS
• C. 80% of SMYS
• D. 95% of SMYS

Answer: (B)

During a pressure test, you want the material to stay in its elastic range, meaning the stress must stay below the yield strength so the test reveals issues without causing permanent deformation. The maximum stress allowed during a pressure test is 90% of SMYS, providing a safe margin that accounts for variability in material properties, temperature, and measurement accuracy. Testing at 100% of SMYS or higher risks yielding, which would distort the pipe and obscure true integrity results. A limit closer to yield (like 95% or 100%) reduces the safety margin, while a lower limit (like 80%) is more conservative than necessary for standard practice. Therefore, 90% of SMYS is the appropriate, widely used limit.

During a pressure test, you want the material to stay in its elastic range, meaning the stress must stay below the yield strength so the test reveals issues without causing permanent deformation. The maximum stress allowed during a pressure test is 90% of SMYS, providing a safe margin that accounts for variability in material properties, temperature, and measurement accuracy. Testing at 100% of SMYS or higher risks yielding, which would distort the pipe and obscure true integrity results. A limit closer to yield (like 95% or 100%) reduces the safety margin, while a lower limit (like 80%) is more conservative than necessary for standard practice. Therefore, 90% of SMYS is the appropriate, widely used limit.