Frequency of weld inspection for pressure vessels
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We conduct major overhauls every year, and many welds of pressure vessels need to be inspected for defects. Some people say there’s no need to conduct inspections every year, but they are worried about equipment failures. What is a reasonable frequency for weld inspection in general medium and low-pressure vessels?
It is not only related to pressure, but also to factors such as temperature and the medium in which the equipment operates. It’s not true that high pressure alone will cause defects; it is first necessary to understand the failure mechanisms of the equipment. Different types of equipment fail in different ways under various conditions, with stress corrosion cracking, corrosion-induced thinning, material degradation, high-temperature hydrogen damage, and mechanical damage being the main categories. Not only non-destructive testing, but also metallography, hardness testing, thickness measurement, spectroscopy, and other methods are available. The key is to analyze possible modes of failure; just as a doctor understands pathology and knows that eating too much can cause diarrhea, they prescribe medication based on those symptoms.