Pressure Piping Research Articles

Design and Analysis of Dehumidifier to Improve Air Quality

Compressed air is used for obtaining brake application in which brake pipe and feed pipe run throughout the length of the coach. Brake pipe and feed pipe on consecutive coaches in the train are coupled to one another by means of respective hose couplings to form a continuous air passage from the locomotive to the rear end of the train. Compressed air is supplied to brake pipe and feed pipe from locomotive also the magnitude of braking force increases in steps with the corresponding reduction in brake pipe pressure. So due to brake binding and brake failures due to pressure drop and high moisture rate so there was need of dehumidifier because of less moisturized air. When passed to braking system it will help the braking system and there will be less brake binding and pressure failure in braking system so with the help of dehumidifier, we can reduce moisture content and pass dry air to the braking system and increase good braking effect and decrease maintenance. As per the result of dehumidifier we have decreased moisture content up to 81.08% and decreased maintenance life by 120 days also this dehumidifier is less small in size than the prior one. From obtained moisture content of 37%, we have decreased it to 7%. Also, it is more efficient to replace silica gel easily in this dehumidifier.

Plasticization-assisted slow crack growth modeling of high-density polyethylene

The existing crack layer model can theoretically predict the slow crack growth behavior of high-density polyethylene. However, it can only be applied to oxidative environments causing chemical degradation. Most oil and gas field components, such as pressurized pipes, are subjected to hydrocarbon exposures, leading to a plasticized material response, i.e., shear yielding instead of crazing. Therefore, the effect of such sorptive media diffusion on the slow crack growth behavior and lifespans tf should be understood. In this work and for the first time, a novel crack layer model is developed that can simulate the diffusion-assisted slow crack growth behavior of plasticized high-density polyethylene. The proposed model was validated by comparing its prediction with experimental results and by conducting a sensitivity study on several input parameters. Using the proposed model, the reported plasticization results were reconstructed successfully including the SCG rate with R2 = 0.95. This study expands the applicability of the crack layer model for the reliability assessment of polyethylene pipes under various environmental conditions, including plasticizers.

Multiaxial ratcheting-fatigue evaluation of pressurized elbow pipe under strong cyclic loading using damage-coupled cyclic plasticity model

Continuous damage mechanics (CDM) is based on the theories of continuous medium mechanics and continuous medium thermodynamics, which considers damage is an irreversible dissipative process within the materials, and employs the field-theoretic approach of image-only science to study the internal macroscopic damage evolution law of the materials and its influence on the deterioration of the macroscopic mechanical properties of the materials. Hence, within the framework of CDM, a damage-coupled cyclic plasticity constitutive model is proposed based on combined isotropic and Chen-Jiao-Kim (CJK) kinematic hardening rule for evaluating the ratcheting-fatigue behavior of 90° elbow pipes under strong cyclic loading in this paper. Stress return mapping and numerical solution procedures of the proposed model are formulated based on the backward finite difference method. Formulation of the consistent tangent operator is presented for the Finite Element implementation of the plasticity model in ABAQUS UMAT. The FE analysis of non-pressurized and pressurized elbow pipes under cyclic displacement-controlled loading is respectively performed using the implemented constitutive model. The results reveal that the predicted results of the damage-coupled cyclic plasticity constitutive model are better than combined isotropic-kinematic hardening model, and well consistent with the experimental data.

Rim Driven Thruster as Innovative Propulsion Element for Dual Phase Flows in Plug Flow Reactors

The purpose of this work was to test a new setup to pump water with entrained air for application in gas fermentation. A mixed flow, where gas is contained in a liquid to be pumped, rapidly reduces the efficiency of a conventional pump, due to the compressibility of the gas. It is not always possible to degas the fluid, for instance in gas fermentation, which is preferably carried out in tubular reactors (loop fermenters) to achieve a high conversion rate of the gaseous feedstocks. Method: In this work, a rim-driven thruster (RDT) was tested in a lab-scale, cold flow model of a loop reactor with 5–30% (by volume) of gas fraction (air) in the liquid (water) as alternative propulsion element (6 m total pipe length, ambient temperature and pressure). As a result, it was found that the RDT, in connection with a guiding vane providing swirling motion to the two-phase fluid, could pump a mixed flow with up to 25.7% of gas content (by volume) at atmospheric pressure and 25 °C and 0.5 to 2 m/s flow speed. In conclusion, an RDT is advantageous over a classic propulsion element like a centrifugal pump or axial flow pump for transporting liquids with entrained gases. This article describes the potential of rim-driven thrusters, as known from marine propulsion, in biotechnology, the chemical industry, and beyond, to handle multiphase flows.

