Subsea stainless options

[matkenmd]

This is more of a survey than a specific question.

I'm curious about preferred material selection for subsea use. In my experience most companies have a small pallet of approved choices for various applications. This pallet is developed over the course of multiple projects, with input from experienced elders as well as other.

For mechanical equipment, sitting on or near the ocean floor, exposed primarily to seawater (not acids or welbore fluids), at ambient subsea temperatures, with >10 year design life....what are some of your favored materials, and why? I'm interested more in stainless and super alloys than other material groups. High strength choices, low cost choices, field-reworkable/weld-repairable choices, etc.

For instance, some I've seen used are: 316, Nitronic, NAB, Duplex, Inconel, Hastalloy, etc.

 

[SJones]

Try reviewing EEMUA 194

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[strider6]

try also
"guide to the use of materials in waters" NACE press.

http://web.nace.org/Departments/Store/Product.aspx?id=fcde6fcd-3e0c-4d93-b38f-0f6873637f7c

or

http://www.corrosionist.com/Corrosion_Control_Seawater.htm

S

Corrosion Prevention & Corrosion Control

 

[jsscott]

Coming from a practical perspective we use 316 a lot. Easily obtained, easy to fabricate with.
Cost aside, crevice corrosion is the biggest problem we have with this material but we'll usually over-engineer any structure to the point where redox doesn't cost us a mooring or a mount system.

For shallow water applications where bio-fouling causes headaches, copper nickel is an attractive alternative. 316 fasteners have an acceptably low electrochemical potential mated to CuNi, at least for the time frames I work within (usually less than 2 yrs.) But its ability to repel cooties makes it my fave (since I'm the lucky guy who gets to scrape off the barny's when cleaning or recovery time arrives...)
-s