ASME B31.3 Pressure Testing
Required Leak Test ASME B31.3 345.1
Prior to the operation of process piping subject to the jurisdiction of ASME B31.3, and after the completion of the required examinations required by paragraph 341 each piping system shall be pressure tested to ensure tightness.
The code indicates preference for hydrostatic pressure testing as it is safer than pneumatic testing. Pneumatic pressure testing can be performed when hydrotesting is not feasible, but safeguards have to be put in place to minimize the hazards associated with the compressed gas stored potential energy refer to ASME B31.3 345.5 for details.
There are some exceptions to the 345.4 hydrostatic pressure testing requirement that are summarized as follows
With the facility owner’s approval piping defined as a Category D system can be service leak tested, meaning it is put into service and examined for leaks while the system is at its operating pressure; refer to B31.3 345.7
A pnuematic test can be performed where the owner deems a hydrostatic leak test impracticable. This is often due to the system fluid service constraints. The hazard of compressed gas energy needs to be factored into the risk assessment of this option; refer to B31.3 345.5 or B31.3 345.6
Where the owner deems the hydrostatic and pneumatic pressure testing impracticable or detrimental an alternative leak test per B31.3 345.9 can be performed, but only if it meets the strict criteria listed in B31.3 345.1 (c)
