High-pressure Pipe Research Articles

Burr inspection of the inside of high-pressure pipe joints by motion imitation of skilled worker

Burr inspection of the inside of high-pressure pipe joints by motion imitation of skilled worker

Design and Installation of Supersonic Free Jet Test Facility with Flow Visualization

A supersonic free jet test facility has been designed and a flow visualization equipment has been installed in order to analyze the flow characteristics of a jet emanating from nozzles. The free jet facility has two storage tanks of 14 m3 and 7 m3 capacity, since it has been designed to carry a maximum pressure of 30 bar. The proper design of the plumbing system has been carried out to transfer the compressed air from the storage tank to the settling chamber. The high-pressure pipes and the control valves have been used to control the compressed air flow to the settling chamber. The nozzle is fixed at the end of the settling chamber through a threaded joint so that nozzles with different profiles can be easily fitted. A pressure gauge is attached to the settling chamber to measure the pressure and the flow is controlled by a globe valve. A vertical z–type Schlieren apparatus has been designed to capture the flow pattern of the jet emerging from different nozzle configurations, which consist of a monochromatic light source, mirrors, knife-edge, and a high-speed camera. The experimental set-up has been installed successfully and clear Schlieren images have been captured from subsonic, under-expanded, and supersonic jet flows. The free jet facility can operate efficiently up to a Mach number of 2.75 with a supersonic nozzle throat diameter of 20 mm.

Pressure Control of High Pressure Tubing Based on Fluid Mechanics

This paper studies the problem of the constant pressure control for high pressure tubing. The main factors affecting the pressure change in high pressure oil pipe are the opening time of check valve and the cam angular velocity. Based on the theory of fluid mechanics, ordinary differential equation and Fourier series, the flow-pressure model and pressure-cam angular velocity model are established, respectively. Furthermore, the above model is extended to the case of multiple nozzles. These three models accurately express the functional relationship between the fuel flow rate, the pressure in the tubing and the cam angular velocity. According to the established models, the pressure in the high-pressure oil pipe can be accurately controlled by adjusting some parameters. Finally, a simulation example is given to verify the effectiveness of the proposed method.

Development of Novel Silicon-Based Thickeners for a Supercritical CO2 Fracturing Fluid and Study on Its Rheological and Frictional Drag Behavior

To address low viscosity of CO2 in supercritical CO2 fracturing, the authors studied silicon-based thickeners for a supercritical CO2 fracturing fluid. Two silicon-based thickeners, namely, PMSQ-VAc and PDMS-VAc, were prepared by solution polymerization and emulsion polymerization, respectively; for each of the thickeners, molecular structural characterization, observation of dissolution in supercritical CO2 with a pco.dimax cs1 high-frequency microscope camera, and exploration of viscosity-enhancing mechanisms were performed; a differential pressure method for fluid flow in a high-pressure delivery pipe was used to calculate viscosity and frictional drag coefficient of the supercritical CO2 fracturing fluid, and rheological behavior and frictional drag behavior of the fracturing fluid under different experimental conditions were evaluated. The test results show that, by solution polymerization, the PMSQ-VAc thickener could be prepared from vinyl acetate and polymethylsilsesquioxane at a mass ratio of 13.95:7.51, with a yield of 84%, a molecular weight of 49,170 g/mol, and a viscosity of 12.86 mPa·s; by emulsion polymerization, the PDMS-VAc thickener could be prepared from dimethylcyclosiloxane, vinyltriethoxylsilane, and vinyl acetate at a mass ratio of 2:1:3, with a yield of 93%, a molecular weight of 76,190 g/mol, and a viscosity of 21.47 mPa·s; in the absence of any cosolvent, both silicon-based thickeners had a good solubility and viscosity-enhancing effect in supercritical CO2, among which PDMS-VAc had a better solubility and viscosity-enhancing effect, enabling the viscosity of supercritical CO2 to be up to 10.12 mPa·s; after being incorporated with the silicon-based thickeners, the supercritical CO2 fracturing fluid exhibited rheological behavior in agreement with shear behavior of pseudoplastic fluid and thus belongs to non-Newtonian fluid; the viscosity of the supercritical CO2 fracturing fluid varied in a nonlinear manner with increasing temperature and pressure, i.e., increasing and then decreasing, and with increasing thickener concentration, the viscosity increased and then tended to be stable; the frictional drag coefficient of the fracturing fluid in pipe flow decreased gradually with increasing flow rate and pipe diameter and increased gradually with increasing viscosity of the fracturing fluid; two fracturing fluid systems consisting of silicon-based thickeners and supercritical CO2 barely or weakly damaged the reservoir core. The silicon-based thickeners are practicable to some extent during supercritical CO2 fracturing and likely to become high-performance, low-cost, pollution-free supercritical CO2 thickeners.

