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Corrosion protection for overseas parts

 

I need to ship some sheet metal parts from China to the U.S. and want to know the best way to keep these parts from rusting before they get here. Once they are here we will paint them. The trip will be about 30 - 45 days by ship. We will be receiving about 1,000 parts a month. The material is AISI 1010 carbon steel sheet that conforms to ASTM A620 [withdrawn] . Is the best way a rust inhibitor - if so can you recommend one that has worked for you? Please let me know.

Thanks,

David McGoff
- Minneapolis, Minnesota, U.S.A.

You are correct in believing that you need a rust inhibitor. The problem is that you need one which may be required to stand up to salt atmosphere (most items such as this are shipped as deck cargo in containers, and containers are not always airtight) and you will need a rust preventative which can be readily removed prior to painting. You should consider the manner in which you will remove the rust preventer as a major consideration in its selection.

A word of caution: I have often seen substances used in the far east as rust preventers which are no longer used in this country and can be difficult to remove e.g. paraffin wax.

Good luck,

Gene Packman
process supplier - Great Neck, New York

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There are many oil-based rust inhibitors that should do a good job. Many call it "Cosmoline" though that is not a generic term.

In essence, it is the same material as auto underbody spray. Some companies I have worked with apply 5 mils wet inhibitor, followed by a layer of kraft (heavy brown) paper. Other companies add subsequent layers of inhibitor and then heavy hardboard and/or boards.

Be very careful about exposure to the sunlight. Many temporary corrosion inhibitors do not have protection from Ultra Violet rays. This can cause an undercutting of the inhibitor and stain the metal.

Subsequent removal is another issue. Make sure the product does NOT have any lead. Most used to but not any more at least in the US. I received some equipment from England that was protected with some material that still had lead as recently as five years ago. Assume nothing.

I use my own solvent blend for removal, being careful to design a product that will do the job but NOT create a hazardous waste in the process. It can be done. Forget what the coating manufacturers say about being able to remove these coatings with a hot, alkaline wash. Stick with mild oil-based blends.

Todd Turner
- Monroe, Louisiana