Acrylic Pipe Research Articles

Effect of Biocover Thickness on Methane Oxidation Rate of Landfill Gas Emission from Municipal Solid Waste Landfill in Tropical Climate Region

The landfilling of municipal solid waste (MSW) in developing countries mostly is carried out by means of open dumping or control landfills. The degradation of organic compounds of MSW inside the landfill will produce the landfill gas, where the main component is methane (CH4) and carbon dioxide (CO2) are categorized as the greenhouse gas (GHG). These gases if not managed properly will escape and increase the GHG accumulation in the atmosphere. There is many methods has been established and apply to reduce landfill gas emission, but mostly required high investment so not affordable for developing countries. Method that might be applied to reduce GHG emissions from landfill in developing countries is utilization the microorganism to oxidizing CH4 commonly called biocover. The purpose of the study was to analyze the effect of biocover thickness on the oxidation efficiency of CH4 from landfill gas in tropical countries. The concentration CH4 in landfill gas throughout landfill simulator reactor (LSR) covered by 20-60 cm of thick the biocover was measured daily by using the gas analyzer (Sewerin, Multitec 540). The LSR was made of acrylic pipe with a diameter of 25 cm and height of 100 cm. The landfill gas was used has an initial concentration of CH4 approximately 30% and the moisture content of biocover used was maintained at 40%. The experimental results obtained shows the CH4 oxidation efficiency of biocover for 20 cm, 40 cm and 60 cm thick were 8.12%, 9.72% and 4.56%, respectively.

Predicting bedload sediment transport of non-cohesive material in sewer pipes using evolutionary polynomial regression – multi-objective genetic algorithm strategy

ABSTRACTSediment transport in sewer systems is an important issue of interest to engineering practice. Several models have been developed in the past to predict a threshold velocity or shear stress resulting in self-cleansing flow conditions in a sewer pipe. These models, however, could still be improved. This paper develops three new self-cleansing models using the Evolutionary Polynomial Regression-Multi-Objective Genetic Algorithm (EPR-MOGA) methodology applied to new experimental data collected on a 242 mm diameter acrylic pipe. The three new models are validated and compared to the literature models using both new and previously published data sets. The results obtained demonstrate that three new models have improved prediction accuracy when compared to the literature ones. The key feature of the new models is the inclusion of pipe slope as a significant explanatory factor in estimating the threshold self-cleansing velocity.

Comprehensive experimental study of liquid-slug length and Taylor-bubble velocity in slug flow

Slug flow is an intermittent two-phase flow pattern that provokes undesirable pressure variations in pipes. Mathematical models are commonly used to study these variations; so that it is necessary to know the experimental liquid-slug length, Taylor-bubble length, and pressure drop to validate such mathematical models.In this work, we experimentally studied the water-air slug flow through an acrylic pipe loop 6 m long and 0.01905 m internal diameter. We assembled infrared sensors on the acrylic pipe to get voltage signals accordingly to the presence of liquid-slugs or Taylor-bubbles. We applied Fourier transform on the voltage signals to obtain dominant frequencies to determining the liquid-slug length.Moreover, we obtained the cross-correlation function to get the delay time between two groups of the voltage signals to determine the velocity of Taylor-bubbles. Additionally, we measured the liquid-slug length by video technique and pressure drop with a digital manometer. The liquid-slug lengths obtained by using dominant frequencies are in agreement with the ones measured by video technique.On the other hand, Taylor-bubbles could touch or not the wall pipe at different inclination pipe angles; this affects pressure drop. Then, we observed the inclination angle when the Taylor-bubble detaches from the wall of the pipe, under different flow conditions. We found that the Taylor-bubble detaching angle is 45°, and as the inclination angle is higher, the slug-liquid and Taylor-bubble lengths are smaller. The detaching angle can be used as a criterion to neglect the gas shear-stress into mathematical models to improve predictions of the hydrodynamic behavior of slug flow.

