pipeline seawater corrosion

[OTHMANE001]

Hello,
I share with you an illustrative photo of the prematurely degradation of a seawater pipe DN 1750mm, Pression 6 bars, a few months ago, we suspect that this is microbiologique corrosion
Please share with us the problem causes of these mode of degradations

 

[stevenal]

Stevenal, what do you mean by that?

You posted a diagram of a two part piping system; one part protected with an impressed current cathodic system, and the second part electrically isolated from the first and un-protected and rusted through. It would appear the system is working where it exists. Can the system be extended? Perhaps the original designer considered the second part replaceable.
I live near a fishing port, and can state that steel hulled boats nearly always use coatings along with cathodic protection.
The local aquarium piping systems are PVC, but I don't think they have anything of the diameter you show.

 

I've had a lot of success with Unobtanium.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[SJones]

W B Holtsbaum, "Internal Stray Current Interference From An External Current Source," Materials Performance, August 2007, pp 40 - 42

An insulating flange, or monolithic isolating joint, is nigh on useless with such a conductive fluid and leads to lovely holes on the unprotected side. Usually, time to perforation is measured in months rather than years, but something worth looking at.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[MJCronin]

I agree with the sage advice of Ironic Metallurgist....

Unobtainium is highly corrosion resistant in seawater (if you can get it) but very expensive

Short of that, go with titanium, it has a superb record in chlorides ....

MJCronin
Sr. Process Engineer