scholarly journals THE VARIATION OF THE STRESSES IN THE AREA OF DIAMETER CHANGE IN GAS PIPELINES

2017 ◽  
Vol 20 (2) ◽  
Author(s):  
MARCU FRĂŢILĂ
Keyword(s):  
Internal Pressure ◽  
Method Of Moments ◽  
Gas Pipeline ◽  
Gas Pipelines ◽  
Axially Symmetric ◽  
Loading Mode ◽  
Variable Diameter ◽  
Symmetric Structure ◽  
Discontinuity Zone ◽  
Diameter Change

<p>The paper presents an analysis of the variation of stresses at a gas pipeline in a geometric discontinuity zone of the diameter. The analysis was performed by assimilating the pipe area with variable diameter with an axially symmetric structure loaded with internal pressure. Stresses were determined using the method of moments, theory for axially symmetrical structures. The analysis was performed according to a set of parameters that define the geometry of a joining between a conical frustum and a cylinder and the loading mode with internal pressure. Efforts and stresses were determined in the meridian direction and in the circumferential direction adjacent coatings combining the two axially symmetries.</p>

scholarly journals An Accurate and Efficient Fitness-For-Service Assessment Method of Pipes with Defects under Surface Load

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5521
Author(s):  
Jianping Liu ◽  
Hong Zhang ◽  
Baodong Wang ◽  
Dong Zhang ◽  
Beilei Ji ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Working Conditions ◽  
Gas Pipeline ◽  
Surface Load ◽  
Critical Surface ◽  
Gas Pipelines ◽  
Defect Depth ◽  
Defect Position ◽  
Pipeline Safety ◽  
Hdpe Pipes

With continued urbanization in China, the construction of urban gas pipelines is increasing, and the safety of gas pipelines are also increasingly affected by urban development and the increased scope of buildings and roads. Pipes with defects are more likely to fail under the surface loads. In this study, uniaxial tensile tests of high-density polyethylene (HDPE) pipes were carried out to obtain the real material parameters of pipe. A pipeline-soil interaction finite element model of HDPE pipeline with defects under surface load was established. The failure mechanism of the urban gas pipeline was studied and the influence of parameters such as internal pressure, defect position, defect depth on the mechanical behavior, and failure of pipelines were analyzed. A failure criterion for HDPE pipes with defects under surface load was proposed based on the limit-state curves obtained under different working conditions. Furthermore, an accurate and efficient fitness-for-service assessment procedure of pipes with defects under surface load was proposed. The results showed that maximum Mises stress of the pipeline gradually increased with increasing surface load and the position of maximum stress changed from the top and bottom of the pipe to the defect position and both sides of the pipe. Finally, when Mises stress of the HDPE pipe exceeds the yield limit, failure will occur. Internal pressure, defect location, and defect depth were found to influence the failure process and critical surface load of the pipeline. Safety evaluation curves of the gas pipeline with defects under surface load were obtained by calculating the critical failure load of the pipeline under various working conditions. Finally, a nonlinear fitting method was used to derive a formula for calculating the critical surface load under different defect parameters. The proposed method provides a useful reference for urban gas pipeline safety management.

Comparison of PIR to PIPESAFE-Based 1% Lethality Zones for Natural Gas Pipelines

2014 ◽  
Author(s):  
Aleksandar Tomic ◽  
Shahani Kariyawasam
Keyword(s):  
Natural Gas ◽  
Small Diameter ◽  
Gas Pipeline ◽  
Accurate Estimation ◽  
Simple Relationship ◽  
Gas Pipelines ◽  
Friction Forces ◽  
Natural Gas Pipelines ◽  
Decay Factor ◽  
Outflow Rate

