Does the fabricator of a B31.3 piping system still have to pressure test components that are manufactured to a standard listed in Table 326.1 when that standard states that the component is hydrotested as a requirement of the standard?
This question sometimes comes up with piping fabricators and with ASME B31.3 Interpretation 23 – 14, there might be some confusion as far as pressure testing of components in a B31.3 piping system. The confusion might come from the second paragraph in Paragraph 326.3, which states the B31.3 testing requirements (and other requirements) are not applicable to components manufactured to a standard listed in Table 326.1 unless specifically stated in B31.3 or the listed document.
An example of a listed standard would be valves manufactured to ASME B16.34, Valves—Flanges, Threaded and Welding End. While it is true that the B16.34 valve manufacturer must hydrotest the valve according to the B16.34 standard, that test would only indicate whether the valve is leak-tight. Furthermore, it is important to realize that valves manufactured to this standard are for many different types of piping system applications and not specifically for B31.3. So in that case, the valve pressure test is not and cannot be acceptable for the required pressure test in Paragraph 345.1, which states that each piping system (i.e., interconnected piping) shall be tested to ensure tightness.
Under B31.3, Paragraph 345.2.2 Examination for Leaks goes further by saying that all joints and connections shall be examined for leaks. Therefore, the required B31.3 pressure test for the fabrication of a piping system must be completed by the fabricator, ensuring that all component joints are examined during the test.