Ferous Contamination of Super Duplex and 6MO SS Tubing
Ferous Contamination of Super Duplex and 6MO SS Tubing
(OP)
I am currently on assignment in a shipyard, commissioning an oil and gas platform. I am responsible for the topside equipment which will provide electrical and hydraulic power to equipment which will be installed subsea.
I am concerned about SS 2507 and 6MO hydraulic tubing, rated at 15k psi, which has been run, and is now accumulating dust from the ongoing fabrication around the platform. You can already see that the ferous-based dust has settled and oxidized in the saliferous coastal environment as the surface of the tubing has, in many places, gone brown.
Would I be right that this ferrous-based oxide layer will be blocking the passivation of the stainless steel tubing and making it susceptible to pitting corrosion?
What would be the most efficient way of removing this surface contamination? I assume a picking operation would be ideal, but is sadly not practicable with the 10's of kilometers of tubing run across multiple layers.
Any insight or experience would be hugely appreciated.
I am concerned about SS 2507 and 6MO hydraulic tubing, rated at 15k psi, which has been run, and is now accumulating dust from the ongoing fabrication around the platform. You can already see that the ferous-based dust has settled and oxidized in the saliferous coastal environment as the surface of the tubing has, in many places, gone brown.
Would I be right that this ferrous-based oxide layer will be blocking the passivation of the stainless steel tubing and making it susceptible to pitting corrosion?
What would be the most efficient way of removing this surface contamination? I assume a picking operation would be ideal, but is sadly not practicable with the 10's of kilometers of tubing run across multiple layers.
Any insight or experience would be hugely appreciated.





RE: Ferous Contamination of Super Duplex and 6MO SS Tubing
Steve Jones
Corrosion Management Consultant
http://www.linkedin.com/pub/8/83b/b04
All answers are personal opinions only and are in no way connected with any employer.
RE: Ferous Contamination of Super Duplex and 6MO SS Tubing
I have seen many 6Mo systems installed that 'blushed' with orange after installation, and the next rain washed it off.
The only location that I would have any concern about would be where the tubing is splashed by seawater, but protected from rain. Here the construction grime can combine with salt, and when it drys out you have a bad mixture. With these alloys that could result in a lot of surface rust, but they won't pit.
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P.E. Metallurgy, Plymouth Tube
RE: Ferous Contamination of Super Duplex and 6MO SS Tubing