Condition-Based Optimal Maintenance Decision Modeling for Corroding Natural Gas Pipelines

2014 ◽  
Author(s):  
S. Zhang ◽  
W. Zhou ◽  
S. Kariyawasam ◽  
T. Huang
Keyword(s):  
Natural Gas ◽  
Probability Of Detection ◽  
Metal Loss ◽  
Gas Pipelines ◽  
Natural Gas Pipelines ◽  
Inspection Interval ◽  
Optimal Maintenance ◽  
Maintenance Decision ◽  
The Cost ◽  
The Impact

This paper investigates the optimal timing of the first inspection for newly-built onshore underground natural gas pipelines with respect to external metal-loss corrosion by considering the generation of corrosion defects over time and time-dependent growth of individual defects. The non-homogeneous Poisson process is used to model the generation of new defects and the homogeneous gamma process is used to model the growth of individual defects. A realistic maintenance strategy that is consistent with the industry practice and accounts for the probability of detection (PoD) and sizing errors of the inspection tool is incorporated in the investigation. Both the direct and indirect costs of failure are considered. A simulation-based approach is developed to numerically evaluate the expected cost rate at a given inspection interval. The optimal inspection interval is determined based on either the cost criterion or the safety criterion. An example gas pipeline is used to examine the impact of the cost of failure, PoD, and the excavation and repair criteria on the optimal inspection interval through parametric analyses. The results of investigation will assist engineers in making the optimal maintenance decision for corroding natural gas pipelines and facilitate the reliability-based corrosion management.

Validation of EMAT ILI for Management of Stress Corrosion Cracking in Natural Gas Pipelines

2014 ◽  
Author(s):  
Toby Fore ◽  
Stefan Klein ◽  
Chris Yoxall ◽  
Stan Cone
Keyword(s):  
High Resolution ◽  
Natural Gas ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Probability Of Detection ◽  
Gas Pipelines ◽  
Line Pipe ◽  
Natural Gas Pipelines ◽  
Electro Magnetic

Managing the threat of Stress Corrosion Cracking (SCC) in natural gas pipelines continues to be an area of focus for many operating companies with potentially susceptible pipelines. This paper describes the validation process of the high-resolution Electro-Magnetic Acoustical Transducer (EMAT) In-Line Inspection (ILI) technology for detection of SCC prior to scheduled pressure tests of inspected line pipe valve sections. The validation of the EMAT technology covered the application of high-resolution EMAT ILI and determining the Probability Of Detection (POD) and Identification (POI). The ILI verification process is in accordance to a API 1163 Level 3 validation. It is described in detail for 30″ and 36″ pipeline segments. Both segments are known to have an SCC history. Correlation of EMAT ILI calls to manual non-destructive measurements and destructively tested SCC samples lead to a comprehensive understanding of the capabilities of the EMAT technology and the associated process for managing the SCC threat. Based on the data gathered, the dimensional tool tolerances in terms of length and depth are derived.

Probability Calculation of Equipment Impact Based on Reliability Method

2014 ◽  
Author(s):  
Jiang Lu ◽  
Wen Wu ◽  
Zhenyong Zhang ◽  
Jinyuan Zhang
Keyword(s):  
Natural Gas ◽  
Survey Data ◽  
Fault Tree ◽  
Gas Pipelines ◽  
Impact Frequency ◽  
Dense Population ◽  
Natural Gas Pipelines ◽  
Reliability Based Design ◽  
Probability Calculation ◽  
The Impact

