A Systematic Approach for Evaluating Dent Severity in a Liquid Transmission Pipeline System

2010 ◽  
Author(s):  
Chris Alexander ◽  
Eelco Jorritsma
Keyword(s):  
Systematic Approach ◽  
Element Model ◽  
Fatigue Curve ◽  
Pipeline System ◽  
Operating Pressure ◽  
Remaining Life ◽  
Recent Experimental Study ◽  
Analysis Methodology ◽  
Transmission Pipeline ◽  
Level 3

An API 579 Level 3 assessment was performed to determine the stresses in a 2% dent in a 20-inch × 0.406-inch pipeline. The intent was to determine the stress concentration factor (SCF) in the dent with a finite element model using geometry data provided from an in-line inspection caliper run. In addition to the analytically-derived SCF, data were also evaluated from a recent experimental study involving a plain dent subjected to cyclic pressure conditions with a profile comparable to the dent in question. This sample was cycled at a stress range of 70% SMYS and failed after 10,163 cycles had been applied. Using the DOE-B mean fatigue curve, combined with the experimental fatigue life, the resulting SCF factor was derived to be 4.20. This value is within 1% of the calculated FEA-based SCF and served to confirm the technical validity of the SCF. The operator provided historical pressure data covering a 12-month period and a rainflow count analysis was performed on the data. Using this data, along with the API X′ design fatigue curve, the estimated remaining life was determined for the dent in question and conservatively estimated to be 65 years. This paper provides details on the analysis methodology and associated results, discussions on the empirically-derived SCF with its use in validating the analytical SCF, and application of the results to estimate the remaining life of the pipeline system. It is the intent of the authors to provide the pipeline industry with a systemic approach for evaluating dent severity using caliper and operating pressure history data.

Designing Offshore Pipeline Systems Divided Into Sections of Different Design Pressures

2004 ◽  
Author(s):  
Gunnar Staurland ◽  
Morten Aamodt
Keyword(s):  
Uniform Design ◽  
External Pressure ◽  
Transportation Systems ◽  
Point Of View ◽  
Pipeline System ◽  
Operating Pressure ◽  
Pipeline Systems ◽  
Upstream Pressure ◽  
Transmission Pipeline ◽  
Design Pressure

Norwegian waters have been a main arena for development of subsea pipeline technology over the last 25 year. The gas transportation systems from Norway to continental Europe comprise the largest and longest sub sea pipelines in the world. Codes traditionally require a pipeline to be designed with a uniform design pressure between stations with overpressure protection capabilities. However, the downstream part of a very long gas transmission pipeline may, after commissioning, rarely, if ever, see pressures near the pressure at the upstream end. There is, therefore, a potential for cost reduction and capacity improvement if two, or several, sections of different design pressure could be used without having to implement sub sea pressure regulation and overpressure protection facilities at the point of transition between the different sections of design pressure. In determining the lower design pressure the shutdown of the pipeline outlet facilities, at any point in time allowing for a practicable, achievable delay for closure of the upstream inlet valve has to be taken into account. The settle out pressure in a “normal” shut-in situation shall then not exceed the lower design pressure. In addition, deep water pipelines are often designed to withstand buckling due to bending and external pressure during installation, and may therefore locally tolerate a much higher internal pressure than the pipeline was designed for. Transmission pipelines crossing deepwater areas may therefore be designed for two or more operating pressures along the pipeline, thereby optimizing the cost. Even more important, for already existing pipelines, the capacity may be significantly increased by utilizing the upstream heavy wall sections. The operating pressure range for a long offshore gas transmission pipeline is very wide compared to an onshore line, typically between an upstream pressure of 150–250 bar, and a downstream pressure of 60 to 80 bar over a distance of several hundred kilometers. It may take hours to notice the closure of a downstream valve on the upstream pressure. Unless the pipeline is extensively packed, it is obvious that the pressure drop along the pipeline may be taken into account by allowing a lower design pressure for downstream part than for the upstream part. Thereby, the investment cost can be reduced. This paper describes the principles of designing a pipeline system divided into sections of different design pressures from a hydraulic point of view. The basis is the offshore standard for designing submarine pipeline systems, DNV OS-F101. The focusing will be on improvements in transportation efficiency, cost reductions and operational issues.

