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Methods to add corrosion protection coating on welded steel assemblies?

H

huleo

Hot Rolled
Joined
Feb 12, 2014
Location
UT
We are working on a project that will be a long, welded assembly that will be subject to high humidity. Due to the welding requirements, any type of precoated material cannot be used. After fabrication, the assemblies will need some type of protection coating. The assemblies are made with steel pipe, rod, etc, so lots of open spaces where losses would be high with a typical spray process. As well, some areas of the assemblies will be difficult to get coated after it is build.

A dip process is honestly probably the most "ideal" but I am somewhat resistant because then a dip tank need obtained and becomes a very specialized process. There are some similar products in the industry now that are dipped, but sounds like health and wellness are out the window and they basically mix solvents and a paint product in the tank and run with it. I can only imagine the gas off! As well, it is my understanding that process does not leave and very good finish.

Something similar to powder coat might work, but this is a VERY cost sensitive project so any process needs considered on a time/cost/complexity basis. My preference is a water based solution but not sure how practical that really is on steel.
 
squirt it or brush it with any concoction of oil,WD-40,waste oil, do it while the weld is warm and dry and it will suck into the pores of the metal
 
huleo said:
We are working on a project that will be a long, welded assembly that will be subject to high humidity. Due to the welding requirements, any type of precoated material cannot be used. After fabrication, the assemblies will need some type of protection coating. The assemblies are made with steel pipe, rod, etc, so lots of open spaces where losses would be high with a typical spray process. As well, some areas of the assemblies will be difficult to get coated after it is build.

A dip process is honestly probably the most "ideal" but I am somewhat resistant because then a dip tank need obtained and becomes a very specialized process. There are some similar products in the industry now that are dipped, but sounds like health and wellness are out the window and they basically mix solvents and a paint product in the tank and run with it. I can only imagine the gas off! As well, it is my understanding that process does not leave and very good finish.

Something similar to powder coat might work, but this is a VERY cost sensitive project so any process needs considered on a time/cost/complexity basis. My preference is a water based solution but not sure how practical that really is on steel.
Click to expand...

maybe check out elektrophoretic deposition
 
Hot dip,Metco arc spray zinc,inorganic zinc /zinc ethyl silicate,zinc epoxy paint......Most of what the blasters did was blast and single coat of high build paint........and sometimes rust stains would be visible before the object left the yard.......Then ,of course there are the idiot engineers who put rain/dirt traps all over their structures....Planned failure at an early date.
 
smack it said:
squirt it or brush it with any concoction of oil,WD-40,waste oil, do it while the weld is warm and dry and it will suck into the pores of the metal
Click to expand...

no, WD-40 is useless as a rust preventive.

no, bluing is useless in a high humidity environment.

have either of you actually made anything and put it outdoors?

If its a "VERY" cost sensitive project, hire some kid and give them a few cans of spray paint. nothing that really works is cheap. make it out of stainless. that works.
 
metalmagpie said:
Hot dip galvanizing.
Click to expand...

This is really the way to go. You must have drain holes at both ends of hollow sections. In the desert galvanized steel will last 100 years. By the seashore about 50 years. I have fabricated many tons of structural steel and it is a proven coating. Most dip tanks are around 3 feet deep and 3 feet wide and may be a long as 40 feet. They can dip one side then lift out and dip the other side but it is not the preferred method.
 
This is being considered a "production job", but actual volumes just don't make it practical for a full on 'coating process facility' at this point. We basically need to get the job going for now and reassess in a year to see what needs done.

I am really inclined to try to get these coated somewhere else in the future as we don't really want to hassle, mess, etc, but I have realized unless you do EVERYTHING for people, they will find some excuse to raise the price unless we streamline the process. This is literally a process that a teenager could do. Right now, Ecoat looks to be the right process for the application. We might just setup and do it outdoors for now but I know if we keep doing it, we really need to get our environmentals in check.

Yes, I am sure someone will tell us we need a $1M facility to test coat 50 parts, but I am sure most can understand.
 
Galvanizers do onsey twosey parts all the time, you do not hot dip in house - there are job shops that just do galvanizing. You have to vent beyond what they say, and then some; and you still will get a few 7$ holes burned by the galvanizer.
there is Azz in Denver and Reno. I like v + s, but Azz has the cool dog that comes on pick ups that runs around the shop.
 
A bit late to the conversation about corrosion protection.

I highly recommend that you look into Dow Chemical METAL PROTECTIVE COATING. We used to buy it in 12-oz spray cans. Stuffs smells a bit when originally applied, but it is the bomb. We used it on a bunch of expensive HSS tooling and other stuff that went thru our wire EDM machines. Our shop was 3/4 mile from the Atlantic so lots of salt in the air.

If I recall correctly, this stuff had endorsement from automotive stamping shop that had forming dies that cost in the $100,000+ range. They said they would coat the dies with the Dow Chemical product and store them outside. It might also come in gallon cans, but not sure. Probably available from MSC or other catalog supply companies if you would like to try a can.

Our firm also used Houghton Rust-Veto in 55 gallon drums. We used it on high volume screw machine parts but sometimes that stuff would leave a thick buildup on radii and threads. We eventually used a mixture of mineral spirits and red tint automatic transmission fluid. That was cheap and worked really well for storage for a few months.
 
Have you priced powder coating? Might not be as pricey as you think. You don't say where in Utah you are, or how long the object is, but there is a place in St. George that can do pretty big stuff at a good price.
 
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