A leak in a fin fan is being repaired while hydrotesting is being conducted on a piping system. What should be done during the repair?

• A. Tightening should continue while pressure is applied
• B. Replace the fin fan immediately
• C. Increase pressure to test the seal
• D. Pressure should be relieved before any tightening is started

Answer: (D)

During hydrostatic testing, the system is under pressure, so any repair work should be done with that pressure removed. Relieving the pressure first eliminates the external load on flanges, bolts, and seals, preventing movement, bolt creep, or gasket damage that could occur if you tighten or adjust components while the system is pressurized. Once the pressure is safely released, you can perform the repair and tighten to the specified torque with the joints at rest, then re-pressurize and re-check for leaks. This approach reduces the risk of a sudden release, further leaks, or equipment failure and keeps everyone safe.