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Go to Editorial ManagerSurge pressure is the additional pressure created when pipes move downward, and swab pressure is the pressure reduction that occurs when pipes move upward. When pipes are raised, it can result in a decrease in the pressure at the bottom of the hole due to the influence of pressure. An investigation showed that surge pressure is important for the circulation loss problem produced by unstable processes in Management Pressure Drilling (MPD) actions. Trip margin is an increase of mud density for providing overbalance so as to recompense the swabbing effect through pulling out the pipes of hole. Through trip margin there is an increase in the hydrostatic pressure of mud that compensates for the reduction of bottom pressure due to stop pumping and/or swabbing effect while pulling pipe out of hole. This overview shows suggested mathematical/numerical models for simulating surge pressure problem inside the wellbore with adjustable cross-section parts. To run the analyzed models, input data such as fluid speed around the drill pipe, pipe movement speed, hole diameter, drill pipe diameter, and internal drill pipe diameter are required. These data can be obtained from the drilling rig website. Swab pressures and surge pressures have been the primary causes of wellbore instability and blowouts in the oil industry for many years, resulting in pressure changes. This review focused on the most important basic theories for calculating the optimal factors related to surge and swab pressures and then linking them to the most important programs for calculating them. One of the most important conclusions from this review is that the optimal speed must be determined for the lowering and raising of pipes, to prevent kick or losses.
In this research work, the influence of cutting parameters and drill point angle on the temperature distribution in dry drilling of stainless steel AISI 304 was numerically investigated by using FE method based on DEFORM-3D V.11 commercial software. Two cutting tools of 10 mm diameter but different in point angles, one is 110° and the other is 118°. These tools were imported from specific website in a format of STL and inserted in the program during modeling of cutting tools. The material of the cutting tools is selected as high-speed steel. The workpiece model is created as cylindrical shape with 50 mm diameter and 5 mm thickness. The cutting parameters are selected as three cutting speeds (100, 200, and 300) rpm, with three feed rates (0.15, 0.25, and 0.35) mm/rev. The depth of hole is fixed for all simulations (3 mm). The percentage of increase or decrease in the resulted temperature according to the various cutting parameter was also calculated and discussed. The best cutting performance of tools according to the change of point angles was also investigated. The results provided a significant influence of cutting speed and tool point angle on the temperature generated in the machined models and very small influence of feed speed on the workpiece temperature.
There is a vacuum created when water goes past a pipe constriction. Air may be pulled into the main flow by drilling a hole in the pipe near where the vacuum happens. Venturi aerator is an example of the application in action. A vacuum is formed at the suction holes of the Venturi tube when there is a small difference in pressure between the input and output sides. To demonstrate the link between total flow rate and Venturi aerator performance, a Venturi aerator (model 1584) was introduced at a specific point in a Biopipe system. For this purpose, a physical model on a pilot scale was constructed and installed in an existing sewage treatment plant. Dissolved oxygen concentrations were measured at four locations along the Biopipe at different values of wastewater flowrates. The study results showed that raising the total flow rate increased the amount of air injected by the Venturi aerator. When the total flow rate was less than 4 m 3 /hour, the Venturi aerator stops sucking air and produces negative consequences.
The welding process involves a very complex thermal cycle, resulting in irreversible elastic-plastic deformation, and residual stresses in and around fusion zone and heat-affected zone (HAZ). A residual stress due to welding arises from the differential heating of the pipes due to the weld heat source. However, the presence of residual stresses in and around the weld zone reduces the strength and life of the component. The objective of this work is to measure the welding residual stress in ASTM (A-106 Gr. b) steel pipes with 4" diameter and 6 mm thickness welded manually (SMAW) in a three-pass butt joint. The shielded metal arc welding process consists of heating, melting, and solidification of parent metals and a filler material in a localized fusion zone by a transient heat source to form a joint between the parent metals. The welding process was carried out without preheating and heat treatment. This measurement of residual stress occurs by using the hole-drilling strain gauge method according to (ASTM E-873), and the experimental results for residual stresses obtained from welded carbon steel pipes are used to provide validation for finite element simulations. The welding process and welding residual stress distribution is calculated by Ansys Finite Element techniques. Theoretical considerations can be assessed by a mechanical model. Overall, there is good agreement between the predicted and measured distributions of residual stress, but the magnitude of predicted stress tends to be greater in the welding region.
In this paper, the Weibull uni-axial and multi-axial distribution function for polyethylene pips under pressure loading were developed and analyzed taking account of residual stress. Tensile test was achieved to determine mechanical properties and the Weibull parameters. Experimental method using the hole- drilling strain-gage method was used to measure the residual stresses in PE pipe and compare with that obtained from numerical finite element method (FEM). The obtained results show that there is a convergence between uni-axial and multi-axial distribution function, but multi-axial distribution function give large values compared to uni-axial distribution function. It was observed that the residual stresses have influence on failure assessment diagram and causes translation from elastic-plastic failure to brittle failure.
Dynamic behavior of pipe conveying fluid at different cross section is investigated. Three kinds of supports are used, which are flexible, simply and rigid supports. The type effect of support on vibration characteristics and dynamic specification are studied. Also, the effect of some design parameters such as pipe material and Reynold numbers are investigated. The governing equations of motion for this system are derived using the finite element method which depends on beam theory. A finite element software (ANSYA-11) is presented to find first three eigenvalue (natural frequency) and eigenvector (mode shape) for pipe system in modal analysis. Velocity and pressure distribution are evaluated in a single phase fluid flow. A coupled field fluid-structure analysis was then performed by transferring fluid forces, solid displacements, and velocity across the fluid-structure interface. Finally the effective stresses (Von mises stress) in piping system are predicted in static analysis at various Reynold numbers, pipe material and pipe supports.