Spools Painted with studs and nuts

[curtis2004]

Hi Everyone,

Piping sub-contractor bolted together carbon steel piping spools and painted as it was bolted all piping spools including studs and nuts too. This is small bore piping (=<2") for Auxiliary Nitrogen System of power plant.
1. Is there any issue with painting all studs and nuts?
2. How about not painting of flange faces?

Thanks,
Curtis

 

[LittleInch]

Yes,

Getting those bolts off in months and years ahead will be far more difficult. Possibility that corrosion will occur under the paint layer un seen.

I assume you mean inside the made up flanges and not the flange face prior to mating? Assuming its all bolted up, painting inside the flanges isn't a real problem.

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

 

[curtis2004]

Hi LittleInch,

Thanks for your brief response. We have 2" x 150# SW flanges. They painted only back and OD surface of the flanges. I think they suppose to paint inside bolt holes, flange face except raised face surfaces. I might be wrong though.
Who knows how properly apply standard ANSI flanges?

Thanks,
Curtis

 

[EdStainless]

In some cases it can make leak testing difficult, we used to require that there was no paint in the flange gaps.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[LittleInch]

In general stud bolts and nuts are protected by a variety of coatings, from cad plating to PTFE and are usually recommended to be greased before and after installation to ease installation and removal and protect them from being painted.

I don't recall bolt holes being painted unless the entire fab was pre spray painted and this required the ends of the flange / sealing faces to be protected with tape and sometimes paper stuffed in the bolt holes to prevent paint getting in there and pooling.

There are no mandated requirements for painting or non painting other than removal from surfaces to be welded.

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

 

[DekDee]

Have you received these on site or are they still in the subcontractors yard ?

 

[bimr]

Bolts, studs and nuts, where used to bolt up piping, valves etc. or otherwise used to connect painted items, should receive a top coat of paint over exposed areas after the connections are made. Painting of bolts makes later disassembly difficult. A bolt material more suitable for corrosive environments may be used to alleviate the necessity of having to paint the bolts, and would facilitate disassembly of the flange joint.

Items such as machined flange surfaces should be protected to prevent damage or contamination during blasting or painting. Normally, the raised surface of a flange is never blasted or painted. (Those surfaces are sometimes referred to as machined, and this is where the gasket sits. The rest of the flange surface is blasted and a coating is applied. If the question originates from a project, the best answer may be found in the project coating specification.

 

[pennpiper]

curtis2004,
You have not given us very much information so we are all just guessing.
May I ask you some questions please?
1, Which "Piping sub-contractor" bolted the spools together and did the painting?
- Was it the Pipe Fabrication Shop sub-contractor?
- Was it a separate Piping Painting Sub-contractor?
- Was it the piping Installation sub-contractor?
- Was the same "Piping sub-contractor" responsible for all three actions:Fab, Paint and Install?

2, Where was the "bolting together and painting" done?

3, Were the spools disassembled after the painting and then reassembled in place at the jobsite?

Sometimes its possible to do all the right things and still get bad results

 

[curtis2004]

Hi Everyone,

Thanks for overwhelming response.

1. Those lines are field run and supported by equipment supplier (Supply & Install) sub-contractor up to tie-in points.
2. Lines are fabricated on site, supports are attached to existing steel, and bolted together.
3. I think they hydro tested piping assembly after installations, and applied prime coat and final coat without disassembling spools.
4. I'm uploading a picture to show you all a fragment of installations.

Thanks,
Curtis

 

[curtis2004]

If this is important, Material of piping - Low Temp CS...

 

[LittleInch]

So in summary for me - it's not a technical issue, but if I was the operator taking it over or going through with a punchlist, I would make the contractor remove all bolts and studs, one at a time, clean them, grease them and put them back. They won't paint them like that again.....

The installation guys might get away with it, they might not.

You would need to see what the installation specification said to be on safer ground either way.

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

 

[DekDee]

Agree 100% with LI.
If grease or a corrosion inhibitor had been correctly applied to the studs the paint would not adhere so it is obvious nothing has been put on the studs.
Pull them out and do it properly,
Regards,
DD