Outside Of Pipe Research Articles

Investigation on Weld Characteristic, Welding Position, Microstructure, and Mechanical Properties in Orbital Pulse Current Gas Tungsten Arc Welding of AISI 304L Stainless Steel Pipe

Orbital pipe welding is carried out in this study by Pulse Current Gas Tungsten Arc Welding (PC-GTAW) without metal filler (autogenous) of AISI 304L stainless steel pipe. The dimensions of the specimen are 114 mm outside diameter and the thickness of 3 mm. This study investigates the effect of pulse current parameters, weld position, and pulse width on the characteristics of weld geometry, mechanical properties, and microstructure. The welding method used in this study is the continuous current and pulse current. The mean current of each parameter is the same at 100 ± 0.5 Amperes, but in the pulse current, there are variations in peak current, base current, peak current time, and the base current time. The welding speed used is constant at 1.4 mm/s. The result of weld geometry on the outside of pipe has shown that the flat (0°) position is concave and the overhead (180°) position is convex due to the influence of gravity. The microstructure indicates that the fine cellular dendritic structures appear at PC-GTAW. The PC-GTAW can produce good mechanical properties such as the tensile strength and the micro-hardness. The tensile strength of the specimen is reduced 14.23 % from the base metal at parameter 65-B and the flat position.

Rerounding of Deflected Thermoplastic Conduit in Well-Graded Aggregate Backfill

Rerounding is a technique for remediating excess deflection in thermoplastic pipe using a pneumatic device vibrating along the vertical axis and pushing against the inside crown and invert to restore the original pipe shape and redistribute the surrounding backfill. Since the process has not been evaluated on high density polyethylene (HDPE) pipe outside of a few reports, and the method is routinely used by contractors to remediate deflected thermoplastic pipes, the Ohio Department of Transportation (ODOT) wanted to evaluate the technology as a lower-cost and less disruptive alternative to the removal and reinstallation of deflected pipes. Three 36-in. HDPE pipes were installed in a well-graded crushed stone aggregate, sand, or AASHTO #57 open-graded aggregate (ODOT Structural Backfill, Types 1, 2, and 3, respectively), and two 18-in. pipes were installed in Types 2 and 3 Structural Backfill. Pipes were intentionally installed with substantial deflection (10% or more) and then rerounded. The pipe conditions were measured and monitored by collecting profiles, measuring vertical deflections and monitoring soil pressures, backfill characteristics, and the depth of pipe corrugation before and after rerounding. This paper focuses on Test Pipe 1 installed in Type 1 Structural Backfill, which was the most resistant to rerounding. Pressure data were consistent with the redistribution of backfill particles, particularly fines.

Numerical investigation of heat exchanger with inserted twisted tape inside and helical fins on outside pipe surface

This research presents numerical investigation of pipe heat exchanger with twisted tape inserted inside and helical fins on outside pipe surface. Various configurations were modelled based on the twist pitch (p) inside the pipe and fin twist pitch (P) over outside of the pipe. The fin twist pitch P (P = P, 2P/3, P/2) on the pipe outside and the inserted tape twist pitch p (p = p, 3p/2, p/2) inside the pipe was varied in the investigation. The hot fluid (water) passes inside the pipe, while the cold fluid (water) passes on the outside of pipe in counter flow direction. The Dittus-Boelter correlation was used for validation. For smooth pipes and the proposed heat exchanger with twisted tapes and helical fins, numerical results were compared. It was found that in inside and outside flows, twisted tape formed longitudinal vortex that helped to increase fluid mixing, thus being higher than that of smooth tube heat transfer rate.

A novel analysis of spun yarn hairiness inside limited two-dimensional space

Surface hairiness of spun yarns is critical to the yarn post-processing deficiency and resultant fabric quality. Several test methods are available for measuring yarn hairiness but they cannot detect the accurate hair amount and precise hair length. This paper provides a novel method to perform accurate hairiness tests on the spun yarn. A new test apparatus was devised by installing a blowing pipe outside of the hairiness testing area comprising a projection receiver and a corresponding laser. The rectangle end plane of the blowing pipe air inlet is vertical to the laser plane and tangent to the edge line of the projection receiver surface. Pressure generated through this inlet stretches yarn wild hairiness straightly in one direction, and fully maps accurate hairiness amount and length configuration on the projection receiver surface. The subsequent measurement showed that this novel test apparatus detected more hairiness with improved accuracy in both number and length of hairiness. Approximately real gravimetric hairiness weight can be obtained by this method which is impracticable for other conventional photoelectric apparatus.

