How do people understand Clause 6.4.5.1 of GB/T 25198-2010 \"Pressure Vessel Heads\"?
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Hello everyone, regarding clause 6.4.5.1 of GB/T 25198-2010 \"Pressure Vessel Heads\", what is your understanding of it? And how is it carried out? Since GB/T 25198-2010 requires heat treatment whenever cold forming is used, is it still necessary to have a provision in Article 8.1.1 of GB/T150.4-2011? Rule 150 specifies that, under the condition that these 4 requirements are met, it is necessary to determine whether the deformation rate exceeds the specified value set by the standards If it is based on the head standard, is it still necessary to perform calculations? Please, experts, share your views. Thank you
25198 refers to the head, while 150 includes other components.
Does a cold-formed titanium head require heat treatment?
Clause 6.4.5.1 of GB/T 25198-2010 \"Pressure Vessel Heads\" and clause 8.1.1 of GB/T 150.4-2011 represent two different concepts. The standard for head fabrication takes into account stress relief heat treatment due to cold working hardening, whereas GB150 considers that when the degree of cold forming is sufficient, it has a significant impact on the material’s properties, and it is therefore necessary to restore those properties.
Do you mean that as long as the end caps are manufactured, inspected, and accepted in accordance with 25198, if they are cold-formed, heat treatment must definitely be carried out?
The old version of GB150 required heat treatment for cold-formed carbon steel heads as well; the new version, following ASME standards, takes the strain rate into consideration. The implementation year of the head standards was prior to GB/T150, which leads to different requirements.
Since the head standard is to be implemented, it should be followed as required, while also complying with the provisions of GB150. Ordinary cold-formed heads undergo stress-relief heat treatment, while those with excessive deformation rates are subjected to performance-restoration heat treatment; in addition, heat treatment specimens of the base material must also be prepared.