The degree of welding procedure review (if any) and who performs the review should be decided depending on the criticality of the pressure vessel. In…
Category: Fabrication
A PQR is a document that proves by mechanical testing that a WPS is capable of producing acceptable weld quality, thereby “qualifying” the WPS. For…
A WPS is a document that specifies the critical welding parameters (called “essential variables” by Section IX) which are required to produce the specific type…
Other higher-temperature postweld heat treatments are also available, but are very uncommon for pressure vessels welds. They would typically only be used when the metallurgical…
Several alternatives to conventional stress relief heat treatment are available, although they are considered to be inferior, and are therefore only rarely used. These alternatives…
The most common form of PWHT is a “stress relief” or “tempering” heat treatment. This heat treatment involves heating the material to a temperature high…
Interpass temperature control is a process of controlling the temperature of the deposited weld metal between specified limits during multipass welds. The lower limit is…
Preheating is the process of raising the temperature of the base metal above ambient temperature immediately before welding and holding it during welding. Preheating is…
Inert backing gas (such as Ar, CO2, or possibly N2 for stainless steel vessels) is required with GMAW and GTAW processes for root passes of…
Shielding gases for GTAW, GMAW and FCAW-G processes are used to shield the welding arc and molten weld metal from nitrogen and oxygen in the…