Buried Steel Pipe Coating

[eqkimball]

I need to spec a coating for an 18" carbon steel pipe w/ welded joints. This will be 3' below ground in a moist environment. The pipe is to be constantly charged with 200 psi untreated water.

Do I need an inside coating if the pipe is always full?

What is a common outer coating for this environment, that can be specified for the supplier?

Thanks.

 

[cvg]

you need to do some corrosion analysis to determine this which will involve characterizing the soil environment as well as the water. In some areas, typical practice for potable water is cement mortar coating and internal lining. You may also need cathodic protection.

 

[unclesyd]

As stated above you need to investigate what's needed in your specific case as there is no universal economic answer to protecting water pipe. I think you will need all of the above

The Acipco sites give you a short course in what is normally used and references. The Denso site gives you what's generally available to lay the pipe.

http://www.acipco.com/aswp/

http://www.acipco.com/steel/coating.cfm

http://www.densona.com/Index.htm

 

[BigInch]

can't beat fusion bonded epoxy with polyethylene mechanical protection coating on top.

**********************
"Pumping systems account for nearly 20% of the world’s energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[brimmer]

Outer coating I recommend FBE or some sort of epoxy.
You will need CP for burried pipe, coatings in conjunction with CP is probably required as well, not recommended to have coating alone.
Inside coating, you will need to determine corrosivity of internal fluid first, and match a coating to the service condition. Not sure how line being full all the time would mitigate against corrosion, you would still need a internal coating if you are going this route to mitigate corrosion.

 

[SJones]

In addition to the other questions:

200 psi untreated water

What is the source of the 'untreated' water?

What is the length of the pipeline? If it's a very short line, it may not be worth putting the linepipe through a pipe coating plant.

Have a look at the attachment to help with an external coating selection.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[eqkimball]

Thanks for the input, everyone.

Steve,
The water source is a pond reservior. There are no chemical additives, as this is for a set of deluge water systems. The total underground network is appoximately 1/4 mi. The link helped greatly, by the way.