Side Of Pipe Research Articles

A Labor-Saving Method of Pipe Uplifting Countermeasure with Geocell-Geotextile Combination

In this study, we proposed a new method which mitigates pipe uplifting by utilizing geocells and geotextiles. The method resulted in labor saving in construction. To verify the effectiveness of the proposed method, we reproduced pipe uplift by conducting push-up tests using a 150-mm-diameter pipe. The test results showed that the proposed method increased the peak resistance and the resistance at large displacement by 1.47 and 3.35 times, respectively, compared to the unreinforced method. The proposed method also increased the peak resistance by 1.13 times compared to the conventional method widely used in Japan. It demonstrated consistently high resistance even after the peak. This indicated that the proposed method is very effective as a countermeasure against pipe uplift. Furthermore, increasing the overall width of the geocell improved the resistance. In this study, two different approaches were used to evaluate the uplift resistance of the pipe. The approaches showed that, with geocell reinforcement, most of the dead weight at the pipe sides and above them contributed to the peak resistance. It was also found that the peak resistance of the proposed method can be predicted to some extent by modifying the previously proposed equation.

Compatibility study of high density polyethylene grade 80 gas pipe with synthetic polyglycol-based brake oil

High Density Polyethylene (HDPE) is one attractive technical option for the transportation and distribution of natural gas and hydrocarbons given the advantages in long-term mechanical strength, lifespan, maintenance costs and resistance to chemical aging. This study investigates the compatibility of extruded pipe material from copolymerized HDPE-80 with DOT 3 brake fluid. Machined standard specimens from inner (IL) and outer (OL) pipe layers are aged in commercial synthetic polyglycol-based oil for 7 days at laboratory conditions. The percent mass changes are +2.2% and +1.9% respectively for IL and OL pipe surfaces. These results are in the same range of published sorption data for other oils and fuels. Stress-strain parameters (E, σ y, σ CD, σ f, ε y, Δ ε CD, ε f) and fracture work are established and thoroughly discussed for both pipe sides. For IL, the reduction of E, σ y and ε f are respectively 28.0%, 13.9% and 22.7%, while for OL they are 22.6%, 7.7% and 25.1%. Globally, it is concluded that strength properties degradation in DOT 3 oil is more important for IL compared to OL. There is an important loss of ductility for both pipe sides. Ageing caused IL crystallinity ( Xc) to increase while OL showed inverse results probably because of frozen anti-oxidants in the outer surface layers following water quenching during extrusion. Before and after ageing, the as-received OL is found to be more resilient to oxidation than corresponding IL, as higher OIT parameters are also shown in the case of crude oil compatibility investigations. DOT 3 brake oil seem to accelerate the degradation of HDPE-80 thermal stability with a higher intensity for IL.

Design and numerical analysis of a novel argon gas tube to reduce impurities in large size casting crystalline silicon furnace

A novel design of argon gas tube within the silicon casting system was developed employing pipe flow and side jet analysis, which facilitates horizontal ejection of argon gas along the silicon melt surface. The aim was to enhance control over gas flow velocity for removing impurities during large size silicon ingot (1400 kg) growth, with special attention on the edge region of ingot. It was found that the diameter of side-facing outlet holes, when oriented along the corner direction, is about 2 times of that along the side center direction, to achieve an extended jet distance reaching corner region. The gas flow and transport of SiO above the silicon melt surface were studied for the proposed gas tube configuration based on 3D numerical simulations. The simulation results reveal the correlation between argon flow rate and resultant gas velocity at the edge of melt surface, which is consistent with the theoretical analysis, particularly for moderate to high argon flow rates. The numerical simulations demonstrated that the proposed gas tube, equipped with eight optimized outlet holes, outperformed the conventional tube in extracting SiO from both central and corner regions above the silicon melt surface.