Effect of water discharge variation on water levels and flow characteristics in pipeline networks

The ability of flow discharge is very necessary in pipeline. When changes in discharge flow in the pipe, the flow pattern and water level will be different. The design of test equipment used is a pipe network made of acrylic pipes with inner diameter (d1) 64 mm and (d2) 44 mm. The fluid used is standard water with a viscosity value of 1.14 cp, fat oil 0 mg/L, and specific gravity 1.0304 gr/cm3. Data collection on the testing pipeline is divided into 10 segments or 10 observation points (OP) per discharge. Variations of debits flowed are 0.5 liters/sec, 1.2 liters/sec, 3.5 liters/sec. The relationship between discharge and depth of flow or water level from the bottom of pipe and the relationship between discharge and flow velocity is directly proportional or linear. The greater of discharge value flowed resulted in a shift in the flow characteristics where the low discharge value, the laminar flow patterns and transitions and high discharge values of flow pattern becomes turbulent.

Analysis of Pressure and Flow Patterns on Two-Phase (Air-Water) Flow in Horizontal Pipes With Scalloped Groove

The groved surfaces are widely researched to reduce pressure drop and control a flow on the surface. In applicative fluids flow is turbulen. So, the grove addition capable of affecting the boundary layer condition near the wall pipes. This will greatly determine the pressure drop and the flow patterns that occur during the fluids flow. The purpose of this researched is to analyse the impact of the number of grooves in pipes against the pressure drop and the occurred flow patterns. In this researched, we used 3 pipes, which total of grooves were 4,8,16 and the pipes without grooves that used as comparator. The observed flow was two phases flow ( air-water). The researched pipes used acrylic pipes with diameter of 1 inch and length of 100 cm with the groove used was type of scalloped groove. Pressure drop occurs in all of the grooves ; 4,8, and 16. The highest pressure drop decrease occurred in groove 16. When there was drop in pressure drop in every single of groove, in low air discharge, bubbly that firmed was more tightly without making slug flow. When the debit was getting bigger, the bubbly was reduced and followed by the emergence of slug flow. The changes in water debit in the decrising of pressure drop in every single of drop, shows the dencity between the bubbly and slug flow that firmed

Predicting Severe Slugging in Toe-Down Horizontal Wells

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 191611, “Existence and Prediction of Severe Slugging in Toe-Down Horizontal Wells,” by Jayanth Nair, SPE, Eduardo Pereyra, SPE, and Cem Sarica, SPE, The University of Tulsa, prepared for the 2018 SPE Annual Technical Conference and Exhibition, Dallas, 24–26 September. The paper has not been peer reviewed. Severe slugging is an important flow-assurance issue, typically observed in offshore pipeline-riser systems. The consequences of severe slugging include flooding of downstream production facilities and an overall decrease in productivity. Severe slugging had been thought to be limited to systems with a downward-inclined pipeline and vertical, catenary, or lazy-S-shaped riser. This paper presents the results of an experimental and modeling study that demonstrates the existence of severe slugging in systems with upward-inclined lateral flow paths, such as a toe-down well. Introduction Severe slugging in offshore pipeline-riser systems with downward-inclined pipelines has been intensely studied because of its serious consequences. Most such studies are related to pipeline-riser systems, but the possibility of severe slugging in toe-up horizontal wells also was demonstrated experimentally in the literature. Toe-up wells are geometrically analogous to pipeline-riser systems because the lateral section in a toe-up well is a mostly downward-inclined flow path. However, there has been no documented evidence of severe slugging in systems with upward-inclined flow paths.• Facility Description A large-scale experimental facility was used in this study. This facility was designed primarily to study flow behavior in horizontal wells. The lateral section in the facility was 236 ft long and comprised 6-in. inner-diameter (ID) pipe, which acted as the casing. The curvature section was made of bent acrylic pipe and had a radius of curvature of approximately 18 ft. The vertical section was 34 ft high with 2-in. ID polycarbonate pipe simulating the tubing. The schematic shows a packerless configuration. In such a configuration, an additional volume was necessary to simulate the effect of an annular volume. This was achieved by adding a 37-ft-high, 6-in.-ID expansion volume. For cases where a packer was required, a solid plug was placed in the system to simulate the packer and the annular volume was disconnected. The end of the tubing location was varied by pulling the tubing or running the tubing deeper. The test fluids were air and water. Air and water entered the facility at the toe of the well. The mass flow rates were measured using flowmeters and were held constant during the tests. As the flow pattern developed along the lateral section, flowing pressures, temperatures, and pressure gradient were measured. Conductivity probes allowed the measurement of slug characteristics. The test facility also included several quick-closing valves. These valves were pneumatically operated and could capture the flow and measure holdup. When the flow reached the top of the vertical section, it returned to the water tank where the air was vented. A separate metering skid was used to inject gas in the tubing to study the effect of gas lift.

