Study on Duration of Hydrostatic Leak Test for Gas Pipeline

2008 ◽  
Author(s):  
Feng Yan ◽  
Yongxue Zhang ◽  
Hong Zhang ◽  
Qingquan Duan
Keyword(s):  
Mathematical Model ◽  
Temperature Variation ◽  
Water Pressure ◽  
Gas Pipeline ◽  
Hot Water ◽  
Leak Test ◽  
First Time ◽  
Water Pressure Testing ◽  
Residual Air ◽  
Test Result

A mathematical model about the duration of hydrostatic leak test for gas pipeline is developed for the first time in the paper. The influences of temperature variation, elastic deformation of the pipe and a certain amount of residual air filled within the pipe are synthetically considered in the model. The results indicate that the duration is longer while the amount of the residual air in the pipe or the volume of pipe is lager under the same pressure dropping. The required duration is increasing with the pressure going up. At the same time, the temperature variation greatly influences the pressure dropping of the pipeline. The conclusions are helpful for determining the reasonable duration of hydrostatic leak test for gas pipeline. Furthermore, it can also provide some references for judging leak test result while hot water pressure testing in winter.

Research on Leak Test for Long Distance Gas Pipline

2012 ◽  
Author(s):  
Feng Yan ◽  
Qing Miao ◽  
Xiangdong Xue ◽  
Yubin Wang ◽  
Daquan Li ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Temperature Variation ◽  
Gas Pipeline ◽  
Explicit Calculation ◽  
Pipeline System ◽  
Test Duration ◽  
Test Medium ◽  
Leak Test ◽  
Long Distance ◽  
Safe Operating

The main purpose of pre-service leak test is to prove the tightness of the pipeline system. It plays an important role to guarantee the safety operating of pipeline. However, the duration of leak test is different in different countries. If the duration of tightness test is longer, the tightness level can be sufficiently detected, which is benefit for pipeline safe operating, but the cost and the time of project must be extended; if the duration of tightness test is shorter, the defect of pipeline can not be fully exposed, which may be left hidden trouble for pipeline safe operating. Meanwhile, the tightness test may be influenced by many factors, for example the test medium, pipeline capacity, pressure, ambient temperature variation, leak detection methods, and so on. Therefore, it is unreasonable to leak test with same duration for different kinds of gas pipeline, which regulated in some standards, for example CSA Z662-11, BS EN1594:2000, ISO 13623:2008, GB 50251-2003, and so on. At the same time, those standards all regulated that the duration of tightness test should be properly extended while the pipeline capacity and ambient temperature variation obviously affect the accuracy of leak test, but the definite value is not regulated. In addition, they also regulated that the pressure increases or decreases during leak test shall be acceptable provided that it can be demonstrated through calculations that the pressure change is caused by ambient temperature variations, but there is no explicit calculation method. Now, the specified duration of leak test in different standards are all based on the engineering experience. Because there is no rational theory way, it makes the identification and modification of the duration for different kinds of pipeline become blind. Based on the theory of fluid mechanics, material mechanics, elastic mechanics, a mathematical model about the duration of leak test for long distance gas pipeline is developed for the first time. The influences of the test medium, pipeline capacity, pressure, ambient temperature variation and other factors which may impact the duration of leak test are synthetically considered in the model. The experimental verification shows that the result calculated by the model is accurate. It can provide reliable theoretical guidance for determining reasonable leak test duration for long distance gas pipeline.

scholarly journals CONTROL SYSTEM OF THE CENTRAL HEATING POINT AND RESEARCH OF ITS OPERABILITY

2020 ◽  
Vol 2020 (1) ◽  
pp. 101-102
Author(s):  
Nikolay Blagodarnyy ◽  
Anton Hvostov
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Water Supply ◽  
Water Pressure ◽  
Hot Water ◽  
Central Heating ◽  
Hot Water Supply

The main tasks of regulating the water pressure and temperature of the heating and hot water supply circuits of the Central heating point are described. A mathematical model of the Central heating point is constructed, and a control system is implemented.

scholarly journals An Optimized Mathematical Model for Items Supplies Planning of a Logistic System

2016 ◽  
Vol 10 (10) ◽  
pp. 133
Author(s):  
Mohammad Ali Nasiri Khalili ◽  
Mostafa Kafaei Razavi ◽  
Morteza Kafaee Razavi
Keyword(s):  
Mathematical Model ◽  
Mixed Integer ◽  
Logistics System ◽  
Proposed Model ◽  
Multiple Objective Decision Making ◽  
System Requirements ◽  
Purchasing Logistics ◽  
The Cost ◽  
The Mathematical Model ◽  
First Time

Items supplies planning of a logistic system is one of the major issue in operations research. In this article the aim is to determine how much of each item per month from each supplier logistics system requirements must be provided. To do this, a novel multi objective mixed integer programming mathematical model is offered for the first time. Since in logistics system, delivery on time is very important, the first objective is minimization of time in delivery on time costs (including lack and maintenance costs) and the cost of purchasing logistics system. The second objective function is minimization of the transportation supplier costs. Solving the mathematical model shows how to use the Multiple Objective Decision Making (MODM) can provide the ensuring policy and transportation logistics needed items. This model is solved with CPLEX and computational results show the effectiveness of the proposed model.

