Hot bolting is used to swap corroded studs or restore preload without a shutdown: one bolt comes out and a new one goes in before the next is touched. Sites limit it to low pressure classes, flanges with enough bolts, and services where the remaining bolts can hold the gasket, and they require a risk assessment because a gasket that blows out with a stud missing puts the leak right in the fitter's face.
Studs on that 8 inch flange are half eaten, permit is approved for hot bolting, one at a time, opposite pairs.
Also heard as
- hot bolt
- hot bolt replacement
Related terms
Spiral wound gasket
A flange gasket made of a V-shaped metal strip wound with a soft filler, held between an outer ring and usually an inner ring.
Raised face
A flange facing where the gasket surface stands slightly proud of the bolt circle area, concentrating gasket load.
Hot tap
A new branch connection made on a pipe or vessel while it stays in service, cutting through a valve.