Pipe Dimensions Research Articles

Experimental study on a novel UHPC grout-filled pipe sleeve with mechanical interlocking for large-diameter deformed bars

Grouted sleeve splice is a competitive alternative to reinforcement connections of accelerated bridge construction (ABC). When it is used to connect large-diameter deformed bars, overlong development length is required, although the decreased amount of connected bars and increased construction tolerance can accelerate construction speed. This paper aims to develop a novel ultra-high performance concrete (UHPC) grout-filled pipe sleeve with bolts for large-diameter deformed bars. It is expected to shorten the embedded length and delay grout crushing and splitting caused by bolts using UHPC's high material properties. A direct tensile test was conducted on 21 specimens to validate the feasibility, investigate the design parameters' effects, and explore the working mechanism of the pipe sleeve. Results show that the proposed pipe sleeve is feasible to connect large-diameter deformed bars with an embedded length of 5db. There are four failure modes including grout bond failure without/with bolts as well as bar bond failure without/with bolts in this test. UHPC without steel fiber is a preferred grout for the pipe sleeve because steel fiber can weaken grout fluidity and reduce bar-grout bond strength as well as grout-pipe bond strength. The existence of bolts can significantly enhance bar-grout bond strength as well as grout-pipe bond strength. The grout-pipe bond performance is sensitive to the depth of bolts in grout, amount of bolts, and distance of bolts to the end. When the pipe sleeve is used for deformed bars with higher strength, bearing capacity is slightly increased and deformation capacity is markedly weakened for bar-grout bond behavior. A greater cross dimension of the steel pipe is a good choice to avoid grout bond failure.

A model of stress concentration factors for external corrosion patches on large-diameter underground cast iron pipes

ABSTRACT Field evidence revealed that buried cast iron water pipes can deteriorate through large localized corrosion patches with lengths greater than 1 m, formed by a cluster of small pits. This study investigated the effect of large corrosion patches on the performance of large-diameter cast iron pipes. Although large corrosion patches are highly irregular in nature, they were idealized as semi-ellipsoids. To validate the approximation of corrosion patch geometries with semi-ellipsoids, comparison of finite element models of scanned corroded pipe geometries with the approximated semi-ellipsoidal patches on the same pipes were conducted. Following this validation, parametric studies were performed, which covered a wide range of the pipe and patch dimensions. Based on the finite element analysis, an equation for stress concentration factors was derived and is presented in this paper. This development will significantly assist the pipe engineers and asset managers in the condition assessment of corroded cast iron pipelines.

A new method to determine elasto-plastic J-integral for steel pipes with longitudinal semi-elliptical surface cracks

Steel pipes have been widely used in the water and petroleum industries where crack-like flaws have long been recognised as a major cause of their failures. This paper intends to develop a new method for determining the elasto-plastic J-integral of cracked pipes made of all types of steel. A solution to elasto-plastic J-integrals is derived for external longitudinal semi-elliptical surface cracks in pressurised steel pipes. A meshing technique is developed in the detailed three-dimensional finite element analysis that incorporates the mixed types of quadratic tetrahedron and hexahedron elements. The developed method is verified with detailed finite element results. It is found in the paper that the general trend of normalised fully plastic J-integral changes with the change of crack depths and aspect ratios, and the magnitude of normalised fully plastic J-integrals can be significantly affected by material properties and pipe dimensions. The developed method can provide a useful tool for the failure assessment of pressurized steel pipes, allowing for a wide range of pipe dimensions, crack geometries and material properties.

Visualization of Acoustic Standing Waves in a Closed Pipe Based on an Electronic Speckle Pattern Interferometer

We visualize acoustic standing waves supported in a closed-end square pipe based on an electronic speckle pattern interferometer and measure the wavelengths of the acoustic standing waves for undergraduate physics lab courses. Generating four acoustic standing waves of frequencies below the cutoff frequency governed by the physical dimensions of the pipe, we obtain the distribution of the irradiance difference of the speckle patterns in the interferogram and compare that to the result of a theoretical calculation. In addition, we estimate the wavelengths of the acoustic standing waves by measuring the distances between adjacent nodes of the speckle patterns. We show that the experimental results and the results of the theoretical calculations are in good agreement. This work facilitates the understanding of electronic speckle pattern interferometers and their applications in visualizations of acoustic waves for undergraduate physics laboratories.

