Increasing Pipe Diameter Research Articles

Transverse impact and axial compression behaviors of glass/epoxy pipes subjected to seawater and impact loading

This article investigates the effects of seawater and impact loading on the impact behavior and compressive strength of impacted glass/epoxy composite pipes. The specimens were immersed into artificial seawater at laboratory conditions for 3, 6, 9, and 12 months. First, the impact tests were carried out on composite pipes at room temperature, and then, the axial compression tests were performed. The results of immersed samples were compared with that of reference specimens (dry). Seawater effect on the force–deflection behavior and failure mechanism is more than impact energy with increase in pipe diameter, while impact energy effect is more dominant than seawater effect for small diameters of the pipe. Compressive strength generally reduces with increase in seawater immersion time and specimen diameter except for the highest diameter.

Internal pipeline inspection using virtual source synthetic aperture ultrasound imaging

Focused ultrasonic monolithic transducers are often used for internal imaging of pipelines. The transducers yield a high lateral resolution as long as the distance between the pipe wall and the transducer corresponds to the transducer focal length. If the distance to the wall changes, for example due to increasing pipe diameter or de-centering of the inspection robot, the lateral resolution is decreased. We propose using synthetic aperture focusing with the virtual source method to extend the effective range of the focused transducer. It is assumed that the measurements are performed over a cylindrical surface, and we employ the Cylindrical Phase Shift Migration algorithm to perform the synthetic aperture focusing. The imaging algorithm is applied to scans of both pointlike scatterers and a corroded pipe surface, and the results demonstrate that a high lateral resolution can be obtained even when the pipe wall is several focal lengths away from the transducer.

Effect of FRP Pipe Scaling on its Adhesive Bonding Strength

Polymer-based materials are emerging as a potential substitute for metallic structures in the oil and gas industry. In this context, fiber-reinforced polymer (FRP) piping is one promising application. An important area of the research pertaining to FRP piping is the connection of pipe sections. Challenges associated with the joining of FRP tubular sections are often considerable, which limits more widespread industrial application. Adhesive bonding is emerging as a promising technique to join tubular FRP structures. The ability to maintain undamaged fiber architecture is a major advantage of adhesive bonding technology. In the present study a strength-of-materials as well as fracture mechanics approach was employed in conjunction with the finite element method to investigate the scaling effects on adhesively bonded tubular sections. It was found that the scaling effects in joined FRP pipe may be significant. For certain composite material configurations the analysis indicated a shift of the region of failure from the pipe structure to pure adhesive (cohesive) failure with increasing pipe diameter.

Analysis of factors affecting the availability of air bubbles to subsurface drip irrigation emitters during oxygation

In this study, we sought to define system features that impact air delivery in subsurface drip irrigation systems. A 58 % decrease in emitter cross-sectional area caused a 71 % reduction in the water flow rate, but the 37 % decrease in emitter air flow rate was statistically non-significant. For emitters with symmetric connectors, delivery of air from the emitters depended on the length of the connector relative to the air layer flowing at the top of the pipe. Emitters with asymmetric connectors yielded greater air flow rates compared to those with symmetric connectors, a result ascribed to a low-pressure region at the tip of asymmetric connectors. When symmetric connectors were used, an increase in pipe diameter was directly related to an increase in the uniformity of emitter air flow rate distribution expressed by the Christiansen uniformity coefficient (CUC), and inversely related to the efficiency of air bubble delivery and mean emitter air flow rate. In contrast, when asymmetric connectors were used, an increase in pipe diameter was associated with a decrease in CUC, and an increase in the efficiency of air bubble delivery and mean emitter air flow rate.

