Quality supervision of pressure vessels

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1. Control material quality. The control of raw materials (including welding materials) is an important aspect of quality control. The manufacturing unit should define the scope of material and procurement control. The control of materials generally should include: selection, substitution, procurement, acceptance, re-inspection, storage in inventory, keeping, distribution, labeling, and transplantation. 2. Control process quality. The manufacturing of pressure vessels is a series of production processes that are carried out in accordance with specific manufacturing procedures. Before commencing production, it is necessary to develop processing procedures for each production step and component in accordance with the requirements of the design drawings, and make corresponding adjustments to these procedures based on production conditions and material substitutions. During the production process, the workshop and production workers must work strictly in accordance with the technical procedures and rules to eliminate arbitrariness. The manufacturing unit shall define the scope of process quality control, and establish and implement management systems or procedural documents for process quality to ensure that the process flow is rational. The process documents are correct and complete, the process implementation is under control, and the product identification is unique. The control aspects generally should include: process review of the design, process flow, development, approval, and use of general and specialized processes, design, use, and maintenance of tooling and molds, product labeling, traceability of mark and label values, records of process implementation control, surface treatment, and protection. 3. Control welding quality. Welding is a major processing method in the manufacture of pressure vessels; tasks such as joining flat plates, connecting tube sections to each other, and attaching tube sections to end caps are all typically carried out through welding, and it plays a very important role in the production of pressure vessels. The quality of a product depends to a large extent on the quality of welding. The manufacturing unit shall establish and implement management systems or procedural documents for welding quality, in order to ensure that the quality of the weld joints of all pressure components (including those where pressure components are connected to non-pressure components) meets the requirements of regulations, rules, standards, and drawings. The control aspects generally should include: the control and management of welding materials, welding procedure qualification as well as the preparation, approval, and use of related procedure documents; welder qualifications and management, welder marking, product welding test pieces, welding equipment, the quality of welding joint alignment or assembly, control and recording of the welding process, and quality control and recording of weld repairs. 4. Control inspection quality. During the manufacturing process, pressure vessels inevitably develop some defects; some of these defects are within the limits permitted by standards and are therefore acceptable ； Some defects exceed the standard requirements and require rework or rejection. Unqualified products must not leave the factory. To achieve this goal, manufacturing plants must implement a system that combines self-inspection, mutual inspection, and specialized inspection, appointing dedicated inspectors to conduct strict inspections of the key production processes. By establishing various stop points and control points, the quality of pressure vessel products can be effectively ensured. 5. Control the quality of non-destructive testing. Non-destructive testing techniques are used in the inspection of pressure vessels, primarily to detect defects inside and on the surface of welds. In the process of quality control in pressure vessel manufacturing, flaw detection evaluation is an important means of quality assessment. The control over the work quality of non-destructive testing and its inspection reliability mainly involves the evaluation of the operators’ skills and the control of the flaw detection procedures. The control aspects generally should include: the development, approval, and use of general and specialized procedures; the qualification and management of inspection personnel; the control of non-destructive testing equipment, facilities, and supplies; the traceability of welds that are to be inspected using non-destructive methods; the control over the process of conducting non-destructive testing; and the quality control and storage of non-destructive testing records, reports, and radiographic films. 6. Control the quality of physical and chemical tests. The manufacturing unit shall establish and implement management systems or procedural documents for the control of physical and chemical testing, in order to ensure that the physical and chemical tests of pressure component materials and welded joints meet the requirements of regulations, rules, and standards. The control aspects generally should include: the formulation, approval, and use of testing procedures; management during testing; testing equipment and instruments; sampling, processing, and testing of specimens; the operation of tests; storage of specimens; recording, reporting, and storage of test results; and quality control for outsourced physical and chemical tests. 7. Control non-conformities. Due to various factors, it is inevitable that during the manufacturing process, certain workpieces or other items may fail to meet regulatory requirements, standards, or documentation specifications. Such situations are referred to as nonconformities; they may also be called non-compliant items or defective products. The manufacturing unit shall establish and implement strict management systems, procedural documents, and process controls for nonconformance control, ensuring that no nonconformances are used in subsequent production stages until they have been rectified. This guarantees that any nonconforming pressure vessels are not released from the factory. Control procedures generally should include: determination, identification, disposition, and documentation of nonconformities, etc.