Revealing hidden debottlenecking potential in flare systems on offshore facilities using dynamic simulations – A preliminary investigation

Three flare systems are modeled and total plant depressurization is investigated using dynamic simulations in order to access the debottlenecking potential. Usually, steady-state simulation of the flare network is used for sizing and rating of the flare system. By using dynamic simulations, effects from line packing in the flare system can be studied. The results show that peak flow during a dynamic simulations is significantly lower than the peak flow used in a steady-state case. The three systems investigated span a wide range in flare system size, both in terms of number of process segments disposing into the flare network, in terms of peak design rate, the flare network pipe dimensions and total hold-up volume. Generally, it is observed that the larger the flare system, the larger debottlenecking potential.

К РАСЧЁТУ ЭЛЛИПТИЧЕСКОГО ЛОМАТЕЛЯ С ЭФФЕКТОМ ПАМЯТИ ФОРМЫ

The investigation purpose consists in the development of a calculation model of a thermo-mechanical power device intended for destruction of concrete structures and hard mineral rock. Its operation principle is based on the transformation of the initial round cross-section into the oval one during realization of alloy form memory that ensures a wedging effect. 
 There is offered the solution of the problem on linear effort definition of a crusher at its impact upon well sides depending on rock resistance and capacity of thermo-mechanical return. The investigation method consists in the modeling of a power pipe with the cylindrical shell at its non-axisymmetric loading as a deformation-power analogue of which a thermo-mechanical diagram is accepted. The essential condition of such an approach is the identity of a task and deformation restoration with samples at the diagram formation and a power element in the structure. 
 Thereupon fundamentally new is a calculation definition of the parameters of reactive stress dependence upon the deformation value of under-restoration at radial bending according to the diagram at the specified deformation by stretching that allows excluding a labor-intensive experiment. 
 As a result of the investigations there are obtained formulae for the definition of a linear effort and also for the computation of pipe dimensions within the limits of design calculation. 
 There is shown an actual example of power characteristics definition. The calculation reliability is confirmed with the application of these power devices during radioactive concrete structure destruction at one of nuclear power plants and at hard rock destruction at emerald field development. In such a way, the thermo-mechanical crusher design offered and a corresponding procedure for calculations can be used in practice without any changes.

Mechanical behavior of buried composite pipelines subjected to strike-slip fault movement

Buried composite pipelines crossing active faults can be deformed significantly due to strike-slip fault movement. Because of the problem complexity arising from material mechanical behavior and imposed large deformation, a numerical analysis was conducted using a nonlinear finite element approach. The lateral displacement incrementally was imposed normal to the pipe axis until one of the pipe layers failed based on the Hashin failure criteria. The effective factors on the buried composite pipeline performance, such as the pipe dimensions, composite lay-up, and soil stiffness, were studied parametrically. The results showed that the winding angle of the composite pipe has significant effects on the response of the pipe subjected to the fault movement, therefore determining an optimum winding angle is very important for practical engineering designs. In addition, the results show that the effect of changing the pipe diameter cannot be predicted easily, and also it is depended on the winding angle. However, changing the soil stiffness did not change the optimum winding angle. Furthermore, the comparison conducted for the studied composite and steel pipes at the similar simulation conditions showed that the composite pipe has a better response until the onset of the failure, and the composite pipe could be considered as a suitable replacement for the conventional buried steel pipeline.