A Structured Approach for Managing Engineering Assessments

2014 ◽  
Author(s):  
Mike Reed ◽  
Reena Sahney ◽  
Darren Skibinsky
Keyword(s):  
Decision Making ◽  
High Pressure ◽  
Systematic Approach ◽  
Program Review ◽  
Pipeline System ◽  
Right Of Way ◽  
Natural Gas Transmission ◽  
Transmission Pipeline ◽  
Structured Approach ◽  
Specific Challenge

Alliance Pipeline, (Alliance), an integrated Canadian and U.S. high-pressure rich natural gas transmission pipeline system, conducts Engineering Assessments for a variety of reasons related to integrity activities such as investigative digs, right-of-way crossings, encroachments and program review; however, the need for a consistent and systematic approach to perform work of this nature was identified. As such, the company launched an initiative to develop a structured approach for undertaking, reviewing and approving Engineering Assessments. The specific challenge in developing a framework for conducting Engineering Assessments is twofold: the framework must be scalable, to address a broad range of situations, while remaining practical to use and understand. In light of these requirements, Alliance chose to adopt a “Tiered” approach to identifying requirements associated with each engineering assessment. The Tier of the Engineering Assessment is defined based on two primary factors: the complexity of the analysis (i.e., whether the methodology of the analysis is well established or not) and the nature of the underlying assumptions (i.e., whether the assumptions associated with the analysis are within established parameters). Once the appropriate Tier has been selected, the framework then provides guidance regarding the specific requirements in the areas of: responsibilities and qualifications of individuals for preparation, review and approval of the assessment as well as documentation. The implementation and use of the structured approach was intended to ensure the Engineering Assessments undertaken within pipeline integrity were technically sound, while recognizing that a broad range of technical complexity, skill level and decision making are associated with Engineering Assessment. Overall, this approach will allow Alliance to achieve a degree of uniformity of its Engineering Assessments in order to manage risks effectively, while addressing the needs of a broad range of scenarios that rely on the methodology.

Pipeline Instrumentation: The British Gas National Transmission System

1987 ◽  
Vol 20 (1) ◽  
pp. 18-25
Author(s):  
P Gilbert
Keyword(s):  
Distribution System ◽  
Transmission System ◽  
Process Conditions ◽  
Pipeline System ◽  
Operating Pressure ◽  
Distribution Grid ◽  
History Of Development ◽  
History Of ◽  
Instrument Engineer ◽  
Transmission And Distribution

The transmission and distribution system operated by British Gas plc is the largest integrated pipeline system in Europe. The whole system comprises a national transmission system which carries gas from five terminals to the twelve gas regions. Each region in turn carries the gas through a regional transmission system into a distribution grid and thence onto its customers. The national, regional and distribution system all present the instrument engineer with different technical challenges because of the way in which they have been built and are operated, however, it is simplest to characterise them by their process conditions. The operating pressure is highest in the national transmission system being up to 75 bar, in the regional transmission system the pressure is usually less than 37 bar, and in the distribution grid it is less than 7 bar. In general, the pipe diameters decrease from the national system downwards, and the measured flowrates are lowest in the distribution grids. This paper is concerned only with instrumentation on the national transmission system. The discussion will cover current technology which is typical of that being installed at present, and concentrates on the more commonly found instrumentation. The paper begins with a brief history of development of the national transmission system and a description of how it is operated. This is followed by a discussion on the application of computers to the control of unmanned installations. A section concerning the measurement of pressure and its application to the control of the system comes next. The main part of the paper contains an analysis of high accuracy flowmetering and the paper concludes with some comments on developments in instrumentation and their application to changing operation of the national transmission system.