A Twice-Open Control Method for a Hydraulic Variable Valve System in a Diesel Engine

In order to solve the cold-starting problem and improve the intake and exhaust pipe temperatures of diesel engines under cold-starting and low- and medium-speed conditions, this paper proposes a twice-open control method for a hydraulic variable valve system. First, a hydraulic variable valve system that can realize a fully variable valve lift and phase angle is applied to replace the original intake system in order to meet the air intake requirements of different conditions. Then, a twice-open control method in which the intake valve opens two times at the exhaust stroke and intake stroke is proposed to improve the intake pipe temperature and solve the cold-starting problem. This paper contains a numerical work analysis. A GT-POWER model is constructed to validate the intake valve twice-open control method. The cylinder pressure, cylinder temperature, intake pipe pressure, and intake pipe temperature are obtained and compared between the original intake valve system and the hydraulic variable valve system with the proposed intake valve twice-open control method. The results show that the twice-open control method can increase the intake pipe temperature to 260 K or even higher, which can improve the cold-starting performance and the exhaust temperature at low and medium speeds. At the same time, the performance under low- and medium-speed conditions is improved.

Synthesis and application of polyer additive system for reducing the pour point depressant of crude oil in exploitation, transportation

Problems encountered when exploiting and transporting crude oil containing solid paraffins is that it easily crystallizes under normal temperature, causing many challenges such as paraffin wax deposition, reduced flow rate, gel formation, loss of pipe pressure... When the crude oil temperature is below the wax appearance temperature (WAT), paraffin will precipitate and separate from the oil. Many solutions that have been and are being used such as insulation, mechanical, thermal, chemical methods, using wax inhibitors - pour point depressants (PPD) and dispersants... The method of using additives to increase solidification temperature or inhibit wax, improve the rheology of crude oil and reduce paraffin deposition is considered one of the most effective method. In this study, polymers made from a combination of three monomers, behenyl acrylate, stearyl methacrylate and vinyl acetate, were studied to find the most optimal combination for the purpose of manufacturing pour point lowering additives for oils.

Experimental and numerical study of combustion in pipe cutting operations with hydrogen-blending gas

This study investigated the flame combustion of gas-containing pipe cutting operations by combining experimental and numerical simulation techniques. Based on the empirical flame length formula and experimental and numerical simulation flame length data, a flame length formula for gas outlet with large aspect ratio was proposed. In the experimental phase, cutting experiments were conducted with cutting slit lengths of 1–11 cm for pipe pressures of 10–550 Pa and hydrogen doping ratios of 0%, 10%, and 20%. The flame lengths were then measured. A hydrogen-doped natural gas combustion model based on the vortex dissipation conceptual model and Grimech-3.0 mechanism was established to simulate the experimental conditions. The flame lengths derived from the numerical simulation were in good agreement with the experimentally measured flame lengths, with an average error of 7.02%. This indicates that the reliability of the numerical model can be verified. The effects of hydrogen doping ratio, tube pressure, and cutting slit length on flame length and thermal radiation range were investigated using the control variable method. The results demonstrated that hydrogen doping reduced flame length and flame length away from the flame. Furthermore, an increase in pipe pressure and single cut length also resulted in an increase in flame length. It was observed that under normal operating conditions, a safe intensity of thermal radiation could be maintained within the operating distance when the operator wore protective clothing.

Effect of flywheels in pump stations for reducing the volume of air chambers

ABSTRACT The most common and destructive event of unsteady flow in pipes is water hammer. This phenomenon is caused by a sudden change in boundary conditions in pressurized pipes. Unsteady flow in pipelines can lead to a significant increase or decrease in pressure. This pressure generation may cause cavitation, bursting of pipes, and failure of the whole system. One type of equipment that can control both positive and negative pressure phases is a pressurized tank. Implementing such a pressure tank can impose increased costs. In order to reduce the design costs, the combination of a flywheel with the pressure tank can be used. In this study, a transmission pipeline from Zarineh River to Tabriz city is numerically simulated, and the effect of increasing the inertia of the flywheel on the reduction of the pressurized tank volume is investigated. The results show that increasing the flywheel inertia from 125 to 165 Nm2 can reduce the pressurized tank volume from 90 to 75 m3.

