scholarly journals On the stress state of a pressurised pipe with an initial thickness variation, subjected to non-homogeneous internal corrosion

2019 ◽  
Vol 121 ◽  
pp. 01013
Author(s):  
Shixiang Zhao ◽  
Yulia Pronina
Keyword(s):  
Pipe Wall ◽  
Numerical Procedure ◽  
Initial Boundary ◽  
Structural Instability ◽  
Thickness Variation ◽  
Initial Thickness ◽  
Minimum Thickness ◽  
Internal Corrosion ◽  
Pipe Wall Thickness ◽  
Initial Boundary Value

The paper concerns 2D problem of an elastic thick-walled pipe with an initial thickness variation, subjected to internal pressure and mechanochemical corrosion. The inner perimeter of the pipe cross-section is elliptical, while the outer is circular. The linear Dolinskii corrosion kinetics model is used. In the general case, structural instability of initial boundary value problems with unknown evolving boundaries can cause the divergence of numerical procedures when modelling the processes under study. It is observed that the attempts to circumvent the divergence of numerical procedure can suppress the manifestation of mechanochemical effect and yield inaccurate results. Thus, it is necessary to find a compromise between competing computational processes. Calculations revealed that the variation of the initial pipe wall thickness within the acceptable pipe wall tolerance can noticeably accelerate the growth of stresses and, consequently, reduce the durability of the pipe. The applicability of analytical solutions for a perfect circular pipe with a reduced thickness, equal to the minimum thickness of the imperfect pipe, to the case under study is also discussed.

Modernization of Hot-Rolled Tubes Rolling Method

2017 ◽  
Vol 265 ◽  
pp. 1048-1052
Author(s):  
D.A. Pavlov ◽  
Aleksandr Aleksandrovich Bogatov ◽  
E.A. Pavlova
Keyword(s):  
Pipe Wall ◽  
Thickness Variation ◽  
Elongation Ratio ◽  
Piercing Mill ◽  
Pipe Wall Thickness ◽  
Wall Thickness Variation ◽  
Rolling Method ◽  
Skin Formation ◽  
Automatic Tandem Mill ◽  
Hot Rolled

A new method of hot-rolled pipes rolling on the automatic tandem mill is suggested. It consists of two rolling stands. This method allows achieving the rough pipe preovalisation before reaching the automatic mill. The rough pipe preovalisation provides even groove filling and the decrease of pipe wall thickness variation. The rough pipe preovalisation will allow increasing the elongation ratio from 1.5 to 2.0 on the lengthwise rolling stand no. 1 and decreasing the elongation ratio on the piercing mill, therefore the chance of rolling skin formation on the external surface of the pipe is decreased. The way to reduce the probability of the formation of a guide mark defect due to the kinematic tension during rolling on a stub mandrel with rough tube preovalisation is investigated. The influence of the kinematic tension factor on the pipe forming in the groove taper at a lengthwise rolling with rough tube preovalisation is explored.

The Use of Reflection Mode Ultrasonic Transceiver Sensor in Pipeline Inspection Guage to Monitor Pipeline Internal Corrosion

2014 ◽  
Vol 70 (3) ◽  
Author(s):  
M. Azreen Firdaus Abd Aziz ◽  
Mariani Idroas ◽  
Zainal Zakaria ◽  
A. Ridhwan Md Zin ◽  
M. Nasir Ibrahim
Keyword(s):  
Wall Thickness ◽  
Pipe Wall ◽  
Percentage Error ◽  
Reflection Mode ◽  
Internal Corrosion ◽  
Pipe Wall Thickness ◽  
Pipeline Inspection ◽  
Corrosion Effect ◽  
Simulated Surface ◽  
Set Up

