Low-pH SCC: Mechanical effects on crack propagation
- CC Technologies Labs., Inc., Dublin, OH (United States)
A better definition of the role of mechanical factors on low-pH stress corrosion crack propagation is needed to aid in the prediction of crack growth rates on operating pipelines and to develop strategies to mitigate this form of cracking. The overall objective of the project was to determine the roles and synergistic effects of pressure, pressure fluctuations, and hydrotesting on low-pH stress corrosion crack growth. All testing was performed in a low-pH electrolyte (NS4 solution) under cyclic load conditions on pre-cracked specimens of one X-65 line pipe steel. The cyclic load conditions in the testing were related to field conditions using the J-integral parameter. This project consisted of the following three tasks, Task 1 - Development of Test Protocol, Task 2 - Mechanical Effects, and Task 3 - Effects of Hydrotesting. The purposes of Task 1 were to prepare the test specimens and experimental apparatus and to establish a standard test protocol for conducting the cyclic load tests and analyzing the test data. The specimen preparation procedures and environmental conditions were similar to those used in a previous project for TransCanada PipeLines (TCPL). The most significant difference between the tests performed in this project and the previous research was in the mode of loading. The previous work was performed under constant extension rate loading while this project was performed under cyclic load conditions. It is difficult to relate test conditions under constant extension rate loading with field conditions. However, the cyclic load conditions in the laboratory test can be directly related to field test conditions using the J-integral parameter. Modifications also were necessary in the data analysis procedure to account for the change in loading mode.
- 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:
- 576146
- Report Number(s):
- AGA-98002866; IN: R 207-01; TRN: 98:001460
- Resource Relation:
- Other Information: PBD: 6 Sep 1996
- Country of Publication:
- United States
- Language:
- English
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