A Rational Design and Operating Strategy for Pipelines Traversing Unstable Slopes

1996 ◽  
Author(s):  
Gordon R. Simmonds ◽  
Z. Joe Zhou ◽  
Alan T. Samchek
Keyword(s):  
Life Cycle Cost ◽  
Rational Design ◽  
Ground Movement ◽  
Remedial Measures ◽  
Directional Drilling ◽  
Operating Life ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Assessment Techniques ◽  
Slow Moving

A common challenge for pipeline designers is the placement and safe operation of pipelines within unstable slopes. Consequently, special design and operation procedures must be created to maintain the integrity of the pipeline through its operating life. Nova Gas Transmission Limited (NGTL) has developed a methodology to monitor pipeline integrity in slow moving (creeping) unstable slopes. This methodology uses Pipeline-Soil Interaction models to produce parameters that are in turn placed in Pipeline Integrity Assessment Techniques such as finite element analysis. For slope movements, pipeline integrity is based on pipeline strain criteria that are established from regulated codes or NGTL’s risk-based criteria. The result is that pipe strain can be estimated over time given a particular soil type and predicted ground movement. The ability to predict when a pipeline is reaching a critical strain allows NGTL to effectively quantify the risk and associated cost for various remedial measures based on a given operating life (life-cycle cost). These remedial measures can take the form of strain relieving outages, re-routing of the pipeline, directional drilling, or conventional geotechnical remedial practices (dewatering, slope grading, buttressing, etc.). Two case studies are presented detailing this present state-of-practice methodology at NGTL.

scholarly journals Mechanical Integrity Assessment of Two-Side Etched Type Printed Circuit Heat Exchanger with Additional Elliptical Channel

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4711
Author(s):  
Armanto P. Simanjuntak ◽  
Jae-Young Lee
Keyword(s):  
Heat Exchanger ◽  
Stress Intensity ◽  
Maximum Stress ◽  
High Stress ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Printed Circuit ◽  
Mechanical Integrity ◽  
Finite Element Analysis Simulation ◽  
Maximum Stress Intensity

Printed circuit heat exchangers (PCHEs) are often subject to high pressure and temperature difference between the hot and cold channels which may cause a mechanical integrity problem. A conventional plate heat exchanger where the channel geometries are semi-circular and etched at one side of the stacked plate is a common design in the market. However, the sharp edge tip channel may cause high stress intensity. Double-faced type PCHE appears with the promising ability to reduce the stress intensity and stress concentration factor. Finite element analysis simulation has been conducted to observe the mechanical integrity of double-etched printed circuit heat exchanger design. The application of an additional ellipse upper channel helps the stress intensity decrease in the proposed PCHE channel. Five different cases were simulated in this study. The simulation shows that the stress intensity was reduced up to 24% with the increase in additional elliptical channel radius. Besides that, the horizontal offset channels configuration was also investigated in this study. Simulation results show that the maximum stress intensity of 2.5 mm offset configuration is 9% lower compared to the maximum stress intensity of 0 mm offset. This work proposed an additional elliptical upper channel with a 2.5 mm offset configuration as an optimum design.

Limit Load Analysis of Cracked Components Using the Reference Volume Method

2006 ◽  
Vol 129 (3) ◽  
pp. 391-399 ◽  
Author(s):  
R. Adibi-Asl ◽  
R. Seshadri
Keyword(s):  
Elastic Modulus ◽  
Three Dimensional ◽  
Local Limit ◽  
Limit Load ◽  
Multiple Cracks ◽  
Element Analysis ◽  
Limit Loads ◽  
Integrity Assessment ◽  
Reference Volume ◽  
Volume Method

Cracks and flaws occur in mechanical components and structures, and can lead to catastrophic failures. Therefore, integrity assessment of components with defects is carried out. This paper describes the Elastic Modulus Adjustment Procedures (EMAP) employed herein to determine the limit load of components with cracks or crack-like flaw. On the basis of linear elastic Finite Element Analysis (FEA), by specifying spatial variations in the elastic modulus, numerous sets of statically admissible and kinematically admissible distributions can be generated, to obtain lower and upper bounds limit loads. Due to the expected local plastic collapse, the reference volume concept is applied to identify the kinematically active and dead zones in the component. The Reference Volume Method is shown to yield a more accurate prediction of local limit loads. The limit load values are then compared with results obtained from inelastic FEA. The procedures are applied to a practical component with crack in order to verify their effectiveness in analyzing crack geometries. The analysis is then directed to geometries containing multiple cracks and three-dimensional defect in pressurized components.

