What type of conduit? Threaded conduit uses straight thread couplings and will not hold pressure.
Why would someone choose conduit for this application? Why not pipe that is designed to hold pressure?
Threaded conduit has tapered threads. See 342.28 and 344.28.
Are standard conduit couplings usable in hazardous locations?
501.15 (A)(1) last paragraph ".... Only explosionproof unions,
couplings, reducers, elbows, capped elbow ...." I assume
explosionproof modifies all the rest of the list, including
couplings, but I can not find anyone that sells
explosionproof couplings?
As I understand it some government installations pressurize conduits (or raceways) to insure that they are not cut into and the conductors/fibers inside are not tapped. They detect pressure drops for this purpose. Do they use special couplings or do standard coupling suffice for this application?
Finally could one use "water-pipe" couplings with tapered threads in stead of conduit couplings, after making sure the coupling would not abrade pulled conductors?