Studies on the bond durability between the steel and 3 layers PE/PP coatings in hot/wet environment

For the last few years, TOTAL has carried out laboratory testing of tri-layers PE and PP pipe coatings in hot wet environment.
The objective was to mimick the disbondment form the steel noted in some cases in the field (with no corrosion associated), and understand the physico-chemical mechanism at the origin of the loss of adhesion experienced.
This paper will sum up the results obtained so far from this RD effort, with a special highlight on the following points :
à Durability of the bond between the steel and the FBE primer/Influence of water diffusion
à Influence of the FBE type and temperature on the disbondment
à Influence of internal stresses on the disbondment of three layers coatings.