Why are pressure vessels subject to non-destructive testing?

For safety reasons, non-destructive testing can detect defects in pressure vessels without causing any damage to them! !

Non-destructive testing involves checking whether there are any defects on the surface or inside of a weld, without causing any damage to the weld itself. Such defects can affect the strength of the weld, and they may also lead to changes in the equipment during its use, resulting in equipment damage and accidents.

It’s just like why people need to get medical check-ups.

The main purpose is to ensure the safe use of pressure vessels throughout their inspection period. The inspections are carried out to detect (1) whether manufacturing defects deteriorate over time during use, and (2) whether new defects arise during the vessel’s service life. For standard non-destructive testing methods such as UT, MT, and PT, the areas that are inspected include welds, heat-affected zones, and the base material adjacent to the welds; the specific scope of inspection is determined by the testing method used.

Check the welding condition of the weld! Generally, for safety reasons, ultrasonic testing is the preferred method when the thickness of the container is not large; if the thickness is greater, X-ray inspection must be carried out by professionals! The purpose is to check whether there are any gaps within the weld, or whether there is slag present!

Non-destructive testing is used to detect internal defects, which is crucial for pressure vessels – a type of special equipment that can have a significant impact on human life and property.

It is mainly to detect weld defects

Non-destructive testing is a method for verifying the quality of pressure vessels; it applies not only to welds and welded joints but also to raw materials such as sheets, pipes, and forgings. There are various methods available, and they are effective without causing any damage to the materials being inspected.

Since the failure of pressure vessels can cause serious harm to people and the environment, especially since such vessels are often used to hold flammable, explosive, toxic, and harmful substances, non-destructive testing is a preventive measure taken to avoid such accidents. It’s to ensure safety.

Non-destructive testing is primarily used to ensure the quality of welds: it allows detection of whether the welds have been fully penetrated, whether there are any slag inclusions within them, whether cracks exist in the welds, and it can also identify issues such as undercutting in the welds. Its purpose is to prevent pressure vessels from leaking or experiencing explosive failure during use. Moreover, the proportion of weld inspections is also related to the design of the equipment; for more details, refer to section 3.7 of GB150 regarding the relationship between weld coefficients and non-destructive testing! The design wall thickness of pressure vessels is related to the selection of the weld coefficient, and the weld coefficient is related to the proportion of non-destructive testing; therefore, the wall thickness of pressure vessels is also connected to non-destructive testing! At the same time, when the thickness of the pressure vessel plates reaches a certain value, both the welds on the plates and the quality of the plates themselves require non-destructive testing! All of this needs to be specified in the technical specifications. Especially given the lifetime responsibility system for pressure vessel design, we designers must ensure that no major technical problems arise, and we also need to know how to protect ourselves!