corrosion risk inside pipe 1

[alain0707]

Dear mates,

Our contractor just finishes hydro test for pipeline 14" (thickness 11.9 mm length 2 km) , and start the rinsing water using foam pig.

The problem he can not start the purging with nitrogen immediately (logistic problem )
And hi proposes to make it after 2 months.

Its can be some risk of corrosion inside the pipe ?


Your advice please

 

[LittleInch]

Yes is the short answer.

Foam pigs are OK but not perfect and you will get some water remaining, especially at low spots. If your water wasn't treated you risk MIC which can be really bad

He could use super dry air to blow through or vacuum pump or swab with MEG. Try to avoid methanol, it's good for water retention but it's nasty stuff...



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

 

[bimr]

Yes, you can use a dehumidifier to control the humidity. The process of rusting begins at 40% RH. Metal components and equipment tend to rust and corrode during storage, assembly or plant shut down due to moisture in the air. Rust is the result of Iron being exposed to Oxygen. Rust is a type of corrosion, meaning that the metal will break down once it is exposed to the chemical process which occurs when it is exposed to the Oxygen.

 

[TugboatEng]

If you treat your hydro test water with corrosion inhibitor you may just leave it in the pipeline until it can be dried. Sodium nitrite is a fast acting film forming inhibitor.

 

[EdStainless]

And he didn't tell you that he couldn't meet the requirements until after the hydro.
Sounds like he is on the hook for a lot of dehumidification. You have to assure that there is no standing water in the system.
Was the hydro water treated with biocide? Low Cl? Those buy you a little time, but not months.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[TugboatEng]

255 gallons of Nalcool 2000 should do the trick ($4000 USD and universally available). A bit of an odd choice but I'm an engine guy and that's the product I'm familiar with. Disposal might be an issue.

 

[1503-44]

Dont you think just maybe we should have a few more details about the pipe material, fluid and service of this system before getting into such specifics. After all this could be medical grade oxygen system for all we know about it now.