Dent Screening Criteria Based on Dent Restraint, Pipe Geometry and Operating Pressure

2020 ◽  
Author(s):  
Sanjay Tiku ◽  
Arnav Rana ◽  
Binoy John ◽  
Aaron Dinovitzer
Keyword(s):  
Finite Element ◽  
Screening Method ◽  
Operating Pressure ◽  
Fe Modelling ◽  
Screening Criteria ◽  
Integrity Assessment ◽  
Magnification Factors ◽  
Assessment Techniques ◽  
Pipe Geometry ◽  
Stress Magnification

Abstract A safety advisory (2010-01), issued by the National Energy Board (NEB) in June 2010, referenced two incidents which were a result of a fatigue crack failure that occurred within shallow dents [1]. The dents in both instances were less than 6% (of the OD). Currently, there is no consensus on how shallow dents or shallow dents with stress concentrators, as called by the ILI tool, are assessed and acted upon. BMT Canada Ltd. (BMT) was contracted by the Canadian Energy Pipeline Association (CEPA) to develop a definition for shallow dents, and two levels of screening method for the integrity assessment of shallow restrained dents and unrestrained dents. These two levels are known as CEPA Level 0 and CEPA Level 0.5 dent integrity assessment techniques that may be applied without finite element modelling or detailed calculations. The BMT dent assessment finite element (FE) modeling method was used to develop an extensive database of dents for different pipe geometries (OD/t), indenter shapes, pipe grades, and indentation depths. The results of the FE modelling were used to develop trends for the stress magnification factors (KM) across the range of pipes and dents modelled. These trends are used as the basis for the Level 0 and Level 0.5 dent screening and assessment approaches that can be used for both unrestrained dents and shallow restrained dents. The results show that for low OD/t pipe geometry and/or low spectrum severity indicator (SSI) [2] dent fatigue life may not pose an integrity threat. These dent screening approached have been adopted in the API Recommended Practice 1183 Dent Assessment and Management, that is currently under development.

Strain-Based Failure Assessment Based on a Reference Strain Method for Welded Pipelines

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Jae-Sung Lee ◽  
Myung-Hyun Kim
Keyword(s):  
Reference Strain ◽  
Structural Integrity ◽  
Equivalent Stress ◽  
Strain Curve ◽  
Evaluation Procedure ◽  
J Integral ◽  
Element Analysis ◽  
Plastic Energy ◽  
Integrity Assessment ◽  
Strain Method

Abstract Engineering critical assessment (ECA) is an evaluation procedure for structures with flaws and has been widely applied for assessing pipeline integrity. The standards for structural integrity assessment, including BS 7910, involve stress-based ECA, and they are known to produce overly conservative results. Therefore, strain-based ECA has been recently developed as an alternative approach. One of the effective methods for improving the accuracy of strain-based ECA is the reference strain method. However, only a limited number of studies have applied this method to welded pipelines. Therefore, a numerical analysis based on strain-based ECA was performed for girth-welded joints with a circumferentially oriented internal surface crack. Particular attention was given to the strength mismatch effects. The equivalent stress–strain curve in BS7910 was used to reflect the strength mismatch effects in the reference strain. The results of the proposed method were validated with the results of a finite element analysis (FEA) in terms of the J-integral. Previous methods and the proposed method exhibit a reasonable correlation of the J-integral in the case of over-matching (OM). In the under-matching (UM) cases, while the previous procedures tended to underestimate or excessively overestimate the elastic-plastic energy release rate in comparison with the FEA, the proposed method evaluated the J-integral of pipelines with sufficient accuracy.