ANALYSIS OF ENTROPY GENERATION, PUMPING POWER, AND TUBE WALL TEMPERATURE IN AQUEOUS SUSPENSIONS OF ALUMINA PARTICLES

In the present paper, the practical efficiency of using aluminaminus;water nanofluid was evaluated numerically by the method of entropy generation; pumping power and tube wall temperature were analyzed. Laminar forced convection by water-based nanofluid flow through a uniformly heated circular tube is considered. A single-phase fluid approach is adopted to investigate the behavior of nanofluid and numerical results are compared with the experimental data. Good agreement is achieved in the developed region. The aim of the present study is to investigate the influence of volume fraction, duct length, Reynolds number, and tube diameter on pumping power, entropy generation, and tube wall temperature to evaluate the nanofluid overall efficiency. The results indicated that increasing volume fraction of nanofluid for heat performance increases the pumping power exponentially and decreases the entropy generation and tube wall temperature linearly, so this suggests that using nanofluid with high volume fraction is not reasonable due to the cost of pumping power. Since it was observed that entropy generation and pumping power increase and tube wall temperature decreases relative to the duct length, this suggests that increasing tube length will reduce the overall efficiency of nanofluids. However, to avoid high wall temperature, duct length cannot be too short. Also, the results showed that increasing tube diameter will decrease entropy generation and pumping power and tube wall temperature remains constant, so it can be concluded that increasing pipe diameter will enhance the overall efficiency of nanofluids. Since the product of the diameter and length is constant, the tube diameter has the maximum value at the point which shows the maximum wall temperature; also, the duct length is minimum at this point, too. Therefore, it can be concluded that the overall efficiency of nanofluid is maximum at this point.

Hydrodynamic and thermal fields analysis in gas–solid two-phase flow

The present work aims to investigate numerically the flowfield and heat transfer process in gas–solid suspension in a vertical pneumatic conveying pipe. The Eulerian–Lagrangian model is used to simulate the flow of the two-phases. The gas phase is simulated based on Reynolds Average Navier–Stokes equations (RANS) with low Reynolds number k– ε model, while particle tracking procedure is used for the solid phase. An anisotropic model is used to calculate the Reynolds stresses and the turbulent Prandtl number is calculated as a function of the turbulent viscosity. The model takes into account the lift and drag forces and the effect of particle rotation as well as the particles dispersion by turbulence effect. The effects of inter-particles collisions and turbulence modulation by the solid particles, i.e. four-way coupling, are also included in the model. Comparisons between different models for turbulence modulation with experimental data are carried out to select the best model. The model is validated against published experimental data for velocities of the two phases, turbulence intensity, solids concentration, pressure drop, heat transfer rates and Nusselt number distribution. The comparisons indicate that the present model is able to predict the complex interaction between the two phases in non-isothermal gas–solid flow in the tested range. The results indicate that the particle–particle collision, turbulence dispersion and lift force play a key role in the concentration distribution. In addition, the heat transfer rate increases as the mass loading ratio increases and Nusselt number increases as the pipe diameter increases.

복사효과를 포함하는 수평관 표면의 온도제어

Procedures for estimation of insulation thickness for a horizontal pipe for condensation control or personnel protection has been investigated, parallel to the previous work of a vertical wall case. Parameters include pipe diameter, emissivity, thermal conductivity, and operating temperatures. The results indicated that the surface emissivity plays a very important role in the design of insulation, specially for the case of high temperature application with low Bi. The effect of surface radiation in such case could be up to 65% of the total. Required insulation thickness for the surface temperature control increases as pipe diameter increases and as surface emissivity decreases. Adequate revision of specifications or standards to include newly invented insulation materials with high emissivity has been also suggested.

Impact of scaling on fracture strength of adhesively bonded fibre-reinforced polymer piping

The development of fibre-reinforced polymer (FRP) piping with high corrosion resistance and specific properties is an attractive engineering proposition with high potential. Advantageous properties make FRP piping a potential candidate for replacing metallic piping structure in the oil and gas industry. Despite the advantages associated with FRP, their application is limited due to, in part, unsatisfactory methods for joining composite subcomponents and inadequate knowledge of failure mechanism under different loading conditions. Aim of the present paper is to study the effect of pipe scaling on the strength of adhesively bonded FRP pipes. Using finite element analysis, a study was performed to investigate dimensional effects on adhesive joint strength based on strength-of-materials and fracture mechanics considerations. Results indicate a shift in failure from adhesive to composite material with increasing pipe diameter. The Tsai-Wu and von Mises failure criteria were employed for the strength analysis of composite pipe sections and the adhesive material, respectively. A fracture mechanics approach was used to assess changes from cohesive failure (within adhesive) to interfacial failure (adhesive/FRP interface) with increasing pipe diameters. © 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of ICM11

Role of Different Parameters in the Optimization of Hydrodynamic Cavitation

AbstractLow pressure setups (up to 150 psi) for creating hydrodynamic cavitation are investigated in this study. The decomposition of chloroform in water is used as a model reaction. The effects of upstream pressure, fluid velocity, Cavitation number, Cv, and β0 on the conversion are compared with regard to the effectiveness (conversion per pass) with changing flow conditions and scale‐up terms within three different setups. The values of Cv and β0 are seen to be significant parameters in optimizing the hydrodynamic cavitation. Moreover, the optimal values of these parameters shift to smaller values with increasing pipe diameter. The influence of a new orifice plate specific parameter, δ, on the collapse conditions, is also described.

