The effect of reeling on the fatigue crack growth rate (FCGR) behavior of welded pipe was investigated both in-air as well as in sour environment. The FCGR behavior of the reeled pipe in various notch locations, such as parent pipe (PP), weld center line (WCL), and heat affected zone (HAZ), did not exhibit any effect of reeling (i.e., the properties in the strained and aged conditions were similar to the as-fabricated welds). Frequency scan FCGR tests in sour environment (pH = 5/0.0031 MPa H2S) exhibited maximum FCGR in the range of 10× to 35× higher than the in-air values at frequencies in the range of 3–1 mHz and 3× to 5× at frequencies in the range of 0.3 Hz (risers). In sour service, WCL exhibited better fatigue performance than the PP and HAZ in all conditions. Fatigue performance of PP and WCL was independent of reeling. The poorest fatigue performance was observed in unstrained HAZ. Fatigue performance of HAZ extrados (side last strained in compression) and intrados (side last strained in tension) was similar and better than unstrained HAZ. It was also found that the FCGR in sour environments was controlled by the internal hydrogen due to bulk charging from the sour environment. The overall conclusion is that reeling has no detrimental effect on sour service fatigue crack growth behavior, i.e., sour service fatigue performance of reeled pipe is the same as unreeled pipe.
Effect of Reeling on Sour Service Fatigue Crack Growth Behavior of Welded API5LX65 Line Pipe
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Contributed by the Pressure Vessel and Piping Division of ASME for publication in the JOURNAL OF PRESSURE VESSEL TECHNOLOGY. Manuscript received February 14, 2015; final manuscript received July 22, 2015; published online November 18, 2015. Assoc. Editor: Kunio Hasegawa.
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Thodla, R., Gordon, J. R., and Gui, F. (November 18, 2015). "Effect of Reeling on Sour Service Fatigue Crack Growth Behavior of Welded API5LX65 Line Pipe." ASME. J. Pressure Vessel Technol. April 2016; 138(2): 021405. https://doi.org/10.1115/1.4031165
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