Investigation of Strain-Based Failure Assessment Based on Reference Strain Method for Welded Pipes

2019 ◽  
Author(s):  
Jae Sung Lee ◽  
Myung Hyun Kim
Keyword(s):  
Reference Strain ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Effective Means ◽  
Equivalent Stress ◽  
Strain Curve ◽  
Evaluation Procedure ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Strain Method

Abstract Pipelines are effective means to transport oil and gas. It is essential to maintain the safety of pipelines with the increasing demand for oil and gas resource. Welded pipelines may suffer damage such as cracks during installation and operation, and the consequence evaluation for such damage is very important. Engineering critical assessment (ECA) is the evaluation procedure for structures with flaws and has been widely applied for assessing the pipeline integrity. Although main standards of structural integrity assessment including BS 7910 are stress-based ECA, it is known to produce overly conservative results. In this regard, strain-based ECA has been recently developed. One of the methods for improving the accuracy of strain-based ECA is the reference strain method. However, only few researches with reference strain method applied to welded pipes are available. Therefore, in this study, a numerical analysis based on the strain-based ECA is performed for strength mismatched girth welded joints with a circumferentially oriented internal surface crack. Equivalent stress-strain curve in BS7910 is employed to reflect the strength mismatch effects in the reference strain. This paper compares the results from the reference strain method and finite element analysis: J-integral and reference strain. Strain capacity of the reference strain method with strength mismatch is also discussed against stress-based ECA.

Integrity Assessment of Cracked Piping Components: Experimental, Analytical and Numerical Studies

2005 ◽  
Author(s):  
J. Chattopadhyay ◽  
T. V. Pavankumar ◽  
A. K. S. Tomar ◽  
B. K. Dutta ◽  
H. S. Kushwaha
Keyword(s):  
Power Plants ◽  
Research Centre ◽  
Experimental Investigations ◽  
Integrity Test ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Pipe Elbow ◽  
Numerical Studies ◽  
Point Bend ◽  
Considerable Work

Integrity assessment of piping components is very essential for safe and reliable operation of power plants. Over the last several decades, considerable work has been done throughout the world to develop a methodology for integrity assessment of pipes and elbows, appropriate for the material involved. However, there is scope of further development/improvement of issues, particularly for pipe bends, that are important for accurate integrity assessment of piping. Considering this aspect, a comprehensive Component Integrity Test Program was initiated in 1998 at Bhabha Atomic Research Centre (BARC), India. In this program, both theoretical and experimental investigations were undertaken to address various issues related to the integrity assessment of pipes and elbows. Under the experimental investigations, fracture mechanics tests have been conducted on pipes and elbows of 200–400 mm nominal bore (NB) diameter with various crack configurations and sizes under different loading conditions. Tests on small tensile and three point bend specimens, machined from the tested pipes, have also been done to evaluate the actual stress-strain and fracture resistance properties of pipe/elbow material. The load-deflection curve and crack initiation loads predicted by non-linear finite element analysis matched well with the experimental results. The theoretical collapse moments of throughwall circumferentially cracked elbows, predicted by the recently developed equations, are found to be closer to the test data compared to the other existing equations. The role of stress triaxialities ahead of crack tip is also shown in the transferability of J-Resistance curve from specimen to the component.

INTEGRITY ASSESSMENT OF THICK WALLED INDUSTRIAL FURNACE TUBES

1993 ◽  
Vol 17 (2) ◽  
pp. 127-143
Author(s):  
R.K. Kizhatil ◽  
R. Seshadri
Keyword(s):  
Thermal Stresses ◽  
Furnace Operation ◽  
Remaining Life ◽  
Element Analysis ◽  
Integrity Assessment ◽  
Firing Rates ◽  
Linear Finite Element ◽  
Core Method ◽  
Furnace Tube ◽  
Integrity Assessments

This paper examines various simplified methods proposed to analyze stresses and predict damage and remaining life in furnace tubes subjected to sustained primary pressure stresses and cyclic secondary thermal stresses resulting from a typical furnace operation. Operational effects such as tube fouling, firing rates, startup-shutdown cycles are considered. Component integrity assessments are carried out using some recently developed techniques. A numerical example of a furnace tube made of HK-40 material is presented, and results obtained using a non-linear finite element analysis are compared with predictions obtained using the elastic-core method.

