Wear resistant inner coating for pipes and pipe fittings

摘要

A pipe or pipe fitting for use in harsh environment such as in petroleum refinery processes for cracking petroleum feedstocks, the pipe or pipe fitting comprising a 0.25 to 2.5 mm thick Co-based metallic coating on an internal surface of the pipe body, the coating having a hypereutectic microstructure characterized by carbides in a cobalt matrix and an average carbide grain size of less than 50 microns, and the Co-based metallic composition overlays the pipe internal surface at an interface which is free of heat-affected zone and which has a diffusion zone which is less than 0.002 inches thick.

主权项

1. A petroleum refinery pipe for use in processes for cracking petroleum feedstocks comprising:
a pipe body substrate selected from among carbon steels, alloy steels, and stainless steels; and a Co-based metallic coating on an internal surface of the pipe body wherein the coating has a thickness between about 0.25 and 2.5 mm thick; wherein the coating composition comprises between 31 and 34 wt % Cr, between 16 and 19 wt % Mo, between 2.1 and 2.5 wt % C, between 0.5 and 1.5 wt % Si, up to 1 wt % B, and between 42 and 50 wt % Co; wherein the coating has a hypereutectic microstructure characterized by carbides in a cobalt matrix and an average carbide grain size of less than 50 microns; wherein the Co-based metallic composition overlays the pipe internal surface at an interface which is free of heat-affected zone and which has a diffusion zone which is less than 0.002 inches thick.