Load-independent creep constraint analysis and solutions for surface cracks in pressurized pipes

Using load-independent creep constraint parameters Q* and Qm*, the variations of crack front stress field and constraint level are analyzed for various crack sizes of pipelines containing internal surface cracks under high temperature conditions. The results show that the trends of stress changes in the axial and circumferential internal surface crack front for different crack sizes are similar. For axial internal surface cracks, when the crack depth to length ratio a/c is the same, the maximum values of crack front Q* and Qm* are shifted from the deepest part of the crack (2Φ/π = 1) to the vicinity of the free surface (2Φ/π = 0.2) as the crack depth a/t increases. As for the circumferential inner surface cracks, when the crack depth a/t exceeds 0.2, the locations where the maximum values of crack fronts Q* and Qm* appear are mainly concentrated in the deepest part of the crack (2Φ/π = 1). Based on the calculation results of the constraint parameters, the empirical formulas for the engineering calculation of the relationship between the average constraint parameters (Qavg* and Qm‐avg*) and the crack size are obtained by fitting.

Microstructural design characteristics of high-density polyethylene for thick-walled pressure pipe applications

Advancements in process technology and structure-property relationship-based design of high-density polyethylene has led to development of high-performance bimodal polyethylene grades suitable for large diameter thick-walled pressure pipe applications. These high-density bimodal products have enhanced design life, high pressure rating and sag resistance for fabrication of large diameter thick-walled pipe. Achieving optimal balance of these performance properties require controlled microstructural characteristics. The design characteristics are intricately influenced by catalyst type and process technology employed in resin manufacturing. In this study, we systematically establish correlations between microstructural characteristics of seven commercially available bimodal PE resins, produced using dual slurry or gas phase reactors, and their most relevant performance properties. We conducted comprehensive microstructural characterization of all samples using GPC-IR (high-temperature gel permeation chromatography coupled with an infrared composition detector), 13C NMR (nuclear magnetic resonance), TREF (temperature rising elution fractionation) and DSC (differential scanning calorimetry) techniques. Additionally, we measured mechanical, thermal, and rheological properties, focusing on crystallization kinetics, density, slow crack growth resistance (PENT and strain hardening modulus SHM) and low-frequency shear rheology of these products. Comparisons were made between key properties of interest, including slow crack growth resistance and low-frequency rheology (relevant for sag resistance), and microstructural characteristics. Theoretical and empirical correlations based on phenomenological models were employed for this analysis. The detailed study contributes to determining the critical levels of short and long chain branching, as well as molecular weight distribution characteristics essential to produce bimodal PE-4710 certifiable high-density polyethylene resins with low sag resistance. These design principles may serve as a foundation for the efficient design of reactor recipes and post-reactor modification processes, contributing to the evolution of pressure pipe polyethylene resin development and paving the way for design of next-generation pressure pipe grades.

Fatigue performance testing and life prediction of welded fuel pipes

The external piping system which connects power devices, valve control devices, actuators, etc. is an essential system on the aero engine. Under the combined effects of high fluid pressure and external vibration, multiaxial fatigue failure is the main factor that seriously affects the safety of the piping system. The objective of this paper is to establish the multiaxial fatigue life model for the typical welded fuel pipe of the piping system by combining fatigue testing, simulation and theoretical analysis which is of great guiding significance for the engineering application of the piping system. Firstly, the fatigue limits of welded fuel pipes under no and 13.5 MPa internal pressure are obtained by rotational bending fatigue tests using the up-and-down method. Three additional stress levels of rotational bending fatigue tests under no internal pressure are supplemented and then the S-N curve is further obtained by the group method. Since the corresponding fracture surface of the specimens locates at the weld toe near the fixed end, peak stress method is adopted to evaluate the fatigue performance of the weld toe on the pipe specimens. In addition, by comparing the fatigue limit with no and 13.5 MPa internal pressured pipes, it is obvious that the equivalent uniaxial stress corrected by Gerber formula is not applicable for the multiaxial fatigue condition which is caused by the combined effect of fluid pressure and displacement load. The local stress concentration factor caused by the weld toe is determined and based on Findley critical plane model, the multiaxial fatigue life model is established which simultaneously takes the local stress concentration effect, mean stress effect and multiaxial stress effect into consideration. The results of rotational bending fatigue tests under 13.5 MPa internal pressure are within the triple error dispersion band and the accuracy of the proposed life model are verified.