Life Cycle Cost Analysis Case Study on Corrosion Remedial Measures for Concrete Structures

2012 ◽  
Author(s):  
Jin How Ho ◽  
Azlan Abd. Rahman
Keyword(s):  
Life Cycle ◽  
Cost Analysis ◽  
Life Cycle Cost ◽  
Net Present Value ◽  
Cost Effective ◽  
Concrete Bridges ◽  
Analysis Tool ◽  
Life Cycle Cost Analysis ◽  
Remedial Measures ◽  
Present Value

Artikel ini membincangkan kajian ringkas berkaitan analisis kos kitaran hayat terhadap langkah-langkah pembaikan pengaratan bagi jambatan dan struktur marin konkrit yang terdedah kepada karbonasi atau serangan natrium klorida daripada air laut atau sumber-sumber lain. Perisian kos kitaran hayat, Bridge LCC 2.0 digunakan untuk menjalankan analisi kitaran hayat untuk tiga kes kajian melibatkan kaedah nilai bersih kini. Keputusan kajian menunjukkan analisis kos kitaran hayat berkeupayaan untuk membantu jurutera dan agensi pengangkutan dalam menilai keputusan penyelenggaraan yang efektif berkaitan dengan masalah pengaratan. Ia boleh digunakan sebagai alat analisis ekonomi kejuruteraan yang membantu mantaksir kos-kos perbezaan dan membuat pilihan terhadap langkah pembaikan pengaratan yang berkesan. Analisis kos kitaran hayat bagi langkah pembaikan dipengaruhi oleh banyak pemboleh ubah seperti kos permulaan, kos penyelenggaraan, tahun kekerapan, dan jangka masa analisis. Amalan terbaik untuk analisis kos kitaran hayat bukan sahaja mengambil kira perbelanjaan oleh agensi, tetapi perlu mempertimbangkan kos-kos oleh pengguna dan analisis sensitiviti di sepanjang jangka hayat sesuatu langkah pembaikan. Kata kunci: Analisis kos kitaran hayat, jambatan konkrit, pengaratan, langkah, pembaikan, pemulihan struktur, keberkesanan kos, kaedah nilai bersih kini (NPV) This paper discusses a short study on life cycle cost analysis (LCCA) on corrosion remedial measures for concrete bridges and marine structures, which are subjected to carbonation or ingress of sodium chloride from sea water and other sources. Life cycle costing software, Bridge LCC 2.0, was used to perform life cycle cost analyses on three case studies, based on net present value method. The analysis of the results showed that LCCA is capable of assisting engineers or transportation agencies to evaluate optimum maintenance decisions in corrosion–related problems. It can be used as an engineering economic analysis tool that helps in qualifying the differential costs and choosing the most cost–effective corrosion remedial measures. Life cycle costs for the remedial measures are influenced by many costing variables such as initial costs, periodic maintenance costs, frequency years and analysis period. The best practice of LCCA should not only consider agency expenditures but also user costs and sensitivity analysis throughout the service life of a remedial measure. Key words: Life cycle analysis, concrete bridges, corrosion, remedial measures, structural rehabilitation, cost-effective, net present value method (NPV)

Quantitative analysis of debris torrent hazards for design of remedial measures

1984 ◽  
Vol 21 (4) ◽  
pp. 663-677 ◽  
Author(s):  
O. Hungr ◽  
G. C. Morgan ◽  
R. Kellerhals
Keyword(s):  
Rational Design ◽  
Design Tool ◽  
Provincial Government ◽  
Remedial Measures ◽  
Runout Distance ◽  
Organic Debris ◽  
Discharge Velocity ◽  
Frequency Peak ◽  
Retention Barriers ◽  
Run Up

Debris torrents, which are rapid flows of soil and organic debris down steep mountain channels, are a major natural hazard in many parts of British Columbia.A series of recent occurrences along the Squamish Highway, north of Vancouver, led the provincial government to initiate a systematic study of debris torrents in this area. This 2 year study involved hazard risk assessment and resulted in the design of a comprehensive system of remedial measures comprising debris retention barriers and basins, channel improvements and diversions, and the reconstruction of bridges. It was necessary in the course of this effort to formulate new design procedures covering the dynamic behaviour of debris torrents, as there was no accepted practical methodology suitable for Western Canadian conditions.This paper provides an approach to determining magnitude (volume of debris material involved), frequency, peak discharge, velocity, conditions for deposition, runout distance, behaviour in bends and run-up against barriers, and dynamic thrust and impact loadings. The procedures are based on some of the more practical concepts available in the specialized literature, supplemented by simple original theories and calibrated against several recent debris torrent events from British Columbia for which sufficiently detailed observational data exists. To be generally applicable, the procedures require a wider and more thorough calibration. They are presented here as working hypotheses that can be used as a guide to the assembly of additional data and provide a rational design tool to supplement the application of experience and judgement. Key words: debris torrents, debris flows, slope hazards, landslide dynamics, remedial measures, engineering design.

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