Dry gas instead of liquid for leak test in pump w/ mech seal.

[moon161]

Does anyone here have experience with using dry gas / cavity decay test instead of presurized water to leak test pumps with rotating mechanical seals?

Thanks,

 

[BEMPE16524]

This method, also called "pressure decay testing" or "cavity decay testing," works by pressurizing a sealed cavity with a dry gas, typically nitrogen or air, and monitoring for pressure drops that would indicate a leak. References:

1. API 682: Pumps - Shaft Sealing Systems for Centrifugal and Rotary Pumps
2. API 610: Centrifugal Pumps for Petroleum, Petrochemical, and Natural Gas Industries
3. ASME B73.1: Specification for Horizontal End Suction Centrifugal Pumps for Chemical Process
4. ASME BPVC Section V: Nondestructive Examination (NDE)
5. ANSI/HI 1.3: Rotodynamic (Centrifugal) Pumps for Design and Application
6. ANSI/HI 9.6.6: Pump Piping for Rotodynamic Pumps
7. ASME PCC-2: Repair of Pressure Equipment and Piping

 

[moon161]

Thanks! Any idea what the gas leakage through a static seal is compared to the liquid leakage?