Effect of pipe installation and external load on buried steel pipe responses: Experimental and numerical investigations

During pipe installation, compacting soil at pipe sides causes an initial pipe deformation which is known as the “peaking” effect. However, in conventional pipe design codes, only pipe deformation caused by vertical overburden is considered while the “peaking” effect is ignored. In this study, a full-scale test was conducted on a Grade X52 steel pipe with a diameter of 600 mm to investigate the impacts of both soil compaction and vertical overburden on pipe deformation. Soil compaction and external load were found to elongate and shorten the vertical pipe diameter, respectively. The “peaking” effect was observed during the installation procedure accompanied by the highest pipe stress measured at the pipe crown. Then, a two-dimensional finite element model was created and validated based on the calculated pipe stresses from the experimental study. A parametric study was performed thereafter to numerically study the impacts of soil water content, pipe wall thickness, compaction pressure, and lift thickness on pipe responses due to soil compaction and external load. An increase in the “peaking” effect is observed with increasing soil water content and compaction pressure, while an increase in pipe wall thickness or lift thickness would cause a decrease in the “peaking” effect.

Comparative Analysis of Buried Pipe Under Heavy Train Loads

With rapid development of railway transportation and increasing demand of oil and gas in China, the heavy haul train load becomes an important factor that threaten the safe operation of pipe. The mechanical behavior of buried pipe subjected to heavy haul train load was investigated in this study. A finite element model was established to investigate the effect of train load. Finally, the multiple train loads were also discussed. Results show that the high stress area occurs under the train track. In the pipe segment below the track, the top of pipe is under compression and the bottom of pipe is under tension. The cross section of pipe is still circular. The maximum vertical and horizontal displacement are at the top and side of pipe. The maximum von Mises stress, axial strain, and displacement of pipe increase with the increase of train load. Under the multiple train loads, there are two high stress and high strain areas at the top and bottom of pipe. With the increase of multiple train loads, the maximum von Mises stress, axial strain, displacement and ovality increase.

Seismic response of buried pipes in sloping medium dense sand

Dynamic centrifugal experiments are conducted to explore the seismic response of buried pipes in sloping medium dense sand. Different ground inclination angles θ, different amplitudes of seismic wave, different boundary conditions of pipe, and different burial depths H are investigated. Test results show that the excess pore pressure (EPP) is asymmetrically distributed around the pipe, with the value along the springline on the uphill side notably larger than that on the downhill side. The generation of EPP continues after the shaking. EPP around the free-moving pipe is smaller and dissipates faster than that around the stationary pipe. Compared with the horizontal ground, 10° and 20° ground inclinations result in a 1.3–1.9 folds increase in EPP beneath pipe and a 2.4–3.4 folds increase in peak uplift displacement. Lateral movement of pipe towards the downhill side and rotation of pipe towards the uphill side are linearly correlated and both increased with a shallower H and larger θ. Due to the pipe-soil interaction, soil displaces along a series of quasi-circular slip surfaces extending from the ground surface on the uphill side to the ground surface on the downhill side. Thus, enough burial depth is required to mitigate the greater displacement of pipe and soil arising from the ground inclination.

Construction of subway station using the small pipe roof-beam method: A case study of Shifu Road station in Shenyang

A case study of the Shifu Road station of Shenyang Metro Line 4 in China, which was constructed using the small pipe roof–beam method, is presented herein. The minimum buried depth of the Shifu Road station is only 4.2 m, and numerous urban and high-rise buildings are constructed above the station. The location, surroundings, geological conditions, design, and construction process of the Shifu Road Station is described herein. The settlement of the pipe roofs, beams, intermediate columns, and side piles; the vault settlement and horizontal convergence of the pilot tunnels; and the surface settlement are monitored. Subsequently, the station is compared with similar metro stations in terms of surface settlement and construction period. The results indicate that the excavation of the transverse pilot tunnel and the negative layer significantly affect the pipe-roof settlement above the intermediate column and the surface settlement of the station center, which constitutes more than 75 % of the total settlement. The surface settlement above the Z3 pilot tunnel is affected significantly by the excavation of the longitudinal pilot tunnel and constitutes approximately 80 % of the total settlement. The vault settlement and horizontal convergence of the pilot tunnels as well as the settlement of the beams, intermediate columns, and side piles exhibit staged changes throughout the construction period. Compared with the surface settlement of similar metro stations, that of the station investigated is approximately 63 % owing to the adoption of the small pipe roof–beam method, thus reducing the construction period by six months at the least. The results obtained show that the proposed method is advantageous for constructing shallow buried large-span metro stations and that it can serve as a reference for various applications.

Experimental and Numerical Prediction Model for the Dangerous Radius of Natural Gas Leakage in Soil.

