Erosion–corrosion studies on 13 Cr steel in gas well environments by liquid jet impingement

Abstract

Experiments have been performed to compare the behaviour of API 5CT L80 13 Cr steel [API 5CT, Specification for Casing and Tubing, 5th edn., API, Washington, April 1995, pp. 6–8.] and API 5CT C90 steel under liquid erosion–corrosion in a simulated sweet gas well environment. Testing was performed on a jet impingement rig capable of firing liquid jets at samples at velocities up to 350 m s −1, in sweet and sour gas environments, at pressures up to 34.5 MPa (5000 psi) and temperatures up to 200°C. Sample degradation was assessed by weight loss, macroscopic examination and scanning electron microscopy (SEM). The API 5CT L80 13 Cr steel demonstrated considerably greater resistance to liquid erosion–corrosion than predicted by the current industry standard, API RP-14E [API RP-14E, Recommended Practice for Design and Installation of Offshore Production Platform Piping Systems, 5th edn., API, Washington, October 1991, 23 pp.]. No severe erosion–corrosion damage was observed on the 13 Cr steel at 100°C, under 4.14 MPa (600 psi) CO 2, with jet impingement velocities of 150 m s −1 using 30 g l −1 NaCl solution. As expected, the carbon steel was found to have suffered severe erosion–corrosion under similar conditions.