Performance comparison of a vertical direct expansion geothermal evaporator: Part I, single U-pipe using different refrigerants

Abstract CO2 is a promising candidate for replacing synthetic refrigerants used in direct-expansion ground-source heat pumps (DX-GSHPs). The present paper, as the first part of two, presents a numerical performance comparison of a vertical single U-pipe direct expansion geothermal evaporator using different refrigerants; namely R744, R410A, R22, R407C, R12345yf, and R134a. Each refrigerant was tested through a borehole heat exchanger (BHE) performance simulation at a constant rate of heat extraction. Operating parameters were chosen so that each refrigerant is subjected to a complete evaporation cycle, and a similar pressure drop from the inlet to outlet of the borehole. Several BHE parameters such as fluid temperature, pressure, mass flow rate, required pipe dimensions, and required power for fluid circulation were evaluated for different refrigerants. Finally, the overall performance of each refrigerant was characterized by the heat exchange capacity for a unit of mass flow rate and pipe surface area. Results showed that CO2 offers unique characteristics favoring the design of compact BHEs, as it required the smallest mass flow and pipe surface area. It is also concluded that the performance of a BHE with CO2 can be significantly improved through using unconventional configurations. This will be discussed further in the second part (PART II).

Performance comparison of a vertical direct expansion geothermal evaporator: PART II, multiple U-pipes

Part I showed that Carbon Dioxide (CO2) is a promising candidate for use in vertical direct expansion ground evaporators, as it requires smaller pipe diameters within the geothermal heat exchanger and lower power for refrigerant circulation compared to conventional refrigerants. Furthermore, pressure change along the geothermal evaporator influences marginally the evaporation temperature leading to quasi-isothermal evaporation of CO2. However, in single U-pipe configurations, small pipe diameter means lower pipe surface area and therefore higher thermal resistance. In Part II, all these advantages are taken into consideration toward proposing new geothermal evaporator configurations with multiple U-pipes (2 to 4 U-pipes in one borehole). R410A is also compared against CO2 for the new configurations. Operating parameters of all configurations were chosen so that CO2 and R410A are both subjected to a complete evaporation for equal total pipe surface area and equal heat extraction rate. Although all configurations have same total pipe surface area, it is shown that adding U-pipes and reducing pipe diameters diminishes borehole thermal resistance significantly. A novel configuration is also proposed to lower pressure drop of CO2 in the 4-U borehole configuration by insulating a portion of the downward U-pipe legs. Decreasing pipe dimensions by adding U-pipes while keeping total pipe surface area constant offers an opportunity to bundle pipes closer to each other and make the evaporator more compact as seen in the proposed Polymer Block configuration.

Analysis of light extraction in light pipes by linear and elliptical grooves using different source aperture angles

An analytical and numerical analysis of light extraction from light pipes using total internal reflection grooves with linear and elliptical profiles is presented. We performed the study considering light sources with different aperture angles, such as sunlight delivered by optical fibers and LEDs. With this analysis, we propose an analytical model based on the edge ray concept that allows selecting the most convenient profile, size, and orientation of the groove to extract light with a desired illumination area according to the source aperture angle employed in the light pipe system. We also have numerically found that for sources with high aperture angles, the light extracted by the linear and elliptical grooves produces similar irradiance and angular distributions, whereas for sources with low aperture angles, the elliptical groove focuses the extracted light and produces a higher angular distribution in comparison to this obtained with the linear groove. Our results are scalable to different light pipe dimensions and provide a systematic way to obtain preliminary designs of grooves for lighting systems that employ optical sources with different aperture angles.

Experimental study using advanced diagnostics to investigate slug aeration and bubble behavior in high liquid viscosity horizontal slug flow

Accurate prediction of slug liquid holdup is critical for accurate calculation of pressure gradient and average liquid holdup in pipes. However, most of the existing slug liquid holdup models are only accurate for a specific range of operating conditions, pipe dimensions, and fluid properties. The majority of these models are empirical, lacking the physical basis of slug aeration mechanisms. In this study, bubble entrainment mechanisms, bubble trajectories, and bubble loss from the slug body were identified. The experimental results from the high-speed camera (HSC) and particle image velocimetry (PIV) enabled detailed investigation of bubble entrainment mechanisms at slug front, bubble deformation and trajectories in slug body. These experimental observations were further analyzed and related to operating conditions and fluid properties. A horizontal 50.8-mm (2-in.) inner diameter (ID) pipe, and high viscosity liquid/air-fluid system (μL ≈ 0.51, 0.68 and 0.96 Pa s) were utilized. Experimental results revealed that the rate of gas entrainment at slug front, the bubble deformation in the slug body, and the number of fragmented bubbles in the slug unit all increase as mixture velocity and liquid viscosity increase, and as surface tension decreases. The proposed slug aeration mechanisms, and bubble behavior and characteristics in the slug body can form the basis for further mechanistic modeling of slug liquid holdup and other parameters required for proper slug flow modeling.

