Study on the Wear Performance of Surface Alloy Coating of Inner Lining Pipe under Different Load and Mineralization Conditions

Testing was carried out in this study to evaluate the friction and wear performance of 45# steel inner liner pipes with cladding, along with four different types of centralizing materials (45# steel, nylon, polytetrafluoroethylene (PTFE), and surface alloy coating) in oil field conditions. Under dry-friction conditions, the coefficients of friction and rates of wear are significantly higher than their counterparts in aqueous solutions. This is attributed to the lubricating effect provided by the aqueous solution, which reduces direct friction between contact surfaces, thereby lowering wear. As the degree of mineralization in the aqueous solution increases, the coefficient of friction tends to decrease, indicating that an elevated level of mineralization enhances the lubricating properties of the aqueous solution. The wear pattern in an aqueous solution is similar to that in dry-friction conditions under different loads, but with a lower friction coefficient and wear rate. The coating has played an important role in protecting the wear process of 45# steel, and the friction coefficient and wear rate of tubing materials under various environmental media have been significantly reduced. In terms of test load, taking into account the friction coefficient and wear rate, the suggested order for centralizing materials for lining oil pipes with the surface alloy coating is as follows: (i) surface alloy coating, (ii) nylon, (iii) PTFE, and (iv) 45# steel.