A lethality zone due to an ignited natural gas release is often used to characterize the consequences of a pipeline rupture. A 1% lethality zone defines a zone where the lethality to a human is greater than or equal to 1%. The boundary of the zone is defined by the distance (from the point of rupture) at which the probability of lethality is 1%. Currently in the gas pipeline industry, the most detailed and validated method for calculating this zone is embodied in the PIPESAFE software. PIPESAFE is a software tool developed by a joint industry group for undertaking quantitative risk assessments of natural gas pipelines. PIPESAFE consequence models have been verified in laboratory experiments, full scale tests, and actual failures, and have been extensively used over the past 10–15 years for quantitative risk calculations. The primary advantage of using PIPESAFE is it allows for accurate estimation of the likelihood of lethality inside the impacted zone (i.e. receptors such as structures closer to the failure are subject to appropriately higher lethality percentages). Potential Impact Radius (PIR) is defined as the zone in which the extent of property damage and serious or fatal injury would be expected to be significant. It corresponds to the 1% lethality zone for a natural gas pipeline of a certain diameter and pressure when thermal radiation and exposure are taken into account. PIR is one of the two methods used to identify HCAs in US (49 CFR 192.903). Since PIR is a widely used parameter and given that it can be interpreted to delineate a 1% lethality zone, it is important to understand how PIR compares to the more accurate estimation of the lethality zones for different diameters and operating pressures. In previous internal studies, it was found that PIR, when compared to the more detailed measures of the 1% lethality zone, could be highly conservative. This conservatism could be beneficial from a safety perspective, however it is adding additional costs and reducing the efficiency of the integrity management process. Therefore, the goal of this study is to determine when PIR is overly conservative and to determine a way to address this conservatism. In order to assess its accuracy, PIR was compared to a more accurate measure of the 1% lethality zone, calculated by PIPESAFE, for a range of different operating pressures and line diameters. Upon comparison of the distances calculated through the application of PIR and PIPESAFE, it was observed that for large diameters pipelines the distances calculated by PIR are slightly conservative, and that this conservativeness increases exponentially for smaller diameter lines. The explanation for the conservatism of the PIR for small diameter pipelines is the higher wall friction forces per volume transported in smaller diameter lines. When these higher friction forces are not accounted for it leads to overestimation of the effective outflow rate (a product of the initial flow rate and the decay factor) which subsequently leads to the overestimation of the impact radius. Since the effective outflow rate is a function of both line pressure and diameter, a simple relationship is proposed to make the decay factor a function of these two variables to correct the excess conservatism for small diameter pipelines.

METHODOLOGICAL ASPECT OF ASSESSING RELIABILITY OF MEDIUM PRESSURE GAS PIPELINES

2021 ◽  
pp. 97-107
Author(s):  
A.I. Pashentsev ◽  
A.A. Garmider
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Methodological Approach ◽  
Gas Pipeline ◽  
Methodological Aspect ◽  
Gas Pipelines ◽  
Gas Flow Rate ◽  
Medium Pressure ◽  
Reliability Calculation

The author’s vision of the methodological aspect of assessing the reliability of medium pressure gas pipelines is presented. Analysis of existing methods for assessing the reliability of gas pipelines with the identification of positive and negative features was carried out, a methodological approach to assessing the reliability of medium pressure gas pipelines by gas flow rate and pressure was developed and tested, and a scale for identifying the results of reliability calculation was developed. The test conducted on the example of a really working gas pipeline with a test for reliability showed its promise.

Flow Assurance in Deep-Water Gas Pipelines: Locating Hydrate Plugging Position in a Fast Way

2021 ◽  
Author(s):  
Jing Yu ◽  
Cheng Hui ◽  
Chao Wen Sun ◽  
Zhan Ling Zou ◽  
Bin Lu Zhuo ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Deep Water ◽  
Pipe Wall ◽  
Gas Pipeline ◽  
Flow Assurance ◽  
Gas Pipelines ◽  
Long Distance ◽  
Hydrate Layer ◽  
Hydrate Deposition ◽  
Water Gas

Abstract Hydrate-associated issues are of great significance to the oil and gas sector when advancing the development of offshore reservoir. Gas hydrate is easy to form under the condition featuring depressed temperature and elevated pressure within deep-water gas pipeline. Once hydrate deposition is formed within the pipelines, the energy transmission efficiency will be greatly reduced. An accurate prediction of hydrate-obstruction-development behavior will assist flow-assurance engineers to cultivate resource-conserving and environment-friendly strategies for managing hydrate. Based on the long-distance transportation characteristics of deep-water gas pipeline, a quantitative prediction method is expected to explain the hydrate-obstruction-formation behavior in deep-water gas pipeline throughout the production of deep-water gas well. Through a deep analysis of the features of hydrate shaping and precipitation at various locations inside the system, the advised method can quantitatively foresee the dangerous position and intensity of hydrate obstruction. The time from the start of production to the dramatic change of pressure drop brought about by the deposition of hydrate attached to the pipe wall is defined as the Hydrate Plugging Alarm Window (HPAW), which provides guidance for the subsequent hydrate treatment. Case study of deep-water gas pipeline constructed in the South China Sea is performed with the advised method. The simulation outcomes show that hydrates shape and deposit along pipe wall, constructing an endlessly and inconsistently developing hydrate layer, which restricts the pipe, raises the pressure drop, and ultimately leads to obstruction. At the area of 700m-3200m away from the pipeline inlet, the hydrate layer develops all the more swiftly, which points to the region of high risk of obstruction. As the gas-flow rate increases, the period needed for the system to shape hydrate obstruction becomes less. The narrower the internal diameter of the pipeline is, the more severe risk of hydrate obstruction will occur. The HPAW is 100 days under the case conditions. As the concentration of hydrate inhibitor rises, the region inside the system that tallies with the hydrate phase equilibrium conditions progressively reduces and the hydrate deposition rate slows down. The advised method will support operators to define the location of hydrate inhibitor injection within a shorter period in comparison to the conventional method. This work will deliver key instructions for locating the hydrate plugging position in a fast way in addition to solving the problem of hydrate flow assurance in deep-water gas pipelines at a reduced cost.