In order to apply the Reliability Based Design and Assessment (RBDA) methodology to evaluate the equipment impact on the onshore natural gas transmission pipelines in China, a research project was undertaken by China Petroleum Pipeline Engineering Corporation (CPPE) based on the framework developed by C-FER Technologies (C-FER) in “Guidelines for Reliability Based Design and Assessment of Onshore Natural Gas Pipelines” (sponsored by PRCI). The objective of the project was to collect native data and calibrate the probability models[1] in order to make it suitable for the situations in China where there is dense population and many newly-built high pressure and large diameter pipelines. The equipment impact model consists of two components: a) the impact probability model which calculates the frequency of mechanical interference by excavation equipment; and b) the failure model which calculates the probability of failure in a given impact. A detailed survey was undertaken in 2012 in order to collect the data required to calculate the impact frequency and the load applied by an excavator to a pipeline. The survey data for impact frequency calculation was gathered based on 19,300km of transmission pipelines from 4 operating companies in China. They reflect current prevention practices and their effectiveness. The frequencies of basic events summarized in this survey used to calculate the probabilities of the fault tree are generally agreement with the data summarized in PRCI’s report. The impact frequencies calculated by the fault tree under typical prevention measures are 400%, 200%, 20% and 0% higher than that in PR-244-9910 report for class 1, class 2, class 3 and class 4 areas respectively, which is due to dense population and more construction activities. Bucket digging forces of 321 types of excavators from 20 manufacturers were gathered. The survey data of the forces are slightly higher than that in the PR-244-9729 report as a whole due to the increase in mechanical efficiency of excavators in recent years. The excavator maximum quasi-static load model was calibrated correspondingly. Equipment impact probability calculation and model sensitivity analysis results are described to present several characteristics of onshore transmission natural gas pipelines in China.

Validation of EMAT Technology for Gas Pipeline Crack Inspection

2012 ◽  
Author(s):  
Richard Kania ◽  
Stefan Klein ◽  
Jim Marr ◽  
Gabriela Rosca ◽  
Elvis SanJuan Riverol ◽  
...  
Keyword(s):  
Natural Gas ◽  
Crack Detection ◽  
Probability Of Detection ◽  
Viable Alternative ◽  
Gas Pipelines ◽  
Validation Process ◽  
Natural Gas Pipelines ◽  
Initial Application ◽  
History Of ◽  
Electro Magnetic

The use of the Electro-Magnetic Acoustical Transducer (EMAT) technology for crack detection by In-Line Inspection (ILI) tools has increased over the last few years. Rigorous validation of the technology leading from the initial application of EMAT inline inspection tools through to determining Probability of Detection (POD) and Identification (POI) has contributed to improved confidence and reliability. EMAT results are being utilized to determine SCC valve section severity, to review and modify hydrostatic test schedules and intervals and could potentially be implemented as a viable alternative to hydrostatic testing. This paper describes the development of an EMAT ILI based program and the related validation process applied by the vendor, pipeline operator and in-ditch personnel. This process is illustrated by demonstrating the performance of the EMAT tool in two 20″ diameter natural gas pipelines which have a documented history of SCC. The tool identified hundreds of features in the two pipelines which were validated both in the ditch and via detailed anomaly sizing.

scholarly journals Modified Leakage Rate Calculation Models of Natural Gas Pipelines

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Qingmin Hou ◽  
Daheng Yang ◽  
Xiaoyan Li ◽  
Guanghua Xiao ◽  
Siu Chun Michael Ho
Keyword(s):  
Natural Gas ◽  
Flow Rate ◽  
Leakage Rate ◽  
Rate Change ◽  
Feedback Effect ◽  
Gas Pipelines ◽  
Natural Gas Pipelines ◽  
Pipe Model ◽  
Flow Rate Change ◽  
The Impact

The leakage rate is an essential parameter for the risk assessment and failure analysis of natural gas pipelines. The leakage rate of a natural gas pipeline should be calculated quickly and accurately to minimize consequences. First, in this study, models to estimate the leakage rate of natural gas pipelines are reclassified, and the theoretical range of application for each model is also analysed. Second, the impact of the leakage on the flow rate upstream of the leak point is considered, and the method of successive approximation is used to realize this feedback effect of flow rate change. Then, a modified hole-pipe model is developed to calculate the natural gas leakage rate in this paper. Compared with the leakage rate calculated by the hole-pipe model, the leakage rate calculated by the modified hole-pipe model is smaller and closer to the actual leakage rate due to the consideration of the feedback effect of the flow rate change. Finally, the leakage rate curves of the hole-pipe model and the modified hole-pipe model under different d/D conditions are obtained through simulation. The simulation results show that the modified hole-pipe model is able to calculate the leakage rate of any leak aperture, such as the hole-pipe model, and also at a higher accuracy level than the hole-pipe model.

Estimating the Cost of Switching Rights on Natural Gas Pipelines

1989 ◽  
Vol 10 (4) ◽  
Author(s):  
Frank C. Graves ◽  
James A. Read, Jr. ◽  
Paul R Carpenter
Keyword(s):  
Natural Gas ◽  
Gas Pipelines ◽  
Natural Gas Pipelines ◽  
The Cost
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