Failure pressure prediction by defect assessment and finite element modelling on natural gas pipelines under cyclic loading
Introduction
In-line inspection provides an accurate technique (e.g., magnetic flux leaking or ultrasonic tool) to detect and size various types of defects on pipelines (Vanaei et al., 2017). Defect assessment based on ILI data analysis is an essential component of pipeline integrity management program (API, 2016; Pluvinage, 2008). In the past decade, the authors’ group has conducted extensive research on pipeline defect assessment. FE based models were developed to evaluate failure pressure of corroded pipelines and predict the defect growth rate (Xu and Cheng, 2012, 2013, 2017; Sun and Cheng, 2018, 2019a, 2019b). The modelling scope is extensive, including the defect geometry (depth, length and width), steel grade, internal pressure, soil strain, interaction of multiple corrosion defects, stress-corrosion interaction, etc.
During ILI operation, the tool moving inside a pipeline may cause vibration, especially when the tool encounters obstacles such as rough inner wall surface, dents, girth weld between pipe segments, corrosion pits, etc. (Zhang et al., 2015, 2020). Vibration will also happen on pipelines that are suspended on erosive soil supports. The vibration can apply a cyclic loading on the inner wall of the pipeline (Zhang et al., 2015), affecting the local stress and strain distributions at the defect and the failure pressure of the pipeline.
The presence of corrosion defects on pipelines can reduce pipe wall thickness and introduce an additional stress concentration, causing reduction of load-bearing capability of the pipelines (Gong and Zhou, 2018; Abdalla et al., 2014). To date, a wide variety of numerical models and computational codes have been developed for pipeline defect assessment (Xu and Cheng, 2012, 2013, 2017; Sun and Cheng, 2018, 2019a, 2019b; Choi et al., 2003; Ma et al., 2013; Chegeni et al., 2019; Wu and Li, 2019; Mondal and Dhar, 2019; Gong and Zhou, 2017). However, to the authors’ best knowledge, none of them has considered the mechanical response due to the ILI-induced vibration and its effect on ocal stress and strain concentrations and the pipeline failure. This work developed a novel method to assess corrosion defect during the ILI tool operation and predict the failure pressure of pipelines under cyclic loading for the first time of its kind.
In this work, a FE model was developed to simulate the stress and strain distributions at a corrosion defect on an X80 steel natural gas pipeline under cyclic loading. A stress-based failure criterion was used to predict the failure pressure of the corroded pipeline. Parametric effects, including internal pressure, defect depth and loading parameters (i.e., cyclic frequency and R-ratio), were modelled. For comparison, modelling was conducted on a pipeline made of a low-grade X60 steel.
Section snippets
Pipeline steels and geometry of corrosion defect
Both X60 and X80 steel pipes were modelled in this work. They represent the typical low- and high-grades of pipeline steel, respectively. The mechanical properties of the two steels are shown in Table 1. To model a corrosion defect, some simplifications were made so that the results could be applicable for a wide range of geometric shapes. In modified ASME B31G standard, the maximum depth and length along the axial direction of pipeline are used to depict a corrosion defect, which is usually
Comparison of the modelling results with testing data as published and the DNV results
A comparative analysis was performed to verify the reliability of the FE model developed in this work. It is noted that selections of the pipe steel, dimensions of corrosion defect and operating conditions ensure a sound base for comparison of the modelling results with experimental data. Fig. 4 shows the modelling failure pressures compared with the published experimental data (Benjamin and Cunha, 2007) and the DNV modelling results. The relative error (RE) between the experimental testing
Conclusions and implication
A FE model is developed to simulate the local stress and strain distributions at corrosion defect on pressured gas pipelines which are under cyclic loading induced by vibration of ILI tool operation. The presence of cyclic loading greatly increases the local von Mises stress and strain at the corrosion defect, reducing the threshold internal pressure to cause local plastic deformation at the defect. As the internal pressure increases, both the von Mises stress and strain increase. The high
Author statement
The first author, Guojin Qin, is a graduate student. He conducted all numerical modelling work, and performed the result analysis. He also drafted the manuscript.