scholarly journals FLOW ASSURANCE IN KUMUJE WET-GAS PIPELINE: ANALYSIS OF PIGGING SOLUTION TO LIQUID ACCUMULATION

2018 ◽  
Vol 9 (9) ◽  
pp. 380-386
Author(s):  
Sarah Akintola ◽  
Emmanuel Folorunsho ◽  
Oluwakunle Ogunsakin
Keyword(s):  
Pressure Loss ◽  
Gas Pipeline ◽  
Gas Condensate ◽  
Flow Assurance ◽  
Gas Pipelines ◽  
Wet Gas ◽  
Highly Sensitive ◽  
Temperature And Pressure ◽  
Pipeline Corrosion ◽  
Assurance Problem

Liquid condensation in gas-condensate pipelines in a pronounced phenomenon in long transporting lines because of the composition of the gas which is highly sensitive to variations in temperature and pressure along the length of the pipeline. Hence, there is a resultant liquid accumulation in onshore wet-gas pipelines because of the pipeline profile. This accumulation which is a flow assurance problem can result to pressure loss, slugging and accelerated pipeline corrosion if not properly handled.

Advances in Abandonment and Disposal Technology of Aging Oil and Gas Pipelines

2021 ◽  
Author(s):  
Jiaqiang Jing ◽  
Wenlu Wang ◽  
Dongrong Wu ◽  
Jinhua Luo ◽  
Shuang Zeng ◽  
...  
Keyword(s):  
Environmental Protection ◽  
Oil And Gas ◽  
Residual Life ◽  
Practical Experience ◽  
Gas Pipeline ◽  
Practical Significance ◽  
Systematic Evaluation ◽  
Gas Pipelines ◽  
Oil And Gas Pipelines ◽  
The Status

Abstract When the operation benefit of an oil and gas pipeline is not enough to cover its operation cost, and the pipeline is no alternative use, seriously damaged, aged or the operation risk exceeds the acceptable range, it is bound to cause serious safety and environmental hazards along the pipeline, especially for the over age pipeline in service, therefore its scientific abandonment and reasonable disposal is particularly important and urgent. Focused on the methods for judging abandonment, retirement modes, cleaning and environmental management of oil and gas pipelines, the characteristics of existing methods for predicting the remaining life of the pipelines and their application in abandonment and disposal are compared and analyzed, and the basis and adaptability of oil and gas pipelines retirement are illuminated. According to the actual situation and environment of the discarded pipelines, the selection basis and applicable conditions of the pipeline and facility disposal methods such as demolition, in-situ shelving and their combination are expounded. It is found that North America has rich experience and mature technology in oil and gas pipeline abandonment and disposal, but many countries, including China, seriously lack scientific and systematic evaluation standards, practical experience, related theoretical and technical investigations. This study has important reference and practical significance for promoting the development of abandonment and disposal technology of an aging oil and gas pipeline, and ensuring the personal safety and ecological environmental protection along the abandoned pipeline. This paper presents the status quo of over age service and abandonment decision-making of oil and gas pipelines in the world, draws lessons from the experience of safety and environmental protection disposal of the global abandoned pipelines, and puts forward the principle and method of abandonment judgment and scientific disposal of the aging pipelines based on residual life evaluation. This method has sufficient basis, strong adaptability and wide application.

Ambient Temperature Effects Upon the Flow in Gas Pipelines at Low Speeds

2005 ◽  
Author(s):  
Gerald L. Morrison ◽  
Pardeep Brar
Keyword(s):  
Velocity Field ◽  
Flow Field ◽  
Ambient Temperature ◽  
Temperature Effects ◽  
Average Velocity ◽  
Gas Pipeline ◽  
Gas Pipelines ◽  
Flow Meter ◽  
Low Speeds ◽  
C 50

The flow field inside gas pipeline meter run is numerically simulated to determine the affects of upstream piping and temperature differences between the meter run pipe and the gas upon the flow. At bulk averaged velocities below 0.6 m/s (2 ft/s) significant changes in the velocity field are present which may alter the response of any flow meter mounted in the meter run. Examples for a bulk average velocity of 0.15 m/s (1/2 ft/s) and temperature differences with magnitudes of 27.7°C (50°F) are presented.

scholarly journals Improving the efficiency of gas pipeline cleaning by controlling the speed of the gas cleaning

