Thursday, March 3, 2011

Hot bolting

Hot bolting is a method of replacing the bolts on a live line. Normally done one bolt at a time. Hot bolting should be used only when there is no other reasonable choice.

The criteria typically followed is something like:
• The operating pressure must be less than 75% of the MAWP as allowed under ANSI B16.5 at the operating temp of the piping or process system to be hot bolted.
• The flange must have a minimum of 8 bolts
• The process temperature must be between 4°and 71° C.
• All flanges and associated system equipment must be adequately supported, i.e. no excessive vibration or pulsation.

Monitoring for hydrocarbons is also a must during the operation. Generally the procedure for hot bolting is the same sequence as for a tightening operation.
• The gasket area must not show signs of leakage. Piping, flanges, and bolts must not be severely corroded, i.e., to the point of affecting their integrity.
• Existing flange bolts/nuts must be tight and of the correct size and grade.

Credits to GregLamberson and other posters here

No comments: