scholarly journals A review of crack growth models for near-neutral pH stress corrosion cracking on oil and gas pipelines

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Haotian Sun ◽  
Wenxing Zhou ◽  
Jidong Kang
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Growth Rates ◽  
Oil And Gas ◽  
Predictive Accuracy ◽  
Growth Models ◽  
Oil And Gas Pipelines ◽  
S Model ◽  
Crack Growth Rates

AbstractThis paper presents a review of four existing growth models for near-neutral pH stress corrosion cracking (NNpHSCC) defects on buried oil and gas pipelines: Chen et al.’s model, two models developed at the Southwest Research Institute (SwRI) and Xing et al.’s model. All four models consider corrosion fatigue enhanced by hydrogen embrittlement as the main growth mechanism for NNpHSCC. The predictive accuracy of these growth models is investigated based on 39 crack growth rates obtained from full-scale tests conducted at the CanmetMATERIALS of Natural Resources Canada of pipe specimens that are in contact with NNpH soils and subjected to cyclic internal pressures. The comparison of the observed and predicted crack growth rates indicates that the hydrogen-enhanced decohesion (HEDE) component of Xing et al.’s model leads to on average reasonably accurate predictions with the corresponding mean and coefficient of variation (COV) of the observed-to-predicted ratios being 1.06 and 61.2%, respectively. The predictive accuracy of the other three models are markedly poorer. The analysis results suggest that further research is needed to improve existing growth models or develop new growth models to facilitate the pipeline integrity management practice with respect to NNpHSCC.

Statistical Initiation and Crack Growth Models for Stress Corrosion Cracking

2007 ◽  
Author(s):  
W. J. Shack ◽  
O. K. Chopra
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Growth Rates ◽  
Field Data ◽  
Growth Models ◽  
Statistical Distributions ◽  
Parametric Dependencies ◽  
Component Failure Rates ◽  
The Times ◽  
Crack Growth Rates

Statistical distributions of initiation times and crack growth rates are needed for probabilistic fracture mechanics models. Times to failure in laboratory tests on small specimens are about a factor of 1000 shorter than the times to failure of comparably sized “specimens” in the field would have to be in order to get realistic component failure rates. Thus while specimen tests are useful in identifying parametric dependencies, it is unlikely that they can be used directly to develop initiation models for field components without using field data. A scaling approach is proposed to provide a method for pooling data from different size components and for extrapolating experience from one set of components to another set. Estimates of statistical distributions for initiation of stress corrosion cracks are developed from field data for BWR pipe cracking and CRDM cracking. Estimates of statistical distributions of crack growth rates are developed by combining phenomenological models for crack growth rates with expert judgment on the range of input parameters to those models.

SCC Behavior of Alloy 690 HAZ in a PWR Environment

2011 ◽  
Author(s):  
Bogdan Alexandreanu ◽  
Yiren Chen ◽  
Ken Natesan ◽  
Bill Shack
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Heat Affected Zone ◽  
Growth Rates ◽  
Water Environment ◽  
Corrosion Cracking ◽  
Alloy 690 ◽  
Crack Growth Rates

The objective of this work is to determine the cyclic and stress corrosion cracking (SCC) crack growth rates (CGRs) in a simulated PWR water environment for Alloy 690 heat affected zone (HAZ). In order to meet the objective, an Alloy 152 J-weld was produced on a piece of Alloy 690 tubing, and the test specimens were aligned with the HAZ. The environmental enhancement of cyclic CGRs for Alloy 690 HAZ was comparable to that measured for the same alloy in the as-received condition. The two Alloy 690 HAZ samples tested exhibited maximum SCC CGR rates of 10−11 m/s in the simulated PWR environment at 320°C, however, on average, these rates are similar or only slightly higher than those for the as-received alloy.

Stress Corrosion Cracking: Chemically Activated Nanomechanics

2016 ◽  
Author(s):  
Bruce C. Bunker ◽  
William H. Casey
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Stress Corrosion Cracking ◽  
Growth Rates ◽  
Communication Systems ◽  
Crack Tip ◽  
Corrosion Cracking ◽  
Design Engineers ◽  
Mechanical Deformations ◽  
Crack Growth Rates

Although dissolution reactions involving water can etch and decompose oxides, truly catastrophic failures of oxide structures usually involve fractures and mechanical failures. Geologists and geochemists have long recognized that water and ice both play key roles in promoting the fracture and crumbling of rock (see Chapter 17). Freezing and thawing create stresses that amplify the rate at which water attacks metal–oxygen bonds at the crack tip. The interplay between water and stressed oxides also leads to common failures in man-made objects, ranging from the growth of cracks from flaws in windshields to the rupture of optical fibers in communication systems. In this chapter, we outline how mechanical deformations change the reactivity of metal–oxygen bonds with respect to water and other chemicals, and how reactions on strained model compounds have been used to predict time to failure as a function of applied stress. The basic phenomenon of stress corrosion cracking is illustrated in Figure 16.1. Cracks can propagate through oxide materials at extremely fast rates, as anyone who has dropped a wine glass on the floor can attest. High-speed photography reveals that when glass shatters, cracks can spread at speeds of hundreds of meters per second, or half the speed of sound in the glass. At the other end of the spectrum, cracks in glass can grow from preexisting flaws so slowly that only a few chemical bonds are broken at the crack tip per hour. Because mechanical failures are associated with cracking, it is critical for design engineers to understand the factors that control crack growth rates for this enormous range of crack velocities (a factor of 1012). In addition, because it is difficult to measure crack velocities slower than 10−8 m/second, it is often necessary to make major extrapolations from measured data to predict the long-term reliability of glass and ceramic objects. Will an optical fiber under stress fail in 1 year or 10 years? Answering this question can require accurate extrapolations down to crack growth rates as low as 10−10 m/second.

SCC Management and Integrity Planning in a Gas Pipeline

2006 ◽  
Author(s):  
David Katz ◽  
Sergio Limon ◽  
Ming Gao ◽  
Rick McNealy ◽  
Ravi Krishnamurthy ◽  
...  
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Growth Rates ◽  
Crack Detection ◽  
Management Strategies ◽  
Field Measurements ◽  
Gas Pipeline ◽  
Oil Pipeline ◽  
Integrity Management ◽  
Crack Growth Rates

Stress Corrosion Cracking (SCC) is a major integrity management concern for many gas and oil pipeline operators. Predictive models for Stress Corrosion Crack growth were developed using laboratory test data from the mid 1970’s, and limited inspection data and excavation measurements from the early 1990’s. Extensive efforts continue to be made to develop strategies for a better management of the SCC problem. In this paper, a study of crack growth rates was conducted on the Williams 16-inch gas pipeline using data from two consecutive in-line crack detection tool runs and direct field measurements. Findings from this study provide a direct measurement of crack growth rates for ILI crack features with depths ranging from 12.5%wt to 40%wt. Future integrity of the pipeline was assessed. The integrity management strategies could be further refined using the calculated crack growth rate, field excavation data and fracture mechanics based API 579 FAD approach.

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