Transgranular stress corrosion cracking of high-pressure pipelines in contact with solutions of near neutral pH

Journal Article · Sun May 01 04:00:00 EDT 1994 · Corrosion (Houston); (United States)

DOI:https://doi.org/10.5006/1.3294348· OSTI ID:7295159

Parkins, R N ^[1]; Blanchard, Jr, W K ^[2]; Delanty, B S ^[3]

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1. Univ. of Newcastle upon Tyne (United Kingdom)
2. Amoco Corp., Naperville, IL (United States). Amoco Research Center
3. TransCanada Pipeline Co. Ltd., Calgary, Alberta (Canada)

Although intergranular stress corrosion cracking (IGSCC) of high-pressure gas pipelines has been known for more than 20 years, a transgranular form (TGSCC) was detected more recently. Instances of TGSCC have been associated with dilute solutions with pH values in the region of 6.5 because of the presence of carbon dioxide (CO[sub 2]). Such pH values indicate relatively little, if any, cathodic current reaches the pipe surface, since hydroxyl ions would be generated and pH would increase to values in the region of 10 if current did reach the pipe surface. Slow strain rate testing (SSRT) of pipeline steel specimens in dilute solutions of pH in the region of 6.5 suggested dissolution and hydrogen (H) ingress into the steel are involved in the crack growth mechanism. The initiation of TGSCC in specimens subjected to cyclic loading and maximum stresses approximating those of an operating line was facilitated by pitting. The geometry of the pits allowed the localized generation of solutions of lower pH than that of the bulk solution outside the pits, thereby facilitating dissolution and H discharge.

• OSTI ID: 7295159
• Journal Information: Corrosion (Houston); (United States), Journal Name: Corrosion (Houston); (United States) Vol. 50:5; ISSN 0010-9312; ISSN CORRAK
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
032000* -- Natural Gas-- Transport
Handling
& Storage
36 MATERIALS SCIENCE
360103 -- Metals & Alloys-- Mechanical Properties
360105 -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
CATHODIC PROTECTION
CHEMICAL REACTIONS
CORROSION
CORROSION PROTECTION
CRACK PROPAGATION
EMBRITTLEMENT
ENERGY SYSTEMS
HYDROGEN EMBRITTLEMENT
IRON ALLOYS
IRON BASE ALLOYS
NATURAL GAS DISTRIBUTION SYSTEMS
PIPELINES
STEELS
STRESS CORROSION