I just got an opportunity to witness hydrostatic test for boilers in my recent EPC project. Hydrostatic test is the most common procedure used to qualify newly manufactured pressure pressure. The purpose is to make sure here is no leak in the boiler.
The procedure was quite simple yet important. Pressure parts shall be subjected to a hydrostatic test pressure which at every point is at least equal to:
1.5 times the MAWP (Maximum Allowable Working Pressure) for ASME section I code.
1.3 times the MAWP for ASME section VIII Div. I code
(The MAWP may be assumed to be the same as the design pressure)
The design pressure of my boilers is 10 barg. When this test applied, the QC engineer increased the pressure of boiler to 10 barg and hold it for 15 minutes. They checked visually the internal of boiler if there’s a leak. Unfortunately, there’s no digital recorder available to record the pressure of boiler during the test. So, we needed to check by our naked eyes the pressure gauge.
After 15 minutes, the increased the pressure to 15 barg at hold it for an hour. After that, they decreased the pressure to 10 barg again, hold it for 15 minutes, then decreased again to 1 barg. The inspection was done visually.