Experimental Investigation on Buckling of Plastic Pipe Reinforced by Winding Steel Wires Under External Pressure

Plastic pipe reinforced by cross helically wound steel wires (PSP) is a new type of plastic-matrix steel composite pipes developed in China recently. PSPs may collapse when they are subjected to an external pressure load. To obtain the buckling behavior of PSPs and provide basic data for Chinese National Standard of PSPs, the testing devices of external hydraulic pressure and vacuum were designed for short-term buckling and creep buckling tests, and corresponding tests had been carried out. The critical buckling pressure, the methods to increase the critical buckling pressure, the relationship between creep deformation and time under different pressures, and the variation of the critical buckling time with critical creep buckling pressures of the PSP were obtained. The results show that the short-term critical buckling pressure of the PSP is higher than that of the HDPE with the same diameter and wall thickness. The critical buckling pressure of the PSP with the same pressure class decreases gradually with the increase of pipe diameter. The resistance to buckling can be increased by installing stiffening rings on the PSP. Furthermore, the PSP shows time-dependent buckling behavior, because of the time-dependent behavior of the matrix. Even if the external pressure load is lower than the short-term critical buckling pressure of the PSP, the buckling failure may still occur, and the time of buckling failure gradually shortens with the increase in the external pressure.

The determination of pneumatic conveying characteristics of chickpea

The pneumatic conveying characteristics of chickpea (Cicer arietinum L.) of the variety Koçbasi were determined. The length, width, thickness, arithmetic mean diameter, geometric mean diameter, sphericity, volume, 1000 seed mass, bulk density, true density, porosity, projected area, terminal velocity, drag coefficient, pressure drop, power consumption, and seed damage, namely mechanical damage, germination test, and seed vigour index, were investigated experimentally. The positive low pressure system was used for the conveying of chickpeas. The power requirement and pressure drop were boosted with increasing the revolution of the blower and conveying capacity decreased with increasing pipe diameter. The highest pressure drop and power requirement were obtained for 54.5 mm pipe diameter, while the lowest pressure drop was found for 70.3 mm pipe diameter. The mechanical damage to the chickpeas for both pipe diameters increased as the revolution of the blower increased.

Investigation of Flow through Orifices in Riser Pipes

In this study the discharge coefficient for circular orifices of different size in two different sizes of riser pipe is investigated experimentally. This type of outlet structure is common in detention ponds to achieve runoff volume control from developed areas in order to meet outflow discharge and water quality requirements. The discharge coefficient is determined by recording the drop in pond water level with time as water flows out of the orifice. The discharge coefficient is found to be a function of head over the orifice, location of the orifice above the floor of the tank, and the ratio of the orifice diameter to riser pipe diameter. The discharge coefficient increases as the head over the orifice decreases and height of the orifice above the floor of the tank decreases. The discharge coefficient reduces as the ratio of the orifice diameter to pipe diameter increases and eventually reaches an asymptotic value. Also, with all other variables being the same, the discharge coefficient is lower for larger size riser pipe. An equation that is a function of head over the orifice and height of the orifice above the floor of the tank is fitted for each ratio of orifice diameter to piper diameter. The coefficients of the equation are found to be a function of the ratio of orifice diameter to piper diameter. A minimum coefficient of determination of 0.78 for the fitted equation suggests that the fit can be used to determine the discharge coefficient for orifices in circular riser pipes.