Application of Nonlinear Elastic Wave Spectroscopy in the Field of Nuclear Energy

Abstract In the field of nuclear energy, two particular applications are considered—the measurement of biological shielding concrete and measurement of high-temperature high-pressure piping. For the measurement of biological shielding concrete, a special manipulator was developed, which is applied through the ionization channels of VVER-440 power plants. Biological shielding concrete is covered on all sides with an 11 mm thick steel liner preventing its assessment using any conventional test method. For the measurement of high-temperature high-pressure piping, acoustic emission sensors installed in the LEMOP system (NPP Temelin) are used for both excitation and data acquisition. In operation, this piping is covered with glass wool insulation, but installed sensors on the waveguides make it possible to assess pipelines without removing the insulation. To demonstrate the material degradation, a set of concrete test specimens and a set of steel test specimens were made. Nonlinear elastic wave spectroscopy is a test method based on measuring the elastic–plastic response of the material whose plastic component is caused by microcracks. Part of this response may be caused by inhomogeneity of the material itself or the nonlinearity of the test system used, which is to be minimized in the measurement. Due to degradation, the number of microcracks increases, increasing the total nonlinear response of the material. The aim of this approach is to monitor the degradation of concrete and metallic materials based on the response of the test system to ultrasonic excitation.

Advent of different grades of HSLA pipeline steels and their structural integrity issues related to welding – ‘A review’

HSLA steels find its application in high pressure pipes for the oil and gas transportation. To maintain the integrity of pipelines which covers long distance from few kilometers to thousands of kilometers different protection methods has been utilized. As these pipes cover very long distance and are joined by different welded joints. Failures of pipelines are generally occurred at the weld joints due to the use of improper welding consumables. Different structural integrity issues such as corrosion, hydrogen induced cracking and stress corrosion cracking may occur due to continuous immersion of weld joint the in severe service environments. This paper is an attempt to review the effect of different welding consumable on welding of HSLA steels.

Analysis and Modeling of Particle Velocities in Premixed Abrasive Water Jets

The premixed abrasive jet possesses a strong strike ability and is widely used in oil and gas exploitation, machining, rust removal, and other fields. The superstrong, forceful impact of the premixed abrasive jet is mainly provided by high-speed abrasive groups. Hence, the abrasive velocity is the basis of this research, by applying the distribution law of abrasive impact force. In this paper, the particle velocity of the premixed abrasive jet is analyzed theoretically, and the corresponding particle velocity model is established. The real-time contrast interpolation method is employed to solve the problem of the variable drag coefficient. Factors such as the nozzle structure, average abrasive diameter, abrasive density, and jet flow are utilized to determine the abrasive velocity of the nozzle outlet. The numerical solution for the abrasive velocity is obtained by dividing the high-pressure pipe and nozzle into several sections, along the axis. Finally, the calculated particle velocity is compared with the particle image velocity measurement (PIV), to verify the correctness of the established model. These results demonstrate that the model calculation is in effective agreement with the experimental results. The deviation between the theoretical value and the experimental mean is 0.18 m/s. The standard deviation of the experimental results is 3.81-4.22 m/s, while the average error is less than 4%.

Phase Transformation Kinetics of Austenite during a Combination of Laser-Hybrid and Multi-Arc Welding of High Pressure Pipes

This study investigated the phase transformation kinetics of austenite in the heat-affected zone of the joints welded by laser-hybrid and submerged multi-arc welding. Optimum cooling rates to form favorable structural-phase composition in the heat-affected zone were found.