Thickness optimization of semi-structural CIPP pressure pipe liners: A mathematical modeling approach

This paper introduces a novel mathematical model to optimize the thickness of semi-structural liners in Cured-In-Place-Pipe (CIPP) rehabilitation based on the host pipe holes criterion defined in current standards. The model considers the residual structural mechanical properties of the damaged host pipe, and holes are defined considering the direction, the area, and the perimeter of the host pipe hole, providing a more accurate estimation of the liner behavior. Results indicate potential thickness reductions of 20%–40% for circular holes, while non-circular holes offer even greater optimization possibilities ranging from 40 to 80%. Moreover, a full-scale test was conducted on a reinforced concrete host pipe of DN 400, damaged with three holes 150 mm in diameter. The full-scale test results were used to refine the numerical model employed in developing the mathematical model, ensuring its accuracy and reliability.

Sensitivity analysis and calibration for a two-dimensional state-space model of metal hydride storage tanks based on experimental data

In this paper, a state-space model of a metal hydride tank is formulated and analyzed in detail. Firstly, a three-dimensional state-space model of the metal hydride tank is simplified by assuming that the tank temperature can be measured. Secondly, the model is completed with a pipe model, which allows to compute the input flow from the pipe pressure that can be easily measured. The proposed model solves the problem that the conventional metal hydride tank models usually take the mass flow rate as input and ignore the pressure as system input. Thirdly, the first-order trajectory sensitivity analysis method is adopted to determine the sensitivity of selected unknown parameters. Latter, the particle swarm optimization algorithm is used to estimate the unknown model parameters from experimental data. Finally, a comparison between experimental data and simulation results demonstrates that the proposed model can reflect the dynamic characteristics of the metal hydride tank.

Comparative analysis of experimental and simulation results of composite circular tube

Abstract In this work, the internal pressure of the composite pipe is analysed and studied when transporting liquid or gas. The quasi-static hydraulic test is designed to simulate the internal pressure of the composite pipe. By using the ABAQUS finite element method, a numerical model of the composite pipe under hydraulic load is established. The strain curves and final failure modes of the test and simulation are compared to verify the feasibility of the finite element method model. Finally, the damage mechanism of the composite tube is analysed according to the numerical model, and it is found that the carbon fibre composite material has an important effect on the bearing capacity of the composite tube.

Hydraulic analysis of jet deflection on Pelton turbine deflector based on CFD simulation

Abstract The deflector of the external regulating mechanism of the Pelton turbine can reduce the pressure of the nozzle structure during the emergency load rejection of the unit, and solve the problem that the pressure in the pressure pipe increases too much and the rotate speed of the unit gets too fast. This paper mainly introduces the flow pattern analysis of jet deflection when the Pelton turbine deflector is in working state. The results of calculation and analysis in this paper are based on the Navier-Stokes equations and k-ω SST turbulent model of CFD simulation.

Exploration and application of welding technology for misalignment of pressure pipe orifices in a pumped storage power station

Abstract Pumped storage power stations are currently the most economical and clean large-scale energy storage method. Pumped storage power stations have flexible start and stop, rapid response, and have six major functions, including peak shaving, valley filling, frequency regulation, phase modulation, emergency backup, and black start. With the transformation of the energy system towards clean, low-carbon, safe and efficient, the operational characteristics of the power system will undergo significant changes, requiring sufficient flexible regulation of power sources and energy storage facilities. It is more urgent to accelerate the development and construction of pumped storage energy. Due to the characteristics of pumped storage installation, high-strength pressure steel pipes are required on the upstream side of the power station units as the water diversion pipeline. This article takes a pumped storage power station as an example to analyze and handle the problem of pipe misalignment encountered during the welding process of pressure steel pipes in the power station. Satisfactory results have been achieved, ensuring the welding quality and providing reference for other engineering projects.

