ANSI/ISA-75.19.01, from the American National Standards Institute and the International Society of Automation, provides requirements for the hydrostatic testing of control valves.
ANSI/ISA-75.19.01 applies to all control valves. It establishes the requirements for the structural integrity and leak tightness of the valves’ pressure retaining parts.
In a hydrostatic test, the valve body is filled with testing fluid and then pressure is applied for a specified length of time. The valve is then inspected for any leakage.
The testing liquid can be water, water with a corrosion inhibitor, or another liquid whose viscosity isn’t greater than that of water.
The testing pressure depends on what material the valve is made of: steel, nickel-base alloy, cast iron, and so on. See the full standard for material-specific hydrostatic test pressures.
The test duration depends on the nominal valve size and valve class.
|Nominal Valve Size||Class 150 & Lower||Class 250 to 600||Class 900 to 1500||Class 2500 & Higher|
|2” & Smaller||1 minute||1 minute||2 minutes||3 minutes|
|2 ½” to 4”||2 minutes||2 minutes||4 minutes||5 minutes|
|5” to 8”||2 minutes||3 minutes||5 minutes||8 minutes|
|10” & Larger||3 minutes||5 minutes||8 minutes||10 minutes|
Three conditions can cause a valve to be rejected:
- There is visible leakage in the valve body assembly.
- There is leakage through static seals and gasketed joints (unless allowed by design).
- The hydrostatic test causes any distortion that impairs the valve operation.
A full copy of ANSI/ISA-75.19.01 can be purchased from the American National Standards Institute.