Environment sensitive cracking of high-pressure pipelines in contact with carbon dioxide-containing solutions. Topical report

Technical Report · Tue Sep 01 04:00:00 EDT 1992

OSTI ID:10169115

Parkins, R N ^[1]

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1. Univ. of Newcastle, Newcastle upon Tyne (United Kingdom)

Field data relating to the transgranular stress corrosion cracking of high pressure gas pipelines indicates that the solutions found between coating and pipe in regions where cracks have occurred have low concentrations of dissolved salts and pH`s of about 6.5, distinguishing them from those that are associated with the common intergranular form of cracking. The lower pH solutions involved with transgranular cracking are the result of the presence of free carbon dioxide and the lack of significant cathodic current arriving at the pipe surface in those locations. Slow strain rate and cyclic loading tests employing solutions simulating those found in the field have shown that transgranular stress corrosion cracks can be generated under laboratory conditions and that they have the same characteristics as are observed in samples from lines that have developed cracks in service. Those similarities extend to the data from both field and laboratory sources showing considerable scatter, indicating the need for appropriate statistical treatment. It is suggested that the mechanism of transgranular cracking involves dissolution and the ingress of hydrogen to the steel and that implies that some of the concepts that have been employed in modeling the intergranular form of cracking will need to be modified for the transgranular case.

• Research Organization: American Gas Association, Inc., Arlington, VA (United States). Pipeline Research Committee
• Sponsoring Organization: American Gas Association, Inc., Arlington, VA (United States)
• OSTI ID: 10169115
• Report Number(s): AGA--94015610; ON: UN94015610; CNN: Contract NG-18-205
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
032000
42 ENGINEERING
420205
CARBON DIOXIDE
CORROSION
CRACKING
NATURAL GAS DISTRIBUTION SYSTEMS
PIPELINES
STATISTICAL MODELS
STRESSES
TRANSPORT AND STORAGE FACILITIES
TRANSPORT, HANDLING, AND STORAGE