Laboratory sulfide stress cracking (SSC) tests were performed on specimens taken from a QT-900 coiled-tubing test string in an attempt to define zones of acceptable sour service. SSC tests were performed at room temperature in brine fluid environments with H2S partial pressures (PH2S) ranging from 0.01 to 10 bars and pH levels from 2.8 to 4.5. In addition, the effectiveness of a new inhibitor for crack prevention was tested. SSC testing, which included NACE Method A tensile, four-point bent beam and slow strain rate test specimens, were performed on as-milled as well as fatigue-cycled tubing. Fatigue cycling of the QT-900 test string was performed on a pressure bending fatigue machine with tubing samples cycled from 33% to 75% of average tested fatigue life. Test specimens were taken from parent metal, bias weld, seam weld (ERW), and butt weld locations. As a result of this test program, acceptable zones of service in sour environments have been proposed although further testing may alter boundary locations.

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