Pipeline SCC in Near-Neutral pH Environment: Recent Progress

1996 ◽  
Author(s):  
W. Zheng ◽  
R. W. Revie ◽  
F. A. MacLeod ◽  
W. R. Tyson ◽  
G. Shen
Keyword(s):  
Crack Growth ◽  
Growth Rates ◽  
Pressure Fluctuation ◽  
Oil And Gas ◽  
Crack Depth ◽  
Pressure Level ◽  
Depth Measurement ◽  
Growth Crack ◽  
Crack Depth Measurement ◽  
Crack Growth Rates

Transgranular stress corrosion cracking in oil and gas linepipe was studied by testing full-scale pipes in soil environments. Three pipes made of Grade 359 (X-52) and Grade 414 (X-60) steels were used. Sixteen cracks were prepared on the external surface of each pipe, and crack growth was monitored and studied as a function of the pressure level and pressure fluctuation, the latter being described by the minimum to maximum stress ratio (R) and the loading rate. The overall results suggest strong mechanical effects on crack growth. Crack growth rates were found to be affected by both the pressure level and the level and rate of pressure fluctuation. For the Grade 414 pipe, reducing pressure fluctuation by increasing R from 0.6 to greater than 0.97 reduced the crack growth rates to below 5*10−9 mm/s, the detection limit of the crack depth measurement system used. Similar effects of pressure fluctuation were also seen for the Grade 359 pipes.

Measurement of Fatigue Crack Growth Rates for Steels in Hydrogen Storage

2009 ◽  
Author(s):  
Yoru Wada ◽  
Kouichi Takasawa ◽  
Ryoji Ishigaki ◽  
Yasuhiko Tanaka ◽  
Tadao Iwadate
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Crack Depth ◽  
Load Ratio ◽  
Gaseous Hydrogen ◽  
Test Machine ◽  
Critical Crack ◽  
Crack Growth Rates

Fatigue crack growth rates (da/dN) in up to 90MPa high-pressure gaseous hydrogen environments of quenched and tempered low alloy Cr-Mo steel: JIS-SCM435 with ultimate tensile strength level of 950MPa were measured utilizing a cycle, ranging from 0.3sec from 1000sec long with a road ratio R = 0.1. The longer cycle time tests (15sec to 1000sec per cycle) were conducted utilizing internal pressure test apparatus by utilizing cylinder (= CY) specimens, while shorter cycle (0.3sec to 25sec per cycle) tests were performed utilizing fatigue test machine using compact tension (= C(T)) specimens. Crack depth of CY specimens were measured by Time Of Flight Diffraction (TOFD) technique and the crack length of C(T) specimens were measured by compliance technique. Both C(T) and CY specimen showed accelerated sub-critical crack growth in gaseous hydrogen compared that in air or inert gas atmosphere. The effect of load ratio was also evaluated.

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.

Effect of crack depth on fatigue crack growth rates for a C–Mn pipeline steel in a sour environment

2010 ◽  
Vol 32 (2) ◽  
pp. 288-296 ◽  
Author(s):  
Colum M. Holtam ◽  
David P. Baxter ◽  
Ian A. Ashcroft ◽  
Rachel C. Thomson
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Pipeline Steel ◽  
Crack Depth ◽  
Crack Growth Rates

Comparison of Multiple Crack Detection In-Line Inspection Data to Assess Crack Growth

2010 ◽  
Author(s):  
Mark Slaughter ◽  
Kevin Spencer ◽  
Jane Dawson ◽  
Petra Senf
Keyword(s):  
Crack Growth ◽  
Crack Detection ◽  
Oil And Gas ◽  
Crack Depth ◽  
Field Investigations ◽  
Integrity Management ◽  
Essential Input ◽  
Maximum Crack ◽  
Inspection Data ◽  
Crack Growth Rates

Ultrasonic inline inspection (ILI) tools have been used in the oil and gas pipeline industry for the last 14 years to detect and measure cracks. The detection capabilities of these tools have been verified through many field investigations. ILI ultrasonic crack detection has good correlation with the crack layout on the pipe and estimating the maximum crack depth for the crack or colony. Recent analytical developments have improved the ability to locate individual cracks within a colony and to define the crack depth profile. As with the management of corroding pipelines, the ability to accurately discriminate active from non-active cracks and to determine the rate of crack growth is an essential input into a number of key integrity management decisions. For example, in order to identify the need for and timing of field investigations and/or repairs and to optimize re-inspection intervals crack growth rates are a key input. With increasing numbers of cracks and crack colonies being found in pipelines there is a real need for reliable crack growth information to use in prioritizing remediation activities and planning re-inspection intervals. So as more and more pipelines containing cracks are now being inspected for a second time (or even third time in some cases), the industry is starting to look for quantitative crack growth information from the comparison of repeat ultrasonic crack detection ILI runs. This paper describes the processes used to analyze repeat ultrasonic crack detection ILI data and crack growth information that can be obtained. Discussions on how technical improvements made to crack sizing accuracy and how field verification information can benefit integrity plans are also included.

scholarly journals Advantageous Description of Short Fatigue Crack Growth Rates in Austenitic Stainless Steels with Distinct Properties

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 475
Author(s):  
Lukáš Trávníček ◽  
Ivo Kuběna ◽  
Veronika Mazánová ◽  
Tomáš Vojtek ◽  
Jaroslav Polák ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stainless Steels ◽  
Growth Rates ◽  
Large Scale ◽  
J Integral ◽  
Scale Yielding ◽  
Residual Fatigue ◽  
Crack Growth Rates

In this work two approaches to the description of short fatigue crack growth rate under large-scale yielding condition were comprehensively tested: (i) plastic component of the J-integral and (ii) Polák model of crack propagation. The ability to predict residual fatigue life of bodies with short initial cracks was studied for stainless steels Sanicro 25 and 304L. Despite their coarse microstructure and very different cyclic stress–strain response, the employed continuum mechanics models were found to give satisfactory results. Finite element modeling was used to determine the J-integrals and to simulate the evolution of crack front shapes, which corresponded to the real cracks observed on the fracture surfaces of the specimens. Residual fatigue lives estimated by these models were in good agreement with the number of cycles to failure of individual test specimens strained at various total strain amplitudes. Moreover, the crack growth rates of both investigated materials fell onto the same curve that was previously obtained for other steels with different properties. Such a “master curve” was achieved using the plastic part of J-integral and it has the potential of being an advantageous tool to model the fatigue crack propagation under large-scale yielding regime without a need of any additional experimental data.

Sign in / Sign up

Export Citation Format

Share Document