Why Perform Hydrostatic Leak Testing?
Hydrostatic Leak Testing is an industry standard for testing components in fluid systems. This test is performed to display defective materials that would not have been previously detected. ASME B31.3 requires this testing to ensure tightness, strength, and conformance to maximum allowable working pressure. To make sure Hays conforms to the latest industry standard each valve design is analyzed during and after Hydrostatic Leak Testing.
The Hydrostatic Leak Test can be performed on valves to ensure integrity is maintained throughout the life of the valve. During Hydrostatic Leak Testing, a valve is filled with highly pressurized water for a specific period. This pressure is significantly higher than the design pressure for an added factor of safety. If at any point the valve leaks this is considered a failure. Failures in valves mainly occur at connection points where a seat, seal or weld is located. Many of Hays valve bodies have multiple connections creating potential failure points during the test. It is critical to find failure points to determine if the valve design needs to change.
Hydrostatic testing of valves is generally performed to expose possible leaks during assembly and its capability to with stand the maximum design pressure. Hays follows the procedure outlined in ASME E1003-13 Standard Practice for Hydrostatic Leak Testing. The amount of time the pressure is held depends on the size of the valve. Test pressures are held for 1.5 minutes per inch of wall thickness, with a minimum time of 10 minutes and a maximum time of 2 hours. At Hays, for commercial valve bodies, we bring the pressure above the design working pressure called out in our specifications. Then the valve is visually inspected while the pressure is being applied, and after the pressure is released, to determine if any leaking has occurred.
Below is a simplified schematic of the test set up here at Hays (Figure 1). An air driven liquid pump is used to pressurize water inside the valve. Because water is nearly incompressible, there is little energy used by the pump to achieve desired testing pressure. When valve reaches test pressure it is inspected for leaks. After the appropriate amount of time has passed, the pump is turned off and the valve is removed. The water drains back into the supply tank and another valve can be tested.
ASME B31.3 – Process Piping – A Code for Pressure Piping is a conformance standard for piping systems and components in piping systems.
ASME E1003-13 – Standard Practice for Hydrostatic Leak Testing outlines the procedure for pressure testing components in piping systems.