Nitrogen Blanket with Plugged Plain Ends?

[ConstantEffort]

Does anyone have experience or recommendations for holding a nitrogen blanket / purge on piping modules and skids for ocean transport when the ends are plain / beveled ends?

The client specs do not permit flanges in these services.

The construction team wants to drop modules on foundations and weld straight away. This rules out adding temporary pipe caps or plates.

I am familiar with hydro test plugs, but I’m doubtful they will hold nitrogen for weeks to months as the pipe sees some bending as the modules are handled and transported.

 

[LittleInch]

Forget nitrogen.

Use oils or similar spray.

 

[georgeverghese]

"The construction team wants to drop modules on foundations and weld straight away. "

Something has to give - there is nothing worse than piping all corroded with salt laden air. Add a sacrificial spool with screwed ends and cap it. Cut the spool off when the module is in place at destination.

 

[ConstantEffort]

Forget nitrogen.

Use oils or similar spray.

The process will not tolerate any preservatives, unfortunately.

The aspiration is that the pipe be cleaned at the overseas module yard, shipped clean, dropped into place, and welded up with minimal field time and labor. No field cleaning, flushing, or blowdowns.

But as George says, something probably has to give.

 

[GBTorpenhow]

You'll have to do the cost/risk analysis - if its a skidded equipment module that must be perfectly clean and dry, is enormously expensive, and has a limited number of nozzles then butt weld caps and cut them off on site might be the play, and tough cookies to the construction team.

If its a piping rack module or something of relatively low cleaning/repair/replacement cost and many butt welding connections, a good tight plastic cover secured firmly over the prepped bevel ends with desiccant packs and/or vapor phase corrosion inhibitor diffusers stuffed inside might be enough.

 

[LittleInch]

Welding of some sort is your only real option if you want to actually pressurise the internals.

This can just be a root run or a seal weld for a metal cap.

Anything else will just fall off.

GBT lays it out quite well. This is where aspiration / desire meets reality..

The issue with plugs I see is that it leaves the end connection exposed.