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This post was last edited by Desert Fish on 2021-11-21 at 19:59. Mandatory requirements for pressure vessels with high pressures (10 MPa ≤ P < 100 MPa): 1. When carbon steel and low-alloy steel plates with a thickness of 12 mm or more (excluding the plates of multi-layer pressure vessels) are used to manufacture the main pressure-bearing components, they must undergo ultrasonic testing on a per-plate basis in accordance with NB/T 47013.3-2015, with the acceptance grade being no lower than Grade II. 2. When aluminum and aluminum alloys are used for the pressure-bearing components of pressure vessels, the design pressure shall not exceed 16 MPa. 3. For Class III pressure vessels with a design pressure of 1.6 MPa or greater, all butt joints of shells of Types A and B shall undergo non-destructive testing (RT/UT). 4. For Type I fiber-reinforced plastic pressure vessels manufactured using the winding process and subjected to pore envelopment, the design pressure shall not exceed 20 MPa. 5. Type III fiber-reinforced plastic pressure vessels must be manufactured using the winding process along with an end-hole enveloping technique; their design pressure shall not exceed 100 MPa, nor shall it be lower than 20 MPa. 6. For Class III pressure vessels with a design pressure of 1.6 MPa or greater at their first periodic inspection, the length required for detecting surface defects shall be not less than 20% of the length of the butt welds. 7. The accuracy of the pressure gauge used in the container must be no lower than grade 1.6. 8. Before installation and use, the level gauge for containers shall undergo a hydrostatic test at 1.25 times the nominal pressure of the gauge. 9. The steel plates used for the shell (excluding the plates of multi-layer containers) shall be subjected to ultrasonic testing one by one in accordance with the provisions of Table 3; the methods for ultrasonic testing of steel plates and the corresponding quality grades shall follow the requirements of JB/T4730.3. 10. When the design pressure is ≥ 4.0 MPa, steel pipes specified in GB/T 8163 such as grades 10, 20, and Q345D shall not be used. 11. When the design pressure is ≥ 1.6 MPa, pressure-bearing components shall not use Q235 series steel plates. 12. Steel pipes of Class III and Class IV as specified in GB/T 12771 shall not be used. 13. Steel pipes specified in GB/T 24593 shall not be used. 14. Heat exchange tubes shall not be of Class VI steel pipes as specified in GB/T 21832. 15. If fixed-type nozzles are used, there shall be no delamination in the steel plate section at the shell opening: (1) The shell steel plate at the opening shall undergo ultrasonic testing and meet Grade II requirements. (2) After boring, the cross-section of the shell steel plate shall be subjected to magnetic particle or penetrant testing, with a grade of I being considered acceptable. This article is from the Design Institute website www.shejiyuan.com