×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Gavonized Corrosion between copper alloy and ss316, duplex

Gavonized Corrosion between copper alloy and ss316, duplex

Gavonized Corrosion between copper alloy and ss316, duplex

(OP)
Hi Experts,

Condition: Pressure vessel and Sea water service.
The flange material: SB-283 C70620.
The bolt materials: SS316 or duplex/supper duplex or Monel.
Question: will it be gavonized corrosion between SB-283 C70620 and SS316 or duplex/supper duplex or Monel.

Thanks,

RE: Gavonized Corrosion between copper alloy and ss316, duplex

90/10 and Monel 400 would work fine together.
Yes the Monel is more noble but not by a huge amount.
316 or 2205 will not survive very long in seawater.
Superduplex is asking for issues.

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

RE: Gavonized Corrosion between copper alloy and ss316, duplex

I have experienced the 90/10 cuni to be highly susceptible to galvanic corrosion from 316 SS. Our installation has 316 SS studs in blind holes CuNi flanges to through holes in steel flanges with SS nuts. This works because we have anodes on the carbon steel structure. However, there are isolated SS bolts attaching the CuNi exchanger to the hull and if the CuNi exchanger is isolated as well we will see corrosion rates exceeding 1/16 inch per year on the CuNi in the vicinity of the SS bolt.

These dissimilar couplings can work provided your anodes never wear out. Once the anodes are gone the system will fail rapidly.

RE: Gavonized Corrosion between copper alloy and ss316, duplex

(OP)
@ EdStainless

How about Incinel, SB-446 UNS NO6625 Gr.1 for sea water service and againt the gavonized corrosion with SB-283 C70620?

Thanks,

RE: Gavonized Corrosion between copper alloy and ss316, duplex

TBE, I think that some other mechanism is at work in your case. It is generally accepted that 90/10 is more noble in seawater than 316.

So going to 625 hardware would be even worse.

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

RE: Gavonized Corrosion between copper alloy and ss316, duplex

May I ask what condition would cause SS to be active vs passive?

RE: Gavonized Corrosion between copper alloy and ss316, duplex

Anything that will breakdown the passive film; low pH, high temperature, mechanical damage (scouring), applied current from a stray source (making the SS the anode).
Once corrosion starts the SS is no longer passive.

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

RE: Gavonized Corrosion between copper alloy and ss316, duplex

My big assumption is that if there are less noble materials nearby the SS is going to favor its passive state in the galvanic cell. In salt water the SS is going to be passive which makes it quite a bit more noble than the CuNi.

Once corrosion starts the SS is no longer passive is certainly true when that applies to corrosion of the SS. Copper alloys near SS are anodic and prevent that corrosion of the SS from starting.

RE: Gavonized Corrosion between copper alloy and ss316, duplex

That is correct.
A potential difference of 0.25V is plenty to drive accelerated corrosion in warm water, it will take a bit more in colder water.

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

RE: Gavonized Corrosion between copper alloy and ss316, duplex

Can we just clarify the location of the bolts: internal in the seawater; external in the atmosphere?

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

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

RE: Gavonized Corrosion between copper alloy and ss316, duplex

(OP)
@EdStainless, thank you. It is a good guideline for me to understand what materials may be possible in the gavanized corrosion condition from the table.
@SJones, the whole floating head soak in the sea water.

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


Resources

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