Emergence of Diamond-like Carbon Technology: One Step Closer to OCTG Corrosion Prevention

Abstract

Careful consideration of corrosion management during component manufacture is critical to protect assets over their useful field life. Recently, a new technology was introduced that can delay or mitigate the onset of corrosion on oil country tubular goods (OCTG) used in oil and gas production operations. The innovative method produces and applies a layered diamond- like-carbon (DLC) to the internal surface of OCTG tubulars by using a plasma enhanced chemical vapor deposition (PECVD) process. The technique makes use of the hollow cathode effect (HCE) to achieve a high deposition rate and a high ion bombardment rate. Initially developed for the coating of internal surfaces of piping with length:diameter aspect ratios less than 20, the process has recently been extended to high aspect ratio piping including OCTG. Its ion bombardment produces a dense barrier of a hard, wear and corrosion resistant DLC surface coating. The improvement in deposition rate and increase in thickness compared to earlier plasma coatings has enabled new applications such as corrosion and abrasion protection. Corrosion resistance is demonstrated based on exposure to HCl and NaCl environments. Mechanical properties include high hardness, high adhesion, and good wear resistance. The new technology enables a widespread use of DLC based coating and has significant potential to increase component life in applications where the internal surface of pipes are exposed to corrosive and abrasive environments especially in the oil and gas industry. The described surface treatment provides a new alternative to traditional polymer type coatings and/or increased alloy contents.

DLC Coatings in Oil and Gas Production

“…Nevertheless, the standard PECVD equipment is not specifically designed to handle efficiently coating deposition on the internal surface of cylindrical substrates. This has been addressed recently by development of a dedicated deposition method using a hollow cathode plasma immersion ion processing method for the deposition of silicon containing DLC coatings [38][39][40]. In this method, the plasma is generated within the pipe itself and a gaseous precursor is introduced and ionized causing a coating to be deposited on the internal wall of the pipe.…”