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1. Forming method: For medium and large-sized end caps, the method of welding together the components first and then shaping them is primarily used. For extremely large end caps that exceed the capabilities of shaping equipment or transportation means, the approach of shaping them in separate sections first and then welding those sections together is employed. Additionally, for end caps that are too large to be transported, it is also possible to shape them as a single unit, cut them into sections, transport those sections to the customer’s site, and then assemble and weld them there. 2. Weld surface quality: The inner surface of the joint weld, as well as the outer surface of the joint weld that affects the quality of shaping, should be polished to be level with the base material before shaping. 3. Timing of non-destructive testing: 100% non-destructive testing (RT or UT) should be carried out after forming. If non-destructive testing was performed before forming, then non-destructive testing should also be conducted on the area where the curved transition meets the straight edge section after forming ； Materials prone to delayed cracking shall undergo non-destructive testing at least 24 hours after welding is completed; in addition, 100% surface inspection (MT or PT) shall be carried out on all joints. 4. Determination of the acceptable level for non-destructive testing 4.1 For containers that require 100% radiographic or ultrasonic testing: The joints of the end caps must undergo 100% non-destructive testing (RT or UT); radiographic testing is required to meet technical standard grade AB, with an acceptable level of Grade II ； Ultrasound testing requires a technical level of B and a compliance level of I (Level II for TOFD) ； When using non-recordable pulse-reflectance ultrasonic testing, radiographic or TOFD testing should also be employed as additional local inspection. 4.2 For vessels that require partial radiographic or ultrasonic testing: 100% non-destructive testing (RT or UT) must be carried out on the head joint; radiographic testing is required to meet technical grade AB, with a acceptance level of Grade III ； Ultrasound testing requires a technical level of B and a compliance grade of II ； When using non-recordable pulse-reflectance ultrasonic testing, radiographic or TOFD testing should also be employed as additional local inspection. 5. Selection of welding joint coefficient: The non-destructive testing requirements for the lap joints of end caps are primarily aimed at addressing the significant deformation that occurs during end cap formation and the resulting expansion of defects, and they are unrelated to the calculation of end cap thickness. Therefore, although the head jointing seams require 100% non-destructive testing (RT or UT), such testing is still only part of the inspection of the entire vessel; the acceptance criteria remain those specified for the entire vessel. As a result, the welding joint factor for head jointing seams is generally taken as that of the longitudinal welding joints in pressure vessels. For example, for containers that require 100% radiographic or ultrasonic inspection, where their weld joints are double-sided butt welds or fully penetrated butt welds equivalent to double-sided welding, the weld joint factor for the head is set at 1.0 ； For vessels that require local radiographic or ultrasonic testing, where their weld joints are double-sided welded butt joints or fully penetrated butt joints equivalent to double-sided welding, the weld joint factor for the head is taken as 0.85 (even if the head has undergone 100% RT or UT). 6. Product welding test pieces: During the hot forming process, the welded joints of lap joints are disrupted, resulting in a change in the microstructure of the metal as well as a decrease in its strength and toughness. Manufacturers must use welding materials with higher strength in advance to compensate for this loss in metal strength, and subsequent heat treatment is employed to improve or restore the material’s toughness. This requires the creation of product welding test pieces to evaluate the effectiveness of such restoration. Therefore, lap joints that require hot forming or further heat treatment (normalizing or normalizing plus tempering) after forming should be accompanied by welding test pieces that are processed together with them. When the container also requires test plates made from the base material, these two can be prepared simultaneously.