Heat Tracing Polypropylene Pipe

[PEDARRIN2]

Has anybody ever applied self regulated heat trace cable (for freeze protection) to polypropylene pipe?

Have an application where trying to supply RO water to an exterior located HVAC unit with humidification.

Not real keen on applying heat trace to a pipe system whose joints are made by heat fusion. I realize the heat trace will not have enough intensity (5-8 W/ft) to melt the pipe, but concerned about localized deformation of the pipe.

 

[MJCronin]

Bad choice of piping by the Piping Engineer ...... polypropylene pipe is not a good idea

There should be a seperate pipe class for this heat traced outdoor service

I suggest a change to Sched 10S Stainless Steel piping

Oh wait !!! .... Tell me it's not already installed and they dumped this problem in your lap !!!

MJCronin
Sr. Process Engineer

 

[1503-44]

Let it drip.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[EdStainless]

don't worry MJ, they can let the Poly freeze and replace it with light wall SS.
Sch 10 (or even Sch 5) SS with some light insulation over it would be the best choice.

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P.E. Metallurgy, consulting work welcomed

 

[bimr]

Yes, I have used automatic thermostatically controlled heat tape. I assume you are referring to small diameter pipe which will probably have to be supported in a tray.

 

[PEDARRIN2]

Cannot use steel pipe as this is RO water being fed to a humidifier.

Pipe is 1" S80.

We specify the self regulating type of heat trace, usually Raychem/nVent.

 

[moltenmetal]

Yes, you can do it. Plastic pipe is heat traced for freeze protection all the time.

Yes, you must use self regulating heat trace- power limiting heat trace with a thermostat is not a solution.

Yes, a metallic skin layer in the form of something like aluminum foil tape, applied to the plastic pipe at the locations where it will be traced, is also a good idea.

No, you can't get away with doing this for freeze protection at higher temperatures, such as the famous stearic acid/plasticene court case.

(

http://www.spitfireresearch.com)

 

[Compositepro]

It might be cheaper and more effective to run two pipes to form an insulated recirculation loop, and heat the water at one end.

 

[EdStainless]

PEDARRIN2, This is usually done with light wall Stainless Steel pipe.
It doesn't require continuous support and it is very resistant to external damage (UV and people bumping it).

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P.E. Metallurgy, consulting work welcomed

 

[PEDARRIN2]

For the stainless steel pipe, would it need to be passivated?