Pressure Cycling Monitoring Helps Ensure the Integrity of Energy Pipelines

2010 ◽  
Author(s):  
Peter Song ◽  
Doug Lawrence ◽  
Sean Keane ◽  
Scott Ironside ◽  
Aaron Sutton
Keyword(s):  
Fatigue Life ◽  
Pipeline System ◽  
Outer Diameter ◽  
Operating Pressure ◽  
Potential Growth ◽  
Integrity Assessment ◽  
Pressure Cycling ◽  
Pressure Cycle ◽  
Primary Focus ◽  
Pump Stations

Liquids pipelines undergo pressure cycling as part of normal operations. The source of these fluctuations can be complex, but can include line start-stop during normal pipeline operations, batch pigs by-passing pump stations, product injection or delivery, and unexpected line shut-down events. One of the factors that govern potential growth of flaws by pressure cycle induced fatigue is operational pressure cycles. The severity of these pressure cycles can affect both the need and timing for an integrity assessment. A Pressure Cycling Monitoring (PCM) program was initiated at Enbridge Pipelines Inc. (Enbridge) to monitor the Pressure Cycling Severity (PCS) change with time during line operations. The PCM program has many purposes, but primary focus is to ensure the continued validity of the integrity assessment interval and for early identification of notable changes in operations resulting in fatigue damage. In conducting the PCM program, an estimated fatigue life based on one month or one quarter period of operations is plotted on the PCM graph. The estimated fatigue life is obtained by conducting fatigue analysis using Paris Law equation, a flaw with dimensions proportional to the pipe wall thickness and the outer diameter, and the operating pressure data queried from Enbridge SCADA system. This standardized estimated fatigue life calculation is a measure of the PCS. Trends in PCS overtime can potentially indicate the crack threat susceptibility the integrity assessment interval should be updated. Two examples observed on pipeline segments within Enbridge pipeline system are provided that show the PCS change over time. Conclusions are drawn for the PCM program thereafter.

Markovian Analysis of Aging Distributed Systems Remaining Life

2014 ◽  
Author(s):  
Anna Bushinskaya ◽  
Sviatoslav Timashev
Keyword(s):  
Distributed Systems ◽  
Markov Process ◽  
Residual Life ◽  
Limit State ◽  
Real Life ◽  
Random Variable ◽  
Operating Pressure ◽  
Remaining Life ◽  
Failure Pressure ◽  
The Moment

Correct assessment of the remaining life of distributed systems such as pipeline systems (PS) with defects plays a crucial role in solving the problem of their integrity. Authors propose a methodology which allows estimating the random residual time (remaining life) of transition of a PS from its current state to a critical or limit state, based on available information on the sizes of the set of growing defects found during an in line inspection (ILI), followed by verification or direct assessment. PS with many actively growing defects is a physical distributed system, which transits from one physical state to another. This transition finally leads to failure of its components, each component being a defect. Such process can be described by a Markov process. The degradation of the PS (measured as monotonous deterioration of its failure pressure Pf (t)) is considered as a non-homogeneous pure death Markov process (NPDMP) of the continuous time and discrete states type. Failure pressure is calculated using one of the internationally recognized pipeline design codes: B13G, B31Gmod, DNV, Battelle and Shell-92. The NPDMP is described by a system of non-homogeneous differential equations, which allows calculating the probability of defects failure pressure being in each of its possible states. On the basis of these probabilities the gamma-percent residual life of defects is calculated. In other words, the moment of time tγ is calculated, which is a random variable, when the failure pressure of pipeline defect Pf (tγ) > Pop, with probability γ, where Pop is the operating pressure. The developed methodology was successfully applied to a real life case, which is presented and discussed.

scholarly journals WAVE ANALYSIS OF A L-BEAM STRUCTURE WITH A BLOCKING MASS

2020 ◽  
Author(s):  
Johnny Tiu ◽  
Richard Bachoo
Keyword(s):  
Systematic Approach ◽  
Building Blocks ◽  
Element Model ◽  
Structural Systems ◽  
Structural Elements ◽  
Wave Analysis ◽  
Beam Structure ◽  
Reflection Matrix ◽  
Geometric Changes ◽  
Transmission And Reflection

