Solved

We don’t have any particularly good solutions here either; applying coupling agent doesn’t help for long, and once we even tried using a pneumatic wrench but still couldn’t get it open. . . . I’m completely speechless; it got cut off in the end. I’ve used looseners, acetylene flames for heating, pneumatic wrenches, and cutters during disassembly; all that’s left is to maintain the equipment more regularly. It’s necessary to purchase bolts that meet the required standards. I bought a batch of stainless steel bolts before, and after installation I found that some of the gaskets had defects. I wanted to remove them and replace them with new ones, but the threads on the bolts were damaged and it was impossible to remove them. In the end, I had to use a cutter to cut them off. It was a real hassle with that batch of bolts. . . It will take several days. . .

Refill and seal regularly when the temperature is not high

In addition to choosing high-quality bolts, it is also necessary to use butterfly springs, which makes installation and removal much easier.

Normally, pour waste lubricating oil first, then apply grease.

It was stretched with bolts, right? Bolt Tensioning? Use a bolt tensioner for disassembly.

There is one spare bolt for each one; a set is kept on hand at all times, and if it cannot be removed when needed, it is simply cut off. There’s no other way.

Oil the bolts; I’m not sure exactly what kind of oil to use

In similar situations, all the methods you mentioned have been tried; they’re more or less the same.

The temperature is high; it’s not safe to apply oil during operation