When is hydrostatic testing of a power boiler typically performed?

• A. 1.5 times MAWP (adjusted for temperature if required)
• B. 1.0 times MAWP
• C. 0.5 times MAWP
• D. Twice MAWP

Answer: (A)

The test pressure for a power boiler is set with a safety margin above what it will normally experience in service. Using 1.5 times the MAWP ensures the structure can withstand pressures well above the maximum working pressure, helping to reveal leaks or weaknesses when the vessel is filled with water. If the test temperature differs from the service temperature, you adjust this pressure to account for how material strength changes with temperature, so the test remains within safe, allowable limits for the actual conditions the boiler will see.

In short, the standard practice is to hydrostatically test at about 1.5 times MAWP (with any needed temperature adjustments), rather than at the exact MAWP, at a lower multiple, or at a much higher multiple.