Regarding the use of equipment after corrosion!
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Some of the equipment in our company has suffered significant corrosion; the original wall thickness of these devices was 15.7 mm, while the current wall thickness is 13 mm. They have been in use for 5 years now. The pressure applied to these jacketed devices is 0.6 MPA, and the medium used is type E (carbonate). I’m not sure whether they can still be used for another two years. Please share your insights, experts!
1) For pressure vessels, it’s not possible to decide whether they can be used based on intuition alone. 2) Does corrosion of the inner wall have no impact on their use?
To analyze the causes of corrosion, each specific case must be examined individually. If the material deteriorates, it should be scrapped promptly. Don’t pick at the sesame seeds and lose the watermelon; if an accident happens, it’s all over. It is recommended to have a professional assessment company conduct an inspection and carry out a safety evaluation
After 5 years of use, the thickness that has been eroded is less than 3 mm; considering uniform corrosion, it can of course be used on further, and not just for 2 years； Because the corrosion rate is less than 0.6 mm per year, and this is predictable; in other words, after 2 years the wear on your equipment will be around 11.8 mm ； Of course, you need to check whether this wall thickness can withstand the design pressure ； Uniform corrosion is not scary; what’s dangerous is localized corrosion, such as pitting corrosion, stress corrosion, intergranular corrosion, and so on. Special attention must be paid to these issues before making any decisions as well as during maintenance. Even if the wall thickness is still 13 mm, local corrosion can still occur, leading to leaks and problems
Based on the degree of corrosion, check whether it is uniform corrosion. If so, calculate the amount of corrosion that will occur over two years, and then determine whether the actual wall thickness after those two years is greater than the thickness calculated based on design specifications. If it is, the component can be used for two years; otherwise, it cannot be used
Identify the causes of corrosion from a process perspective and make improvements； For large-area wall thickness measurement of the equipment, it is up to the design institute to decide whether it can be used; based on what you’ve described, it can still be used, and it’s even been over two years since its installation.