Prediction of the dangerous radius of natural gas plays an important role in reducing the hazards of a buried natural gas pipeline after leakage. The factors affecting the diffusion law of natural gas in soil after leakage are mainly divided into the pipe, soil, and environmental sides. Previous studies focused on the effects of leakage pressure, leakage aperture, and leakage direction on the pipe side and porosity and water content on the soil side. In this paper, experiments and numerical simulations are conducted for further investigating the effects on the diffusion of natural gas in soil of the soil type (porosity and granule diameter) and layered structure among the soil side factors and soil temperature as environmental side factors. The contour radius corresponding to 5% volume concentration (the lower limit of natural gas explosion in soil) is defined as the natural gas dangerous radius for analysis. Based on comprehensive analysis of the effects of the factors, a prediction model is proposed for the dangerous radius of natural gas in soil with leakage pressure, leakage aperture, porosity, and granule diameter as the dominant influencing factors, which is of great significance for locating the source of the leakage.

Cracking Failure Analysis of Pipe to Flange Weld Joint

Cracking failures occurred frequently in blowdown pipe to flange weld joint, and the root crack appeared on the blowdown pipe side of the weld joint and extend into the base metal of pipe. To explore the reason why cracking failures occurred on the blowdown pipe side of the weld joint, the weld joint was analyzed via macroscopic and metallographic structure observation, and blowdown pipe was tested by physical and chemical property testing, and corrosion scale was analyzed by SEM, EDS, and XRD. The dent and thinner wall thickness of pipe are found in the internal pipe to flange weld joint. Widmanstatten metallographic structure is found in heat affected zone (HAZ), fusion zone (FZ) and weld metal zone (WZ) of weld joint. Stress concentration form in the weld joint at blowdown pipe side during welding due to the dent and different wall thickness. Under the action of gas vortex in the dent of weld joint, corrosive droplets aggravate the localized corrosion of the weld joint. Stress corrosion cracking (SCC) were initiated in FZ and WZ from the surface of weld joint and propagated into the base metal of pipe under the combined actions of stress resulting from weld process and during operation, and corrosion.

Numerical simulation of nanofluids forced convection in a corrugated double‐pipe heat exchanger

AbstractIn this study, the heat transfer and flow characteristics of TiO2‐H2O nanofluids with TiO2 mass fractions of 0.0, 0.1, 0.3, and 0.5 wt.% in corrugated and smooth double‐pipe heat exchangers were compared using numerical simulations. The results demonstrated that TiO2‐H2O nanofluids effectively enhanced the heat transfer compared to deionized water, and that the heat exchange capacity gradually increased with the TiO2 mass fraction. The corrugated pipe heat exchanger disturbed the fluid flow on both the shell side and pipe side, breaking the boundary layer and creating vortices in the corrugated zone. This provided a higher heat transfer capability than the smooth double‐pipe heat exchanger, but also increased the fluid flow resistance in the pipe. In general, the use of nanofluids and corrugated pipes was found to significantly improve the heat transfer efficiency of the double‐pipe heat exchanger.

Estimating the spectrum of leak noise in buried plastic water distribution pipes using acoustic or vibration measurements remote from the leak

An appropriate model of leak noise at source is necessary in analytical and numerical approaches to investigate the characteristics of leak noise measured remotely from the leak in buried water pipes. It is extremely difficult to measure leak noise at source in practice, so an inverse method is needed to predict this from measurements made either side of the leak at convenient access points. This paper presents such a method, and illustrates the approach using four data sets from three different test sites. The method requires that the noise propagates in the pipe according to a simple model of wave propagation within the frequency range over which leak noise is detected at the sensors. Using the measured data, the real and imaginary parts of the wavenumber are estimated, and these, together with an estimated position of the leak between the two sensors, the frequency response functions corresponding to the sections of the pipe either side of the leak position are estimated. If pressure measurements are made, then both the level and shape of the leak noise spectrum can be estimated, but if accelerometers are used then only an estimate of the shape of the spectrum is possible. From the measurements presented, it is found that it is not possible to state categorically that the leak noise spectra decays according to a particular frequency power law. There is some evidence that it decays with a frequency power law of ω-1, which agrees with previous laboratory based experiments, but this is not definitive in all cases.

