Study on crystallization characteristic of 3PE anti-corrosion coating for steel pipeline

摘要

Three layers polyethylene (3PE) anti-corrosion coating was widely used in oil or gas transmission pipelines in the world. Special HDPE (SHDPE) was used in the outer layer of 3PE coating, which is very important to the performance of the whole coating system. However, till to now fewer study about SHDPE crystallization have been reported. In this paper, the crystallization characteristic of SHDPE and 3PE coating were investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), modulated differential scanning calorimetry (MDSC). The results showed that, the crystallinity and lamella thickness of SHDPE were decreased with the increase of cooling rate in fabrication process. Middle adhesion layer of 3PE coating accelerated nucleation and improved the crystallinity of the near zone PE layer. The skin region of 3PE coating had lowest crystallinity due to the highest cooling rate, and the crystallinity was increased from skin to core region of 3PE coating.