Flow patterns and pressure gradient correlation for oil–water core–annular flow in horizontal pipes

The water-lubricated transportation of heavy oil seems to be an attractive method for crude oil production with significant savings in pumping power. With oil surrounded by water along the pipe, oil–water core–annular flow forms. In this paper, the characteristics of oil–water core–annular flow in a horizontal acrylic pipe were investigated. Plexiglas pipes (internal diameter = 14 mm and length = 7.5 m) and two types of white oil (viscosity = 0.237 and 0.456 Pa·s) were used. Flow patterns were observed with a high-speed camera and rules of flow pattern transition were discussed. A pressure loss model was modified by changing the friction coefficient formula with empirical value added. Totally 224 groups of experimental data were used to evaluate pressure loss theoretical models. It was found the modified model has been improved significantly in terms of precision compared to the original one. With 87.4% of the data fallen within the deviation of ± 15%, the new model performed best among the five models.

Simulation of the parametrs of the acrylic and specular light pipe for transmitting light radiation of the LED matrix

In this article, we simulated the parametrs of an acrylic and specular light pipe to transmit radiation from the LED matrix. The results of the experiment can be estimated using the dependence of the light flux on the number of reflections in the specular light pipe. Evaluation was conducted in the software package “Mathcad”. The possibility of providing illumination from 6 to 30 lx using the system of transportation of artificial light of roads \\ streets \\ squares depends on the class of the object. The study of the transmission of light through a specular and acrylic light pipe has shown that under equal conditions of light transport (the same power, the same aperture, the equal length of the light pipe, the same diameter of the light pipe), the acrylic fiber has the advantage. Losses using acrylic light pipe of 2000 mm are 24% whereas using specular light pipe they are 45%. However, if there is no limitation in the diameter of the light pipe, then it is preferable to use a specular one. For example, at 150 mm the losses are no more than 13%, which is not achieved with an acrylic light pipe even with a diameter of 10 mm, since when the radiation aperture is kept, a reduction in diameter leads to an increase of the interaction of the radiation with the walls of the acrylic rod and increase of the optical path.

Experimental validation of time-reversal technique for defect detection in air-filled pipes using high frequency acoustic waves

Pipeline systems are extensively used for the transportation and distribution of the gas, water and petroleum products. The sustainability of the pipelines can be improved by utilizing the transient (acoustic)-based defect detection methods (TBDDM). In these methods, the probing pressure wave is generated in the pipe system, and the measured response is used to identify the defects. In this paper, experiments are performed on the acrylic pipe to study the acoustic wave propagation. The acrylic pipe is filled with air such that rigid pipe assumption is valid. Theoretical predictions applied with time reversal and match-field processing are validated with the experiments for the leak detection in a pipe system. The waveforms of Gaussian-modulated sine wave and Chirp are utilized as the transmitted signals in the frequency range of 1–15 kHz. The experimental results show that time-reversal technique is capable of accurate detection with a good resolution.

Influences of Pore Water Content and Covering Depth on Carbon Steel Corrosion in Soil