Analysis of the Damage of Boiler Bottom Slope Pipe in Steam Power Plant

Bottom slope pipe on boiler system in one of steam turbine power plant had been damaged. The damage was dent on the outside of pipe and was suspected as a result from foreign object impact from outside pipe. From chemical composition examination and hardness test, it showed that nothing wrong with the selection of the pipe. From visual inspection, there is no other factor such as corrosion or deposit formed inside the pipe was found. Analysis of cause of damage in the pipe then further conducted by observing microstructure and hardness value on the area which experience damage. Simulation on mechanical and thermal analysis had been conducted to determine what and origin of foreign object which impacted on pipe and the temperature when it was happened. From the observation, of microstructure and hardness test showed that pipe had been experience plastic deformation on temperature under recrystallization temperature. Simulation results also confirmed that the initial assumption on cause of pipe damage from foreign object, which is small size slag that felt from very high location so that caused high speed impact on pipe. Thermal analysis result also supporting the suspicion that slag impact on pipe was occurred in temperature under recrystallization of pipe material.

Development of Contactless Sand Production Test Instrument

Background:Sand production is an important factor affecting reservoir exploitation. Excessive sand production affects the oil well life, causes the damage to the oil recovery device and brings serious hidden danger in the process of safety production.Objective:This paper presents a sand content computation model for the crude oil, which uses the power of sand production and Parseval theorem, develops a system to monitor the sand content.Method:The main problem of designing the mechanical structure and matching layer for sand sensor is introduced. Furthermore a contactless Doppler ultrasonic method is used to develop sand amount detection system‚ finally the system measurement accuracy is calibrated by the developed calibration system.Conclusion:The sand production computation model can describe the relationship between sand monitor output and sand amount; compute the oil sand carrying ratio. The sand sensor is installed on the outside of pipe, not directly contacted with the sand particles. Measurement accuracy of the sand production is higher than the same type instrument.

A guided wave sensor based on the inverse magnetostrictive effect for distinguishing symmetric from asymmetric features in pipes.

The magnetostrictive guided wave sensor with a single induced winding cannot distinguish axially symmetric from non-axially symmetric features in a pipe, because it is impossible for the sensor to detect the non-axially symmetric mode waves. When we study the effect of the change of the magnetic field in the air zone for receiving the longitudinal guided wave mode, we find that the change of the magnetic flux in the air zone is almost equivalent to the change of the flux in the pipe wall, but in opposite directions. Based on this phenomenon, we present a sensor that can detect the flexural-mode waves in pipes based on the inverse magnetostrictive effect. The sensor is composed of several coils that are arranged evenly on the outside of pipes. The coils induce a change in magnetic flux in the air to detect the flexural-mode waves. The waves can be determined by adding a phase delay to the induced signals. The symmetric and asymmetric features of a pipe can be distinguished using the sensor. A prototype sensor that can detect F(1,3) and F(2,3) mode waves is presented. The function of the sensor is verified by experiments.

A New Reinforcement Measure Suited for Space Truss with No-Fire Operation

A new reinforcement measure with no-fire operation is presented, which is very suitable for space trusses which are located in gas stations. A finite element model (FEM) is presented with shell elements and multipoint constraint elements. With this FEM, nonlinear analyses are carried out. Analytical results show that integral failure of reinforced pipe is caused by yielding of original pipe inside. So it is not necessary to reinforce original pipe using steel pipe bonded outside with high yield strength. With the increase of length of bonded pipe outside, loading according to elastic stage and ultimate bearing loading increase, it is clear that the length of bonded pipe outside is an important factor which influences the bearing capacity.