Design of a Water Transmission Pipeline with an Analytical Probabilistic Model

A challenge that utilities face is to design new water transmission systems with incomplete information concerning future water demand. With an increase in water demand caused by population and economic growth, a design chosen today may deliver inadequate operating pressures to meet higher-than-expected demands in the future. This paper presents an analytical probabilistic model that evaluates the expected level and uncertainty of pressure head at the end of a design period (e.g., 20 year) linked to pipe-diameter decisions in a new water transmission pipeline subject to uncertainty in water demand. The model is developed by deriving a cumulative distribution function (CDF) of pressure head from a probability density function of peak demand. The CDF of pressure head is used to compute measures of central tendency and variability in pressure head and is validated with Monte Carlo simulation (MCS). The model is applied to the design of a new transmission pipeline with pipe break and pump outage scenarios. The results indicate that increasing pipe diameter increases median pressure head, decreases standard deviation, and lowers uncertainty associated with pressure head predictions. Pressure head percentiles generated with the analytical probabilistic model closely match those generated with MCS.

Experimental studies on resistance characteristics of high concentration red mud in pipeline transport

Red mud will flow in paste form under high pressure during pipeline transport. It belongs to a two-phase flow of materials with high viscosity and a high concentration of non-sedimentation, homogeneous solid-liquids. In pipeline transport, its resistance characteristics will be influenced by such factors as grain size, velocity, concentration, density, grain composition and pipe diameter etc.. With the independently developed small-sized tube-type pressure resistance test facility, studied the resistance characteristics of red mud concerning the three influencing factors, paste concentration, velocity and pipe diameter, which attract the most attention in projects. The fine grain size of the red mud is d50= 13.02 μm. According to the experimental results, the pressure loss in transport will increase along with the increase of velocity and will fall along with the increase of pipe diameter. A 1% difference in paste concentration will result in a 50%∼100% difference in pipeline resistance loss. These experimental data is hoped to be direct guidance to the design of high concentration and viscous material pipeline transport system.

Pneumatic Conveying Characteristics of Cotton Seeds

The pneumatic conveying characteristics of delinted and fuzzy cotton seeds (Gossypium hisutum L.) of Gulerbey and Nazilli 84 S varieties were determined. The length, width, thickness, arithmetic mean diameter, geometric mean diameter, sphericity, volume, 1000 seed mass, bulk density, true density, porosity, projected area, terminal velocity, drag coefficient, pressure drop, power consumption, and seed damage, namely mechanical damage, germination test, and seed vigour were investigated experimentally. The positive low-pressure system was used for conveying of cotton seeds. The length, width, thickness, arithmetic mean diameter, geometric mean diameter, sphericity, volume, 1000 seed mass, bulk density, true density, porosity, projected area, terminal velocity, and drag coefficient ranged from 9·06 to 10·89 mm, 4·73 to 5·88 mm, 4·23 to 5·15 mm, 5·74 to 7·31 mm, 5·82 to 6·89 mm, 61·37 to 64·03%, 95·11 to 121·40 mm3, 106·50 to 126·50 g, 296 to 632·10 kg m−3, 1000 to 1075 kg m−3, 41·20% to 71·59%, 31·90 to 52·70 mm2, 8·12 to 11·31 m s−1, and 0·462 to 0·684, respectively. The power requirement and pressure drop increased with increase in air velocity and decreased with increase in pipe diameter. As the conveying capacity increased, the power requirement and pressure drop increased. The highest pressure drop and power requirement were obtained for Gurelbey (delinted) and Nazilli 84 S (delinted) varieties, while the lowest pressure drop was found for Nazilli 84 S (fuzzy) and Gurelbey (fuzzy). The mechanical damage to the cotton seed for all varieties increased as the air velocity increased. The average values of germination and vigour index for all varieties at the inside pipe diameters of 43·1 mm and 70·3 mm decreased after pneumatic conveying. After conveying the germination and vigour index of Nazilli 84 S (delinted) decreased from 92% and 2·32 cm to 28% and 1·10 cm for 44·43 m s−1 at the inside pipe diameters of 43·1 mm.

Dynamics of jetsam layer in continuous segregation of binary heterogeneous particles in gas–solid fluidized bed

Investigations on the dynamics of height of defluidized jetsam layer were carried out during the continuous segregation studies of heterogeneous binary particles in a fluidized bed system. The effect of bottom discharge pipe, flow rates of gas and solid and composition of flotsam in the feed on the growth of defluidized layer has been studied. It is found that the steady state defluidized bed height decreases with increase in gas velocity, feed composition and bottom discharge pipe diameter, and decrease in solid flow rate. A model based on the exponential growth of the defluidized bed height is used to compare the experimental data on the dynamics of defluidized bed height. Correlations are developed for growth constant and steady state bed height in terms of operating and geometric parameters. The agreement between the model and experimental data is satisfactory.

