A New Application Process That Assures Good Adhesion of Fusion-Bonded Epoxy Coatings Exposed to Very Severe Conditions

The long term anticorrosion protection of buried pipelines is linked to the ability of coating materials to ensure a barrier effect against corrosive components such as water and salts.

On the other hand, in order to withstand in-service stresses, the coating also needs to have good adhesion on the steel substrate, even under drastic conditions that combine high temperature and humidity.

As regards FBE (fusion bonded epoxy) coatings, it has already been demonstrated that barrier performance is due to the hydrophobic nature of the coating and consequently its ability to maintain a high glass transition temperature, despite humid and hot surroundings.

In order to maintain adhesion under such conditions, good substrate preparation is the key to success. Indeed, the usual recommendations are based on chemical pre-treatments of steel, through the application of chromate or phosphate based products.

A new application process (SILPIPE® patent pending) for FBEs, used either as monolayer coatings or as primers in multilayer systems, is proposed. This process includes a no-rinse chemical treatment with a solvent free and non toxic product; SILPIPE® SCT.

This paper demonstrates the interest of this process through the adhesion performance of FBE coatings immersed in hot water.