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Proper temperature and humidity level for storing steel & EG

Q. What is the proper temperature and humidity level to keep steel from rusting? We buy large quantities of steel tubing and sometimes get flash rust on the steel.

Bryan Lepley
- Kalamazoo, Michigan


 

A. I don't believe you can prevent steel from rusting to some extent in almost any ambient atmosphere, where temperature makes diurnal moves and there is some moisture in the air. Maybe in Death Valley, CA for certain parts of the year.

You will need a rust preventative coating for MI.

Here is an old formula:

200 gal. Tung Oilamazoninfo; heat to gelatinous stage
add:
20 gal. sardine oil
cool;
add:
60 gal. whale oil
sardine oil, 200 gal.
1/2% b.v. manganese cobalt drier

If whale oil is too pricey, you could probably find other proprietary formulas:-)

Tom Pullizzi
Falls Township, Pennsylvania 


February 19, 2009

A. Hi, Tom. Must this be sperm oil, or will any whale oil do? Next time I'm on Nantucket when the whalers come in I'll check what they're getting for it these days :-)

If not a proprietary rust preventative, maybe we should race forward in time to WWI and cosmoline?

More seriously, if the warehouse can be maintained at as low humidity and temperature as practical, rusting can probably be limited. Still, flash rust is more a function of the surface condition than the storage conditions. A clean, pickled surface can flash rust in hours -- before it hits the shipping dock, let alone the receiving dock.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey


+++++++

Q. EG metal brackets parked in our warehouse for 6 months are found rusty at bend areas & spot weld areas. I suspect this is because of my warehouse environment.
I would like to know the following:

1.Recommended temperature & humidity of storage area to store this galvanised steel.

2. Recommended temperature & humidity to test the e.g., parts inside the chamber. (My objective is to inspect the part upfront to confirm that the part cannot rust if stored in good environment for at least 6 months.)

Appreciate your valuable advise.

Thanks
Frank

Milton Franklin
Supplier Quality Engineer - Marsiling, Singapore


+++++++

A. Is the bending & welding performed before or after plating?
Is the zinc plating chromated? Chromating is essential in a humid environment.
To what specification is the zinc plating and chromating performed?
What material(s) are the storage racks?

The (hot dip) galvanizing societies have information on storing zinc-coated material to avoid white corrosion. Also, on touch-up of damaged zinc coatings.
American Galvanizers Association (AGA) http://www.galvanizeit.org
Galvanizers Association of Australia (GAA) http://www.gaa.com.au/
Galvanizers Association (UK) http://www.hdg.org.uk/

Ken Vlach
- Goleta, California  

Ken received a special
"Contributor of the Year" award
from finishing.com for his numerous
helpful and well researched responses

November 21, 2012

A. Hi Milton.

EG is not actually galvanized, it is zinc electroplated, and offers far less corrosion resistance than actual hot dip galvanizing because of the greatly reduced thickness.

While it is good to store the stuff properly, as dry and as cool as practical, it is also vital to know the plating specs and to assure that they are maintained -- because all your efforts will be to no avail if the vendor reduces the plating thickness/quality, and all your expensive efforts may be unnecessary if they increase it.

But very important, regardless of temperature and humidity, is air circulation. Zinc reacts with the air to form very stable, impervious, and corrosion resistant zinc carbonate surfaces. This depends upon good exposure to the carbon dioxide in the air, and is one reason that accelerated corrosion testing of galvanized materials is not very indicative of their actual corrosion resistance. You may wish to do a search for "white rust" or "wet storage stain" on this site or on the internet as a whole for further information. Good luck!

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Brick, New Jersey

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