Experimental and analytical investigation on friction resistance force between buried coated pressurized steel pipes and soil

Experimental and analytical investigation on friction resistance force between buried coated pressurized steel pipes and soil

Numerical Simulation and Consequence Analysis of Full-Scale Jet Fires for Pipelines Transporting Pure Hydrogen or Hydrogen Blended with Natural Gas

The use of existing natural gas pipelines for the transport of hydrogen/natural gas mixtures can achieve large-scale, long-distance and low-cost hydrogen transportation. A jet fire induced by the leakage of high-pressure pure hydrogen and hydrogen-blended natural gas pipelines may pose a severe threat to life and property. Based on the Abel–Nobel equation of state and a notional nozzle model, an equivalent pipe leakage model is established to simulate high-pressure pipeline gas leakage jet fire accidents. Large-scale high-pressure hydrogen and natural gas/hydrogen mixture jet fires are simulated, showing the jet impingement process and obtaining an accurate and effective simulation framework. This framework is validated by comparing the simulated and experimental measured results of flame height, flame appearance and thermal radiation. Several combustion models are compared, and the simulated data show that the non-premixed chemical equilibrium combustion model is superior to other combustion models. The influence of the pipe pressure and the hydrogen blending ratio on the consequences of natural gas/hydrogen mixture pipeline leakage jet fire accidents is explored. It is found that when the hydrogen blending ratio is lower than 22%, the increase in the hydrogen blending ratio has little effect on the decrease in the thermal radiation hazard distance.

Numerical analysis of stress distribution in the pressurized composite pipe buried in the soil

In the present research work, a comprehensive study on the stress analysis in the two composite pipes bonded by a layer of DP 410 adhesive and a socket buried in the soil has been performed. The pipe material was considered as a four layers of epoxy-fiber glass with different fiber orientations (cross-ply, angle-ply and quasi-isotropic). The soil dimensions and properties as well as the traffic load (H-20) were based on AASHTO. The simulation of the stress analysis was performed using ANSYS software. In the present study, the influences of bed distance, temperature change, internal pressure, traffic load, fiber orientation angle and layups, and gap distance on stress distribution in the buried composite pipe have been investigated. The findings revealed that the annual temperature change in the soil and the pipe enhances the stresses in the joint components to a maximum value of 5.5 MPa at a pipe temperature of −22 °C. Moreover, the outcomes indicated that the adhesive layer is the most sensitive component to any rise in the load prism, as well as other loads, for a buried pipe at a depth of 120 cm. The maximum and minimum state for von Mises stress component were related to, in turn, quasi-isotropic and angle-ply laminations.

An effective point cloud registration method for three-dimensional reconstruction of pressure piping

Abstract At present, industrial scenes with sparse features and weak textures are widely encountered, and the three-dimensional reconstruction of such scenes is a recognized problem. Pressure pipelines have a wide range of applications in fields such as petroleum engineering, chemical engineering, and hydropower station engineering. However, there is no mature solution for the three-dimensional reconstruction of pressure pipes. The main reason is that the typical scenes in which pressure pipes are found also have relatively few features and textures. Traditional three-dimensional reconstruction algorithms based on feature extraction are largely ineffective for such scenes that are lacking in features. In view of the above problems, this paper proposes an improved interframe registration algorithm based on point cloud fitting with cylinder axis vector constraints. By incorporating geometric feature parameters of a cylindrical pressure pipeline, specifically the axis vector of the cylinder, to constrain the traditional iterative closest point algorithm, the accuracy of point cloud registration can be improved in scenarios lacking features and textures, and some environmental uncertainties can be overcome. Finally, using actual laser point cloud data collected from pressure pipelines, the proposed fitting-based point cloud registration algorithm with cylinder axis vector constraints is tested. The experimental results show that under the same conditions, compared with other open-source point cloud registration algorithms, the proposed method can achieve higher registration accuracy. Moreover, integrating this algorithm into an open-source three-dimensional reconstruction algorithm framework can lead to better reconstruction results.