Regarding the issue of the impact temperature for 20 pipes
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I am currently dealing with equipment designed by a design institute: the cylinder material is Q245R, the forgings are made of 20II, and the pipes are 20 steel pipes as specified in GB/T6479-2013. The compressed components and welded joints are required to undergo Charpy V-notch impact tests at -20 degrees Celsius. Here’s the issue: For plates of grade Q245R and 20II, the impact test at -20 degrees meets the standard requirements. However, for pipes, the 20-grade steel specified in GB/T6479-2013 is subject to the provisions of clause 5.1.5 in GB/T150.2-2011; the minimum operating temperature for such steel is 0 degrees, so an impact test at 0 degrees must be conducted. Can a 20-mm steel pipe be subjected to impact tests at -20 degrees Celsius at this time? Even if such impact tests are carried out, as long as the impact energy meets the requirements specified in clause 5.1.5 of GB/T150.2-2011, does that ensure that the minimum operating temperature for 20-mm steel pipes as specified in GB/T6479-2013 can be -20 degrees Celsius? Is there any basis for this? Aside: If designed in accordance with standard requirements, would choosing 20 pipes constitute a problem with the material selection? :lol
What is the design temperature? If the design temperature is not lower than 0 degrees, it is feasible to raise the requirements for impact testing. Increase resilience reserves. However, if the design temperature is -20 and grade 20 steel is chosen, this contradicts the provisions of GB150.2
The design temperature is room temperature, while the ambient temperature is around -14 degrees
The design temperature must be provided by the process as a value. As for whether to consider the ambient temperature, it is determined by the process engineering team
Another issue is that since the standards specify 0 degrees as the requirement, with a minimum operating temperature of 0 degrees, it is necessary to conduct impact tests at -20 degrees. This not only introduces additional conditions that increase costs but also conflicts to some extent with the 0-degree impact requirement specified by the standards. Since you want one with good impact toughness, using 10 steel will do; why go through all these complicated procedures? What do you think?
I can’t remember; it was either 50 degrees or 70 degrees, I think
Yes, it is possible to specify low-temperature shock in the contract; see the attachment
Thank you, it is indeed possible to request a lower temperature. It seems the standards still haven’t been properly examined. :D
Since it is used at room temperature, I don’t think there’s a need for -20°C shock testing.
The GB 6479-2013 standard specifies that it is permissible