Need to Paint a Pipe - SSPC Spec? and Paint Type 1

[JoelTXCive]

We have an existing 60" steel pipe that conveys excess rainwater across a ditch. We are going to widen the ditch and expose more of the pipe. (We are also adding another bentcap to support the pipe)

The pipe was installed in 1986 and I do not think it has been painted since then. (see below photo)

Since we are making other modifications to the pipe; now might be a good time to paint it. Also, I have no idea what the buried portion of the pipe looks like.

My questions are: (sidenote: I'm the structural guy and know very little about painting, but have been roped into this project)

1) What level surface preparation should we specify? SSPC SP-6 Commercial Blast Cleaning?

2) What type of paint? Here is our typical paint callout: "PIPE TO BE PAINTED WITH TNEMEC SERIES FC22 EPOXOLINE OR APPROVED ALTERNATIVE. (100% SOLIDS EPOXY RATED FOR IMMERSION SERVICE 20 MILS DFT)"

Thank you in advance for any tips.

 

[TugboatEng]

The surface area is small. Setting up to blast is going to cost more than the blast itself. Make the commitment and go to SSPC-10. After a white metal blast you can prime with a zinc rich primer and then top coat with your choice of surface tolerant epoxy.

 

[brimmer]

There's no photo. If you are setting up for blast you may as well go to SSPC-10, you'll get it cleaner with a better anchor pattern. Most coatings fail because of inappropriate surface prep. That coating calls for SSPC-10 in immersion service anyway (in its data sheet, you must follow this). Also, if it is exposed to daylight, you will need a top coat over, as these epoxies are not resistant to UV light.

 

[MotorCity]

Can't help with the prep or painting, but just a word of caution.

Looks like this is in a residential-ish area. Be on the lookout for locals who may call the environmental police.

I cannot think of a surface prep or coating arrangement that would not somehow expose the stream to by-products of the process.

 

[dik]

You may need a polyurethane top coat over the epoxy topcoat... epoxy doesn't do so well under UV.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[TugboatEng]

Surface tolerant epoxies don't require a top coat. They will fade over time and if you change your mind you will be outside of the recoat window. You'll have to commit to one or the other at the beginning.

 

[dik]

Also have to be careful that some coating systems don't like a coating over, after a period of time...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JoelTXCive]

Thank you all for the input. This project died while we were waiting on geotech, but it's alive again.

MotorCity brings up a very good point about pollution or contamination due to the blast cleaning and painting.

Is anyone aware of a specification or pollution control standard that I could cite?

I'm thinking that Oil & Gas pipeline companies have to paint their pipes all the time; so maybe there is a pollution or environmental specification out there somewhere?

 

[RustSlayer]

JoelTXCive,

SSPC(now AMPP) publishes a containment guide, SSPC Guide 6. This is a great jumping off point. You would need to specify the level of containment and monitoring schedule from within the guide and not just generally reference it.

https://store.ampp.org/sspc-guide-6...ris-generated-during-paint-removal-operations

You may also want to consider the coating contractor to be SSPC QP-2 qualified, which is an audited qualification for field removal of hazardous waste.

There are products that can be used with minimal surface prep, or a tie coat to promote adhesion. Rustbond, Noxyde etc. Most coating manufacturers could assist you with this.

 

[hokie66]

I would seize on the limited surface preparation which RustSlayer mentioned. This does not look like a good location for blast cleaning.

What I would do, and that is from a heavy industrial viewpoint, is to do hand preparation, then a mastic coating. My go to has for years been Carbomastic 15, but I would discuss your situation with Carboline. You can overcoat the Carbomastic if desired.

file:///C:/Users/Al/Downloads/Carbomastic_15_PDS%20(1).pdf

 

[RustSlayer]

A while back I was an inspector on a pipe over water like this. The contractor performed the hand tool prep off of a giant Styrofoam barge anchored to both abutments. The barge was covered in tarps and the hand tooling produced minimal debris. It worked but I was a little hesitant to get on it the first time

Hokie66's recommendation of Carbomastic 15 is a good one. If you are in cold weather or the project is going to be performed in the colder months, there is a low temp version called Carbomastic 615. Most manufacturer's have a similar product as well. Between the pipe and it's supports is probably worse than the exposed areas, by the way. They can lift the pipes and prep/paint underneath if desired.

 

[TugboatEng]

There is another option that requires minimal surface prep but it's expensive. Denso tape is an example. As a benefit, the hooligans won't like climbing on it.

 

[FacEngrPE]

An approach for the buried part of the pipe - assuming it is uncoated or perhaps coated in an unknown manner - is passive cathodic protection.
UFC 3-570-01 Cathodic Protection, is a good reference.

Internal corrosion may be a problem, depending on the initial corrosion allowance.

 

[SJones]

For the age, and exposure, things actually don’t look too bad. It might well be a very different story when you start exposing the buried pipe. The coating selection will be driven by the need to have both atmospheric and underground performance - some of the above recommendations might not have the dual characteristics. A viscoelastic tape wrap coating may well be suitable, and could have health, safety, and environmental benefits, including not having to completely remove the existing coating. Check out such coatings as Stopaq, or Viscotaq.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.