Which action should be taken prior to performing a hydrostatic test?

Prior to performing a hydrostatic test, it is essential to remove pressure relief valves. This is because pressure relief valves are designed to open at a specified pressure to protect the system from over-pressurization. If these valves remain in place during the test, they may malfunction or open, providing inaccurate readings and potentially compromising the integrity of the test. Removing them ensures that the pressure test reflects only the strength and integrity of the piping system and its fittings, without any unintended release of pressure that could occur through an open valve.

The other actions would not be appropriate or necessary for ensuring the accuracy and safety of the hydrostatic test. Leaving control mechanisms in place, for instance, could lead to unintentional operation during the test, and leaving orifice flanges in place might prevent a proper seal needed for the test. Similarly, not removing blinds could critically affect the test conditions by creating false barriers or leaks that could skew results. Thus, removing pressure relief valves is a vital step in preparation for a hydrostatic test.