The hydrogen (H) concentration (COH) at the inside surface of linepipe steels containing different media was determined and compared with values obtained in field tests. Test media included NACE TM0177, NACE TM0284, modified NACE TM0284, and field-produced water saturated with hydrogen sulfide (H2S). Results showed field conditions were more severe than TM0284 but less severe than modified TM0284. Data suggested a medium buffered to a pH of 4.1 to 4.7 might reflect field conditions. Results also suggested diffusion coefficient values obtained from breakthrough times could be used in the calculation of (COH) in field tests without sacrificing accuracy. It was shown that analysis of breakthrough time data can provide some idea of the degree of the relative trap density in linepipe steels.

Subject
Hydrogen induced cracking, Pipe surfaces, Water, Piping, Hydrogen concentration, Probes, Diffusion, Linepipe, Pipelines, Acidity, Permeation, Steel, Hydrophobic interaction chromatography
Keywords:
carbon steel, cracking, field test, hydrogen, hydrogen-induced cracking, hydrogen permeation, hydrogen sulfide, pipelines, sour gas, trap density
NACE International
1994
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