Numerical Simulation and Design of a High-Temperature, High-Pressure Fluid Transport Pipe

When designing a hand caliber with a high-temperature, high-pressure internal fluid transport pipe, reliability, safe use, and performance must be considered. Reliability refers to the stress caused by thermo-mechanical load; safe use refers to the low-temperature burns that might occur upon contact, and high-temperature burns caused by gas leakage occurring in the cylinder gap; and performance refers to projectile velocity. In this study, numerical simulation methods for heat transfer, structure analysis, and gas leakage are proposed so that solutions can be designed to account for the above three criteria. Furthermore, a hand-caliber design guide is presented. For heat transfer and structural analysis, mesh size, the transient convective heat transfer coefficient, and boundary conditions are described. Regarding gas leakage, methods reflecting projectile motion and determination of the molecular weight of the propellant are described. As a result, a designed hand caliber will have a high reliability, because the thermo-mechanical stress is lower than the yield stress. There will be little risk of low-temperature burns, but there will be a high temperature-burn risk, owing to gas leakage in the cylinder gap. The larger the cylinder-gap size, the greater the gas leakage and the smaller projectile velocity. The presented numerical simulation method can be applied to evaluate various aspects of other structures that require high-temperature, high-pressure fluid-transport pipes.

A critical review on dissimilar welds joint between martensitic and austenitic steel for power plant application

Abstract In this review article, microstructure and mechanical behavior of the dissimilar welded joint (DWJ) between ferritic-martensitic steel and austenitic grade steel along with its application have been summarized in Ultra Super Critical (USC) power plant. Creep-strength enhanced ferritic-martensitic (CSEF/M) P91 steel was developed to sustain at extreme operating conditions of ultra-supercritical (USC) power plants, and later, P92 was developed to achieve better mechanical properties, higher creep-rupture strength and high operating temperature with the reduction in wall thickness as compared to P91 steel. The most common application of P91/P92 material in power plants includes high pressure and high-temperature steam piping, headers, super-heater tubing, and water-wall tubing. The other most commonly used material in the power plants is austenitic stainless steel, i.e., SS 304 L. The austenitic grade stainless steel offers high resistance to corrosion due to the high wt. % chromium and nickel content (18–20 and 8–12, respectively). Due to the low carbon content, the SS 304 L is less sensitive to the sensitization problem and offers excellent weldability. The joining of these dissimilar materials is frequently required in the power generation industry. The current review focuses on the main difficulty associated with dissimilar welding of martensitic P91/P92 and austenitic grade stainless steel. The different chemical composition, mechanical, physical and metallurgical properties of the martensitic P91/P92 and austenitic grade stainless steel leads to the problems such as hot cracking and carbon migration. The other weldability issues are the formation of a brittle intermetallic compound, the formation of soft transaction heat affected zone along with martensitic steel, δ ferrite formation in fusion zone, diffusion related problem, and residual stresses, which necessitates thorough study and qualification of welds. The effect of coarsening of various precipitates such as M23C6 carbides, MX carbonitrides, and effect of laves phase, z-phase, and sigma phase on mechanical property, and creep-rupture strength of DWJ are also discussed in detail. Based on the literature reviewed, it has been found that some of the above-stated problems can be solved by using nickel-based filler wire due to its intermediate physical and mechanical properties. The selection of the proper filler metal is another vital issue in dissimilar welds joint that is also covered in this review article. The reason behind the formation of the unmixed zone, filler deficient region, peninsula, island, beach, migrated grain boundaries, solidified grain boundaries, and solidified subgrain boundaries during DWJ of martensitic P91/P92 and austenitic grade stainless steel is also discussed. The heat treatment is required to eliminate the heterogeneous microstructure during the dissimilar welding. The effect of post-weld heat treatment (PWHT) on the microstructure and mechanical behavior of the DWJ also reviewed. The residual stress developed during the DWJ may cause the premature failure of the components under service, has also been discussed in detail. The effect associated with the residual stress deformation has been reviewed in the different conditions of the DWJ.

Numerical Simulation and Experimental Confirmation of a Bimetallic Pipe Forming Process.

