Home /
Search 🔍
the Site

Chime right in! (no registration req'd)


"Inexpensive In-Process Rust Protection/Plating"

June 16, 2021

Q. We have a product that is comprised of (2) pieces of carbon sheet steel (HSLA Grade 50). They are welded together and we need to provide rust protection. After welding they are shipped out of the country for assembly. We had considered using pre-galvanized material, but are apprehensive about welding galvanized material (not only does it produce poisonous gas, but it would also introduce raw weld bead and a HAZ with compromised plating). The items being welded together have a tunnel which, if electroplated, would leave a section un-plated.

We are looking for a plating or dip coating that we could apply post welding and provide in process rust prevention (beyond a basic water based rust preventative that we apply post tumbling). We thought of a zinc phosphate, but have not had great luck with that to date. Any suggestions?

Jake Snyder
- Rochester New York

June 2021

A. Hi Jake. You may realize this, but for the benefit of other readers, zinc is far less 'poisonous' than, for example, aspirin. Galvanized material does not produce 'poisonous gas', but welding it can release large amounts of zinc oxide fumes and -- although zinc is an essential nutrient and helpful in combating colds -- inhaling too much can certainly give you metal fume fever, and perhaps worse (like too much of almost anything). With good ventilation and proper welding hoods though, welding probably presents no significant risk to the welders.

The component can probably be hot dip galvanized after welding if you wish, but zinc or manganese phosphate followed by a corrosion inhibiting oil may be your best bet. Acres of sheet metal is zinc phosphated every day, so it may be more a matter of optimizing the process than writing it off.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

June 17, 2021

thumbs up sign Hi Ted,

I appreciate the input - I will definitely reach out to a few suppliers to see if any of them have a higher volume phosphate line than we do (we have a small batch line).

We'll also investigate just welding the galvanized material. That might be the easiest option in the long run since this is going on an automated welding line, we might be able to add a rust inhibitor station for a minor cost to the program.


Jake Snyder [returning]
- Rochester New York

finishing.com is made possible by ...
this text gets replaced with bannerText
spacer gets replaced with bannerImages

Q, A, or Comment on THIS thread SEARCH for Threads about ... My Topic Not Found: Start NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

Chemicals &
Consult'g, Train'g
& Software

About/Contact    -    Privacy Policy    -    ©1995-2021 finishing.com, Pine Beach, New Jersey, USA