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In this article, focused on the bending of a small-size copper pipe and proposed a theoretical model of a pipe bending fixture. A fixture is made to bend type K (B-75) copper pipes for industrial purposes in air conditioners. This pipe bending fixture is designed according to the geometry of the bending of a pipe using Rotary Draw Bending (RDB) process. Simple and easily operated a pipe bending fixture is designed and fabricated to bend the pipe to require diameter during a radius and angle. SS304 is used for a pulley and mild steel is used for other parts of the machine and force applies manually. Two major drawbacks in pipe bending are wall thinning and change in cross-section ovality that determines the quality and extent of a pipe forming. The required relationship between the die must be maintained to achieve tube accuracy through rotary draw bending operation. The most critical parameter to be considered while bending pipes are bend angle, bend radius, pipe thickness, and pipe diameter. The main objective behind this fixture to reduce wall thinning over the entire bent area and keep the force distribution uniform over the bent area. Another is that the cross-section of the bent pipe is oval to minimal. The design of the pipe bending fixture has been made using solid edge modeling software. [ABSTRACT FROM AUTHOR]

Pipe bends are the critical components in piping systems. Pipe bends deform in its own plane and out of plane when it is subjected to bending load. Pipe bends exhibit shell type geometry and their shell type behavior due offers greater flexibility. In comparison with straight pipe of same size, material and under similar loading conditions, pipe bends are accompanied by larger magnitude of stresses and strains. Hence there is a need for reliable estimation of load capacity and deep understanding of elastic-plastic behaviour under different combined loading conditions. The current research aims at studying the elastic behaviour of pipe bends, under in-plane moment loading and the effects under internal pressure. The numerical method is employed to model and analyse the pipe elbow subjected to Internal pressure varying from 0% to 40% of the yield pressure in increments of 20%. The results are exhibited in the form of load deflection plots. The analysis work has been extended to the above stated component made up of Graphite-epoxy composite. The identical boundary conditions have been considered. The behaviour of the composite elbow under the varying loading conditions is believed to be good compared to the conventional one. The work helps towards the potential replacement of the conventional one with the new proposed elbow. [ABSTRACT FROM AUTHOR]

Cold water pipes (CWP) used in ocean thermal energy conversion installations must be able to withstand wave loads, deep seawater currents, and the weight of the pipe itself. Seawater currents shake the cold water pipe in a horizontal direction which causes the pipe to experience bending loads and the structure of the pipe material will experience tensile-compressive loads. So that it is required the properties of pipe material such high strength and better flexibility that it is not easily broken. In the material selection, High Density Polyethylene cold water pipe material reinforced with glass fiber is suitable for CWP material and corrosion-resistant as well. The formation of glass fiber reinforced High Density Polyethylene composite materials, which using hot press molds to obtain better results of combining High Density Polyethylene fiber and matrix and increasing resistance to tensile loads. The results of the tensile test of the material formed by hot pressing from High Density Polyethylene composite with fiberglass, indicating that the toughness and strain of the material with short fibers were better than that of long fibers. In short fiber, there is an increase in tensile strength by 2.7%, toughness with 42%, and strain by 35.2%. This increase in toughness and strain is required for CWP, in order to the use of short fibers becomes more appropriate for CWP construction. The improved toughness of this short fiber fiberglass provides an excellent basis to produce cold water pipe materials in Ocean Thermal Energy Conversion installations. The mechanical properties of short fibers High Density Polyethylene composites will be able to accept tensile loads from currents, waves and weight from the cold water pipe itself in the cold water pipe construction. [ABSTRACT FROM AUTHOR]

The design, modification, and construction of the universal bending machine involved a selection of engineering materials such as mild steel for its high impact strength, aluminum for its ductility, cast iron for its high hardness, bearings for its finer finish workpiece, gears, and plunger for their rough finish on the workpiece. The frame is welded together following the proposed design and dimensions of the machine using electric arc welding to ensure the proper joining of materials. The hydraulic jack is fixed in place where it pushes the movable part of the machine easily, thus; causing the tighter or loosened angle of bends on pipes. Bearings are responsible for rotation and pathway through which the pipes are passed, these are placed at the top of the structure for easy access. The turning wheel was constructed to cause rotation of the bearings which helps exert the force from the jack to the pipe being bent and also pushes the pipe through the created pathway. The machine was run on various pipes of different materials to know the strengths and limits of the machine's performance. [ABSTRACT FROM AUTHOR]