2020 ◽  
pp. 29-35
Author(s):  
V. Ya Grudz ◽  
N. B. Slobodian
Keyword(s):  
High Speed ◽  
Moving Boundary ◽  
Linear Part ◽  
Initial Pressure ◽  
Gas Pipeline ◽  
Technological Scheme ◽  
Gas Pipelines ◽  
Technological Parameters ◽  
Degree Of Reduction ◽  
Main Gas Pipeline

An important aspect of improving the hydraulic efficiency of pipeline transport is its periodic cleaning with mechanical cleaning devices. Cleaning gas pipelines with cleaning pistons is a technologically complex process. It is advisable to adjust the speed of the piston to increase the efficiency of cleaning the pipeline with the crossed track profile. On the ascending and plain sections of the route, maintain a high speed of movement of the device, and on the descending it to reduce. To slow down the movement of the piston in the downstream sections of the main gas pipelines, it is proposed to change the technological scheme of the linear part. It is suggested to use a looping connection to change the flow chart. The change of the speed of movement of the treatment device when changing the technological scheme of the main gas pipeline was evaluated. The influence on the dynamics of the movement of the cleaning piston of the main parameters of the pipeline and looping, as well as the parameters of the movement of the piston itself, are investigated. A mathematical model of the process is built, on the basis of the implementation of which the regularities of the treatment device movement when changing the technological scheme of the gas pipeline are established. An equation was obtained to find the ratio of the mass flow rates of gas in the main gas pipeline before and after connecting the loop, which can be solved by the iteration method. The algorithm is developed and the program of calculation of the degree of reduction of the speed of movement of the piston is developed, depending on the kind of technological parameters and technical characteristics of the treatment device and the pipeline. Based on the calculations, the graphical dependences of the relative speed of the piston on the technological parameters and technical characteristics of the main pipeline were constructed. The authors found that the greatest effect on the degree of reduction of the speed of the piston has the length of the loop. It has been investigated that a decrease in the initial pressure and an increase in the final pressure, as well as an increase in the pressure drop at the moving boundary, lead to an improvement in the braking conditions

scholarly journals APPLYING DUDUCTIONS FROM NAVIER STOKES EQUATION TO FLOW SITUATIONS IN GAS PIPELINE NETWORK SYSTEM

2019 ◽  
Vol 1 (1) ◽  
pp. 10-18
Author(s):  
Mathew Shadrack Uzoma
Keyword(s):  
Stokes Equations ◽  
Optimal Level ◽  
Gas Pipeline ◽  
Navier Stokes ◽  
Network System ◽  
Gas Pipelines ◽  
Navier Stokes Equation ◽  
Flow Equations ◽  
Flow Models ◽  
Energy Equations

Navier Stokes equations are theoretical equations for pressure-flow-temperature problems in gas pipelines. Other well-known gas equations such as Weymouth, Panhandle A and Modified Panhandle B equations are employed in gas pipeline design and operational procedures at a level of practical relevance. Attaining optimality in the performance of this system entails concrete understanding of the theoretical and prevailing practical flow conditions. In this regard, Navier Stoke’s mass, momentum and energy equations had been worked upon subject to certain simplifying assumptions to deduced expressions for flow velocity and throughput in gas pipeline network system. This work could also bridge the link among theoretical, operational and optimal level of performance in gas pipelines. Purpose: The purpose of this research is to build a measure of practical relevance in gas pipeline operational procedures that would ultimately couple the missing links between theoretical flow equations such as Navier Stokes equation and practical gas pipeline flow equations. Such practical gas pipeline flow models are Weymouth, Panhandle A and Modified Panhandle B equations among others.Methodology: The approach in this regard entails reducing Narvier Stoke’s mas, momentum and energy equations to their appropriate forms by applicable practical conditions. By so doing flow models are deduced that could be worked upon by computational approach analytically or numerically to determine line throughput and flow velocity.The reduced forms of the Navier Stokes velocity and throughput equations would be applied to operating gas pipelines in Nigeria terrain. The gas pipelines are ElfTotal Nig. Ltd and Shell Petroleum Development Company (SPDC). This would enable the comparison of these gas pipelines operational data with theoretical results of Navier Stokes equations reduced to their appropriate forms.Findings: The follow up paper would employ theoretical and numerical discretization computational methods to compare theoretical and numerical discretization results to give a clue if these operating gas pipelines are operated at optimal level of performance.Unique contribution to theory, practice and policy: The reduced forms of Nervier Stokes equations applied to physical operating gas pipelines network system is considered by the researcher to be an endeavor of academic excellence that would foster clear cut understanding of theoretical and practical flow situations. It could also open up a measure of understanding to pushing a flow to attaining optical conditions in practical real life flow situations. Operating gas pipelines optimally would reduce the spread of these capital intensive assets and facilities and more so conserving our limited reserves for foreign exchange.

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