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

Welding with a little bit of paint after grinding

Welding with a little bit of paint after grinding

Welding with a little bit of paint after grinding

We have an existing beam to column connection that we now have to weld the shear plate to the beam web.
The existing connection has been painted.
The welders can grind most of the paint away, but cant grind all the paint at the joint.
Please, all the CWI's respond, anyone else with experience, any suggestions?

RE: Welding with a little bit of paint after grinding

After grinding and other prep., burn the remaining paint off with a torch, clean up the ash with a powered wire brush and a hand brush, then wipe the surface down. There are some fluxes and rod coverings which are somewhat tolerant of slight surface impurities. I don’t intend to mean you can weld through a puddle of paint, oil or water, but you don’t need a shot blasted clean surface either. Talk with a few local welding material suppliers for their weld prep. recommendations.

RE: Welding with a little bit of paint after grinding

Agree with dhengr.

The devil is in the details; she also wears prada.

RE: Welding with a little bit of paint after grinding

Sounds like a plan.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: Welding with a little bit of paint after grinding

In practice, GTAW will almost always fail (porosity, inclusions, surface defects) if anything but a very clean newly-ground surface is welded.
SMAW is more forgiving to very small bits of paint left on the surface - if, for example, paint is removed by simple hand wire brushing or impact hammer (needle gun). Your best weld requires the weld to be melting together clean filler, clean base metal, and new clean metal.

RE: Welding with a little bit of paint after grinding

While the SMAW or even FCAW will tolerate a little residual paint and still produce a respectable weld, I find it interesting few people consider the age of the paint to be a concern. If the structure was built before the 1980's, I would question whether the paint was lead based. Grind, burning, or welding is going to "release" the lead into the worker's breathing area. Then again, some people consider their workers to be expendable. Can't say I agree with that approach. Get the paint tested if it has been in place for 30 years.

Best regards - Al

RE: Welding with a little bit of paint after grinding

There are no welding fumes that are safe to breathe, so what are you going to do differently after you get test results?

RE: Welding with a little bit of paint after grinding

You can't protect the welder if you don't know what you're dealing with.

Best regards - Al

RE: Welding with a little bit of paint after grinding

Maybe use paint stripper and a wire brush once the paint has lifted.

RE: Welding with a little bit of paint after grinding

A good old stick/arc/SMAW welder will weld straight through the paint/rust easily. I'm glad at least some people know the health concerns...

you're going to need less than $100. The mask that will actually protect from lead and mold and any, ANY other unknown particles is called:

-3M 60926 Multi-Gas/P100 (HEPA)

The 3M 6000 series is the one you want, the p100 is a hepa filter is needed whenever you are using heat or vaporizing these bad chemicals, the 926 version has an extra charcoal filtering so they won't be inhaling vaporised lead.

This is a cheap mask... please do not make them wear a cotton mask that will only serve to capture particles and force the user to breathe all their air through a blackened cancerous cotton ball (been there done that found a new job).

Replacement filters are below $30 by the way. also they make a half face version so it's small and will fit under the welders hood. It must fit under the mask or the welder will complain and not use it

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