Reliability computation for a gas pipeline beam section with cracklike defects

In the context of the theory of random variables, a mathematical model is obtained for the probability of the nondestruction of a gas pipeline beam section in the presence of a longitudinal crack, which is located by means of pigging. A solution is obtained for the case when the fracture toughness of pipe steel, its physical and mechanical characteristics, loads, and the pipeline dimensions are nor mally distributed. An allowable mathematical expectation of the crack length is found for which the standard pipeline reliability and operational safety for the remainder of the service life are provided.     

Computation of strength reliability of a straight section of a trunk gas pipeline

An algorithm for probability computation of the strength reliability of a straight section of a trunk gas pipeline, where the ultimate strength of pipe steel, internal gas pressure, temperature difference, and pipe wall thickness are normally distributed, has been developed.     

Calculation of the strength reliability of an elastically bent section of a trunk gas pipeline

In the framework of the random number theory, a mathematical model is developed that enables one to calculate the static model factor of the strength reliability of an elastically bent section of a gas pipeline (nondestruction probability). The model is applied to the case where longitudinal normal stresses due to internal pressure, temperature, and the curvature function of the pipeline are normally distributed. The obtained data may be used as a basis for warranting the lifetime and preventing emergency failure of elastically bent sections of a pipeline as a result of deteriorated strength.     

Statistical modeling of the remaining life of a section of a main gas pipeline by low-cycle loading

On the basis of a deterministic formula, by the Monte Carlo method, the distribution of the remaining life of a gas pipeline according to the criterion of low-cycle fatigue is found in the form of a nonlinear function of 12 random arguments under the condition that strength characteristics of pipes, stress characteristics, strain amplitudes, and section sizes are normally distributed. Based on these data, a probabilistic forecast is made of the remaining reliability indices of those pipeline sections where means of nondestructive testing of operability are unavailable.     

Calculation of the reliability of the beam segment of a gas pipeline according to the stiffness criterion

A mathematical model for estimating the reliability of an aboveground beam segment of a gas pipeline according to the stiffness criteria has been developed in the framework of the Gaussian distribution of random quantities. The expected value of the gas pipeline wall thickness according to the predetermined reliability is determined that depends on the ratio between the expenditures for scheduled and emergency replacements.     

Calculation of the strength reliability of curved pipe inserts of a main pipeline

In the context of the theory of random variables, an expression is obtained for the strength reliability index (the probability of nonfailure) of curved pipe inserts of a gas pipeline when the physicomechanical characteristics of the metal, pipe diameter and wall thickness, gas pressure, temperature difference, and bending radius are distributed normally. Studies allowed us to establish the optimum reliability indices of curved pipe sections of a main gas pipeline for which its failure-free operation over a specified lifetime is ensured.     

Method of calculating the reliability of a gas pipeline segment under transverse-longitudinal bending

A mathematical model for estimating the reliability of an underground gas pipeline segment, which is described as a flexible rod element subjected to axial compression and transversal bending, is developed. The mathematical expectation of the pipeline’s wall thickness according to the required reliability, when the initial parameters are distributed according to the Gaussian law, is found. The results of the investigation are intended for design bureaus and enterprises for long-distance gas transfer.     

Calculating the reliability of a straight line segment of a gas pipeline under crack-like defects

In the framework of the random number theory, a mathematical model describing gas pipeline nonfailure reliability according to crack growth resistance criterion when the crack resistance of the pipe steel, the operation pressure of the cargo gas, the diameter and wall thickness of the pipe, the Poisson ratio, the linear expansion coefficient of the pipe metal, the Young modulus, and the temperature drop through the wall are all distributed according to the normal distribution law, has been obtained. The permissible value of the mathematical expectation of the longitudinal crack length has been found under which the standard reliability and safe operation of a defect segment of a gas pipeline is guaranteed.     

可燃工业气体管网主控阀的选用

通过阀门性能对比,确定了当介质压力≤4.0MPa时,可燃工业气体管网应优先选用气动固定式球阀。     

Reliability analysis of a compression section of a gas pipeline with the presence of longitudinal cracks

An algorithm is developed to find the expectation of the length of a longitudinal crack for a defective pipe at which the normative safe reliability level for a gas pipeline is maintained. The solution is obtained for the condition that crack resistance of pipe steel, compression force, gas pressure, coefficient of linear expansion, modulus of elongation, temperature difference of pipe walls, pipe diameter, and thickness are normally distributed.     

