A review of modelling high pH stress corrosion cracking of high pressure gas pipelines

Griggs, J.; Gamboa, Erwin; Lavigne, Olivier

doi:10.1002/maco.201508454

Cited by 19 publications

(8 citation statements)

References 70 publications

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“…3,[26][27] Thereafter, Stage 2 starts when the mechanical driving force at the crack tip causes sustainable crack growth through the film rupture mechanism. 12,[28][29][30][31][32] The crack growth rate increases significantly in comparison with the previous stage. Therefore, the intergranular crack advances in the pipe's thickness within a relatively short time frame compared to Stage 1b.…”

Section: Introductionmentioning

confidence: 99%

Crack Growth Sensitivity to the Magnitude and Frequency of Load Fluctuation in Stage 1b of High-pH Stress Corrosion Cracking

Niazi

Nelson

Lamborn³

et al. 2021

Corrosion

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Pipelines undergo sequential stages before failure caused by High pH Stress Corrosion Cracking (HpHSCC). These sequential stages are incubation stage, intergranular crack initiation (Stage 1a), crack evolution to provide the condition for mechanically driven crack growth (Stage 1b), sustainable mechanically driven crack propagation (Stage 2), and rapid crack propagation to failure (Stage 3). The crack propagation mechanisms in Stage 1b are composed of the nucleation and growth of secondary cracks on the free surface and crack coalescence of secondary cracks with one another and the primary crack. These mechanisms continue until the stress intensity factor (K) at the crack tip reaches a critical value, known as KISCC. This investigation took a novel approach to study Stage 1b in using pre-cracked Compact Tension (CT) specimens. Using pre-cracked specimens and maintaining K at less than KISCC provided an opportunity to study crack initiation on the surface of the specimen under plane stress conditions in the presence of a pre-existing crack. In the present work, the effects of cyclic loading characteristics on crack growth behavior during Stage 1b were studied. It was observed that the pre-existing cracks during Stage 1b led to the initiation of secondary cracks. The initiation of the secondary cracks at the crack tip depended on loading characteristics, i.e., the amplitude and frequency of load fluctuations. The secondary cracks at the crack tip can be classified into four categories based on their positions with respect to the primary crack. A high density of intergranular cracks formed in the cyclic plastic zone generated by low R-ratio cycles. The higher the frequency of the low R-ratio cycles, the higher the density of the intergranular cracks forming in the cyclic plastic zone. The crack growth rate increased with an increase in either the amplitude or the frequency of the load fluctuations. The minimum and maximum crack growth rates were 8×10-9 mm/s and 4.2×10-7 mm/s, respectively, with R-ratio varying between 0.2 and 0.9, frequency varying between 10-4 Hz and 5×10-2 Hz, and at a fixed stress intensity factor of 15 MPa.m0.5. It was found that avoiding rapid and large load fluctuations slowed down crack geometry evolution and delayed onset of Stage 2. The implication of these results for pipeline operators is that reducing internal pressure fluctuations by reducing the frequency and/or amplitude of the fluctuations can expand Stage 1 and increase the reliable lifetime of operating pipelines.

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Section: Introductionmentioning

confidence: 99%

Crack Growth Sensitivity to the Magnitude and Frequency of Load Fluctuation in Stage 1b of High-pH Stress Corrosion Cracking

Niazi

Nelson

Lamborn³

et al. 2021

Corrosion

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“…It is widely accepted [1,5,6] that CF and stress corrosion cracking (SCC) are the dominant failure modes of environment-assisted cracking (EAC) depending on the loading scheme. Despite extensive and considerable research conducted on the inner mechanisms of SCC in pipeline steels [7][8][9], there are few papers focused on CF, especially for the less corrosive or critical environments. The former investigates the crack behavior in corrosive environments under constant loads and several classic features and modes have been characterized according to the crack morphologies and critical situations.…”

Section: Introductionmentioning

confidence: 99%

Effect of Water Environment on Fatigue Behavior in X80 High Strength Steel CO2 Arc Welding Welded Joint

Zhao

Liu

et al. 2021

Metals

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Fatigue life tests and fatigue crack growth rate (FCGR) tests in the air and water environment were conducted on X80 pipeline steel welded joints (welded by CO2 arc welding). Scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) were utilized to investigate the internal influential mechanisms of the water environment during fatigue crack initiation and propagation stages, respectively. Results show that a great many oxide particles induced by the water environment gradually formed the fatigue crack initiation site and decreased fatigue life of welded joints. Meanwhile, the preferred grain orientation of <001>//ND and CSL boundaries of Σ3, Σ11, Σ13c, Σ17b, Σ25a, and Σ25b are both prone to fatigue propagation when loading in the water environment. In addition, a coalescence of the stress intensity factor (SIF) range and water environment accelerated FCGR by motivating secondary slip systems of {112}<111> and {123}<111> in bcc crystalline structures.

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“…2,4 The effect of the residual stress/strain and/or the effect of the texture have been examined to explain unusual intergranular stress corrosion crack paths observed in low-carbon steels and other materials such as stainless steels and nickel-based alloys. 2,7,[8][9][10][11][12][13][14][15] This paper presents the characterisations of the Canadian pipeline samples used in previous studies 2,4 particularly in terms of texture and microstructure, subsequently comparing these results to those previously obtained for the Australian pipe samples. 3,5,7,14 These results are used to help evaluate whether anisotropy in these features (resulting mainly from pipe metallurgical and manufacturing processes) are responsible for the crack inclination path.…”

Section: Introductionmentioning

confidence: 99%

High-pH inclined stress corrosion cracking in Australian and Canadian gas pipeline X65 steels

Lavigne

Gamboa

Griggs

et al. 2016

Materials Science and Technology

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High-pH stress corrosion cracking is a form of environmental degradation of gas pipeline steels. The crack path is intergranular by nature and typically perpendicular to the maximum applied (hoop) stress (i.e. perpendicular to the pipe outer surface). Some unusual instances of cracks have been observed in Canadian and Australian X65 pipes, where cracks grow away from the perpendicular for considerable distances. This paper presents a comparative study in terms of crack morphology, mechanical properties and crystallographic texture for these Australian and Canadian pipe steels. It is shown that the crack morphologies are quite similar, the main difference being the angle at which the cracks propagate into the material. This difference could be explained by the different through-wall texture and grain aspect ratio measured in the two materials. The interdependency of crack tip plasticity, crack tip electrochemistry and anisotropy in microstructural texture seems to heavily affect the resulting inclined crack path.

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A review of modelling high pH stress corrosion cracking of high pressure gas pipelines

Cited by 19 publications

References 70 publications

Crack Growth Sensitivity to the Magnitude and Frequency of Load Fluctuation in Stage 1b of High-pH Stress Corrosion Cracking

Crack Growth Sensitivity to the Magnitude and Frequency of Load Fluctuation in Stage 1b of High-pH Stress Corrosion Cracking

Effect of Water Environment on Fatigue Behavior in X80 High Strength Steel CO2 Arc Welding Welded Joint

High-pH inclined stress corrosion cracking in Australian and Canadian gas pipeline X65 steels

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