Aging gas transmission pipelines are prone to internal corrosion due to the presence of carbon dioxide and hydrogen sulphide in the natural gas constituents. Commonly, the in-line inspection tool known as Pipeline Inspection Gauge (PIG) is applied to perform the corrosion inspection of the pipeline. This paper describes an ultrasonic instrumentation system for PIG to monitor internal corrosion of pipeline. The system consists of ultrasonic transceiver sensor, ultrasonic driving circuitry and data acquisition system. The hardware is equipped with a sensor carrier which is propelled along the test pipeline. The time of flight (TOF) of the ultrasonic wave is measured and was used to evaluate the internal corrosion of pipeline. An initial experimental instrument was set up to perform the distance measurement test at a frequency of 390 kHz, to simulate the changes of pipe wall thickness due to corrosion effect. Surface anomalies were created at different positions to simulate the changes of pipe wall thickness due to the corrosion effect. Variation in measured distances implied the existence of the surface anomalies. The results of the simulated surface anomalies showed that the percentage error was less than + 5%. The large value of average DC voltage gave indication of distance increment due to the depth of the surface anomalies. The developed ultrasonic instrumentation system is capable to monitor the internal corrosion of pipeline.

scholarly journals ABSORPTION-DELAY MODELS OF HEAT TRANSPORT

2003 ◽  
Vol 13 (05) ◽  
pp. 645-660
Author(s):  
R. E. SHOWALTER ◽  
D. B. VISARRAGA
Keyword(s):  
Kinetic Models ◽  
Temperature Jump ◽  
Pipe Wall ◽  
Initial Boundary ◽  
Initial Boundary Value Problem ◽  
Convective Transport ◽  
Order Kinetic ◽  
Microstructure Model ◽  
Initial Boundary Value ◽  
Absorption Delay

A temperature jump in water traveling through a pipe is delayed by the absorption of heat into the pipe wall. The convective transport of heat by the water and the conductive exchange with the interior pipe wall are described by an exact but highly singular micro-model. The limiting form of this parabolic initial-boundary-value problem is a distributed microstructure model, which can successively be better approximated by simpler first- and second-order kinetic models. This model provides a means to validate and calibrate these classical multi-temperature kinetic models which are used to describe the delay.

scholarly journals Thermodynamic Properties of Vapors from Speed of Sound

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Muhamed Bijedić ◽  
Sabina Begić
Keyword(s):  
Thermodynamic Properties ◽  
Differential Equations ◽  
Speed Of Sound ◽  
Numerical Procedure ◽  
Initial Boundary ◽  
Initial Boundary Value Problem ◽  
Ideal Gas ◽  
Temperature Range ◽  
Initial Values ◽  
Initial Boundary Value

A numerical procedure for deriving the thermodynamic properties (Z, cv, and cp) of the vapor phase in the subcritical temperature range from the speed of sound is presented. The set of differential equations connecting these properties with the speed of sound is solved as the initial-value problem in T-ϕ domain (ϕ=ρ/ρsat). The initial values of Z and ∂Z/∂Tρ are specified along the isotherm T0 with the highest temperature, at a several values of ϕ [0.1, 1.0]. The values of Z are generated by the reference equation of state, while the values of ∂Z/∂Tρ are derived from the speed of sound, by solving another set of differential equations in T-ρ domain in the transcritical temperature range. This set of equations is solved as the initial-boundary-value problem. The initial values of Z and cv are specified along the isochore in the limit of the ideal gas, at several isotherms distributed according to the Chebyshev points of the second kind. The boundary values of Z are specified along the same isotherm T0 and along another isotherm with a higher temperature, at several values of ρ. The procedure is tested on Ar, N2, CH4, and CO2, with the mean AADs for Z, cv, and cp at 0.0003%, 0.0046%, and 0.0061%, respectively (0.0007%, 0.0130%, and 0.0189% along the saturation line).

Convergence of Finite Fifference Method for Parabolic Problem

2003 ◽  
Vol 3 (1) ◽  
pp. 45-58 ◽  
Author(s):  
Dejan Bojović
Keyword(s):  
Convergence Rate ◽  
Boundary Value Problem ◽  
Heat Equation ◽  
Parabolic Problem ◽  
Initial Boundary ◽  
Initial Boundary Value Problem ◽  
Variable Coefficients ◽  
Rate Estimate ◽  
Convergence Rate Estimate ◽  
Initial Boundary Value

Abstract In this paper we consider the first initial boundary-value problem for the heat equation with variable coefficients in a domain (0; 1)x(0; 1)x(0; T]. We assume that the solution of the problem and the coefficients of the equation belong to the corresponding anisotropic Sobolev spaces. Convergence rate estimate which is consistent with the smoothness of the data is obtained.

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