Enhanced scale inhibition and anti-wax capacities of passive materials via ultrasonic rolling processing

Abstract

Scale damage and wax formation on pipelines surface have become prevalent issues in the development and production of the oil and gas industry throughout the world. The utilization of the ultrasonic surface rolling process (USRP) on pipeline surfaces is a promising protective approach and its universal verification for the enhancement of the scale inhibition and anti-wax capacities of passive materials is presented in this work. The effect of USRP on surface integrity (including roughness, cross-sectional microstructure, residual stress and water contact angle), scaling and wax deposition behavior, passive film structure and characteristics are experimentally analyzed by comparing three passive materials (13Cr stainless steel, 825 nickel-base alloy and Ti6Al4V alloy) with 3Cr carbon steel. The results indicate that USRP can effectively reduce the surface roughness and contribute to the growth of passive film due to the enriched passive elements on the metal surface, which consequently endow the passive materials with reduced surface free energy and enhanced anti-scaling/anti-wax capacities. Furthermore, benefitting from the surface passivation, the enhancement in the corrosion resistance of the film helps to provide good chemical stability. The main reason for why USRP has a protective effect on the scale inhibition and anti-wax capacities of the passive materials is also elucidated. The input energy of USRP not only achieves chip-free polishing and triggers structural response changes in the surface and subsurface plastic deformation but also produces a unique passivation response that can alter the chemical composition, thickness, compactness and defect density of the passive film. This in turn leads to significant changes in its corrosion resistance, which is related to the semiconductor characteristics of the materials, surface energy, and hydrophilic–hydrophobic physical and chemical properties. This results in a significant inhibitory effect on the deposition of scaling ions or wax crystals at the passive film/solution interface.