An Investigation of Two-Phase Slug Flow in Inclined Pipelines

Two-phase slug flow in inclined pipelines can cause significant practical operating problems. When slugs flow in an inclined pipeline that contains sections of different inclinations, they undergo a change of length and slug flow characteristics as the slug moves from section to section. In addition, slugs can be generated at low elbows, dissipate at top elbows and shrink or grow in length as they travel along the pipe. A mathematical model and a computer program were developed to simulate these phenomena. The model was based on the sink/source concept at the pipeline connections. A connection between two pipeline sections of different slopes was conveniently called elbow. An elbow accumulates liquid as a sink, and releases liquid as a source. The sink/source has a characteristic capacity of its own. This capacity is positive if the liquid can indeed be accumulated at the elbow or negative if the liquid is actually drained away from the elbow. The hydrodynamic flow model was also used to calculate the film liquid holdup in horizontal and inclined pipelines. The model can successfully predict the liquid film holdup if the liquid film height is assumed to be uniform through the gas pocket. The overall effect of a hill or terrain on slug flow depends on the operating flow rates and pipeline configurations. For special cases of near constant slug frequency corresponding to moderately high superficial liquid and gas velocities, this effect was found to be small. The film liquid holdup decreased with increasing pipe diameter. The unit slug length increased at the upstream inclined pipes and decreased at the downstream inclined pipes with increasing pipe diameter. The possibility of pseudo-slug generation was increased at large pipe diameters even at high sink capacities. At low sink capacities, no pseudo-slugs were generated at high superficial velocities. The slug flow characteristics were more affected by low superficial gas and liquid velocities, large pipe diameters and shallow pipeline inclinations.

Pulsating flow in circular pipes — the analysis of thermal stresses

Flow pulsation in externally heated pipes generates a pulsating temperature field, which, in turn results in oscillating thermal stresses across the pipe wall. In the present study, pulsating flow inside a circular pipe, which is externally heated, is considered. The flow and temperature fields are computed numerically using a control volume approach. The resulting thermal stresses across the pipe wall due to temperature variation in the transverse direction are computed. Pressure pulsation at the pipe inlet is employed to produce the flow pulsation. The simulations are extended to include different pipe lengths, pipe diameters and pipe thickness. It is found that pipe diameter has a significant effect on the effective stress levels; in which case, the amplitude of the oscillation in stress levels across the pipe wall reduces considerably with increasing pipe diameter. Moreover, the effect of Reynolds number is more pronounced at mid and outlet planes such that increasing Reynolds number amplifies the amplitude of stress levels in the pipe.

Pumping characteristics of a thermosyphon applied for absorption refrigerators with working pair of LiBr/water

A thermosyphon with a separate heating chamber was taken into consideration as a model device for a high-temperature generator in a small capacity absorption refrigerator with LiBr/H 2O solution. Quantitative measurements of operating characteristics of the thermosyphon were made as functions of pipe diameter, pumping height and heating power. It was found that vapor production rate is mainly affected by the heating power, and the flow rate of pumped liquid is limited by the pumping height. It was also observed that, as the pipe diameter increases, dependency of liquid flow rate on the pumping height becomes stronger. For a LiBr/H 2O solution system, ratio of vapor production rate to liquid flow rate was found to be well correlated as a function of the power input. Present experimental data are expected to provide useful information for determination of design parameters of a thermosyphon.

Holographic investigation of brittle crack propagation in plastic pipes

Plastic pipes dominated the low pressure gas distribution piping market during the last decade. Research on steel pipes has long since indicated that the susceptibility to rapid crack propagation (RCP) increases with increasing diameter. Although most plastic pipes used in gas distribution systems are of small diameter (<200mm), there is a tendency to use larger diameter piping, with increasing wall thickness. Based on simple physical principles it is reasonable to expect that susceptibility to RCP in plastic gas distribution piping will also increase with increasing pipe diameter and wall thickness. Although installed pipe sizes seem to be safe, it is imperative to obtain an understanding of the various factors that affect RCP in plastics. Some recent incidents show it is necessary to find criteria to assess the safety of larger diameter piping before such piping is installed in distribution systems. In particular, the newly developed third generation polyethylene materials, of which large diameters are already produced, need extended RCP evaluation.