The issue of impact energy for weld evaluation of pressure vessels
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Dear experts, I’m a newcomer here and have a question: For a device designed for operating at -30 degrees Celsius, regarding the weld joint where 16MnDR and Q345R are connected, should the process evaluation use Q345R with impact resistance at -40 degrees Celsius or Q345R with impact resistance at 0 degrees Celsius? If Q345R is used for elements such as stiffeners, welded to the 16MnDR cylinder in such joints, is it acceptable to select the grade of Q345R (with 0-degree impact resistance) based on the principle of choosing the lower grade, without taking into account the design temperature?
You use the 16MNDR rating, along with the welding material, to weld this
Can Q345R be used in an environment of –30°C?
"How could a main welding joint connecting 16MnDR and Q345R even exist? There’s a problem with the original poster’s description!
For welding of gussets and similar components, weld seam evaluation is sufficient; impact testing is not required.
Thank you all for your answers. The pressure-bearing components of the equipment are made of 16MnDR, but the flanges on the cylinder are made of Q345R. If the welds connecting these flanges to the cylinder are treated according to the principle of using the lower grade material, then Q345R should be used. I would like to choose a qualification standard based on Q345R, but considering that welds connecting pressure-bearing and non-pressure-bearing components also require qualification, and such qualifications must meet the product requirements, it seems necessary to take into account the design temperature of -30 degrees. Therefore, the qualification for 16MnDR + Q345R should use a standard that takes into account impact resistance at -40 degrees. I’m not sure if this approach is correct Also, whether impact testing is required should be determined based on whether the material standards for the base metal on both sides of the weld in question specify such requirements, right? It has nothing to do with whether it is a fillet weld or a butt weld, right?
That’s right; it’s not for process evaluation that 16MnDR+Q345R is used. Currently, the welds in the products are formed by joining 16MnDR (for the cylinder body) with Q345R (for the stiffening plates). Our existing process evaluations cover two types: Q345R with 0-degree impact resistance and Q345R with -40-degree impact resistance. I would like to use Q345R with 0-degree impact resistance for the welds resulting from the joining of 16MnDR (cylinder body) and Q345R (stiffening plates), as I believe that, following the principle of using the lower value, since Q345R is specified for the stiffening plates in the design, it is sufficient for the welds between these plates and the cylinder body to meet the 0-degree impact resistance requirement. However, considering the design temperature of -30 degrees, it seems appropriate to give priority to the design temperature requirements over this principle of using the lower value. Therefore, based on the design temperature, the impact resistance requirement for 16MnDR+Q345R should also be at -30 degrees; hence, the process evaluation using Q345R with -40-degree impact resistance should be chosen. I’m not sure if it’s correct to first consider the design temperature and then apply the principle of choosing the lower value
How can there be a shock value of -40 for Q345R? Where do the acceptable criteria come from?
:For lol, use the welding assessment of 16MNDR+16MNDR to conduct impact tests at -40°C. .