Numerical simulation and experimental investigations on a three-roller setting round process for thin-walled pipes

In order to reveal the process principle of three-roller setting round process and optimize the setting round strategy, the three-roller setting round process is simulated and experimented. The results show that there are three positive bending regions and three reverse bending regions in the cross section of pipe in the setting round process. The absolute value of equivalent stress and equivalent strain not only decreases from both ends to the geometric neutral layer along the thickness direction of pipe but also decreases from the center of each positive and negative bending region to both sides along the circumferential direction of pipe. The distribution of maximum stress and minimum stress conforms to the characteristics of pure bending deformation in the setting round process. The direction of tangential stress is the direction of main stress, and the direction of tangential strain is the direction of main strain. The geometrical dimensions of pipe do not change in axial and radial directions. The residual ovality of pipes with different initial ovality is basically the same, which proves that the uniform curvature theorem of reciprocating bending is correct. The residual ovality of pipes decreases with the increase of the reduction. With the increase of the relative thickness of pipes, the optimum reduction of pipes decreases gradually. Comparing experimental results with simulation results, the residual ovality of pipes can be less than 0.2%.

Pipe-to-pipe friction welding of dissimilar Al-SS joints for cryogenic applications

In the present investigation, dissimilar materials such as AA6063 and SS304L having pipe dimensions of 60.33 mm outer diameter and 3.9 mm wall thickness were friction-welded with different conditions of process parameters. Nondestructive tests such as radiography test (RT) and liquid penetration test (LPT) were carried out on the welded pipes in order to qualify weld joint. Thermal shock test and helium leak tests were performed on the successful welded samples in order to check its ability to work with cryogenic application. The results revealed that the pipe-to-pipe configuration of dissimilar Al–SS joints was produced successfully by friction welding using continuous drive. There were no defects presented in the joint area as revealed by RT and LPT. Thermal shock test and helium leak tests have also confirmed the soundness of joints. Higher deformation of Al base material results in the huge flash formation of Al that results in the sleeve formation of Al pipe on SS pipe. The helium leak test has confirmed the soundness of joints without any defects after its testing at 1.2 psi pressure. More than 60% of joint efficiency was obtained from Al–SS friction-welded joints.

An Application of Computational Fluid Dynamics to Optimize Municipal Sewage Networks; A Case of Tororo Municipality, Eastern Uganda.

Two-phase pipe flow is a common occurrence in many industrial applications such as sewage, water, oil, and gas transportation. Accurate prediction of liquid velocity, holdup and pressure drop is of vast importance to ensure effective design and operation of fluid transport systems. This paper aimed at the simulation of a two-phase flow of air and sewage (water) using an open source software OpenFOAM. Numerical Simulations have been performed using varying dimensions of pipes as well as their inclinations. Specifically, a Standard k- turbulence model and the Volume of Fluid (VOF) free water surface model is used to solve the turbulent mixture flow of air and sewage (water). A two dimensional, 0.5m diameter pipe of 20m length is used for the CFD approach based on the Navier-Stokes equations. Results showed that the flow pattern behaviour is influenced by the pipe diameters as well as their inclination. It is concluded that the most effective way to optimize a sewer network system for Tororo Municipality conditions and other similar situations, is by adjusting sewer diameters and slope gradients and expanding the number of sewer network connections of household and industries from 535 (i.e., 31.2% of total) to at least 1,200 (70% of total).

