Trends in Independent Valve Pressure Testing

Before the industry slowdown of 2008, some end users performed third-party pressure testing of valves for use in critical service according to the acceptance criteria of ASME B16.34, API-598, API-6D, etc.

However, since that time, requests for independent valve pressure testing have increased greatly. This increase has been noted on non-destructive evaluations (NDE) such as radiographic testing (RT), magnetic particle inspection, liquid penetrant inspection (Figure 1) and visual inspection of valve body castings to meet customer specific requirements or industry standards such as ASME B16.34 Section 8 for special class services.

Performing NDE such as RT on a valve body/bonnet casting requires the full disassembly of the valve to gain unobstructed access to critical areas of the casting. Once an RT is complete and the castings verified as defect-free or the castings weld-repaired to meet industry codes, the valves can then be assembled, bolting torqued to OEM specification and the valve fully pressure-tested to ensure no seat or shell (atmospheric) leaks. The increased volume of RT inspections thus means an increased volume of valve pressure testing.

The world has become more environmentally conscious and the additional valve NDE can be seen as a result of this. This increase in NDE volume has meant addition of personnel and equipment; however, this is a positive sign for testers because it means increased work load.