At what percentage is a boiler hydrostatically tested?

A boiler is hydrostatically tested at 150% of its maximum allowable working pressure (MAWP). This testing method involves filling the boiler with water and pressurizing it to ensure that there are no leaks, and to verify the integrity of the boiler's structure under conditions that exceed its operational limits. Testing at this increased pressure helps to identify any potential weaknesses in the boiler material or construction that might not be evident under normal operating conditions.

By conducting the hydrostatic test at 150%, inspectors can confidently determine the integrity and safety of the boiler, ensuring it can operate safely under the intended maximum pressure. This practice is essential for maintaining safety standards and preventing potential failures during normal operation.