Application of 3D printed polymer composite as capacitive sensor

PurposeThe purpose of this study is to demonstrate the usage of three-dimensionally (3D) printed polylactic acid (PLA)-carbon black (CB) conductive polymer composite in the measurement of the void fraction and liquid level.Design/methodology/approachPLA-CB conductive polymer composite is 3D printed through fused deposition modelling (FDM) technique and used as a capacitive sensor for void fraction measurement and liquid level sensing. The sensitivity of 3D printed ring and concave type capacitive sensors are compared for void fraction measurement. The effect of electrode length, thickness and pipe dimension on the capacitance achievable for the particular void fraction is studied. Concept of fringing capacitance is used for the sensing of liquid level.FindingsCompared to the concave design comprising four electrodes, the ring-type capacitive sensor produced better results in void fraction measurement. Increase in pipe diameter and electrode length results in the enhancement of capacitance arising from specific void fraction. For a 100 mm diameter pipe, the capacitance of the 150 mm-long concave electrode (0.4 mm thick) increased from 9.98 to 67.77 pF as the void fraction decreased from 100% to 0%. Development of the fringing capacitance in 3D printed PLA-CB composite helps in the measurement of liquid level. Both parallel finger topology and interdigital electrode configuration are able to sense the liquid level.Originality/valueAbility of the 3D printed conductive PLA-CB composite to act as a capacitive sensor is experimentally analysed. Performance of different electrode configuration is tested for both void fraction measurement and liquid level sensing. Results of experimentation prove that FDM printed PLA-CB composite is suitable for the void fraction and liquid level measurement.

EVALUATION AND ANALYSIS OF DEBIT AND PRESSURE ON NETWORK DISTRIBUTION PDAM TIRTA KAHAYAN KOTA PALANGKA RAYA

PDAM Tirta Kahayan of Palangkaraya city has a technical problem regarding with inadequate service standard (coverage level). As a result from the direct observations at the service area of PDAM Tirta Kahayan of Palangka Raya city, there were numerous public complaints related to PDAM services, especially the issue on fees, debit and distributed water pressure. Lossing water in PDAM Palangka Raya City ranges from 23% -35%. The aims of this study is to identify the condition of the pipeline distribution network of PDAM Tirta Kahayan in Palangka Raya City, to evaluate the debit distribution patterns and pressure on pipeline network of PDAM Tirta Kahayan Palangka Raya City by simulating the Epanet 2.0 program and to compare the simulation results with the exiting conditions, moreover to analyze the improvement alternatives debit and pressure on distribution piping networks. Based on the results of the simulation of Epanet 2.0 program there are still some locations that have debits and flow rates below 0.3 LPS. This is due to differences in elevation, the distance which is getting much more apart from the service source and mismatching of the pipe dimension. The improvement alternatives that have been made are by installing booster pumps in several locations that aim to increase the flow and flow velocity, continuous reservoir filling and regulation of distribution pump operation; therefore the water pressure is always maintained.

Thermal and economic analysis of preinsulated and twin-pipe heat network operation

This study focuses on the economic analysis of the heating network modernization by using preinsulated pipes and twin-pipes. The cost analysis is based on different type, diameter, and technological diagrams of different heating network pipe variants (from DN25to DN100) and various types of insulation. Net present value (NPV) analysis comparing a five variants of the heating network pipes (Case 0: Pipes with insulation PUR standard; Case 1: Pipes with insulation PUR plus; Case 2: Pipes with insulation PEX standard; Case 3: Twin-Pipes with insulation PUR; Case 4: Twin-Pipes with insulation PEX). The value of NPV, which is the highest (NPV = 7000 €, DN65, case 2 and NPV = 5200 €, DN50, case 4) among presented variants is the best choose to consider during the investment. Despite the higher prices of Twin Pipe system, they are more profitable due to shallow heat transfer losses. Heat losses are calculated for various heating networks, including preinsulated and twin-pipe heating networks. The remaining heat loss calculation is based merely on temperature levels and thermal resistance factors (in the ground), determined using the pipe dimensions and materials. It is found that the most cost-effective from an economic point of view is the use of TwinPipe system. These pipes are more expensive, but the heat losses that occurs during their use are much smaller compared to preinsulated pipes. Short return time of such an investment (6–7 years) with 100 m of pipe installed and positive NPV causes that this type of pipes is the best investment in the case of district heating networks. The results shown that Case 3 (PEX insulation) is more economicaly beneficial than Case 4 (PUR insulation).

