Field installed corrosion resistant coating 1

[jayrod12]

Gents,

Seems like a basic question but I'm going to ask none-the-less.

I've got a current situation where a set of granite stairs is supported by steel framework. The steel is about 4 years old and is already showing significant surface corrosion. Generally this steel is enclosed in an non-accessible crawlspace that is likely high humidity due to inadequate ventilation.

I've already given the owner the "you should provide proper ventilation in here" talk but I'm fully expecting that not to happen.

Access was gained for review as the adjacent staircase is now getting a similar steel structure installed.

My question is, have any of you used a corrosion inhibiting coating that was successfully field installed on existing steel?

My first thought was they should be wire wheel/sand blasting the current steel, prime and then paint. Is paint enough or is there something heavier duty available?

For the new steel we will likely be applying the same coating due to the amount of field welding required there would be too many touch ups required to shop install a coating.

 

[Ron]

jayrod12....due to limited access and ventilation, sandblasting might not be an option. If you want good surface prep, you can consider blasting with dry ice. Otherwise, brush wheels and side grinders would be the way to go.

Once prepared, use a good quality zinc rich primer. Top coat with a good quality coating (may or may not be zinc rich). Good quality coating materials for this application would be Carboline or Tnemec. Use a high quality solvent based coating, not a water based coating (unless you want to consider a moist-cured urethane coating). Epoxy coatings can be used for both the primer and the top coat.

Pay attention to the coating thickness. The primer should be at least 5 mils. The top coat should be done in two coats, each being 3 to 5 mils. Have each coat tinted a different color for easy inspection for holidays.

Shop primers for stairs and rails are usually on the order of 1 to 2 mils thick.

 

[thaidavid40]

With the right surface preparation in the field, an epoxy coating will give many more years of service than an alkyd enamel paint, when resisting a humid environment.

Thaidavid

 

[jayrod12]

Thanks Gents,