Beyond clean: KAW’s full-service tank wash

When is a clean tank dirty? That’s an answer our experienced tank cleaners know – do you?

Before some tanks can accept loads they must be more than clean – they may need to be passivated and stain-free as well. As a full-service tank wash, we take pride in providing these additional services to our customers. But what, exactly, do they entail?

In this post, you’ll learn what passivation and stain removal mean, how we perform them, and why they’re important.



As many tank truck companies will tell you and to clear up a common misconception: stainless steel is not actually stainless. In the right – or wrong – conditions, even stainless steel can pick up stains and corrosion. That’s because it isn’t the steel itself that resists stains – it’s the film that forms on its surface when the steel is exposed to oxygen. (The film is inert or “passive,” which will become important later.)

If the film becomes corrupted, the steel loses its stain resistant powers, which is how certain products can stain your stainless tank.

A stain can be a headache and a half if it isn’t removed. Some plants take one look at your stained tank and refuse to load – for good reason. Depending on the products in question, that old stain could seep into the new load and ruin the whole tank.

That’s why we offer stain removing services that can remove many stubborn stains on the inside of tanks.

Due to buffing, scraping and the stripping abilities of the products we use for stain removal, the tank requires passivation after stain removal to protect the stainless from future stains and replace its corrosion-blocking properties. But what exactly happens to a tank when our tank cleaners put it through the passivation process?


We passivate tanks to restore the stain-resistant film after the steel has been treated. Acids, grinding, sulfides – these all corrupt the film. We restore it with a solution that removes iron from the surface of the tank and helps reform the protective layer.

Ideally, this means that you won’t need to go through either process for a good, long time.

To learn more about all the truck maintenance and other services we offer, check out our tank cleaning page!