The wave vibration approach regards the vibrations present within a structure as waves, whereby each wave flows along a structural member and upon meeting a discontinuity; portions of the incident wave are reflected and transmitted across the discontinuity. The reflected, transmitted and propagating wave transformations are represented mathematically by matrices, which are used to develop a set of wave relation equations at each discontinuity that can be used to describe the frequency response of the system holistically. This method creates a systematic approach of analysing structures by utilizing common cases as building blocks for a specific structure. The L-joint, described as two beams meeting at right angles; is a ubiquitous case for spatial portal and structural frames, which may become geometrically complex. Such structures are well suited to a wave vibration approach due to the large number of geometric changes and the prevalence as well as recurrence of specific cases. In this paper, the L-joint expanded to include a blocking mass, typically employed in structural systems and allows for the isolation and reflection of vibration away from contiguous structural elements. Included are; variance of transmission and reflection matrix components as the size of the blocking mass increases, numerical examples and comparison to a Finite Element Model developed in ANSYS.

Reliability-Based Assessment Method of Buried Pipeline at Fault Crossings

2020 ◽  
Author(s):  
Qian Zheng ◽  
Xiaoben Liu ◽  
Hong Zhang ◽  
Samer Adeeb
Keyword(s):  
Neural Network ◽  
Finite Element ◽  
Finite Element Model ◽  
Limit State ◽  
Element Model ◽  
Normal Operation ◽  
Operating Pressure ◽  
Peak Strain ◽  
Highly Nonlinear ◽  
Fault Displacement

Abstract The tectonic fault, which is one of the most common geohazards in field, poses great threat to buried pipe segments. Pipes will process to buckling or fracture due to large strain induced by continuously increasing ground displacements during earthquakes. Therefore, it is imperative to conduct safety analysis on pipes which are buried in seismic areas for the sake of ensuring normal operation. However, the highly nonlinearity of pipe response restricts the proceeding of reliability assessment. In this study, a hybrid procedure combining finite element method and artificial neural network is proposed for reliability-based assessment. First of all, the finite element model is developed on ABAQUS platform to simulate pipe response to strike-slip fault displacements. Thus, the strain demand value (the peak strain value obtained by finite element model in each design case) can be collected for database establishment, which is the preparation for neural network training. Thoroughness of the strain demand database can be achieved by a fully comprehensive calculation with consideration of influencing factors involving pipe diameter and wall thickness, operating pressure, magnitude of fault displacement, intersection angle between pipeline and fault plane, and characteristic value of backfill mechanics. Sequentially, Back Propagation Neural Network (BPNN) with double hidden layers is trained based on the developed database, and the surrogate strain demand prediction model can be obtained after accuracy verification. Hence, the strain-based limit state function can be respectively determined for tensile and compressive conditions. The strain capacity term is simply assumed based on published papers, the strain demand term is naturally superseded by the surrogate BPNN model, and Monte Carlo Simulation is employed to compute the probability of failure (POF). At last, the workability of the proposed approach is tested by a case study in which basic variables are referred to the Second West-to-East natural gas transmission pipeline project. It indicates that ANN is a good solver for reliability problems with implicit limit state functions especially for highly nonlinear problems. The proposed method is capable of computing POFs, which is an exploratory application for reliability research on pipes withstanding fault displacement loads.

Optimization of pipeline system with multi-hoop supports for avoiding vibration, based on particle swarm algorithm

2020 ◽  
pp. 095440622094711 ◽  
Author(s):  
Xudong Liu ◽  
Wei Sun ◽  
Ye Gao ◽  
Hui Ma
Keyword(s):  
Excitation Frequency ◽  
Particle Swarm ◽  
Element Model ◽  
Optimization Method ◽  
Operational Reliability ◽  
Particle Swarm Algorithm ◽  
Pipeline System ◽  
Pipe System ◽  
Swarm Algorithm ◽  
Single Pipe

