General Rules for Inspection of Pressure Vessels

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General Rules for Inspection of Pressure Vessels Sequence Number Inspection Items Inspection Content and Technical Requirements Inspection Methods and Tools 1. Drawing Inspection Verify the validity and compliance of the design drawings; ensure they meet current regulatory and standard requirements. Examine the seal of the design unit as well as the design documents. 2. Validity and Compliance of Design Changes Review the documents related to design changes. 3. Materials Materials used for the main pressure-bearing components (parts) must come with quality certificates that comply with regulatory standards. There should also be material markings, inspection/verification reports, and traceability information. Examine the quality certificates and inspection/verification reports. 4. Substitution of Materials Such substitutions must be approved following established procedures, and supporting documentation must be available. Inspect the actual materials and relevant vouchers. 5. Welding Materials Welding materials must have quality certificates that comply with regulatory standards. When re-inspection is required, it shall be carried out, and it is possible to trace and verify the welding procedure documents, the actual products, as well as the relevant certificates. 6 Appearance and geometric dimensions: The visual quality of the welded joints must not exhibit cracks, pores, cratering, or spatter ； Edge biting shall be inspected visually in accordance with the Acceptance Specifications and relevant standards. 7. The visual quality of the base material must not show any signs of corrosion, cracks, bubbles, scarring, folding, inclusions, delamination, or mechanical damage. 8. The dimensional dimensions of the product are to be checked using a straightedge, steel tape measure, and metal ruler. 9. The inner diameter of the housing is to be measured with a steel tape measure and metal ruler. 10. The roundness of the housing should be 1% of the inner diameter Di, with this value not exceeding 25 mm. 11. The length of the housing… 12. The straightness of the housing shall not exceed 0.1% of the length of the cylinder; for vertical containers over 30 m in length, it shall be (0.5L/1000 + 15), measured using wire, metal ruler. 13. The minimum length of each cylinder section must be at least 300 mm, as measured with a steel tape measure and metal ruler. 14. The arrangement of welds must comply with the Acceptance Specifications, design drawings, and product standards; inspection is to be carried out visually, using a steel tape measure and metal ruler. 15. The minimum thickness of the cylinder and end caps is to be determined using a metal ruler, calipers, vernier calipers, and ultrasonic thickness gauge. 16. The shape deviation of the inner surface of the end caps shall not exceed 1.25% of Di in terms of outward bulging ； The inward depression shall not be greater than 0.625% Di. Head gap gauge, metal ruler, feeler gauge 17: There shall be no longitudinal wrinkles on the straight edges of the head. Metal ruler, feeler gauge 18: For the outer circumference of the head, see Table 2 below. Steel tape measure 19: Total depth of the head: (-0.2%~0.6%) DN. Metal ruler, steel tape measure; Head gap gauge 20: Height of the straight edges of the head: (-5%~10%) h 21: Slope of the straight edges – for a height of 25, it should be ≤1.5 when inward and ≤1.0 when outward. Right-angled ruler, platform; Metal ruler, feeler gauge. For a height of 40, it should be ≤2.5 when inward and ≤1.5 when outward. 22: The maximum and minimum differences in inner diameter are shown in Table 2 below. Metal ruler, steel tape measure 23: For appearance and geometric dimensions, see Table 3 for the remaining height of Class A welded joints. Inspection gauges for Class A and B welded joints, metal ruler 24: Remaining height of Class B welded joints 25: Dimensions of the weld feet for Class C and D welded joints are determined based on the thinner thickness of the welded parts ； When the thickness of the reinforcement ring is ≥8 mm, the weld leg length = 70% of that thickness, and it must be ≥8 mm. For welding inspections, reference is to the scales, templates, and metal rulers specified. The allowable misalignment for Class 1 welding joints is detailed in Table 1; for Class 2 welding joints, reference is to the inspection templates, metal rulers, and feelers. For Class A welding joints, the angular deviation in the circumferential and axial directions is (δS/10 + 2) mm, with this value not exceeding 5 mm. Templates for checking the circumferential angular deviation of welding joints, along with metal rulers, are used for this purpose. For Class B welding joints, metal rulers are sufficient for checking angles. The maximum depth, length, and continuous length of undercut on the weld surface are specified as P 329. Undercut is not allowed in seven types of containers; for other containers, the undercut depth must be ≤0.5 mm, the continuous length must be ≤100 mm, and the total length of undercut on both sides of the weld must not exceed 10% of the weld length. Right-angled rulers, steel tapes, depth micrometers, and welding inspection scales are used for these checks. The orientation and dimensions of pipe ends are determined using metal rulers, steel tapes, and protractors. The positions of supports and the spacing between anchor bolt holes should be even, with the diameter of the central circle, the chord length between adjacent holes, and the tolerance between any two holes all not exceeding ±3 mm. The positions and dimensions of the main internal components should be such that they avoid weld areas as much as possible. The flange surface should be perpendicular to the pipes or cylinder walls, with the deviation not exceeding 1% of the flange’s outer diameter (if the outer diameter is less than 100 mm, it is assumed to be 100 mm), and this deviation must not exceed 3 mm. Right-angled ruler, metal ruler, feeler gauge, level; 35 – The holes for flange studs and the centerline of the equipment’s spindle are aligned in the middle or centered. Metal ruler, steel tape measure; 36 – Welding procedure qualification, with welding processes that comply with the JB4708 standards ； 37 Complete records of welding process inspections; welding test plates for products meet the design specifications and JB4744 standards, along with performance reports and samples related to these test plates. 38 Welders’ qualifications and stamps comply with the relevant regulations as well as the welding process documents; welder certificates and welding records are checked. 39 Records of repairs to welded joints are in accordance with the relevant regulations; corresponding verification documents are available. 40 Non-destructive testing: Non-destructive testing reports, along with the methods used, inspection ratios, areas inspected, and the reports themselves, all comply with the relevant regulations, design specifications, and standards; these reports are verified. 41 Non-destructive testing markings comply with the process documents and JB/T4730 standards; verification documents and actual samples are checked. 42 Heat treatment: Heat treatment reports meet the requirements of the relevant regulations, standards, and design specifications; heat treatment processes, reports, and temperature-time records are verified. 43 Temperature-time records for heat treatment. 44 Pressure testing: Pressure testing reports meet the requirements of the relevant regulations and design specifications; on-site inspections are conducted during pressure testing. 45 Airtightness testing: Airtightness testing reports are verified. 46 Product nameplates: Product nameplates comply with the requirements of the relevant regulations and product standards; physical samples and copies are checked. 47 Markings and paint packaging: Paint markings and packaging meet the design specifications and standards; visual inspection is carried out. 48 Safety accessories: Certificates of conformity for safety accessories are checked. 49 Product delivery documents: Technical documents and materials related to product delivery meet the requirements of the relevant regulations, licensing conditions, and product standards; these documents and materials are verified