Heat trace and induction

[Eddy Current]

I was one a job where we ran about 500 ft of heat trace wire, i wasnt the one that ran the wire so im not sure what kind of wire it was or if it was some sort of cable. The wire was run along the pipeline and ran over top of a
U bolt. We were told we had to take all of it down and run it through the U bolt because of induction. I think we were supposed to let it run through the U bolt but not let it touch the U bolt, but im not sure. Can anybody explain this?

 

[dkeaux@gmail.com]

Sounds like a preferance

 

[Eddy Current]

The U bolt is straped to a small T shaped stand could it induce enough to carry through the steel stand? Seems like they needed some particular reading to ground.

 

[Rick Christopherson]

If induction is a problem outside of a u-bolt, then running it through won't change that. Whoever was dictating this doesn't understand the principle.

 

[rcwilson]

Here's my guesses at the basis for the objection. Induction is not one of them.

The U-bolt is probably a support for the pipe and the heating cable is to keep the pipe contents form frezzing or precipitating. If the heating cable design needs intimate contact with the pipe to get the proper heat transfer, running the cable over the U-bolt may create an airspace that impedes heat transfer. Heat loss at a pipe support is much higher than along the rest of the pipe. Higher heat loss and less effective heat transfer could combine to make a cool spot in the pipe. Maybe the objection was due to concerns about freezing the pipe contents at the U-bolt support.

Another mechanical concern is pipe movement due to thermal expansion and how that affects the cable. If the support was meant to allow pipe movement but the heating cable was contacting the stationary support, the cable might become damaged by the relative movement.

 

[Eddy Current]

I have a little more info the wire. It was one 500mcm lugged to plates extending from the pipe line ever probably 50 feet or so. It is an impedance line.


There were two stations with a PLC type panel and a transformer.


Does anybody know how an impedance line works and how one 500mcm in and out works on an impedance line?