Stress corrosion cracking of pipelines in contact with near-neutral pH solutions

Technical Report · Sat Jul 01 04:00:00 EDT 1995

OSTI ID:441670

Parkins, R N

While much has been learned about low pH stress corrosion cracking in the decade since it was recognized, a review of the published papers and reports since the least overview of the subject in 1992 indicates that there is still much to be understood about this matter. Probably the most significant strides have been made by TransCanada Pipelines Limited in developing procedures to assist in the identification of sites on lines most likely to experience cracking. Most of the laboratory studies have involved dilute solutions based upon those found in the vicinity of cracks in operating lines, but the possible role of bacteria, for which there is supporting field evidence, has not received systematic study. If meaningful modeling of low pH cracking is to be achieved, there is need for more data on crack initiation and the early stages of growth with stressing conditions no overly excessive by comparison with service conditions. There is also a need, related to modeling, of an understanding of the mechanistic aspects of cracking, since while it is known, not least from visible evidence of corrosion on the sides of cracks, that dissolution occurs within the crack enclave, there is indirect evidence that the ingress of hydrogen into the steel may be involved also in the overall crack growth process. If hydrogen is involved then existing models based upon high pH cracking, and involving a quantifiable dissolution mechanism, will not be directly applicable to the low pH problem.

• Research Organization: American Gas Association, Inc., Arlington, VA (United States)
• Sponsoring Organization: American Gas Association, Inc., Arlington, VA (United States)
• OSTI ID: 441670
• Report Number(s): AGA--97003264
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
36 MATERIALS SCIENCE
CRACK PROPAGATION
HYDROGEN EMBRITTLEMENT
MATHEMATICAL MODELS
MECHANICAL TESTS
NATURAL GAS
PARAMETRIC ANALYSIS
PH VALUE
PIPELINES
STRESS CORROSION