Is it feasible to do piping internal coating on site? 1

[Zul78289]

Dear all engineers,

on our project we already ordered pipe with 78" size in service to flow gas to a new flare stack. but cause of some condition, we must idle the pipe and stack until 3 years from now. the flare stack is installed to a derrick structure along with another new flare stack but different line track. My question is :

1. is it possible to do internal coating on site to this 78" pipe because we already send it to the site?
2. How many the duration needs approximately to finish the internal coating work?
3. and whats the minimum thickness of the coating?

thank you all.

Warm regards.

 

[1503-44]

That depends mostly on the quantity of pipe you are talking about. Onsite work is usually more costly per unit and more prone to errors and quality control irregularities. Pipe coaters have trained persnonel and all the equipment on hand. And they usually have yards ready to coat pipe near to all the world's highest pipe consuming locations. Nothing to move around. Aside from that, coating a large quantity of pipe is far more efficient in a dedicated pipe coating yard, but of course it would still not be practical for a pipe coater to coat just a small number of pipes for you. This logic applies to application of either external or internal coatings ... and just about everything else for that matter. Logistics can enter into the matter, however either way you still must transport the coated pipe and the coating materials one way or another (where's the savings in that) plus the coating application machines must be located and maintained on a (maybe remote) site. You may also need a large appropriate storage area and ... don't forget office, another unloading-loading operation, pipe handling cranes, truck and car parking, traffic effects ... and security. It is usually less costly just to transport large quantities of bare pipe to a dedicated coating yard, then move the coated pipes alone to the installation site, rather than putting all of that stuff in the field. Size of the coated pipe and the resulting number of joints that you can load on each truck might have some bearing, as that affects the number of trucks that you will need to have running around. A limit of two or three joints of coated pipe per truck is going to be costly.

The quantity of pipe that you are talking about is 95% of the logic as to how you should go about solving this task. Installation location vs location of pipe coater's yard might be some of the other 5%.

 

[LittleInch]

What you're really talking about isn't internal coating, but pipe preservation.

So: Can you seal off both ends of this pipe and flare stack or insert a plug in the flare end?

If so then just vent it through with Nitrogen and seal it off under a bit of positive pressure so you can periodically check the seals are ok and leave it.

If not you could ask some of the pipe coaters about how to spray on an internal spray coat of some preservative - water or oil based.

Also look up utility companies who internally line sewers etc. They often have crawler robots which move along spraying stuff on the inside. Or they spray in a "fog" which gradually coats the inside. e.g.

https://www.hiteknologysolutions.co.uk/gas-pipes-outdoor-preservation/

or

https://www.aegion.com/-/media/Aegi.../Zerust/Zerust_Pipeline Preservation_2019.pdf

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

 

[Zul78289]

Dear all,

Thank you for the responses.

Mr. Ax1e, just to confirm so the most consideration is about the quantity of pipe and it is more costly but it is possible to the internal coating on site yes? your answer is very clear for me and very comprehensive.

Mr. LittleInch, that's my second option if its not possible to do pipe preservation. thank you for remind me, thats right we are going to find the best solution for pipe preservation. i thought about make the line pressurized with nitrogen. here's the step :
1. we seal the flare end, take the segment till the top of derrick.
2. we inject the nitrogen to the line
3. if we want to operate again, vent the nitrogen. take down the flare end & unseal the tip.
4. take up the flare then operate

can we do that? thank you

 

[LittleInch]

Basically yes, but I would sweep all the air out first with Nitrogen before you seal it. also you might want to drain the line down or blow 2-3 times the volume through the line to remove any standing water ( Nitrogen is usually very dry).

Usually there is some positive pressure left on the line ( can be very small) which is measured and checked regularly and if required the Nitrogen is topped up if there is small leak somewhere.

This assume internal corrosion is your issue but is a common means of preserving pipes and pipelines when not in use.

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

 

[Zul78289]

Dear Mr. Littleinch,

yeah definitely right, our concern is how to maintain the idle of the flare pipe and stack for 3 years in our planning. the 2 options like i said, do pipe preservation like internal coating but we must do it on site because of the pipe already sent. second option by sealing the flare tip and inject nitrogen to pressurized the line. the second option cost maybe only for the demounting work and remounting the flare stack to the derrick structure.

and the conclusion, by your explanation maybe it is more feasible to do the second option since Mr. Ax1e said that internal coating is very high cost.

If you have any suggestion, it is highly appreciated and thank you.

Regards