10 common mistakes when doing corrosion maintenance

Corrosion onboard steel vessels is an in-evitable occurrence that we will have to deal with best possible.
This corrosion may appear from multiple reasons but the solution is almost always the same.

Produce A Clean Surface with a Rough profile and Sufficient paint

To achive this we will need to know what good surface preparation is, and what mistakes we should avoid.

Mistakes we do:

deck cleaning by brush

General cleaning

1. Salt is not washed away.
2. Oil is not removed sufficiently by detergent.
3. Dirt is not removed.

Cleaning should be done prior starting the surface preparation and before each coating. If in doubt clean.

Onboard corrosion training

Surface preparation

4. The corrosion is not properly removed
5. The surface is not rough
6. The remaining paint have not been feathered and roughened

These mistakes are usually caused by not knowing the surface quality needed and using in-efficient tools that can’t do the job.

measuring stick


7. The Humidity too high (or low) when painting.
8. Insufficient thickness of primer is applied. (click to read more)
9. Poor mixing of the paint. (click to read more)
10. Too short or too long interval between coatings.

How the mistakes affect us

85 % failes due to poor surface preparation

About 85% of corrosion is by insufficient surface preparation.

Lowering this will lead to a huge saving in cost, man powers and repairs

The remaining 15 % is mainly caused by mechanical impact, stress, heat, cold, chemicals or other external factors.

We can try to minimize this, but on a working vessel spanners will be dropped and fire hoses will be dragged over the deck.

Having a structured corrosion strategy will help the crew to avoid these mistakes and to do efficient maintenance every time.

Enjoy the view of a beautiful ship

Safe sailing

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2 thoughts on “10 common mistakes when doing corrosion maintenance

  1. Hi Bo,

    I fully agree with your point # 2 regarding surface preparation. One more point I would like to add hear about use of Needle Gun. In my personal experience due to use of Needle Gun the steel gets hurt and also the salt particles (if any) gets more impinged. Hence this should be avoided as far as possible except handling some odd nooks and corners. If this has to be used, the surface must be washed well with Fresh Water.

    1. Hi Amit
      You are right, when used as the primary tool for removing onboard corrosion, the needle gun does not give a good surface by it self, and there are other more efficient ways to do corrosion maintenance.

      Usually needle gunning is followed by cleaning with a rotating brush and direct painting. This will almost ensure that corrosion will emerge shortly.

      If you use it as part of the process to remove the thick rust scales and loose paint. You should, as you point out, make sure the surface is cleaned with fresh water and soap and by an abrasive medium (disc or sand), followed by another fresh water cleaning.
      Then you will likely have a good clean and rough surface which is ready for painting.

      For other than small areas, the needle gun is a time consuming, noisy and inefficient tool that should be avoided.

      I will discuss alternatives and give better guidance on the surface preparation in further blogs.

      Safe sailing and have a nice day

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