Pressure Safety Relief Valve (PSV) Calibration & Bubble Leak Testing per API 527

Pressure Safety Valves (PSVs) and Pressure Relief Valves (PRVs) are the primary defense against overpressure catastrophe in boilers, pipelines, and chemical reactors. Calibrating set pressure and seat tightness per API 527 is mandatory for plant safety.

1. Set Pressure Verification and Cold Differential Test Pressure (CDTP)

When testing on a test bench at ambient temperature, calculate CDTP to compensate for backpressure and elevated operational process temperatures. Use a high-precision hydraulic/pneumatic test bench like the DB Barion-H Series (1000 Bar) with needle fine-adjustment to slowly ramp pressure at 0.1 bar/sec until pop point.

2. API 527 Bubble Leak Rate Measurement

Measure seat tightness at 90% of set pressure by immersing a standard tube (5/16-inch OD x 0.035-inch wall) in water at a 1/2-inch depth. Count bubbles per minute against API 527 Table 1 allowable limits.