Carbon steel is widely used as structural materials in soil, but it suffers from corrosion. There are lots of environmental factors that may influence the corrosion of the steel structures in soil. For instance, water content, soil covering depth, soil particle size, pH, temperature, anions (Cl− and SO4 2−) and microorganism1 may be considered as the environmental factors. In order to understand the corrosion mechanism in soil, the influences of these factors must be systematically investigated. In this study, the corrosion of carbon steel has been monitored in silica sands of different water contents and covering depths by electrochemical impedance spectroscopy (EIS). A pair of identical carbon steel (SM490A) sheets was embedded 2 mm apart in parallel in epoxy resin. The dimension of the carbon steel sheet was 5 mm × 10 mm. The silica sand of 100 μm particle size was used as artificial soil. The mixture of the silica sand and 3% NaCl solution was placed on the carbon sheet electrode using an acrylic pipe (inner diameter 30 mm). The soil covering depth was defined by the height of the silica sand. It was changed to 10, 30 and 50 mm. The pore water content W in soil was changed to 100, 90, 80, 70%. It was calculated by W=(V Water/ V Pore)×100 [%] where V Pore is the pore volume in soil and V Water is volume of the added NaCl solution. The V Pore was determined from the volume of the solution when all the pores were completely filled with the solution. EIS was measured at the open circuit potential with amplitude of 10 mV and frequency range of 100 kHz to 10 mHz. The charge transfer resistance R ct was determined by curve-fitting. The reciprocal R ct -1 was used as an index of the corrosion rate of carbon steel. At all the pore water contents, the corrosion rate of carbon steel decreased with time at the early stage because oxygen in soil was consumed by the corrosion reaction, and then reached a steady value within several days. The corrosion rate under the steady state condition was strongly dependent of the pore water content. The maximum corrosion rate was observed at 90 % water content, which was about 19 times higher than 100%. This is attributed to the enhancement of the cathodic reaction (diffusion of oxygen) due to the increase of the gas phase. On the other hand, the corrosion rate decreased with decreasing the water content below 90%, probably due to the suppression of the anodic reaction by decrease of the liquid phase. At 100% water content, the corrosion rate under the steady state condition was independent of the covering depth because the cathodic reaction of the corrosion changed from oxygen reduction to water reduction. At 90% water content, however, the corrosion rate decreased with the increase of the covering depth. The corrosion rate was inversely proportional to the covering depth. It means that oxygen diffusion through the silica sand controls the corrosion of carbon steel at 90%. On the other hand, at 80 and 70%, the corrosion rate was independent of the covering depth. This is because that the corrosion is controlled by the anodic reaction. 1) I.S. Cole and D. Marney, Corros. Sci., 56, 5 (2012).

Observation on the drag reducing effect of low concentration chitosan solution in turbulent pipe flow

Polymer-based drag reducing agent (DRA) is used widely in various industries due to its ability to enhance fluid flow as well as economically beneficial to various sectors. This study is conducted to observe the drag reducing effect of chitosan as DRA and observed its effect on the turbulent flow inside the pipe. The experiment is conducted in a closed loop circulation system where water is the transport medium. The pipe system consist of acrylic pipes with 0.013 m, 0.025 m and 0.038 m diameter. The chitosan was extracted from shrimp shells and five different concentration of chitosan were tested. The degree of deacetylation of the chitosan shows 97% which indicates its solubility in water. It was found that the highest drag reduction percentage were obtained from 0.038 m pipe of 33 ppm concentration which is 28%. The flow pattern inside the pipe is also analysed and discussed in this study

The effect of magnetic nano-fluids (Fe3O4) on the heat transfer enhancement in a pipe with laminar flow

In this research, the effect of magnetic nano-fluids (Fe3O4) on the heat transfer enhancement in a pipe with laminar flows (Re numbers of 171, 228 and 285) were examined. Different heats (15.75 and 20.6 W) were applied to an acrylic pipe to analyse the effect of magnetic nano-fluids for transferring the heat and reducing the wall temperature on a non-metal material pipe. Variations of nano-particles (volume percentage) were used in the nano-fluids solution: 2, 3 and 4%, respectively. The magnetic nano-fluids (Fe3O4) were prepared from 32.5 g of FeCl3.6H2O (ferric chloride) and 12.7 g of FeCl2.4 H2O (ferrous chloride) by using a co-precipitation method. The material characterisations using XRD and FE-SEM confirmed that Fe3O4 single phase occurred and shown that the average size diameters of the nano-particles are within a range of 20-40 nm. The experimental results suggested that the cooling capability can be enhanced by adding magnetic nano-particles controlled by permanent magnet and increasing the heat transfer in the magnetic nano-fluids system. The aggregation of the magnetic nano-particles following the magnetic field applied from the permanent magnet increases the convection heat transfer from the heating source to the nano-fluids, and thus reducing the wall temperature of the acrylic pipe.

Distortion of Velocity Profiles of Water Flow with Heavy Molecular Weight Polymers

Transportation of fluids in pipelines is common in many industrial processes. The energy requirements for this transport is high because of the need to overcome the occurring frictional pressure drop or drag. However, the addition of high molecular weight polymers to fluid flows has been known to cause a reduction in the frictional pressure drop. It has also been reported to cause other changes in the flow including changes in the turbulence characteristics, holdup as well as asymmetry of the velocity profiles. In this work some experimental results are presented in order to gain better insight into the deviations from axisymmetry of velocity profiles of water flow in pipes when drag reducing agents are added. Drag reduction studies were carried out in a horizontal 14mmID acrylic pipe with hydrolyzed polyacrylamide and different molecular weights polyethylene oxide used as additives in fully developed flows. Asymmetry was observed at both transitional and turbulent flow regimes for all tested polymer types and it increased with molecular weights. While the molecular weight and degree of formation of entanglements and aggregates of the polymer fibers are indicated as the causes of the observed profile asymmetry, the contribution of system/setup imperfections can be ruled out.

