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I. Supervisory inspection of end caps. Leadership of the General Administration: Hello! In accordance with the requirements of TSG 21-2016 for large-volume pressure vessels, end caps with weld joints require supervision inspections. For the end caps with weld joints that we purchase now, the certificates issued by the local supervision authorities of the end cap manufacturers are titled “Certificates of Supervision Inspection for End Cap Manufacturing.” The statements in these certificates read either “The supervision inspection was successful in accordance with the commission agreement” or “In line with the requirements of the Special Equipment Safety Law and the Regulations on the Supervision of Special Equipment, the end caps meet the requirements of GB/T 25198-2010, and the supervision inspection was successful”; the provisions of TSG 21-2016 are not mentioned in these certificates. Question 1: Is it reasonable to issue a commissioning supervision inspection certificate for the supervision inspection of end caps? Question 2: Is the basis stated in the supervision and inspection certificate reasonable? I hope the leaders of the General Administration will provide a response. Thank you! Reply: 1. Please comply with the relevant requirements in Chapter 6 of the \"Safety Technical Inspection Regulations for Fixed Pressure Vessels\" (TSG 21-2016). 2. Certificate for the supervision and inspection of special equipment manufacturing (pressure vessels): Please refer to Annex G of the \"Safety Technical Supervision Regulations for Fixed Pressure Vessels\" (TSG 21-2016). II. Consultation on the inspection of end cap products. Dear leaders of the General Administration: 1. Regarding clause 6.5.1 of GB/T25198-2010 \"Pressure Vessel End Caps\", for splice weld joints formed by first assembling the plates and then welding them, 100% radiographic or ultrasonic testing shall be carried out using the methods specified in the drawings or the order technical agreement. Can NB/T 47013.10-2015 \"Non-destructive testing of pressure equipment – Part 10: Ultrasonic testing by diffraction time difference method\" be used for non-destructive testing? 2. As a manufacturer of end caps, the customer provides the raw materials, and we are responsible for panel assembly, welding, testing, and heat treatment. Can such end cap products be submitted to a supervision and inspection agency for verification in order to obtain an official inspection certificate? Please give me some advice. Thank you! Reply: 1. For standard-related questions, please consult the organization responsible for drafting or overseeing the standards. 2. Heads that are manufactured separately and have welds or require heat treatment after shaping need to be subject to inspection. III. Issues regarding the supervision and inspection of welded end capsDear leaders of the General Administration: According to 6.1.2.1(3) of the Large Capacity Vessels Regulations, supervised inspection is required for welded end caps that are manufactured separately. Must the non-destructive testing of head welding be carried out by the head manufacturer? The end caps are welded by the user themselves – does the end cap manufacturer still need to carry out supervision and inspection? Thank you! Reply: End caps that are manufactured separately and have welds or require heat treatment after shaping need to undergo manufacturing inspection. For end caps that are not shipped separately, the requirements for the manufacturing and inspection of pressure vessels apply. IV. Factory data for the head cover. Dear leaders of the General Administration! Regarding the factory data for heads in the Code for Fixed Pressure Vessels: the phrase “The manufacturer of the pressure vessel’s pressure-bearing components (heads, forgings) shall provide the quality certificates (certificates of conformity, inspection certificates, test reports, material data sheets, etc.) to both the pressure vessel manufacturer and the user, with the quality certificate for the heads being provided to the user” shall be revised to “Quality certification documents for the pressure-bearing components shall be provided to the ordering party”. Can it be understood that the quality certification documents for the end caps need not be provided to the user, but can be kept only by the pressure vessel manufacturing unit? Looking forward to a reply, thank you! Reply: Please comply with the requirements of the \"Safety Technical Inspection Regulations for Fixed Pressure Vessels\" (TSG 21–2016) and the relevant amendments to Amendment No. 1. V. Heat Treatment of Cold-Formed Heads. Leaders of the General Administration: Hello! According to 6.4.5.1 of GB/T25198-2010, steel hemispherical, elliptical, disc-shaped, and flat-bottomed end closures that are formed as a single piece or by first assembling the panels before shaping them should undergo heat treatment after cold forming ； Provisions in 8.1 of GB150.4-2011 regarding heat treatment for compressed components formed from steel plates: C) Heat treatment is required for carbon steel and low-alloy steel when the thickness exceeds the specified limit; d) Heat treatment is required for carbon steel and low-alloy steel when the degree of deformation and thinning exceeds the prescribed limits ； So, which of the above regulations should be used to determine whether a cold-formed head made of carbon steel requires heat treatment? Reply: It shall meet the requirements of relevant specification standards. For standard-related inquiries, please contact the standard management organization or the standard drafting organization. VI. Welding process qualification for head joints. Dear leaders of the General Administration: Hello! Our company has 1 pressure vessel: the cylinder and the head are made of Q345R material, and the steel plates are supplied in a normalized state. According to the technical requirements, the entire vessel needs to undergo stress-relief heat treatment, and the vessel head requires welding together. Is heat treatment in the form of normalizing plus stress relief required for the welding procedure qualification of the head joint welds? Reply: For specific technical issues, please consult technical institutions or experts. VII. Inspection of Heads with WeldsDear leaders of the General Administration: Article 14 of Amendment No. 1 to the \"Safety Technical Inspection Regulations for Fixed Pressure Vessels\" TSG 21-2016 stipulates that clause 6.1.2.1(3) of these regulations shall be amended to read: \"(3) The following components manufactured separately: heads (with welds or those that require heat treatment after shaping)\\", and manufacturing inspections shall be carried out on such components. Question: 1. Are the heads processed by a head manufacturing factory using materials provided by the customer (rather than materials purchased from the head manufacturer) considered separate units that leave the factory as finished products? 