coating system based on zinc alloy electroplating for dry lubrication of premium OCTG connections: assessing anticorrosion performance

摘要

The latest polymer-based system of dry lubrication CLEANWELL® has been developed as analternative to storage and running compounds for the VAM® premium OCTG connections.It keeps the well clean by preventing discharge of dope into the environment and the well bore. Italso reduces operational costs by eliminating rig preparation stages and improving runningperformance.The solution that has been developed combines: (i) an electrodeposited zinc-based metal plating,which provides anti galling properties and protects the steel from corrosion in storage conditions;and (ii) an organic topcoat which improves lubrication and running performance through a lowfriction coefficient.The lifetime during storage on yards – in terms of atmospheric corrosion and paint disbonding –was assessed by accelerated cyclic corrosion tests and thermal shock tests in laboratory as wellas long-term exposures to natural environments with various climates. The results highlight thehigh durability of the technology thanks to the cathodic protection provided by the zinc-basedplating.The degradation in well conditions, especially the resistance to crevice corrosion, was assessedthrough specifically designed high pressure and high temperature corrosion tests in autoclaves.