PENGARUH VARIASI TEMPERATUR TERHADAP KETEBALAN LAPISAN PERMUKAAN DENGAN ELECTROPLATING PADA STAY MAIN PIPE SIDE COVER

Various items of jewelry, crafts, motorcycle parts, automobile and equipment manufacturers need a final touchthrough the electrical layer electroplating technology. The coatings intended to improve the surface of the object, sothat the more brilliant, shiny, resistant to corrosion, and the objects surface become harder. Electroplating is ametal coating on a conductive solid objects with the aid of electric current, where its process is used to manipulatethe nature of a subtrate by coating with other metals. The coated metal is shaped already on SPCC plate of SuzukiSmash motor vehicle parts, namely stay main pipe side cover. The metal used in electroplating coating is zinc. Thistest uses a plate SPCC specimens, amounting to 4 pieces. In the implementation of the electroplating coating using avariation of temperature 20 0C, 28 0C, 35 0C and 45 0 C. The research results showed that the electroplating processat a temperature of 28 0C to produce the coating thickness of 23 μm. The violence of hard coating is found at thetemperature of 28 0C with violence of 135.6 kg / mm 2. The micro structure of the surface layer is uneven, and thereare fine black holes. The corrosion resistance is obtained for quite good electroplating layer at the variationtemperatures of 28 0C and 35 0C with Area Failed Rating Number 9 ie (0% -1%).

Analysis on Mechanical Properties of the Buried Pipeline Considering Pipe-soil Interaction

Mechanical deformation of buried pipeline under vertical load is the result of pipe-soil interaction. In order to reveal the necessity of pipe-soil interaction while investigating mechanical properties of buried pipeline, the ANSYS commercial software is employed to construct pipe-soil interface and simulate pipe-soil coupling effect. With the newly developed model, mechanical properties of pipe under vertical static load are analyzed. Numerical solution is subsequently compared with analytical solution. The results reveal that (1) There is maximum Von Mises stress at internal surface of pipe side under overlying load, and minimum Von Mises stress appears in the pipe shoulder at angle of about 45°to x-axis; (2) The pipe-soil interaction has significant effect on analyzing the deformation and distribution of stress of buried pipeline; (3) Vertical displacement obtained from Marston model is larger than that obtained from newly constructed numerical model; (4) The deformation of pipe is obviously constrained by backfilled earth around the pipe. For a buried pipe, especially the elastic pipe, it is necessary to consider pipe-soil interaction while analyzing its mechanical properties.

Failure analysis of service exposed austenitic stainless steel pipelines

Several leaks appeared in Austenitic Stainless Steel (ASS) pipelines installed for transporting water in a test loop after a few years of operation at Indira Gandhi Centre for Atomic Research, Kalpakkam. The locations of leaks were mostly on pipe fittings like bends, but a few were noticed on the pipe away from the fittings too. This paper presents the results of failure analysis carried out on leaking of pipes and fittings. Investigation carried out include optical as well as scanning electron microscopy, energy dispersive spectroscopy, electron back scattered diffraction analysis and microhardness measurements. In addition, double loop electrochemical potentio-kinetic reactivation experiments were conducted on specimens extracted from the pipe side and fitting side of a weld that was found leaking. Further ASS pipe welds prepared with different surface finish conditions were exposed to the environment of the installed pipeline and surface degradation in these pipe welds were compared to reveal the effect of surface treatment on degradation of the welds. It is found that the sensitization along with residual stress generated during welding facilitated intergranular stress corrosion cracking in pipe fittings made of AISI 304 stainless steel resulting in the leaks observed in the pipe fittings. Cracks initiated from the corrosion pits present near the weld, which most likely would have formed due to improper cleaning given to the weld zone after completion of the weld. Leak observed in the pipe is attributed to the crevice corrosion that progressed from a defect present in the pipe making it grown across the thickness. The defect itself was result of an improper repair by arc welding, of a discontinuity that was found in the pipe. The pipe is produced from sheets by resistance welding and the origin of the discontinuity is the poor joint formation during resistance welding. The paper also gives recommendation on good fabrication practices to be followed so that similar kind of failures could be avoided in future.