Pipes made of Polyvinyl Chloride (PVC) are widely used in households and in the industrial world to transfer clean and dirty water. The elbows of PVC Pipes available in the market have a large pressure loss because they are not designed aerodynamically. This study aims to determine the loss of water flow in PVC pipes experimentally. The models investigated are elbow available in the market and elbows made by bending the pipes 90o with a radius of 2 Diameter of the pipe. Diameter of the pipe is 21 mm. The experimental investigation is carried out by varying the water flow rate in the pipe, namely 20, 25, 30 and 35 liter/minute. The experimental results show that the pressure loss at the elbows available in the market is greater than that of the bent pipe. [ABSTRACT FROM AUTHOR]

In this work, the design analysis of older and modified exhaust pipe of a four stroke diesel engine are presented and compared. The exhaust gases produced inside a combustion chamber of the engine should be discharge quickly to the atmosphere through exhaust pipe. The flow of exhaust gases mainly depends on back pressure and velocity. During this process, there is a possibility of increase in back pressure due to pipe bends and elbows which hinders the power output of the engine. The measurable outcomes from this research work is to reduce the back pressure to a fair amount which helps in overcoming the power losses. This ultimately will helps in saving the fuel consumption's. The study aims to modify the design of exhaust pipe by reducing the number of exhaust pipe bends. Computational fluid dynamic (CFD) investigation is carried out by modeling the actual geometry of the exhaust pipe. The reduction in the number of bends is correlated with back pressure and frictional losses. The modified design of the exhaust pipe is found to be effective in reducing the pressure drop to around 11.6%. [ABSTRACT FROM AUTHOR]

Recently, the shipbuilding industry has been able to develop new production methods. This new method promotes design automation in order to produce ships more efficiently. Engine room design, including the piping system, is a complex process especially in the pipe routing problem. This process requires a considerable number of man hours. This paper presents a new approach for optimization of pipe routing system. The Dijkstra’s algorithm is used to obtain short path by considering some constraints like number of pipe bends and pipe cross. The method works by generating some candidate paths based on the given parameters geometrically. The non-geometric parameters such as material cost and installation cost will also be assessed. Then by using the algorithm, the desire option from various candidate paths will be evaluated. This study discusses the details of the above methods. In addition, simulation test of a several piping systems were conducted to show the pipe routing design procedure in detail and to verify the effectiveness of the proposed methodology. [ABSTRACT FROM AUTHOR]

This paper is tackling the elbows bending process using hot mandrels. Through this process the pipe is pushed over a fix or mobile mandrel, which defines the expansion and the radius of curvature and is very important that mandrel deformation to be minimum. The paper presents the finite element model developed for the process described above, the optimization of tool parameters used to obtain and validate the simulation conditions in order to evaluate the effect of different materials on mandrels performances. The numerical simulation analyses were carried out by finite element analysis software NASTRAN and LS-DYNA which has a vast array of capabilities to simulate extreme deformation problems. Results obtained following the manufacturing process FEM simulation optimization are expected to reduce the mandrel production and exploitation costs. [ABSTRACT FROM AUTHOR]

In this work a low cost and easy to manufacture multiple radius pipe bending machine is designed to bend a given diameter conduit pipe in a required bending radius. In most of the industries, pipe bending is a salient requirement. In market there are different types of pipe bending machines available. But most of them can bend only a particular diameter pipe into a specified bending radius. To bend into different bending radius the die and other related parts need to be changed. Even some pipe bending machines are available to bend a particular diameter pipe into any bending radius but either they are very expensive or difficult to manufacture. So this project is to design a machine to satisfy our requirement. The working of this machine is simple and also the cost of manufacturing is comparatively cheaper than what is available in the current market. This machine can bend a pipe up to 32mm diameter to a minimum bending radius of 150mm. The material of the machine used is mild steel and hydraulics with piston-cylinder is used as power source. Static analysis of different parts is also carried out in ANSYS and finally a prototype is fabricated in order to test the machine and it is successful by all means. [ABSTRACT FROM AUTHOR]