The corresponding author, Dr. Frank Cheng, is the principal investigator of the project. He planned the scope of work and designed the research plan. He worked with the first author to analyze the results, and revised the manuscript for submission.
Declaration of competing interest
None.
Acknowledgement
This work was supported by China Scholarship Council (CSC no. 201908510201) and the University of Calgary.
References (26)
- et al.
On the failure pressure of pipelines containing wall reduction and isolated pit corrosion defects
Comput. Struct.
(2014) - et al.
Effect of corrosion on thin-walled pipes under combined internal pressure and bending
Thin-Walled Struct.
(2019) - et al.
Development of limit load solutions for corroded gas pipelines
Int. J. Pres. Ves. Pip.
(2003) - et al.
Importance sampling-based system reliability analysis of corroding pipelines considering multiple failure modes
Reliab. Eng. Syst. Saf.
(2018) - et al.
Assessment on failure pressure of high strength pipeline with corrosion defects
Eng. Fail. Anal.
(2013) - et al.
Burst pressure of corroded pipelines considering combined axial forces and bending moments
Eng. Struct.
(2019) - et al.
Assessment by finite element modeling of the interaction of multiple corrosion defects and the effect on failure pressure of corroded pipelines
Eng. Struct.
(2018) - et al.
Modelling of mechano-electrochemical interaction of multiple longitudinally aligned corrosion defects on oil/gas pipelines
Eng. Struct.
(2019) - et al.
Investigation by numerical modeling of the mechano-electrochemical interaction of circumferentially aligned corrosion defects on pipelines
Thin-Walled Struct.
(2019) - et al.
A review on pipeline corrosion, in-line inspection (ILI), and corrosion growth rate models
Int. J. Pres. Ves. Pip.
(2017)
Finite element analysis on mechanical behavior of semi-exposed pipeline subjected to debris flows
Eng. Fail. Anal.
Reliability and failure pressure prediction of various grades of pipeline steel in the presence of corrosion defects and pre-strain
Int. J. Pres. Ves. Pip.
Development of a finite element model for simulation and prediction of mechano-electrochemical effect of pipeline corrosion
Corrosion Sci.
Cited by (32)
Pipeline condition assessment and finite element modeling of mechano-electrochemical interaction between corrosion defects with varied orientations on pipelines
2023, Tunnelling and Underground Space TechnologyRoadmap to urban energy internet: Techno-enviro-economic analysis of renewable electricity and natural gas integrated energy system
2022, Journal of Cleaner ProductionCitation Excerpt :Nowadays, natural gas pipelines between cities are interconnected, and the reduction of natural gas demand will also lead to changes in node pressure, resulting in network pressure fluctuations. Excessive pressure fluctuations will affect the safety of the whole system (Qin and Cheng, 2020). Consequently, it is necessary to consider the pressure fluctuation of the pipeline network caused by the reduction of natural gas use when designing the urban energy internet.
Dynamic interaction of the pipe-soil subject to underground blasting excavation vibration in an urban soil-rock stratum
2022, Tunnelling and Underground Space TechnologyA new method for assessment of burst pressure capacity of corroded X80 steel pipelines containing a dent
2022, International Journal of Pressure Vessels and PipingCitation Excerpt :Moreover, an X65 steel was also selected for modeling to provide additional confirmation in terms of the modeling reliability. Generally, models used for FE analysis for steels include the bilinear stress-strain relationship [22], isotropic hardening model [47], true stress-strain data [48], and Ramberg-Osgood (R–O) relationship [1]. As suggested by API 579-1/ASME FFS-1 2016 [49], the R–O model was used for both X65 and X80 steels in this work.
Failure analysis of CO<inf>2</inf> corrosion of natural gas pipeline under flowing conditions
2022, Engineering Failure AnalysisFailure pressure estimation for an aged and corroded oil and gas pipeline: A finite element study
2022, Journal of Natural Gas Science and Engineering