Coupled convection heat transfer of water in a double pipe heat exchanger at supercritical pressures: An experimental research

An experiment about coupled convection heat transfer of water in a double pipe heat exchanger at supercritical pressure was conducted. The effects of experimental variables on the heat transfer were investigated, and the buoyancy effect on the heat transfer of the outer pipe was analyzed emphatically. There is a difference between the peak heat transfer coefficient temperature and the pseudo-critical temperature, and the difference increases with the increase of pressure. This phenomenon is caused by the temperature gradient and the variations of thermal-physical properties in the heat transfer section. The mass flow rates of the inner pipe side and outer pipe side were always equal, and one side will offset the effect of the other side on the heat transfer. The heat transfer coefficient of the outer pipe increases with the increase of water temperature at the inlet of the inner pipe when the mean bulk temperature is lower than the pseudo-critical temperature, due to the buoyancy effect decreases at the same time. While, the buoyancy effect is almost independent of the water temperature at the inlet of the inner pipe when the mean bulk temperature is higher than the pseudo-critical temperature, due to the buoyancy effect is non-significant. A new heat transfer empirical correlation was proposed, which includes 94.01% of experimental data are within ±25% error bars.

Clinical analysis of 54 patients with non-syndromic enlarged vestibular aqueduct

Objective:To further recognize the clinical characteristics of non-syndromic enlarged vestibular aqueduct through the retrospective analysis of cases, with the purpose of providing references for clinical diagnosis and treatment. Method:Collect 54 cases of non-syndromic enlarged vestibular aqueduct, and analyze their clinical characteristics after history taking, physical examination, audiometry and imaging examination. Measure the biggest width of midpoint between internal and external of vestibular aqueduct on temporal bone thin-section CT, and analyze the relationship between the pipe width and sides of ear, types of hearing loss and degree of hearing loss through t test. Result:All 54 patients with non-syndromic enlarged vestibular aqueduct had bilateral ear involvement. There were 42 cases with prelingual deafness, 12 cases with postlingual deafness, and there were 38 ears with severe deafness, 70 ears with profound deafness. Ninety-six ears of hearing loss showed sensorineural deafness, and 12 ears manifested mixed deafness. The biggest width of midpoint between internal and external of vestibular aqueduct spread over 1.60-3.90 mm, and the average was 2.60 mm. There were no significant differences in data between left and right sides, degree of hearing loss and type of hearing loss. Conclusion:Non-syndromic enlarged vestibular aqueduct mainly manifests serious sensorineural deafness, and the diagnosis depends on imaging examination. There is no difference in the degree of expanding between left and right ear, and the extent of enlargement is not related to the type and the severity of hearing loss.

Finite Element Plastic Limit Loads of Complex Cracks in Pipes With Two-Layered Materials.

Based on the detailed three-dimensional (3D) finite element (FE) limit analyses, the present study investigates the plastic limit loads of complex-cracked pipes with two-layered materials for determining maximum load-carrying capacity or critical crack length of pipes with two-layered materials. The complex cracks in pipes with two-layered materials consist of a partial through-wall crack and 360-deg circumferential surface crack in the inner side of pipe in the same plane in pipe, which could be developed in the preemptive weld overlay region on the dissimilar metal weld (DMW) of nuclear pipe. In terms of FE limit analyses for complex-cracked pipes with two-layered materials, total thickness of pipe, depth of 360-deg internal surface crack, length of partial through-wall crack and the effect of strength mismatch between two materials are systematically considered in the present study. As for loading conditions, axial tension, global bending moment, and internal pressure are employed in the present FE analyses, and then, the confidence of the present FE procedure is confirmed by comparing the FE results with the existing solutions for complex cracks in single material. The results of the present FE plastic limit loads are compared with the existing solutions for complex-cracked pipes with two-layered materials. Also, a simple approach using equivalent single material based on the weighted average concept instead of using the properties of two materials is suggested for predicting plastic limit loads of two-layered materials. The present results can be applied to leak-before-break (LBB) analyses of nuclear piping with weld overlay.