Characteristic and Erosion Study of Uncoated Sand Proppant Using Impingement Test

The characterization and properties of sand from beaches in Malaysia that has potential to be used as proppant in hydraulic fracturing was investigated through impingement tests. Eight sand samples were obtained from eight different locations in Malaysia; three samples from West Coastal beaches (Selangor) and five from East Coastal beaches (Kelantan). These impingement tests were conducted by varying several parameters i.e. size ranges of sand, type of targeted metal and distance of nozzle standoff from target. In these tests, air was fed through an acrylic pipe with inner diameter of 8 mm and 4 m length at gas velocity of 100 m/s and flow rate of 200 l/min. 250 g of sand samples were fed in compressed air stream and the samples were projected toward targeted metal i.e. mild steel and aluminium with a 90° of impingement angle. These tests were conducted at different separation distance of 0.5, 2.5 and 5.0 inches of nozzle and target. The results were analysed by measuring the mass loss of the metals after impingement and the images of the impinged metals were captured using camera. The highest metal loss was obtained when the targeted metal was impacted with the largest size range of sand samples. The mass loss of mild steel ranged from 0.03 to 0.16 g and 0.10 to 0.22 g for aluminium, at a variable distance between the nozzle and metal target due to higher hardness of mild steel than aluminium. The mass loss reduced when the distance between nozzle and metal target increased due to energy loss because of the inter particle collision.

Comparison between rotation swirler and non-rotation swirler in a horizontal swirling flow pneumatic conveying

This paper proposes an application of a rotation swirler to swirling flow pneumatic conveying for reducing the conveying velocity and pressure drop decrease. A comparison with the swirling flow pneumatic conveying generated by a non-rotation swirler and axial flow pneumatic conveying was made, the total pressure drop decrease, minimum conveying velocity, energy consumption, and additional pressure drop decrease were evaluated experimentally. In addition, the cross-section profiles of the particle velocity and particle fluctuation velocity along a pipeline near the minimum pressure drop decrease were measured by the PIV (Particle Image Velocimetry) technique. The pipeline was a 5-m-long horizontal straight acrylic pipe with an inside diameter of 80 mm. Polyethylene particles of diameter of 2.3 mm were used as the conveying materials. The initial swirl number was varied from 0 to 0.66. The solid mass flow rates of 0.1, 0.28, and 0.47 kg/s were applied, and the superficial air velocity was varied from 9 to 16 m/s. It is revealed that the total pressure drop decrease and power consumption of the swirling flow using the rotation swirler exhibit the smallest values among all cases in the region of low air velocity, and are almost the same as the axial flow in the high air velocity region. The particle velocity and particle fluctuation velocity of the swirling flow originated by the rotation swirler are almost the same as the axial flow in the acceleration regime, but become larger than that of the axial flow near the bottom of the pipeline in the fully developed regime.

DESIGN OF MOBILE AND FUNCTIONAL PHOTOBIOREACTOR

Recently, microalgae are used in sectors such as agriculture, food, cosmetics, animal feed, energy. Raceways are used for the most common open systems for high density cultivation when tubular photobioreactors are used for closed systems. In two decades, there have been significant developments in different photobioreactor designs for commercial scale production of alternative species in the production of commercial microalgae. There is no risk of contamination as a result of controlled cultivation in tubular photobioreactors. This allows intensive and pure cultivation.In this study, 75 x 69 mm acrylic pipes were used for the tubular photobioreactor. Each flow path is set to 2 m. By using a 40 liter closed-loop unit while the total volume of acrylic pipes is 60 liters, total volume is designed as 100 lt. In this photobioreactor designed and prototyped, suitable conditions were established for the cultivation of different microalgae strains. The tubular photobioreactor is made mobile and functional. In this photobioreactor, pH, optical density, biomass values are controlled.As a result, a mobile and functional photobioreactor has been designed to enable the cultivation of different microalgae strains for different sectors for microalgae growing. This photobioreactor is suitable for continuous, semi-continuous and continuous production.