Non-destructive evaluation of pipe wall thinning utilizing long-pulsed magnetic field

In the conventional eddy current testing (ECT), it is difficult to estimate wall thinning from outside of pipes without removing the covered materials due to the large lift-off between a pipe surface and a sensor. In order to overcome this difficulty, a long-pulsed excitation system has been developed with a magnetic sensor, by which the magnetic flux can be penetrated deeply inside pipes because of low frequency and small induced eddy current. In this paper, the numerical results and measured results of the newly developed long-pulsed excitation system are shown. The results show the effectiveness of the proposed long-pulsed method for a large lift-off evaluation to wall thinning.

Based on Risk Source Pipe Leakage Emergency Device and Sealing Method Research

Along with the rapid development of chemical industry and the progress of science and technology, there exist safety risks for a large number of risk source pipelines. On the basis of the conventional containment measures for risk source leakage, this paper designed two types of emergency devices and corresponding rapid closure methods. One type is the pipeline leak sealing airbag inside the risk source. It is constituted by sealing institutions, diversion institutions, keep institutions and fixed institution. During the work, the sealing airbag gets inflated to realize the rapid closure inside in the piping. It is applicable to the sealing of the heat, water supply, the chemical pipeline, and even large pipe leakages. It also provides the diversion function. The second type the external leakage sealing gasbag for the risk source pipelines. It is compositioned by the belt type rubber air mattress,left and right sides of adjustable bits semi-manipulator mechanism. It is mounted using the belt type rubber layers of tilt superposition around in pipe outside. When needed the air gets inflated inside the gasbag, making each layer of air cushion tension bridle and mutual extruding, to execute rapid closure for the pipeline leakage. These two types of devices are easy to carry, require low professional training, while are highly efficient for the fast closure of the pipeline leakages.

マイクロフォンによる配管外部からのキャビテーション検知(機械力学,計測,自動制御)

Cavitation induced vibration and erosion of pipes are the potential damaging factors in a piping system. To prevent such trouble, it is necessary to develop the detection method of cavitation phenomena. Especially, in power plants, it is preferred to detect them from the outside of piping during operation. In this paper, detection of cavitation phenomena was experimentally investigated using microphones placed outside of piping at upstream and downstream of an orifice. Following results were obtained: (1) According to the progress of cavitation phase, output voltage of the microphone varied, and the amplitude and number of the pulse-shaped signals increased. However, it migh be difficult to distinguish them from surrounding noises in an operating plant. (2) Microphone outputs were confirmed to be radiasion sounds caused by vibration on surface of the piping based on measurements of time difference between accelerometer output and microphone output. (3) The results of 1/3 octave band analysis revealed, noises by cavitation increased in the region of high frequency accoding to the progress of cavitation. In transitional phase, high frequency noises at the downstream from the orifice were larger than upstream. (4) The RMS (root mean square) values ratio of microphone output at upstream and downstream of the orifice varied according to the progress of cavitation, and increased by applying a high band pass filter. Therefore, comparison of RMS values at upstream and downstream of the orifice might make it possible to detect cavitation phenomena in a piping system of operating plants.

Detection of Cavitation with Accelerometer Mounted on Outer Surface of Piping

Cavitation induced vibration and erosion of pipes are the potential damaging factor in a piping system. To prevent such trouble, it is necessary to develop the detection method of cavitation phenomena. Especially, in power plants, it is preferred to detect them from the outside of piping during operation. In this paper, detection of cavitation phenomena was experimentally investigated using accelerometers mounted on the outer surface of piping at upstream and downstream of an orifice. As the results : (1) According to the progress of cavitation, output voltage of the accelerometer varied, and the amplitude and number of the pulse-shaped signals increased. However, it might be difficult to distinguish them from noises in an operating plant. (2) It was difficult to recognize the characteristic frequency of cavitation, because the power spectrum density was broad up to the accelerometer limit of 45 kHz. (3) The flow directional distribution of RMS (root mean square) values of accelerometer outputs varied greatly according to the progress of cavitation. Therefore, comparison of RMS values at upstream and downstream of the orifice might be possible to detect cavitation phenomena in a piping system of operating plants.

