High Temperature piping - Air-to-Soil interface

[gfdoug]

Hello all,

I am in the process of looking for a product to use as corrosion / moisture protection on a steel pipeline at the air-to-soil interface. The line will be running at approximately 240+ Deg. F filled with decant oil. The pipe will be covered with a polyurethane thermal insulator above-grade.

I have gone through the typical products that I have used in the past and have found that none of them will work here:
• FBE Scotchkote 5233 (3M) - Operating temperatures: -100 °F to 230 °F
• FBE Scotchkote 5342 Toughkote (3M) - Operating temperatures: -100 °F to 230 °F
• Dupont NAP-GUARD 2500 Series - Operating temperatures: up to 225 °F
• Dupont NAP-ROCK 7-2610 - Operating temperatures: Same as Dupont NAP-Guard 2500 Series (due to being applied on top of the 2500 series)

Even the high-temperature products that most of these companies provide will not safely withstand the continuous temperatures that I am looking at. For instance, Viscowrap-HT only withstands a continuous 176 deg. F.

The desirable characteristics of the coatings are:
1) Effective electrical insulator
2) Effective moisture barrier
3) Applicable to pipe that will not adversely affect pipe properties
4) Easy to repair
5) Resistant to disbanding when under cathodic protection

Are their other products or solutions that I can utilize in this situation?

A couple of options that I have been given are:
-Bituminous enamels - Typically 30-180 deg. F
-Liquid epoxies and phenolics - Up to 200 deg. F
-FBE - Seen above, typically -100 to 230 deg. F
-Mill-applied tape systems - Up to 200 deg. F primer
-Waxes - Waterproof overcoat not suitable for this situation
-Concrete - Might not be suitable for characteristics 3 & 4, potentially the best option though

Thanks,

-G

 

[LittleInch]

Try thermally sprayed Aluminium. Good for 500C

http://www.surfacetechnology.co.uk/thermal-spray-coatings/thermal-spray-aluminium-tsa/

I doubt any of the standard polyolefin type coatings will be good for that, though PP is supposed to be Ok up to 125C,

see thought there are others

http://www.brederoshaw.com/solutions/offshore/3lpp.html

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[gfdoug]

Thanks LittleInch,

You seem to always have sound advice. So I appreciate your comments as an avid forum-lurker.

I will look in to both of these options more in detail. At first glance, the polyolefin only protects to 230F (on-shore) and 285F (off-shore). I am not sure what the driving factor is behind this (maybe standards-driven), but maybe it is possible to achieve the 285F on-shore in a way.

For the thermally sprayed aluminium, I looked at the website provided. The data sheet is about as vague as a "data sheet" could be, but the assertions are definitely hopeful to me. I requested more technical information from them in hopes that it could be the solution I need.

Thanks again!

-G

 

[rconner]

[see also issues discussed e.g.

http://www.eng-tips.com/viewthread.cfm?qid=348604

and probably other threads]

 

[LittleInch]

Those links are only a start point for you to investigate further.

At 120C you're going to have to use some sort of thermal insulator or protection for personnel protection. Insulation brings on CUI issues, anything else means fairly large issues over thermal loss or steam production when it rains / mist.

Thin coatings won't get the outer temperature down much or at all so I think your issue is more complex than simply getting a coating.

There are other options, but none are particularly cheap or easy.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[VerneE]

Try glass-foam insulation, cover that with a water - proof wrap. Expensive, but it is the only thing that I have used that works, keeps the pipe safe. Expansion for the pipe within the insulation and other special construction requirements need to be followed (per manufacturers instruction).