Three layer Polyethylene (PE) and Polypropylene (PP) corrosion protection coatings play a significant role in the overall performance, integrity and lifetime of steel pipelines.
With its introduction in the ‘90ties, the Polypropylen (3LPP) coating was mainly developed for the high temperature application in order to close the gap between the possible max.80°C design temperature for PE coated pipes up to the desired 110°C and offered a higher mechanical protection versus the existing LDPE and MDPE compounds at that time, for example for coatings of horizontal drilling pipes.
The 3layer coating standard ISO21809-1 indicates a design temperature for the PP system of -20°C up to 110°C, however a foot note under the table warns for handling, installation and transportation below the 0°C. This in fact means that when choosing unsuitable epoxy, PP adhesive and PP top coat systems, the pipe might already reach the site with coating damages caused by transport through cold temperature zones.
This can lead to a significant restriction in the flexibility on the construction site related to storage, handling, transportation and installation for the contractor and pipeline owner. Furthermore, in future the exploration will take place in even colder regions than today, thus requiring improved coating systems for those climates.
The paper describes the market need for such a specific low temperature PP system, compares to the normal PP system and provides data on the possible physical performance envelope of such materials and their related test methods to compare with.