Process Standards for Pressure Vessel Fabrication

Pressure vessels are critical in oil and gas, chemical, power, and pharmaceutical industries, containing gases or liquids at non-ambient pressures. Their fabrication requires strict standards to ensure safety, integrity, and compliance with international codes like ASME BPVC Section VIII and China’s GB/T 150.4—2024. This article summarizes core standards covering key fabrication stages.

1. General Principles

Fabrication must prioritize safety, quality, and traceability, with a comprehensive quality management system (QMS) overseeing all activities. Facilities need qualified equipment, and personnel (welders, NDT technicians) must hold valid certifications to ensure competence.

2. Material Control

Raw materials (plates, forgings, welding materials) must meet design specs, with selection based on service conditions. A full traceability system tracks materials from procurement to assembly, including mill test reports (MTR). Raw materials undergo strict inspection for surface defects, dimensions, and chemical/mechanical properties.

3. Forming, Assembly and Welding

Forming (cylinder rolling, head forming) controls temperature and parameters to avoid material damage. Assembly ensures component alignment, with nozzle orientation verified against drawings. Welding follows qualified procedures (WPS/PQR) per ASME Section IX; welders must be certified, and welds undergo visual and NDT inspections (RT, UT, MT, PT).

4. Heat Treatment and NDT

Post-weld heat treatment (PWHT) relieves residual stresses, with parameters based on material and thickness. NDT detects defects without damage, performed by certified technicians using calibrated equipment at key stages (after welding, heat treatment).

5. Pressure Testing and Final Inspection

Hydrostatic testing (1.5×MAWP) is preferred to verify pressure resistance; pneumatic testing (1.1×MAWP) is used when water-sensitive. Final inspection includes dimensional checks, quality record review, and standard marking. A Manufacturer’s Data Report (MDR) is compiled for certification.

Conclusion

Adhering to ASME and GB/T standards ensures pressure vessel safety and reliability. Strict quality control at every stage—from material selection to delivery—minimizes failure risks. These standards evolve with industrial demands, emphasizing continuous improvement in fabrication practices.