Thread Content
Mandatory requirements for Cr-Mo steel containers: For Cr-Mo (Cr-Mo-V) steel containers, the following requirements apply: 01 Steel studs made of 30CrMoA, 35CrMoA, or 40CrNiMoA – when used at temperatures below -20°C, impact tests must be conducted at those temperatures (with the minimum temperature being -100°C for 30CrMoA, -70°C for 35CrMoA, and -50°C for 40CrNiMoA). The impact energy required is specified in Table 14. 02 40CrNiMoA shall satisfy P≤0.015%, S≤0.008% ； 03 30CrMoA steel for studs: when used at temperatures < -40°C to -70°C, P ≤ 0.020% and S ≤ 0.010% ； When the operating temperature is < -70°C to -100°C, P ≤ 0.015% and S ≤ 0.008%. 04 35CrMoA is a steel used for studs; when the operating temperature is between -40°C and -70°C, P should be ≤0.020% and S should be ≤0.010%. 05 After the surface of the groove prepared by thermal cutting is finished, magnetic particle testing is conducted, and it meets Grade I standards. 06 There shall be no undercut on the surface of the container welds. 07 If any welding repairs are carried out after post-weld heat treatment, the repaired area shall be heat-treated again. 08 For materials prone to delayed cracking (such as 12Cr2Mo1R), non-destructive testing shall be carried out at least 24 hours after welding. For welded joints of 09 15CrMoR, 14CrMo1R and their corresponding forgings with a thickness greater than 16 mm, Class A and B welded joints shall undergo 100% non-destructive testing (RT/UT/TOFD), while the surfaces of Class C, D, and E welded joints shall be inspected by magnetic particle or penetrant testing. 10 For vessels made of other Cr-Mo low-alloy steels of any thickness (other than 15CrMoR and 14CrMo1R), the A and B class weld joints shall undergo 100% non-destructive testing (RT/UT/TOFD), and the surfaces of the C, D, and E class weld joints shall be inspected by magnetic particle or penetrant testing. 11 The surfaces of defect grinding or weld repair areas, as well as the surface of any cuts resulting from the removal of clamps and struts, shall be subjected to magnetic particle or penetrant testing. 12 Materials prone to delayed cracking (such as 12Cr2Mo1R) require magnetic particle or penetrant testing on the surface of their welded joints. 13 For spherical tank weld joints with a tendency to delayed cracking (referring to Cr-Mo steels and low-alloy steels with Rm≥540 MPa), non-destructive testing shall be conducted at least 36 hours after welding is completed.