Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Cathodic protection of SS316L "internal" parts

Cathodic protection of SS316L "internal" parts

Cathodic protection of SS316L "internal" parts


Hi all,
I have a doubt and I am really not expert in corrosion engineering so I am searching to gain some knowledge here.

I have a SS316 module designed to work subsea under cathodic protection. There is a valve installed in the module with an internal mechanism, also made in SS316L. The internal mechanism is made mainly of small parts, like spring and pins, normally those parts are made in super duplex or Ni alloys but not in this case because everything shall be only 316.

Electrical continuity can be guaranteed all time for all the small parts and the valve body, which is directly under cathodic protection.

Do you see any residual risk for the small parts of the valve or is the electrical continuity basically a sufficient condition to consider the complete system under cathodic protection?


RE: Cathodic protection of SS316L "internal" parts

I take it then that since someone mandated 316 that this is only a short-term application.
Because those internals will not hold up well.
They may see a little benefit from the CP, but will not be much.
If this is to used long-term you should get to work spec'ing out the Ni alloy replacement.

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

RE: Cathodic protection of SS316L "internal" parts

One more consideration is that if this is ever removed from the water and allowed to dry without being thoroughly rinsed the concentration of salt during drying can open up a whole plethora of issues for stamped, drawn, and otherwise not-annealed 316 components.

RE: Cathodic protection of SS316L "internal" parts

Are the valve internals actually exposed to the seawater?

Steve Jones
Corrosion Management Consultant


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

RE: Cathodic protection of SS316L "internal" parts

Thank you for your reply.

Here an update:
- SJones: Internal parts of the valve are in direct contact with seawater for long period of time (during operation)
- Edstainless: thank you for your opinion, but this time 316 shall be used under water for 20+ years because service is hydrogen transport. Hydrogen embrittlement and seawater is a very challenging duo for material selection.....
Can you please tell me why you think that parts will be corroded if there is cathodic protection? This is the part I am missing at the moment
- TugboatEng: thanks well noted, I will rise the risk

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close