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GB/T25198-2023 \"Head of Pressure Vessels\" replaces GB/T25198-2010 \"Head of Pressure Vessels\". Compared with GB/T 25198-2010, apart from structural adjustments and editorial changes, the main technical changes are as follows: terms and definitions have been added (see Chapter 3)； The nominal diameter DN of the head has been changed to the head diameter D (the inner or outer diameter of the head) (see Chapter 4, Chapter 3 of the 2010 edition) ； The shapes and parameters of the elliptical heads and disc heads based on the outer diameter have been modified (see 5.1, Table 1; 4.1, Table 1 in the 2010 version) ； The head type parameters were modified, the code for the conical head type was changed, and a conical head type without straight edges was added (see 5.1, and 4.1 and 4.2 of the 2010 version) ； The header marker has been changed (see 5.2, 4.3 in the 2010 version) ； Requirements for risk assessment and control, as well as supervision and inspection, in the manufacturing environment and for head fabrication have been added (see 6.1.5, 6.1.6, 6.1.7) ； The content related to the preparation of raw materials has been modified; the information on materials has been moved to the sections on manufacturing, inspection, and acceptance. Additionally, provisions regarding material segmentation and labeling have been added (see 6.2, 6.3, 6.4, Chapter 6 of the 2010 edition) ； Added requirements for pressure vessel heads made of zirconium material ； Requirements for composite panel materials have been added; requirements for ensuring the performance of materials after processing have been introduced and clarified; requirements for corrosion resistance testing have been modified (see 6.2.2, 6.2.3, 6.2.4, and 5.2, 5.3 of the 2010 version) ； The requirements for grinding and welding repairs have been changed (see 6.5.2, 6.2.2 in the 2010 version) ； The requirements for groove machining and the surface have been changed (see 6.5.3, 6.2.3 in the 2010 edition) ； The requirements for the layout of joint panels and welds have been changed (see 6.5.4, 6.3.2 in the 2010 version) ； The specifications for the surface color of welds and heat-affected zones in titanium and titanium alloy heads have been revised, and specifications for the surface color of welds and heat-affected zones in zirconium heads have been added (see 6.5.4.7 and 6.2.9 in the 2010 edition) ； The content regarding head forming has been modified, with forming inspections added (see 6.6, 6.7, and 6.3 in the 2010 version) ； The heating methods and general requirements have been changed; requirements for process heating, provisions for determining the effective heating area, and requirements for heat treatment measurement records have been added. The requirements regarding the heating medium have also been adjusted (see 6.6.2.1, and 6.3.1.1, 6.3.1.4, 6.3.1.5 of the 2010 version) ； Requirements for controlling the heating temperature of zirconium and zirconium composite plates have been added (see 6.6.2.5, 6.8.3.7) ； The recommended temperature for warm forming of austenitic stainless steel heads has been added (see 6.6.2.6) ； Added a control requirement specifying that the butt joint should be based on the inner circumference or inner diameter for closures made of composite panels ； The diameter range, outer circumference, and inner diameter tolerance requirements have been changed (see Table 5) ； The tolerance requirements for the shape and dimensions of the end caps have been changed, and the use of other measurement methods is now permitted (see 6.7.9; 6.3.8 in the 2010 version) ； Added control and measurement requirements for the ferrite content in austenitic stainless steel heads designed for temperatures below -40°C and subjected to strain strengthening treatment ； Requirements for heat treatment documents and automatic recording of heat treatment temperatures have been added (see 6.8.1.2, 6.8.1.3) ； The value of the deformation rate used to determine whether annealing is necessary after cold forming of oval, disc, and conical end caps made of aluminum-magnesium alloys and aluminum-magnesium-silicon alloys, titanium and titanium alloys, and brass (except H96) (see 6.8.3.3, 6.8.3.4, 6.8.3.5, and 6.4.5.2, 6.4.5.3, 6.4.5.4 of the 2010 edition) ； Added consideration of the impact of flat plate deformation rate on head manufacturing ； Requirements for product test pieces/metal base heat-treated test pieces have been added (see 6.9) ； Added methods for non-destructive testing and modified the relevant requirements (see 6.10, 6.5 in the 2010 edition) ； The requirements for factory data have been changed (see Chapter 7, Chapter 7 of the 2010 edition) ； The product logo has been added (see Chapter 8).