B31.3 Closure Welds
What is a closure weld?
A closure weld, also called a golden weld, as defined in the ASME B31.3 Process Piping Code, is the final weld connecting piping systems or components that have already been successfully leak tested.
If the strict rules of ASME B31.3 paragraph 345.2.3(c) are followed, the closure weld will not need to be leak tested. To qualify as a closure weld specific in-process, and volumetric examinations are required. The in-process examinations include some of the following activities, joint preparation, cleanliness, preheating, fit-up, internal alignment, WPS variables, filler metal confirmation, joint position, VT and MT or PT of root pass, VT between passes, VT of final weld, with RT or UT of the final.
Typically the closure weld is the final weld where no further connections or welds will be made. Closure welds will not be proof tested from the pressure test and as such they make adherence to the in-process and volumetric examinations vital for safety and reliability.
What is the purpose of a closure weld?
A closure weld allows for completion of a piping system in those cases where the last weld can only be made after a pressure test has been conducted.
Closure welds are common where new spools or sections of pipe are installed into existing systems, where isolation for pressure testing is impracticable. The welds in the spool will be pressure tested before installation, and the closure welds are then handled by the rules of ASME B31.3 345.2.3(c).
Requirements
B31.3 closure welds must meet the requirements detailed in the following ASME B31.3 paragraphs
345.2.3(c) Closure Welds
345 Testing / 345.1 Required Leak Test
344.7 / 344.7.1 In-Process Examinations
344.5 Radiographic Examination or
344.6 Ultrasonic Examination
345.2.3(c) Closure Welds
(c) Closure Welds. The final weld connecting piping systems or components that have been successfully tested in accordance with para. 345 need not be leak tested provided the weld is examined in-process in accordance with para. 344.7 and passes with 100% radiographic examination in accordance with para. 344.5 or 100% ultrasonic examination in accordance with para. 344.6.