Most oil and gas is transported by pipeline, and corrosion causes a great threat to the service life of the pipeline; bimetallic pipe, which combines the advantages of good mechanical properties, good corrosion resistance, and relatively low price, is a good choice for high-pressure and corrosion-resistant pipe, but its manufacturing process and stress distribution are more complex than single metal pipe. JCO is a widely used cold forming method for pipes which is named by the shape of the plate in the forming process, i.e. J-shape, C-shape and O-shape, and the forming process is an important parameter that determines the level of imperfections and residual stresses in a pipe, and residual tensile stress will accelerate corrosion failure of the pipe. In this study, the three-dimensional (3D) finite element method (FEM) is used to simulate the pre-bending and JCO forming process of a 2205/X65 bimetallic pipe. The model and the simulated results are validated by digital image correlation (DIC) experimental and the opening width of the formed pipe billet, respectively. The influence factors of the stresses are studied. Further, a two-dimensional (2D) model is established to study the characteristics of bimetallic plate bending and the stress distribution at the interface of different materials, and the results are compared with that of three-dimensional model.

Shaping of gallate-based metal-organic frameworks for adsorption separation of ethylene from acetylene and ethane

Shaping metal-organic frameworks (MOFs) powders into formed bodies plays a crucial role in opening up the excellent properties of MOFs to a broad range of applications. Gallate-based MOFs, termed as M-gallate (M = Co, Mg, Ni), have shown excellent performance for adsorption separation of C2 hydrocarbons. However, the industrial applications of MOF powders will inevitably confront problems of high pressure drop, pipe blockage, and dust pollution. Herein, we use hydroxypropyl cellulose (HPC) as a binder to produce gallate-based MOFs pellets. The crystal structure of the well-shaped materials after molding remained intact, and the surface area of the materials hardly decreases after shaping. Adsorption isotherms of C2 hydrocarbons including ethylene, ethane and acetylene on the activated powders and pellets of M-gallate were recorded and compared with the outperformers. The shaped pellets were also examined by breakthrough experiments on the fixed-bed separation of C2H2/C2H4 (1:99, v/v) and C2H4/C2H6 (50:50, v/v) gas mixtures. These results proved that M-gallate pellets was promising candidates for the practical industrial realization of C2 hydrocarbons separation.

Pressure Control of High-Pressure Oil Pipe

In this paper, to realize the pressure stability control of high-pressure oil pipe, the dynamic differential equation of fuel oil inlet and outlet is established based on the theory of mass conservation. According to the change of the pressure in the high-pressure tubing, an optimization model is established to achieve precise control of the working time of each part of the high-pressure oil pipe.

Creep–Fatigue Interaction of P91 Steam Piping Subjected to Typical Start-up and Shutdown Cycles

The possibility of creep–fatigue interaction occurring in steam pipes of power generation plants during operation has been on the front burner for years. Often, failure of the pipes during operation is attributed to either creep alone or fatigue alone. Of recent, some failures are speculated to be due to simultaneously coupled interaction between creep and fatigue, especially when the failure occurs earlier than anticipated. The literature shows that such studies are very limited and indeed under-researched. Thus, there is a dire need to systematically investigate this coupled creep–fatigue phenomenon and provide clarity as the failure of high-pressure steam piping has consequential and very significant effects on the suppliers and end users. In this work, a special Fortran user subroutine script of a phenomenological modified hyperbolic sine creep model was developed and implemented in Abaqus CAE/2019 finite element code to initially determine the creep behavior of a P91 steam piping network subjected to a typical daily start-up and shutdown cycle. Subsequently, fe-safe/TURBOlife software was employed to investigate whether the failure induced by the start-up and shutdown cycles was due to fatigue alone, creep alone or due to creep–fatigue interaction. Interestingly, the study showed that the failure of the piping network under the specified operating conditions is specifically due to creep alone. Furthermore, the intrados of the elbow in the piping network was identified as the region most prone to failure, and the piping network will only survive a total of 7.1 and 7.7 years under these operating conditions for both machined and fine-machined surfaces, respectively. These results were thereafter analytically validated, and it showed a strong correlation with the numerically determined creep rate.

