Painting of cold pipe

[tickle]

I have just installed a tie in piece into some plant gas distribution pipework. This is down stream of a pressure let down/metering station and has cold gas passing through it.

The newly installed pipework did not get painted prior to installation and therefore must be done in situ. Particularly because the pipe is below the water table (fresh water)

Because the gas is cold the outside of the pipe suffers from condensation of water. Does anyone have any experience of coating cold (5 deg C) and wet metal?

The relative humidity is generally low but the dew point is above the surface temperature of the pipe. There is not any opportunity to heat the gas in the metering station. I understand that there are suitable paints for cold surfaces and wet surfaces, but not sure about the two scenarios together.

I would be grateful for any assistance.

Tickle

 

[TD2K]

I doubt you will have any luck painting a wet surface and getting a good coating. Preparation is critical to the success of any coating and trying to paint/coat a wet surface is just something that to my mind isn't feasible wrt a quality coating that will last. I'd put it on the work list for the next shutdown.

 

[sechon2001]

It is very hard to solve such a case.
If primer was painted,I would like to recommend you applying insulation for protecting pipe from rust.
You can try also to use water soluble paint on the surface temporaty if possible.
Anyhow line should be dried to apply normal paint.

Good luck!


Chunhong Park P.E.
LG Engineering & Construction Corp.

 

[tickle]

Thank you for your responses.

The pipework is on a power station and I am afraid that there is no foreseeable shutdown anticipated (Power staions are like that). The pipe is to be buried and the spear pumps (that are keeping the water table down) are to be turned off. The pipe will be wrapped prior to burial, however the surface of the pipe spools needs to be painted in advance.

I was hoping that there was products and/or procedures available to assist me. I was thinking that cold climates such as Alaska faced a similar problem.

 

[tickle]

The solution that has been adopted is to tent up the spool piece and to de humidify the air using a Munters wheel within the tent and coat with a suitable paint for application on the cold pipe.

 

[Chemical16]

Tickle , I feel there are cold pipe applications in Marine paints category , specific details I will sent you soon , any way its always advisable to have coat of material which may form a protective chemical layer or coat the pipe before submerging it .

D.K.Shukla

 

[pmover]

tickle,
in cold climates, most surface preparation and coatings are applied before piping systems are placed in service (i.e. before construction), unless indoor application. if not indoor, then, some type of enclosure (tent or prefabricated structure that easy to move) is used for such minimal work (i.e. final tie-ins, damage during construction, etc.).
by the way, north slope construction during the winter is most active here in alaska as it minimizes impact to environment (snow and ice covered tundra, lakes, etc.). winter residential/commercial construction takes place indoors using plastic (large rolls), tents, or tarps covering the buildings.
perhaps a simply-constructed enclosure can be made that allows coating of pipe.
-pmover

 

[nakhulkannan]

Can anybody help me?
Is there any thumb rule formula for calculating blast & paint cost per tonne of steel
blast sa2.5
Paint nor mal 3 coat epoxy system

Thanks

R.kannan
kannan@bwceng.com

 

[TD2K]

I would estimate paint costs per area, not on a weight basis. Unfortunately, while I have some numbers for you, they are back in my office and I don't have access to them here.

 

[TD2K]

Sorry, I should have finished. I can give them to you but it will be a week or so before I'm back in the office.