Corrosion Fatigue Performance of Girth Welded X65 Seamless Pipe for Flowlines

Abstract Welded API 5L Gr X65 is being used in flow line applications, the flow lines are laid by J laying, S laying, or by a reeling operation. The influence of the reeling on the corrosion fatigue performance of welded X65 pipe has not been well documented. This work is aimed at quantifying the effect of reeling on the corrosion fatigue performance of welded X65 pipe in air as well as sour environments. Fatigue crack growth measurements were performed on SENB specimens to determine the ∆K vs da/dN curves in air with the fatigue crack propagating through the thickness of the pipe. Parent pipe material, heat affected zone (HAZ) and weld center line were tested in air. Frequency scanning experiments from 1Hz to 1mHz were performed on Single Edge Notch Beam (SENB). Specimens of the HAZ and weld centerline were tested in sour environment to determine the knockdown factor associated with the sour environment. The results of the test program will be presented along with a discussion on the effects of reeling on the fatigue performance of welded pipe in air and sour environments.