Fuel system control design based on mass conservation

Fuel entering and ejecting high-pressure fuel pipe is the basis of fuel engine operation. The intermittent operation of high-pressure oil pump and injector will lead to the change of pressure in high-pressure oil pipe. This paper studies the influence of the opening and closing of one-way value and the speed of cam angle on the pressure in high-pressure oil pipe. Because the fuel flow is unstable in the high-pressure fuel pipe, it is necessary to determine the influence of pressure change on fuel density, and then calculate the mass of fuel supply and fuel injection in unit time. Considering the principle of mass conservation, the problem can be transformed into the length of single opening time of one-way valve when the mass of fuel entering and leaving the high-pressure oil pipe is equal in unit time interval. At the same time, by deducing the influence of the single opening time of the one-way value on the pressure in the high-pressure oil pipe, the single opening time of the one-way valve when the pressure of the high-pressure oil pipe reaches equilibrium after 2s, 5s and 10s is 0.610895ms, 0.425998ms and 0.373376ms respectively. Consider the working principle of the fuel system on the basis of the above considerations. Fit the function relationship between the needle lift and working time, deduce the change rule of flow volume of injector with time, and calculate the volume and mass of fuel injected by the injector in the working cycle. The results show that the high-pressure oil pump supplies oil 94 times in a working cycle of the injector, and the time required for the cam to rotate for one circle is 1.064ms, and the angular velocity of the cam is 5.906rad/ms. In this paper, based on the theory of unsteady liquid motion, mass conservation and energy conservation of fluid mechanics, many elements involved in the problem stem are analysed and related, and the control model of one-way valve switch and cam angular velocity is given.

Influence of the Feed on the Quality of the Sealing Surface of the Shutoff Assemblies of High Pressure Fitting During Diamond Smoothing

Ensuring the tightness of high-pressure valves operating in aggressive environments at high temperatures and pressures is an important task. To increase the wear resistance of the contacting nodes of the reinforcement, improve the quality of the surface, a method of diamond smoothing is proposed, which allows to reduce roughness, to reduce deviations from roundness of high-pressure pipes. In the work, studies were carried out that made it possible to identify the optimal surface treatment modes by the diamond smoothing method, to reduce the surface roughness several times without using lapping and polishing of reinforcing units.

Influence of Frequency-Dependent Friction Modeling on the Simulation of Transient Flows in High-Pressure Flow Pipelines

Abstract Frequency-dependent friction can be an important dissipative factor for unsteady flows. In this research investigation, various popular models have been reviewed thoroughly and then applied to evaluate frequency-dependent friction in high-pressure transient flows. Three piezoresistive transducers were used to measure pressure signals along a 2 m high-pressure pipe: the first and the third signal were assumed as boundary conditions in a homemade code that is able to solve the velocity and pressure fields along the pipe. The simulation pressure data have been compared with the pressure signal measured by means of the transducer installed in the middle of the pipe. In addition, an injector model has been applied to a 2 m pipe in order to perform additional simulations in which the rail pressure time distribution and the electrical current time history to the injector are provided as boundary conditions. It has been observed that when frequency-dependent friction is taken into account, more accurate pressure results are generally obtained along the injector supply line than in the case in which the viscous stress is calculated by only taking into account the steady-state Darcy–Weisbach contribution. On the other hand, on the basis of a comparison between the obtained numerical results and experimental traces, the improvement is not related to the method by which the unsteady friction is evaluated. Therefore, the simplest frequency-dependent friction model is recommended to simulate high-pressure transient flows in pipes with a shorter aspect ratio than 800 and lower Reynolds numbers than 104.

Numerical Simulation of Pressure Control in High Pressure Pipe

When the injector works, how to control the fuel inlet valve so that the fuel pressure in the high-pressure fuel pipe is kept at a constant value. The method of calculation and numerical simulation is presented.

The Pressure Control Strategy Adjustment of High-Pressure Oil Pipe

This paper is based on the background of China Undergraduate Mathematical Contest in Modeling Competition A in 2019. Corresponding analysis based on the data given in this question, calculated changes in pressure in the high-pressure tubing according to the different operating conditions for fuel entry and spewing out, in order to determine some operating parameters of the fuel injection system, so as to improve engine efficiency and economic efficiency. The differential equation is constructed by the mass conservation formula under the corresponding conditions, and using MATLAB to implement Runge-Kutta methods to find the numerical solution of the corresponding differential equation.

Evaluation of residual stresses and structural-phase composition in longitudinal welds of high pressure pipes

ABSTRACT The features of the formation of residual welding stresses and structural-phase composition in welded joints of the longitudinal joints of high-pressure pipes for gas pipelines are considered.