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!
  • Students Click Here

*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

To specify pacification or not

To specify pacification or not

To specify pacification or not

I have a requirement to electropolish an interior surface of a 304 stainless steel box, 24" cubed. Should I have my shop passivate all welds prior to EP?
Is there a degree of polish I can specify? or do I specify to my vendor;"best brite surface finish attainable"? It's the interior surface thats important to my customer.
The exterior of the box will have carbon steel members for reinforcements (vacuum service), I realize the these exterior members will be corroded (rusted in color and finish) but without lacking in strength.

Thanks For your Input


RE: To specify pacification or not

No, it is redundant/unnecessary to passivate prior to electropolishing.  Electropolishing (includes a nitric acid rinse) gives a superior passivation.

However, you must descale, e.g., wire brush (SS wire only), pickle, beadblast, mechanical polish, buff, etc.  Electropolishing can handle some heat discoloration http://www.ableelectropolishing.com/pdf1021.htm but not heavy scale.

Also, electropolishing gives brightness via micro-smoothing, but doesn’t remove macro-roughness such as scratches.  It generally gives a 50% improvement in RA on polished surfaces.  See http://www.electromatic.com/process.html for illustrated process description.

In corrosive environments, the smoother the surface finish the better.  Of course, in vacuum, this gives less outgassing.  Typically, polishing with 320 grit abrasives (SiC used with lubrication) will achieve a finish better than 0.5 micrometres Ra.  Electropolishing then further improves corrosion resistance and brightness.  http://www.assda.asn.au/Teastain.pdf

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


eBook - Integrating the Engineering Ecosystem
Aras Innovator provides multiple options for integrating data between systems, depending on the scenario. Utilizing the right approach to meet specific business requirements is vital. These needs range from authoring tools, federating data from various and dissimilar databases, and triggering processes and workflows. Download Now
Research Report - Simulation-Driven Design for SOLIDWORKS Users
In this engineering.com research report, we discuss the rising role of simulation and the paradigm shift commonly called the democratization of simulation. In particular, we focus on how SOLIDWORKS users can take advantage of simulation-driven design through two analysis tools: SOLIDWORKS Simulation and 3DEXPERIENCE WORKS. Download Now
White Paper - Industry 4.0 and the Future of Engineering Education
With industries becoming more automated, more tech-driven and more complex, engineers need to keep their skills and knowledge up to date in order to stay on top of this wave—and to be prepared for the Industry 4.0 future. The University of Cincinnati offers two online Master of Engineering degree programs designed specifically for practicing engineers. Download Now
eBook - The Design Gridlock Manifesto
In this eBook, you’ll learn 6 ways old CAD technology slows your company down and hear how design teams have put those problems to rest. “The Design Gridlock Manifesto” shares first-hand modern CAD experiences from 15 companies around the world. 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