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Title: Hydrogen degradation of pipeline steels. Summary report

Technical Report ·
DOI:https://doi.org/10.2172/5985541· OSTI ID:5985541

The research has shown that Stage II fatigue-crack-growth acceleration indeed diminishes with increasing stress ratio to almost negligible levels at R = 0.8. However, an important new finding has been that hydrogen promotes premature transition to Stage III (rapid) fatigue-crack growth when the maximum stress intensity in hydrogen reaches a critical value. The critical K/sub max/ can be correlated with the monotonic elastic-plastic fracture toughness J/sub IC/ measured in hydrogen. Pipe-section tests have shown that subcritical-crack growth in standard hardness pipeline steel base metal and typical weld heat-affected zones should not be a problem in practice. Rapid crack growth would occur by fatigue loading at considerably lower stress intensities than those that would cause subcritical-crack growth. Alternatively, hydrogen has been shown to cause premature subcritical-crack growth in steel heat treated to simulate pipeline hard spots. A burst pressure loss of over 20% was found in that case. Encouraging results were found with the studies on inhibitors. It was determined that oxygen, sulfur dioxide, and carbon monoxide provide strong inhibition of the worst effects of hydrogen, including fatigue-crack growth at low stress ratios, premature transition from Stage II to Stage III fatigue behavior, and subcritical-crack growth in simulated hard spots.

Research Organization:
Battelle Columbus Labs., OH (United States)
DOE Contract Number:
AC02-76CH00016
OSTI ID:
5985541
Report Number(s):
BNL-51855; ON: DE85008930; TRN: 85-007662
Resource Relation:
Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
Country of Publication:
United States
Language:
English