A method to calculate the reliability of the gas pipeline segment under axial compression

An algorithm is presented for probabilistic calculation of the gas pipeline strength reliability for the case when the ultimate strength of the pipe steel, compressing force, gas pressure, Young’s modulus, temperature drop, pipe thickness, and diameter are distributed normally.     

Development of inspection gauge system for gas pipeline

An autonomous pipeline inspection gauge system has been developed for determining position, orientation, curvature, and deformations such as dents and wrinkles of operating pipelines by Korea Gas Company and Seoul National University. The most important part of several subsystems is the Strapdown Inertial Measurement Unit (SIMU), which is integrated with velocity and distance sensors, weld detection system, and digital recording device. The Geometry Pipeline Inspection Gauge (GeoPIG) is designed to operate continuously and autonomously for a week or longer in operating gas pipelines. In this paper, the design concepts, system integration, and data processing/analysis method for the PIG will be presented. Results from the recent experiment for a 58 kilometer gas pipeline will be discussed.     

Probabilistic forecasting for life of a cross-country gas pipeline under stress-corrosion damages

The life distribution and reliability indices for a cross-country gas pipeline under stress-corrosion are determined by a determinate formula with the use a static modeling method. As a result, the optimum planned replacement interval for the damaged gas pipeline that eliminates its crashes is established.     

Estimating the reliability of elastically curved segment of gas pipeline using the criterion of crack growth resistance

In the framework of random number theory, a mathematical model describing the reliability of an elastically curved segment of a gas pipeline according to a crack growth resistance criterion for the case where the physicomechanical characteristics of the pipe steel, fracture strength, gas pressure, temperature drop through the wall, and radius of the elastic curve are distributed according to a normal (Gaussian) law is developed. According to this data we find the permissible sizes of cracklike defects under which the safety of operation and residual rated lifetime of potentially dangerous segments of a gas pipeline are guaranteed.     

一种气体管道用大口径止回阀的设计

瓦斯抽放管道对气体流过时压力损失要求较高,而目前市场上的止回阀依靠介质自身的压力开、闭阀门阀瓣,压力损失较大。设计了一种旋启式止回阀,在传统的阀体上增加了控制部分,止回阀正常工作时,阀瓣被吊起,减少了气体通过阀门的阻力;系统断电时,阀瓣能自由落下,阻止气体回流。     

浅谈我国主要天然气长输管线压缩机使用情况

介绍了常用压缩机在西气东输和陕京一线上的使用情况,并对不同管线应用的压缩机型号、运行参数、检测标准、压缩机的维护保养以及在线监测系统等方面进行分析。     

管道机器人可靠性分析模糊评判方法研究

基于模糊数学和系统可靠性的理论，提出了一种管道机器人可靠性分析的模糊评判方法，该方法是将机器人分为若干子系统，各子系统可靠性影响因素相同，而每个子系统的因素重要程度模糊子集和单因素评判矩阵不同，这样不仅从评判模型上考虑了各影响因素的不同作用，而且在方法上考虑了各影响因素对不同子系统的不同作用程度，因此更具有综合的特点。     

Evaluation of strength reliability of an oil-and-gas pipeline wall

As a result of the probability solution of the condition that the ring stress is lower than the limit stress, the fourth-order algebraic equation for determining the expected value of the wall thickness for the case when the initial parameters are normally distributed has been obtained. The sensitivity of the reliability of an oil and gas pipeline to the variations in the pressure, strength limit, diameter, and wall thickness has been studied, which improved its operation safety.     

Evaluation of pipeline reliability in the stop-valve junction zone

The algorithm for probability calculation of the strength reliability of a gas main in the stop-valve joint area is calculated when the ultimate stress of pipe steel, operation gas pressure, the Poisson ratio, diameter, and pipe wall thickness are distributed properly. Bending pressure occurs in the process, since pipe joints present themselves as edge effects.     

燃气管道用聚乙烯球阀

介绍了燃气管道用聚乙烯球阀的材料选择、类型结构、性能特点和应用。