Regarding the issue of cracks appearing on the container
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I would like to ask everyone: A container made of stainless steel 304 has developed many cracks at its bottom recently. The medium stored in the tank contains no chloride ions, no alkalis, and no ammonia; therefore corrosion fatigue and hydrogen embrittlement cannot be the causes. The equipment has been in use for 23 years; could the cracks be caused by its use beyond the recommended lifespan?
There are many factors, and the medium is just one of them. Do you have the results (report) of the most recent regular inspection? What is the result? (Take a look.) If the design does not specify a service life, then pressure vessels that have reached 20 years of use must undergo a \"suitability for use assessment\" before they can continue to be used; the outcome of this assessment determines whether they can be used further and what the schedule for the next regular inspection will be.
This post was last edited by Buddha and Orchid on 2018-11-15 at 15:07. There is no such rule. For containers that have exceeded their designed service life, if the user entity wishes to continue using them, it must submit them for inspection to a special equipment inspection agency. Special equipment inspection agencies will develop an inspection plan to inspect the equipment; it is not necessarily required that a usability assessment be conducted. A usability assessment is applicable to containers with serious defects; it is only necessary when one does not wish to address those defects and instead wants to continue using the container despite them. For details, please refer to Articles 7.1.7 and 8.9 of TSG21-2016.
Regarding the issue of chloride ions, it should be understood that written procedural instructions are not the governing standard; instead, testing of the medium is necessary. Chloride ions often end up in containers along with other substances such as rainwater, leading to stress corrosion cracking.
The above is the original text. It’s just that, considering the specific situation mentioned by the original poster, problems have already arisen; continuing to use it should be subject to a usability assessment.
I wonder if cracks will appear from using it beyond its intended lifespan
The presence of cracks has no direct relation to whether the item has exceeded its service life. The design service life for most designs is arbitrarily determined by the design agencies, without systematic consideration of various types of damage that may occur during the container’s operation. Moreover, even if such considerations are taken into account, the actual conditions during use can vary greatly; as a result, it is possible that the container fails before reaching its designed service life, or it may remain in good condition even after that time has passed.