The concept of the main bolt of equipment
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Regarding the concept of the main equipment bolts, in my opinion, any bolt used for the main pressure-bearing components of a vessel is considered a main equipment bolt. I’m curious to hear what other friends think.
In fact, every bolt on the equipment is important; without any of them, the equipment cannot be considered complete, otherwise it wouldn’t have been taken into account during design. For the bolts on critical flanges, their failure (in various forms) can cause significant damage and harm to equipment as well as to people and property; such bolts are known as main bolts or critical bolts, and special care must be taken when installing them or loosening them.
It can be said that it’s the bolts used on the main compression elements. To put it more broadly, those compression elements are also quite important; none of the components can be ignored.
I support the view from the second floor. However, it should be noted that for any alloy steel fasteners larger than M14, it is necessary to check the qualifications of the manufacturer (pressure pipeline component manufacturing license) at the time of purchase.
Article 25 of the Code specifies that for equipment with a size of M36 and above, the main bolts are considered primary compression members, and re-inspection of the materials used for them is required, mainly because the failure of bolts of such sizes to meet specified standards can cause significant hazards. In fact, every bolt is crucial; any negligence can pose a threat to the safety of equipment and personnel. For example, the failure of a bolt on a sight glass has led to an accident resulting in one casualty.
As mentioned above, bolts of grade M36 or higher are the main compressive elements, but the tolerance specifications don’t require re-inspection, right? The tolerance specifications only impose re-inspection requirements on the main compression components such as steel plates and forgings. But generally, to ensure quality, we still conduct random re-inspections on the bolts. Bolt failure is a gradual process; the most important thing is to conduct regular inspections during use to ensure safety.