In the dynamics design of aero-engine pipeline systems, it is necessary to avoid the excitation frequency of the engine (mainly including the rotational frequencies of high pressure and low pressure rotor systems) to improve the operational reliability of the pipeline system. In this study, a single-pipe system with multi-hoop supports was chosen as the research object, and a method based on the particle swarm algorithm was developed to optimize the layout of the hoops for effectively avoiding vibration of the pipeline system. A finite element model (FEM) of the pipeline system was created and the group of spring elements with non-uniform distribution of stiffness values was used to simulate the hoop support for improving the analysis accuracy of the model in the modeling process. Taking the hoop position as design variable, an optimization model of the pipe hoop layout was established, which aims at avoiding one or two excitation frequencies at the same time. Furthermore, the calculation procedure of optimizing pipe hoop layout using the particle swarm algorithm was given. Finally, a case study was carried out, the rationality of the created FEM was validated by experiments, and the optimal layout of hoops was obtained using the proposed optimization method.

Data Analysis and Model Validation of Natural Gas Transmission Pipeline With Compressor Station

2019 ◽  
Vol 4 (3) ◽  
Author(s):  
David Cheng
Keyword(s):  
Performance Analysis ◽  
Natural Gas ◽  
Model Validation ◽  
Measurement Data ◽  
Gas Pipeline ◽  
Pipeline System ◽  
Actual System ◽  
Natural Gas Transmission ◽  
Transmission Pipeline ◽  
Performance Analysis Tools

Abstract Data from the distributed control system (DCS) or supervisory control and data acquisition (SCADA) system provide useful information critical to the evaluation of the performance and transportation efficiency of a gas pipeline system with compressor stations. The pipeline performance data provide correction factors for compressors as part of the operation optimization of natural gas transmission pipelines. This paper presents methods, procedures, and an example of model validation-based performance analysis of a gas pipeline based on actual system operational data. An analysis approach based on statistical methods is demonstrated with actual DCS gas pipeline measurement data. These methods offer practical ways to validate the pipeline hydraulics model using the DCS data. The validated models are then used as performance analysis tools in assessing the pipeline hydraulics parameters that influence the pressure drop in the pipeline such as corrosion (inside diameter change), roughness changes, or basic sediment and water deposition.

An Optimization Model for the Energy Consumption vs. Gas Cooling Requirements in a Large NPS 56 Gas Transmission System

2006 ◽  
Author(s):  
Neda Razi
Keyword(s):  
Energy Consumption ◽  
Ambient Temperature ◽  
Transmission System ◽  
Optimization Process ◽  
Pipeline System ◽  
The South ◽  
Transmission Pipeline ◽  
Gas Cooling ◽  
The Impact ◽  
Gas Refinery

Optimization of a large gas transmission pipeline results in reduced fuel consumption or higher capability and improves pipeline operation. In the current study, we have done an extensive research to optimize the operation of a huge NPS 56 pipeline system using gas cooling. This gas transmission line (the 4th major gas transmission pipeline of the National Iranian Gas Company, NIGC, or IGAT4) is designed to move over 110 MMSCMD (4.0 BCFD) of natural gas from the Assaluyeh Gas Refinery. This gas refinery which in turn receives gas from the huge gas reservoir of the South Pars Field (Iranian off-shore) is located in the south of Iran. The length of this system is over 800 kms (500 miles) with over 700 MW of compression power and aerial coolers at all compressor stations. This system passes through a very tortuous terrain with significant changes in elevation and ambient temperature which makes the optimization process even more challenging. The main objective of this project was to develop a customized tool to optimize the operation (energy consumption) of this gas transmission pipeline with all the existing system variables. The emphasis was on the impact of gas cooling (effective operation of aerial coolers) on the optimization process which in turn leads to the fuel minimization or higher capability. In this process, the impact of ambient temperature, soil temperature throughout the entire route of the pipeline, cost of electricity & fuel gas, heat transfer and Joule-Thompson effect were carefully considered. The tool was finally developed and was successfully tested on this gas transmission system which resulted in extremely accurate results. This tool could be further generalized to be used for other transmission systems.

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