Integrity Planning and SCC Management in a Liquid Pipeline

2004 ◽  
Author(s):  
Bill Gu ◽  
Wayne Feil ◽  
Richard Kania ◽  
Ming Gao ◽  
Ravi Krishnamurthy
Keyword(s):  
Stress Corrosion ◽  
Crack Growth ◽  
Growth Rates ◽  
Crack Detection ◽  
Management Strategies ◽  
Field Measurements ◽  
Oil Pipeline ◽  
Integrity Management ◽  
First Time ◽  
Crack Growth Rates

Stress corrosion cracking (SCC) is a major concern for many gas and oil pipeline operators. Extensive efforts continue to be made to develop strategies for a better management of the problem. Predictive models for stress corrosion crack growth were developed using lab testing data, limited inspection and excavation measurements since mid 70s and early 90s, respectively. In this paper, a systematic study of crack growth rates was conducted on the Imperial Oil Rainbow 24 NPS pipeline based on the two consecutive UltraScan Crack Detection (USCD) tool runs and field measurements. Findings of this study provide, perhaps, for the first time since the phenomenon was discovered, a direct measurement of crack growth rates for shallow cracks (in the category of <12.5%wt). Future integrity of the pipeline was assessed and the integrity management strategies were refined using the determined crack growth rate and fracture mechanics based approach. In addition, the susceptibility of SCC was studied in detail using a decision tree approach for data mining. Some important correlations between SCC susceptibility and environmental and mechanical variables were identified and presented. Findings on SCC susceptibility are discussed in terms of environmental and loading parameters such as soil, drainage, topography, pressure, and CP along the pipeline.

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.

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.

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.

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