2. Heads with \"welds\" have an unclear definition of these welds; some of these welds are welded and subject to non-destructive testing by the head manufacturing factory, which makes it difficult to understand how supervision and inspection can be carried out at the manufacturing plant for such heads with welds. What we don’t understand is that the users themselves purchase the materials, carry out welding and non-destructive testing; the head manufacturing factory only shapes the heads, and the inspection agencies are also unable to supervise the welding process on site. We understand that supervision and inspection should be conducted on-site. For heads that are not welded by the head manufacturing factory, no non-destructive testing reports or radiography films can be provided during supervision and inspection. Moreover, when the customer carries out welding, there are no documents to prove whether the welders employed by the welding contractor possess the necessary qualifications, nor do there any records of welding procedure qualification or welding procedure specifications. May I ask, although such end caps have welds, the supervision and inspection is not carried out at the end cap manufacturing plant. Should the supervision of these end caps be conducted by the user themselves through the local inspection authorities? Users and manufacturers are in a continuous dispute over this issue. Looking forward to a reply! Thank you so much! Reply: The head forming work can be outsourced, but welding cannot. Processes such as welding must be carried out in facilities that have the appropriate manufacturing permits. Headings that are shipped separately and have welds or require heat treatment after shaping need to be subject to inspection. VIII. Is substitution required if the head markings differ? Dear leaders of the General Administration, the design marking on the pressure vessel’s design drawings for the head is EHA450*8(6.5), but the marking on the finished heads produced by the manufacturer is EHA450*8(7.2). The minimum thickness of these finished heads meets the design requirements; however, the marked minimum thickness does not correspond to the design-specified minimum thickness. Is there any indication as to whether substitute materials are needed in this situation, or whether other procedures should be followed? Reply: Not needed. IX. Outsourcing of head forming: May I ask whether the outsourcing party responsible for boiler head forming (without welding or non-destructive testing) needs to have manufacturing qualifications? Is supervision and inspection required? Reply: No manufacturing qualifications are required. X. Determination of the non-destructive testing level for end caps. Dear leaders of the General Administration, regarding containers, 20% RT testing is required for welding joints of categories A and B in the cylinder section, with a satisfactory level set at grade III; whereas 100% RT testing is required for welded end caps. How should then the satisfactory level for radiographic testing of end caps be determined? Reply: Please carry out the work in accordance with the requirements of the design drawings and the standards applicable to the product. XI. For externally supplied end caps (tube sheets) that have welds, and where the welding is not performed by the external supplier, is it necessary to arrange for supervision and inspection? Leadership of the General Administration: TSG 07-2019 B1.1.5 stipulates that “for furnace chambers and end caps (tube sheets) that have welds, supervision and inspection during the manufacturing process shall be carried out.” ”If the weld is not welded by an external contractor but by the manufacturing unit, is it the external contractor who is responsible for the supervision and inspection? Is it still the manufacturing unit that is responsible? Our factory is a boiler manufacturing unit; we send the assembled sheets to a head manufacturing plant for the external processing of the boiler heads. Is it necessary for that plant to issue a supervision and inspection certificate for these heads? Should it still be our factory, in conjunction with the boiler manufacturer, to handle the supervision inspection of the end caps? If our factory conducts supervision inspection on the head, is it necessary to issue a separate supervision inspection certificate for the head? Or can it be done together with the boiler manufacturing inspection? Reply: It is the responsibility of the manufacturing unit; for specific requirements, please refer to the \"Rules for Supervision and Inspection of Boilers\". XII. Use of spherical dome heads. Hello, esteemed authorities! Our company specializes in the production of Class D pressure vessels, and we currently want to use a domed head as the closure for the vessel’s door. However, we found that in the SW6 software, there is no option for selecting a domed head as a closure type. GB150 recommends the use of dome heads. I would like to ask whether a dome head can be used for Class D pressure vessels. Thank you! Reply: It should meet the requirements of the product standards. 13. Can a company with an A3 spherical tank on-site welding license manufacture heads larger than 1800 mm? Dear General Administration, our company holds the qualification for on-site welding of A3 spherical tanks; according to the new licensing guidelines, may we manufacture heads that are larger than 1800 mm? Reply: No qualification requirements are needed for head manufacturing. The head plates are pressed into shape by qualified units and transported to the site, where they are welded together to form the head; the diameter of the head is greater than 1800 mm. Does the company’s qualification for on-site welding of A3 spherical storage tanks allow it to weld such end caps on site? Reply: No qualification requirements are needed for head manufacturing; heads with welds must undergo supervision and inspection during the manufacturing process. 14. Determination of the non-destructive testing level for end caps. Dear leaders of the General Administration, regarding containers, 20% RT testing is required for weld joints of categories A and B in the cylinder section, with a satisfactory level set at Grade III; whereas 100% RT testing is required for welded end caps. How should then the satisfactory level for radiographic testing of end caps be determined? Reply: Please proceed in accordance with the requirements of the design drawings and the standards to which the product complies.