How should terms in pressure vessels be understood?

When indicating a particular option that is especially suitable among several possibilities, without mentioning or ruling out other options; or when indicating it as the preferred choice but not necessarily the one required; or when expressing disapproval without prohibiting a certain possibility, the positive term to use is “suitable””； The antonym is “not suitable”.

Can it be understood as: \"Not advisable\" = \"Cannot\", or \"Not advisable\" = \"It’s also okay\"?

It’s not that it’s impossible, but rather that one should try to avoid choosing it；

It’s not appropriate. First of all, it means it’s not possible; secondly, if it’s necessary to use it, then it’s still possible

It shouldn’t be mandatory, which means it’s best not to use it; only use it if there is really no other option.

Technical specifications and standards often use terms such as \"not suitable\" or \"average,\" which, in my opinion, are copied from foreign standards without taking into account the fact that the meanings of Chinese words can vary greatly or even be completely opposite. In practical situations, it should not be interpreted as being impossible; it is generally understood to mean that it is necessary to do so. If there are other standards of the same level or higher that contain conflicting requirements, those other standards shall take precedence; otherwise, this standard shall be followed.

There is no strict prohibition, but it is not recommended

Haha, I just discussed the relevant terminology with experts from the Emergency Management Department. According to national standards: It is strictly prohibited – never touch it; touching it constitutes a serious violation, leading to immediate suspension of production and punishment of those responsible. Highest priority – non-negotiable: production may not be halted, but corrective actions must be taken. If it is still found that no corrections have been made upon subsequent inspections, then production will be suspended for rectification. Secondary priority. Not recommended: It is not advised, but after a comprehensive assessment, since there is no impact on safety, no corrective action may be necessary. Of course, points can still be added after making the necessary improvements in accordance with advanced management standards. Giving priority to the lowest value is not a mandatory requirement; these terms are explained on the first page of the relevant specifications