Instability of horizontal oil-water flows based on the signal-dependent complex admittance representations

Horizontal oil-water two-phase flows are characterized by unstable motions of interfacial wave and entrained droplets. An experiment of horizontal oil-water flow was made in an acrylic pipe with an inner diameter of 20 mm. A measurement system of concave capacitance sensor is designed to detect the real and imaginary parts of flow complex admittance. An Adaptive Optimal Kernel Time-Frequency Representation (AOK TFR) of the complex admittance angle is used to characterize the flow instability in terms of total energy. A detrended cross-correlation analysis (DCCA) of the oil-water complex admittance is conducted to investigate the instability multi-scale flow structures. The cross-correlation coefficients at large and small scales enable to characterize the instability of the oil-water interface and the entrained droplets in continuous phases, respectively. The result suggests that the DCCA cross-correlation coefficients and the total energy extracted from AOK TFR are accordant in uncovering the instability of horizontal oil-water flows.

Analysis of Gas and Liquid Two-Phase Slug Flow Production Logging Interpretation Model in near Horizontal Shale Gas Wells

The development of shale gas reservoir is mainly based on horizontal well production. Slug flow of gas-liquid two-phase is invariably encountered in inclined wells and horizontal wells of a producing environment. Due to gravitational differentiation, oil-water two-phase flow pattern, the local velocity and local phase holdup along the radial direction of pipe in near horizontal wells will perform complicatedly. This paper presented the results of an experimental study and a theoretical analysis of two-phase gas/water flow in horizontal and highly inclined systems. Extensive experiments were conducted using a test loop made of 124 mm diameter acrylic pipe with inclination angles from the horizontal of 0°, 5°, 15°, 45°, -2°, -5° and -10°, and with the total flow rate ranging from 50 to 800 m3/day. Based on the research on the law of slug flow dynamics model for gas-water two-phase flow in near horizontal pipeline, the theoretical analysis and experimental researches were done to propose the expressions of stable and exact production logging interpretation model for two-phase flow in near horizontal pipeline. The performance of the proposed method for estimating water holdup and water superficial velocity is in good agreement with our measurements. As a result, the slug flow dynamics model of gas-water two-phase flow in near horizontal wellbore was developed. The application effect of production logging in near horizontal wells had been improved.

Separated oil-water flows with drag reducing polymers

The effects on velocity and turbulent properties of drag reducing polymers added in the water phase of oil-water flows were studied with Particle Image Velocimetry (PIV). The experiments were performed in separated horizontal oil-water flows in an acrylic pipe with an internal diameter of 14 mm. The test fluids were tap water (1.0 mPas, density = 1000 kg/m3) and a middle distillate oil (Exxsol D140; viscosity = 5.5 mPas, density = 828 kg/m3). Magnafloc 1011 (hydrolysed copolymer of polyacrylamide and sodium acrylate, HPAM; mol. wt. = 10 × 106 g/mol) was used as drag reducing agent in the water phase at 20 ppm concentration. Results showed that the polymer reduced frictional pressure drop at all conditions studied. The addition of polymer decreased the interface height and increased the in-situ average water velocity. The velocity profile in the water phase became more parabolic compared to the flow without polymer while the maximum velocity value increased. In addition, when polymer was added the axial stress tensor decreased close to the interface and the wall but increased in the middle of the flow, while the Reynolds and radial stress tensors reduced throughout the water phase. Two types of polyethylene oxide (PEO) polymers with different molecular weights, 5 × 106 g/mol and 8 × 106 g/mol were also tested. Drag reduction was found to increase with polymer molecular weight but depended also on the mechanical degradation of the polymers at high Reynolds numbers and on their ionic strength.

The Visualization Study on the Slug Flow Mechanisms of the Air-Water Two-Phase in a 50 mm Horizontal Pipe

The slug flow phenomena are often encountered in various industrial applications such as petroleum, process, and power plant. The presence of slug flow should be avoided as it causes structural damage due to resonance, corrosion and pipes blast. From the view point of multiphase flow, the understanding of the slug initiation mechanism is very important in pipeline design. This research is conducted using horizontal transparent acrylic pipes with diameters of 50 mm with a variation on the superficial velocity of water between 0,1 m/s and 0,77 m/s and superficial velocity of air between 0,31 m/s and 6,2 m/s. In the present experimental study, the slug initiation mechanisms was explained by visual observation by using high speed video cameras. As the results, the slug flow initiation mechanism were clarified. Furthermore, the proposed of flow initiation map was introduced.