How to treat corrosion on 55MVA transformer

[SA07]

Hi
We have 2 outdoor 55MVA transformers. There is corrosion on the top part. Can you please advise how this can be treated?
We are a power plant in a tropical island, near the sea. In the yard, there are 2 cooling towers and a demin plant. Droplets from the cooling tower is quite corrosive. Near the demin plant, there may be fumes of acid and caustic soda. We can only work on the transformers once per year during our annual shutdown. Thanks

 

[SA07]

Please see pics

 

[FacEngrPE]

Except for the fact that this is a transformer, it is a rather common coatings selection problem, similar to selecting a coating for steel in salt spray, like a port waterfront or steel ship hull.

For all of the better products the success of the coating is hugely dependent on the surface preparation. Your selection likely is going to be somewhat dependent on what is available in your local market.

I have had good success on steel in salt spray with both high performance 2 part urethane, and 2 part epoxy coatings. The epoxy will "chalk", the urethane does not. Apply the coating in accordance with the recommendations in the product data sheet. Alkyd enamel paints have a much shorter service life in salt spray, they last longer if the surface prep removes all of the rust.

Products that claim to be OK to paint over rust, will not stop corrosion if the rust blisters are not removed before painting!

Perhaps someone else can comment on managing surface prep in a switch yard.

 

[prc]

You have to thoroughly clean the surface removing rust and all previous paint coatings. Then apply a zinc-based epoxy primer ( 50 microns thick) + Epoxy based high build micaceous iron oxide ( 140 microns) + acrylic aliphatic polyurethane paint ( 50 microns) Total a minimum of 240 microns thick paint.

 

[FacEngrPE]

I should have mentioned that Products that claim to be OK to paint over rust, all have a very short service like unless your surface prep is as specified for the high performance paints.
prc's selection has a very good chance of outlasting the transformer, even in a harsh environment.

 

[Mlmlzx]

I think it has to be washed first by sandpaper and then suitable protection layer has to be done.

Sincerely,