Multi-objective optimization of liquid-liquid mixing in helical pipes using Genetic Algorithms coupled with Computational Fluid Dynamics

Abstract The identification of the best possible helical pipe geometry for optimal mixing is challenging since the two central objectives (minimizing pressure drop while maximizing mixing efficiency) cannot be reached simultaneously; they lead to concurrent target functions. The present study identifies optimal configurations using multi-objective optimization for the flow of two miscible liquids in helical pipes. A flow optimization library (OPAL++) was used to automatically control the numerical simulations. The objective is to optimize the helical pipe dimensions, maximizing mixing efficiency ( M c ) and simultaneously minimizing the pressure drop per unit length ( Δ P / L ). The pipe diameter (d), coil diameter (D) and pitch (P), were widely varied within 4–50 mm, 10–500 mm, and 5–100 mm, respectively. Additionally, the Reynolds number (Re) was varied within 20–60, covering the optimal range for liquid mixing in helical pipes. After performing a total of 1226 simulations over 30 optimization generations, a Pareto front was obtained, containing all concurrent optimal solutions. The results revealed that the reduction of any of the geometrical parameters can generally improve mixing. The change of D or P slightly affects the pressure drop, while the reduction of d increases the pressure drop significantly. All configurations in the Pareto front show a strong linear correlation between d and P, showing that P should be kept as small as possible. A globally optimal individual is suggested based on minimizing the Euclidean distance to the extreme point of the objective functions ( M c = 1 , Δ P / L = 0 ). Finally, correlations are proposed for predicting the pressure drop and the mixing coefficient. The resulting optimal geometry and its associated process conditions are recommended to ensure excellent mixing at minimum pumping power.

Effect of axial force and bending moment on the limit internal pressure of dented pipelines

The extrusion and scraping action of rocks at the bottom of buried pipelines can lead to dent and scratch defects. Beside internal pressure, the pipelines should also bear other forms of loads during its operation, such as bending moment and axial force. The combination of internal pressure and these loads can make the pipe easy to damage. In order to study the influence of bending and axial loads on the limit internal pressure of dent-scratch pipelines, large numbers of finite element calculations are carried out in this paper. Through the comparison with experimental results, a failure criterion is proposed for finite element analysis (FEA). It is found in actual buried pipelines during pipe inspection that the existed maximum bending strain is equal to 0.4%. Take the bending moment which leads to the axial strain of 0.4% as the reference moment. A series of finite element calculations are conducted to analyze the influence of various bending loads on the limit internal pressure of pipelines with dent-scratch defects. In addition, the effect of axial compression loads on the limit internal pressure is also studied by FEA. According to the finite element results, it is concluded that both axial load and bending moment can decrease the limit internal pressure compared to one subjected to internal pressure only. Moreover, the tendency of the impact is approximately linear. Finally, an expression of limit internal pressure with respect to pipe material, pipe and defect dimensions and the magnitude of axial force is fitted, which provides a strong guidance for the safety assessment of the defective pipelines.

Transitional water flow in steady-state

• Analytic function of the steady-state water flow in the transitional Reynolds area. • Expected to be adaptable to all temperatures above freezing point and pipe dimensions. • Satisfies gradient at laminar flow boundary Re = 2000 and the gradient at turbulent boundary Re = 4000. • Developed for the calibration of roughness values in water networks. • Incorporates Colebrook–White’s friction factor in Darcy–Weisbach’s pressure drop relation. In this paper we derive a mathematical description of the steady-state water flow in the transitional Reynolds area, i.e. between Reynolds numbers 2000 and 4000. Specifying the flow as two dimensional function of the pressure drop and the roughness of a conduit pipe, a description is obtained which not only satisfies the boundary conditions, but also the gradient on the laminar-transitional as well as the transitional-turbulent boundary to a sufficient degree of accuracy. This is motivated by the need to identify individual friction parameters per pipe in a water supply network, a necessity for being able to detect and localise faults reliably. It occurs that although some flows have never been in the turbulent regime, one often yet mistakenly tries to find roughness values for corresponding pipes during the network’s calibration. In order to let the calibration algorithm itself decide if an appropriate pipe flow has been laminar or turbulent, a continuous and smooth description in between is needed. Effectively, this work lays part of the foundation for water network calibration algorithms, which fully account for the different flow regimes using pressure sensors primarily.