Bends are essential components of fluid flow systems, facilitating compact, light weight designs. But they can also be the cause of complex secondary flows, losses and variable heat transfer rates in the fluid flow lines. Nature of flow within pipe bends for unsteady, incompressible viscous fluids are well known. The secondary flow and separation in incompressible flows are dependent of the flow Reynolds number and the radius of curvature of the bend. However the flow characteristics for compressible flow through pipe bends are of considerable interest since the flow may choke at the bend with the possibility for strong oscillations due to secondary flows or separation. This will cause a change in the mass flow rate through the pipe bends for compressible flows. These factors emphasize the need for a detailed understanding of the flow behavior of compressible flow within pipe bends. [ABSTRACT FROM AUTHOR]

This article proposes a definition of the Reynolds number in a form, which is applicable point-wise to an entire volume of fluid. This dimensionless number is termed a local Reynolds number in the article. In the article a few examples of the local Reynolds number distribution are shown using CFD. Those examples are straight pipe, pipe bend and a Karman vortex trail behind a cylindrical wall. Only RANS turbulence models were used, however the local Reynolds number could be at least theoretically applied to any data with a sufficient resolution. In the conclusion some potential uses are hypothesized, like an evaluation of proximity of boundary conditions in a CFD simulation or a comparison of turbulence models as well as general comparison of cases. [ABSTRACT FROM AUTHOR]

Throughout the oil and gas industry corrosion and erosion damage monitoring play a central role in managing asset integrity. Recently, the use of guided wave technology in conjunction with tomography techniques has provided the possibility of obtaining point-by-point maps of wall thickness loss over the entire volume of a pipeline section between two ring arrays of ultrasonic transducers. However, current research has focused on straight pipes while little work has been done on pipe bends which are also the most susceptible to developing damage. Tomography of the bend is challenging due to the complexity and computational cost of the 3-D elastic model required to accurately describe guided wave propagation. To overcome this limitation, we introduce a 2-D anisotropic inhomogeneous acoustic model which represents a generalization of the conventional unwrapping used for straight pipes. The shortest-path ray-tracing method is then applied to the 2-D model to compute ray paths and predict the arrival times of the fundamental flexural mode, A0, excited by a point source on the straight section of pipe entering the bend and detected on the opposite side. Good agreement is found between predictions and experiments performed on an 8" diameter (D) pipe with 1.5 D bend radius. The 2-D model also reveals the existence of an acoustic lensing effect which leads to a focusing phenomenon also confirmed by the experiments. The computational efficiency of the 2-D model makes it ideally suited for tomography algorithms. [ABSTRACT FROM AUTHOR]

Bent ducts add loss and decrease efficiency. Many researchers have conducted the performances of bent ducts, but their shapes of inlet and outlet are same. However, the bent duct which has different shape of inlet and outlet has not been investigated. In this investigation, the focus is on a bent duct which is annular at the inlet and circular at the outlet. The performance of such bent duct is investigated under inlet speed of 54 m/s and Reynolds number of 238,000. Wall static pressure tappings are located on the surface of the bent duct to measure the static pressure. 5hole probe is traversed at the inlet and outlet of the bent duct to measure the flow. To investigate the flow in the bent duct, computational fluid dynamics (CFD) is conducted in this study. As a result, it presents static pressure distribution on the bent duct surface, streamwise velocity profile of the bent duct and total pressure loss profile at outlet of the bent duct. Flow field at outlet of the bent duct has 3 distinctive regions; two separations regions due to inner pipe and curvature of the bent duct and one core of houseshoe shape. [ABSTRACT FROM AUTHOR]

Variety of pipes with different types of layout is widely used in enterprise. Flow resistance and turbulence is increased by irrational layout of the pipes and flow conditions, and even the pipe system vibration will occur induced probably by fluid disturbance. In this paper, three typical bend pipes in three-dimension are analyzed from pressure loss and streamline by numerical simulation. The straight and bend section of the pipe is generated and meshed by the hexahedral elements. The quality of meshes is good, and the grid cells are about 300,000. Calculation shows that the first type with the inlet and outlet in opposite direction in one plane has the least resistance coefficient. Therefore, adopting plain layout may be the best choice of the three types mentioned in the paper. [ABSTRACT FROM AUTHOR]

This paper summarizes recent work aimed at improving the understanding of Lamb wave propagation through pipes with bends. A series of pipes with different bend radii were investigated experimentally and with numerical simulation (Finite Element). With both longitudinal and torsional excitation, numerical and experimental tests performed showed mode conversion due to the presence of the bend. The influence of both the bend radius and the bend length on the transmission of the incident wave is shown. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]