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Containers with large temperature gradients: The following requirements apply to containers with large temperature gradients: 01 In situations where there is a sharp temperature gradient, welding joints that are not fully penetrative shall not be used for the connections. 02 Reinforcing rings should not be used in situations with sharp temperature gradients. For low-alloy steel vessels with Rm≥540MPa, the following mandatory requirements apply: 01 When materials that are not listed in the harmonized standards of these regulations are used for the main pressure-bearing components, the material manufacturer must undergo a technical evaluation of the new material in accordance with clause 1.9 of these regulations before such use is permitted. 02 When a material manufacturing unit produces a material for the first time, it shall undergo a new material technology review in accordance with the provisions of 1.9 of these regulations. 03 The steel plates used for the pressure-bearing components of pressure vessels should be produced using an off-oven refining process. 04 Carbon steels and low-alloy steels specific for pressure vessels, with P≤0.025% and S≤0.015%. 05 Special carbon steels and low-alloy steels for designing pressure vessels in temperatures below -20°C, with P≤0.020% and S≤0.010%. 06 Welding test specimens of the product shall be prepared. 07 All Class A and B butt joints shall undergo non-destructive testing (RT/UT). 08 The surface of its welded joints must be inspected using magnetic particle (MT) or penetrant testing (PT); in addition, surface non-destructive testing of the welded joints should be carried out after the pressure test.