Characteristics of Strength and Deformation of Inner/Outer Local Wall Thinned Straight Pipes

The experimental and the analysis for effects of circumferentially local wall thinning on the fracture behavior of pipes were carried out. Local wall thinning for experimental was machined on the outside of pipes in order to simulate the metal loss due to erosion/corrosion. In addition, the pipes with local wall thinning on the inside were carried out FE analysis, and it made a comparative study with that of outside. Failure mode could be classified into ovalization, local buckling and crack initiation depending on the thinned length and thinned ratio. Three-dimensional elasto-plastic analyses were able to accurately simulate fracture behaviors of inner/outer local wall thinning. Therefore the fracture behavior of the inner local wall thinning can be estimated with the outer local wall thinning.

NORM Contamination—Now You See It, Now You Don’t

Contamination from naturally occurring radioactive material on the inside of piping or tanks in refineries can usually be easily detected from the outside by external gamma measurements with simple count rate meters or more complicated gamma spectroscopy instruments. Usually, such contamination is from radium in equilibrium with its progeny. A number of different gamma rays are emitted by this mix. However, due to certain processes or circumstances, a significant amount of NORM can be present without the characteristic gamma signature of radium and its progeny. The process of cracking low molecular weight hydrocarbon gases from crude oil allows radon through but leaves radium behind. The radon enters the process piping and decays, depositing its short-lived decay products or progeny. When the short-lived progeny decay, all that is left are alpha and beta emitters. When this occurs, measurements taken on the outside of piping indicate no elevated levels of gamma radiation; however, elevated levels of alpha and beta radiation can be detected on the inside of the piping. 210Pb is usually the only gamma emitter detected on the inside of the piping and, its gamma ray energy is such that little if any penetrates the walls of the piping. Since one of the release criterion for piping material is an external dose rate of less than 50 microR h(-1), it is possible that a survey from the outside of the piping can be negative when, in fact, thee can be appreciable contamination on the inside of the piping.

アイスプラグを利用した配管残留応力除去方法

A stress relief method using ice plug for butt weld joint of piping is described. The method is as follows. Two ice plugs are formed inside piping, and isolate a section which include weld joint. An internal pressure of isolated section increases as ice plugs grow, and it gives tensile strain to pipe wall of the section. After the pressure reaches target level, the pressure is released and the residual stress decreases. The stress relief method is named by authors as Twin Ice Plug (TIP) method. This paper described details of this process, measuring of internal pressure from outside of piping, controlling internal pressure, and the effect of stress relief.The internal pressure of isolated section is estimated by the strain measured by strain gauge on outer surface of the section. A control of a pressure of the section is done by controlling supply rate of refrigerant (LN2) and heating pipe wall. The maximum internal pressure reached in this method is 40 MPa for 4BSch4O (O.D.=114.3 mm, t=6.0 mm) stainless pipe and 22.5 MPa for 6BSch4O (O.D.= 165.2 mm, t=7.1 mm). The residual stress of as GTA weld joint of stainless pipe is measured, its maximum value is more than +300 MPa. The effects of this method are confirmed by measuring residual stress of 4BSch40 6BSch40 joints that are treated by this method. The residual stress of inside surface decreases and changes to compression, and that of outside surface also decreases to under 100 MPa.

配管の高速自動溶接に関する研究 Ｉ 溶接施工

Pipeline installation requires the use of a welding method presenting high pipe-laying efficiency and therefore high welding speed.The present report describes the development of welding procedure by the automatic one side downhill welding method using high-current-density GMAW with regard to the girth welding of pipe. In this method, the groove root is made tight and non-gapped, and welding is performed in the narrow gap with little deposit metal, in order to shorten the pipe alignment and welding time. An appropriate procedure for this method was established by developing the downhill welding which uses copper backing on the pipe inside and small diameter solid wire on the pipe outside. When the standard welding conditions are deviated from, the welding arc will touch the copper backing sometimes causing the copper to deposit on the root bead. This deposition of copper on root beads causes not only cracking of beads, but decreasing pipelaying efficiency due to consumption of copper backing. As a result of various researches, this problem was resolved by preparing another groove on the pipe inside in addition to the groove on the pipe outside. The use of the improved shape of groove expanded the zone of appropriate welding conditions for root pass toward the high-speed welding side. The built-up sequence was divided basically into three kinds of passes, the root pass, intermediate pass and cap pass, and each pass was expressed graphically to facilitate the selection of welding conditions for assuring no welding defects and high welding efficiency.This welding method was applied into a welding system with the development in computor control technique and with the development in internal clamp.