WHAT ARE THE LIMITATIONS OF HOT TAPPING, LIMITED BY FLUID, FLAMMABILITY OF FLUID, CLADDING, LINING - Video

Limitations of Hot Tapping
Hot tap connections shall not be made in any of the following cases:

Limited by Fluid Types:
Lines carrying the following shall not be hot-tapped.
Acid
Caustic
Elemental sulfur
Oxygen
Chlorine
Ammonia
Potentially toxic materials
Any material which may cause metallurgical damage when heated.

Limited by Flammability of Fluid:
Hot taps are not suitable for pipes or vessels containing materials that are flammable below atmospheric pressure or mixtures that will support combustion.

Limited by Material Degradation:
Hot taps are not suitable if the pipe material to be welded may suffer metallurgical or physical degradation from the heat of welding.

Limited by PWHT Requirement:
Piping requiring post-weld heat treatment, for any reason, shall not be hot-tapped.

Limited by Pipe Cladding or Pipe Lining:
Hot tapping shall not be performed in piping, or vessels that are clad or lined.