Issues regarding butt welding of Class B joints in dissimilar steels with varying thicknesses
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Regarding the selection of the weld procedure qualification for 5 mm of S30408 and 8 mm of Q245R, can the existing weld procedure qualification for welding dissimilar steels of 8 mm S31603 + Q345R be used instead? Regarding the process evaluation for the butt welding of 8mm-thick stainless steel and carbon steel, how is the range for the base metal thickness determined? Should it be a coverage range of 8–16, or 1.5–16? Should the requirements be applied separately? A thickness range of 1.5–16 for the stainless steel side, and 8–16 for the carbon steel side? Since Q345R and Q245R are required to undergo impact testing per the regulations, stainless steel, according to GB150, is exempt from such testing at temperatures below -196°C. For these types of test plates, is impact testing necessary? If so, which areas should be tested: the heat-affected zone on the carbon steel side, the weld area, and the heat-affected zone on the stainless steel side? How should the impact testing requirements be determined? Should the impact temperature be set in accordance with the requirements for Q345R? I would like to ask whether, for butt welds using plates without edge trimming, the welding procedure qualification for thin plates is applied as a basis; are there specific provisions in the procedure qualification to address this situation?
Regarding the butt jointing of dissimilar steels and joints with unequal thicknesses that do not meet the requirements specified in Procedure Evaluation Form 9, shall we discuss these together?
According to the grading rules for group numbers, the grade number of Q345R is higher than that of Q245R; therefore, a new welding procedure qualification is required. The thickness range can be in accordance with Table 9 specified in NB/T47014.
Currently, the equipment components are made of S30408 with a thickness of 5 mm and Q245R with a thickness of 8 mm. The existing process evaluations relate to the butt welding of Q345R and S31603 with a thickness of 8 mm each.
This is for use with expansion joints, right? The weldability assessment for joining 8mm S31603 and 8mm Q345R, which are different types of steel, is sufficient; since the standard does not prohibit it, its use is allowed
Yes, it’s on the expansion joint. It should be possible to find relevant information through technical sources, but as for this thickness, I’m not sure how to determine the most appropriate value