Estimation of the bulk and shear moduli of soil surrounding a plastic water pipe using measurements of the predominantly fluid wave in the pipe

Leak noise correlators are commonly used to detect and locate leaks in buried water pipes. They use the cross-correlation function between leak noise signals measured using hydrophones or accelerometers placed on the pipe either side of the leak. The efficacy of a correlator is dependent upon knowledge of the speed at which the leak noise propagates along the pipe as well as how much it attenuates with distance. The leak noise is carried in a predominantly fluid-borne wave in the pipe, which is heavily influenced by the pipe and soil properties. Although the pipe properties can be determined relatively easily, estimation of the soil properties surrounding the pipe is more problematic. It is desirable to have an accurate estimate of the soil properties, so that current models can be developed and used to improve understanding of leak noise propagation and hence leak detection capabilities. In this paper a novel approach to determining the bulk and shear moduli of the soil from measurements of the predominantly fluid-borne wave in a buried plastic pipe, is described. The measured data are compared with corresponding data predicted from a model, and the soil properties are determined using an optimization algorithm. The method is applied to two different sites, one in the UK, where the soil properties surrounding the pipe are representative of sandy soil, and one in Brazil, where the surrounding soil has properties that are representative of clay soil. It is found that the bulk and shear modulus can be estimated in the pipe buried in sandy soil, but in the clay soil it is only possible to estimate the shear modulus.

Determination of the work life of low-temperature heating surfaces

Prolongation of heat and power equipment resource, which for the time being, is the only way out of the critical situation, gives a significant economic effect. Considering the uniform nature and low rate of low-temperature corrosion when burning water-fuel emulsions with water content of 30%, method for estimating service life of metal low-temperature heating surfaces at pipe metal surfaces temperature above 60°C has been proposed, at which uniform corrosion is observed. In the published literature, there are practically no data of impact on service life of low-temperature heating surfaces simultaneous influence of corrosion rates on gas and water sides of heating surfaces. The reliability of conclusion about the reliability of pipe heating surfaces largely depends on validity of conclusions made on the basis of calculations and especially taking into account experimental data of processes affecting reliability. It is on the basis of calculation results that it is possible to identify most tense elements that need to be subjected to detailed control. Therefore, in essence, reliability of entire methodology for assessing achieved and remaining resources depends on them. The paper presents a method for conducting computational studies of simultaneous influence of corrosion processes on gas and water sides of pipes and comparative assessment of service life of low-temperature heating surfaces when the limit states of metal are reached at acceptable and limit values of tensions and minimum possible thickness of pipe wall under influence of gas-chemical and water-chemical regimes and considering the data of experimental studies of processes affecting the reliability of work. To determine the time of calculated and residual service life of metal under uniform corrosion, a method for determining minimum residual thickness of metal has been presented, which still provides predestructive maximum allowable tension for remaining pipe wall thickness

An experimental study on gas/liquid/solid three-phase flow in horizontal coalbed methane production wells

Coal particles caused by well drilling and completion, hydraulic fracturing, and formation pressure decreasing would migrate into the horizontal well carried by fracturing flow-back fluid, formation water and CBM, and then deposit on the low side of pipe leading to the decrease of cross section area of pipe for flow and even blocking of the pipe. The purpose of current research was to obtain the flow pattern while there was stationary solid particle bed on the low side of the pipe and an explicit equation to predict the height of solid particle bed was proposed. In this study, with the coal particle, water, and air as the solid, liquid, and gas phases respectively, gas/liquid/solid three-phase flow experiments in horizontal well were carried out and 4 crucial factors including different water flow rate, gas flow rate, coal particle size, and coal particle mass concentration were considered. Fluid's real apparent velocity was defined and used to analyze the distribution of flow pattern coordinate points. Results show that the flow pattern coordinate points determined by real gas apparent velocity and real water apparent velocity distribute near the flow pattern transition lines of Taitel and Dukler flow pattern map. Besides, coal particle size, water flow rate, and gas flow rate have obvious impact on the height of coal particle bed and the coal particle mass concentration has a negligible effect while the height of interface between gas layer and water layer is only dramatically affected by the gas flow rate. At last, an explicit equation for predicting the cross section area of coal particle bed based on the experimental data was proposed which is crucial to predict the flow pattern and calculate the pressure drop in horizontal well. The predicting cross section area of coal particle bed is in good agreement with the measured cross section area of coal particle bed and the average relative differences are 9.38% and 13.45% for stratified smooth flow and stratified wavy flow respectively. The equation is applicable for a range of coal particle size (8–30 mesh) and water apparent velocity (0.025–0.123 m/s).