A Meshless Method for Solving the Mathematical Model Associated the Leakage Problem in Gas Pipeline

2014 ◽  
Vol 986-987 ◽  
pp. 1418-1421
Author(s):  
Jun Shan Li
Keyword(s):  
Differential Equation ◽  
Mathematical Model ◽  
Partial Differential Equation ◽  
Inverse Problem ◽  
Basis Function ◽  
Meshless Method ◽  
Numerical Solutions ◽  
Basis Functions ◽  
Gas Pipeline ◽  
The Mathematical Model

In this paper, we propose a meshless method for solving the mathematical model concerning the leakage problem when the pressure is tested in the gas pipeline. The method of radial basis function (RBF) can be used for solving partial differential equation by writing the solution in the form of linear combination of radius basis functions, that is, when integrating the definite conditions, one can find the combination coefficients and then the numerical solution. The leak problem is a kind of inverse problem that is focused by many engineers or mathematical researchers. The strength of the leak can find easily by the additional conditions and the numerical solutions.

Application of Magnetoelastic Effect of Ferromagnetic Material in Stress Measurement

2012 ◽  
Vol 496 ◽  
pp. 306-309 ◽  
Author(s):  
Yan Ping Shi ◽  
Shu Hua Fan
Keyword(s):  
Mathematical Model ◽  
Stress Measurement ◽  
Ferromagnetic Material ◽  
Induced Voltage ◽  
Practical Application ◽  
Magnetic Pole ◽  
Magnetoelastic Effect ◽  
Voltage Output ◽  
Contact Sensor ◽  
Test Result

A new non-contact sensor with three magnetic pole based on magnetoelastic effect was designed, and its operation principle and mathematical model of induced voltage output were given. The output characteristic of the sensor affected by field current intensity, frequency, and the gap between the probe of the sensor and the surface of the material tested was analyzed by testing. The calculation result based on the output model found by the paper accord basically with the test result. The results of the test have showed that the measuring precision and sensitivity of the sensor can meet the demands of the general practical application.

MATHEMATICAL MODELING OF CONCRETE STRUCTURE CORROSION IN BIOLOGICALLY AGGRESSIVE ENVIRONMENTS

2021 ◽  
Vol 3 (102) ◽  
pp. 55-67
Author(s):  
VARVARA E. RUMYANTSEVA ◽  
SVETLANA A. LOGINOVA ◽  
NATALIA E. KARTSEVA
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Parabolic Type ◽  
Cement Concrete ◽  
Mass Conductivity ◽  
Kinetics And Dynamics ◽  
Biological Corrosion ◽  
First Time ◽  
Fourth Kind

In the aquatic environment, biocorrosion is an important factor affecting the reliability and durability of concrete structures. The destruction of cement concretes during biological corrosion is determined by the processes of mass transfer. The article presents the development of a calculated mathematical model of liquid corrosion in cement concrete, taking into account the biogenic factor. For the first time, a model of mass transfer in an unbounded two-layer plate is considered in the form of differential equations of parabolic type in partial derivatives with boundary conditions of the second kind at the interface between concrete and liquid and of the fourth kind at the interface between concrete and biofilm. The results of a numerical experiment are presented to study the influence of the coefficients of mass conductivity and mass transfer on the kinetics and dynamics of the process.

scholarly journals Hysteresis in Muscle

2017 ◽  
Vol 27 (01) ◽  
pp. 1730003 ◽  
Author(s):  
Jorgelina Ramos ◽  
Stephen Lynch ◽  
David Jones ◽  
Hans Degens
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Hysteresis Loop ◽  
Mechanical Systems ◽  
Single Fibre ◽  
Scientific Disciplines ◽  
Main Components ◽  
First Time ◽  
Muscle Models ◽  
Clockwise Hysteresis

This paper presents examples of hysteresis from a broad range of scientific disciplines and demonstrates a variety of forms including clockwise, counterclockwise, butterfly, pinched and kiss-and-go, respectively. These examples include mechanical systems made up of springs and dampers which have been the main components of muscle models for nearly one hundred years. For the first time, as far as the authors are aware, hysteresis is demonstrated in single fibre muscle when subjected to both lengthening and shortening periodic contractions. The hysteresis observed in the experiments is of two forms. Without any relaxation at the end of lengthening or shortening, the hysteresis loop is a convex clockwise loop, whereas a concave clockwise hysteresis loop (labeled as kiss-and-go) is formed when the muscle is relaxed at the end of lengthening and shortening. This paper also presents a mathematical model which reproduces the hysteresis curves in the same form as the experimental data.

Analytical Buckling Loads of Columns Weakened Simultaneously with Transverse Cracks and Partial Delamination

2019 ◽  
Vol 19 (03) ◽  
pp. 1950027 ◽  
Author(s):  
Igor Planinc ◽  
Simon Schnabl
Keyword(s):  
Mathematical Model ◽  
Analytical Solution ◽  
Boundary Conditions ◽  
Parametric Study ◽  
Transverse Crack ◽  
Transverse Cracks ◽  
Buckling Loads ◽  
Crack Location ◽  
Benchmark Solution ◽  
First Time

This paper focuses on development of a new mathematical model and its analytical solution for buckling analysis of elastic columns weakened simultaneously with transverse open cracks and partial longitudinal delamination. Consequently, the analytical solution for buckling loads is derived for the first time. The critical buckling loads are calculated using the proposed analytical model. A parametric study is performed to investigate the effects of transverse crack location and magnitude, length and degree of partial longitudinal delamination, and different boundary conditions on critical buckling loads of weakened columns. It is shown that the critical buckling loads of weakened columns can be greatly affected by all the analyzed parameters. Finally, the presented results can be used as a benchmark solution.

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