A pressure vessel is a closed vessel that can withstand pressure. The pressure vessel has a wide range of uses, and it plays an important role in many sectors such as industry, civil and military industry, as well as in many fields of scientific research. 

Inspection of pressure vessels

External inspection

Also known as in-operation inspection, the main contents of the inspection are: whether the external surface of the pressure vessel has cracks, deformation, leakage, local overheating, and other abnormal phenomena; Whether the safety accessories are complete, sensitive, and reliable; Whether the fastening bolts are intact and fully tightened; Whether the foundation subsidence, tilt and corrosion layer damage and other abnormal phenomena. External inspection is not only the work of inspection personnel but also the daily itinerant inspection items of operators. If any phenomenon endangering safety (such as crack, deformation, serious leakage, etc.) is found, the operation should be stopped and the relevant personnel should be reported in time.

Internal and external inspection

Internal and external inspection of pressure vessel This inspection must be carried out after stopping and cleaning of vessel's interior. The main content of the inspection includes the whole content of the external inspection, but also the corrosion and wear phenomenon of the internal and external surface; Use the naked eye and magnifying glass to check whether there are cracks in all welds, the transition zone of the head and other stress concentration parts. If necessary, use the ultrasonic or radiographic inspection to check the internal quality of the weld; Measure wall thickness. If the measured wall thickness is less than the minimum wall thickness of the container, the strength should be checked again, and the pressure reduction use or repair measures should be put forward; For containers that may cause changes in the metallographic structure of metal materials, the metallographic examination should be carried out if necessary; The main bolts of high pressure and ultra high-pressure containers should be checked for cracks by magnetic powder or coloring. Through the internal and external inspection, analyze the causes of the defects tested and put forward treatment suggestions. A re-inspection will be carried out after repair. The internal and external inspection cycle of pressure vessels shall be once every three years, but the inspection cycle of vessels with strongly corrosive media and highly toxic media shall be shortened. The inspection period should also be shortened for containers with serious defects found in operation and those with poor welding quality and unknown corrosion resistance of materials to the medium.

A comprehensive inspection

A comprehensive inspection of pressure vessels In addition to the above inspection items, the pressure test (generally hydrostatic test) should be carried out. Non-destructive inspection of major welds or inspection of all welds. However, for containers with very low pressure, non-flammable, non-toxic, and non-corrosive media, if no defects are found, after obtaining certain experience, a non-destructive inspection can not be done. A full inspection cycle for containers is generally conducted at least once every six years. For the qualified containers containing air and inert gases, the comprehensive inspection period can be extended appropriately after obtaining the user experience and one or two internal and external inspections to confirm that there is no corrosion.

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