Info on Buried Pipeline Coatings

[CRG]

Hello,

I am looking for comparative data on external pipeline coating systems for onshore-below grade carbon steel pipe with active cathodic protection. Gas pipeline will be a new 900#, B31.8, DOT regulated line. Any information or discussion would be appreciated.

Currently systems of interest are:
X-True Coat
Fusion Bonded Epoxy (FBE) --- Scotchkote 206N
Three layer system -- FBE base with copolymer adhesive layer and extruded Polyethylene topcoat

Of interest is cost, performance, and availably of pre-coated pipe. What coatings have you been using for buried steel pipelines?

CRG

 

[pmover]

FBE

have the fbe applied at the factory before transpotation to job site. joints to be coated with fbe as well after welding and inspection (x-ray, etc.). "jeep" the pipe section before burial.
key factor is to have good clean cover (soil) that is free of rocks and/or other debris that can damage the pipe coating.
-pmover

 

[MJCronin]

CRG,

I would try NACE and review some of the "Recommended Practices" for coating of UG carbon steel systems.

Look at:

http://www.nace.org/nace/content/technical/s-r/standardsstatuschart2ver2.asp

Good luck...

MJC

 

[BRIS]

The three layer polyetheylene is more or less an industry stanard solution and is good in terms of cost and performance. As an altrnative to epoxy and the 3 layer system you could also consder single coat rigid (rigid meaning cross linked polymer) polyurathane coatings. These caotings are showing excellent performance and have the advantage of flexibility and easy field repair. Polyurathane can also be used to finish site girth welds in place of heat shrink sleeves.

Brian

 

[odem]

CRG,
Most of the projects that I have been involved in (both the engineering and construction side) were done with FBE. It is a fairly inexpensive system and is easy to use in the field. Repairs to the coating can be made very easily and coating of the field joints is simple as well. Shrink sleeves are common or FBE can be field applied.
Depending upon client requirements you can vary the thickness of the FBE for the mainline and any road/river crossings that you may have.

Three layer/X-tru coat coatings are very good coatings but they are a little more difficult to deal with in the field. It is much harder to repair and when it becomes necessary to cut a joint of pipe, the coating is very difficult to work with. In some cases, these systems require special processes to coat field joints (ie, sandblasting, solvent cleaners, etc.).

Generally speaking, FBE is widely used and is considered a standard coating for underground applications. Most places that sell pipe have FBE coated pipe in stock. Unless you have some very strange soil conditions, FBE should be suitable for your line.

Odem