Cathodic Protection for 316 Stainless Steel

[lekhang]

Greetings

My question concerns the use of cathodic protection for a 316 stainless steel seawater screen.

I believe that any type of stainless steel will not need cathodic protection, as stainless steel in general is pretty resistant to corrosion.

However, the screen will be submerged in seawater at all times. I've read online that stainless steel structures in a "splash zone" will require cathodic protection. I don't know if being submerged in seawater will facilitate the need for cathodic protection.

Any advice? Thanks in advance.

 

[unclesyd]

I don't know the actual recommendations for your application but we have CP on our carbon steel and 316 SS river water screens, both static and moving.

There are many ramifications to you proposal so if you could comeback with a little more information it would be great help in getting better advice.

What is it mounted to?

Is the intake flow all time?

Will you screen have any crevices?

 

[SJones]

You may wish to Google for NiDI Reference Book 11 003 and download it (free) for review.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdoweb/

 

[EdStainless]

316 is not considered resistant to crevice corrosion in seawater. Some level of CP will be needed to achieve a reasonable life.
If you really want it to last in seawater without protection you will need to use a 6% Mo super-autenitic or a super-ferritic stainless.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[lekhang]

unclesyd

1) The screen is mounted to a 316 stainless steel frame. The bolts will also be 316 stainless steel.

2) Yes, seawater will be flowing all the time.

3) This is a brand new screen. The space between the bolts and the frame could be possible crevices, but I'm not sure.

EdStainless

What is considered a reasonable life? I do not have much experience so your input would be greatly appreciated.

Thank you everyone for your help.

 

[btrueblood]

If this is a standard woven-wire screen, then every place that two wire overlap will form a crevice.

 

[mcguire]

316 is inadequate for immersion in seawater. 2205 would be the correct alloy if you want to avoid corrosion, except in crevices. If you can tolerate a little corrosion, use alloy 2003 from Allegheny.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[FYS]

Hi,

Please can you advise, Instrument Unit (316 SS) being imerssed in ground water (high water table - wet season. The units are going to be insulated (from cold).

What is the best solution for it:

1- Coated first with Epoxy coating, then wrap it with insulating materil.

 

[FYS]

you can apply CP to the 316 SS, in sea water.