Papers by Keyword: Threaded Connection

Abstract: The failure analysis of 110S tubing during acidizing process was addressed. Results showed that serious pitting corrosion occurred on the outer wall of tubing, and there was no obvious pitting on the inner wall. The maximum pitting depth on the outer wall was 1019 μm. According to the results of simulation corrosion test, needle-shaped pitting appeared on the sample surface in the test without inhibitor, the maximum depth of pitting was 158 μm; and no pitting was found on the sample surface in the test within 1.5% TG501 inhibitor; the original pitting were deepened after spent acid test, and the sample with no pitting at the beginning also showed deep pitting corrosion after 96 hours spent acid test. It was indicated that the spent acid accelerated the development of pitting significantly. The external surface corrosion of the 110S tubing was caused by the chemical reaction between the high-concentration acidifying liquid and the outer wall of the tubing. There is a gap between the tubing and coupling threaded connection, which caused the acid solution entered into the thread position, and hence the severe corrosion of the thread and pin end of the tubing happened, the joint strength was continuously reduced with corrosion development till the tripping of the coupling, and then the lower string dropped. Some suggestions were proposed for avoiding or slowing down this kind of failure based on this study.

Abstract: A detailed analysis of the expansion process will not only provide proper estimates for processing accuracy, but will also provide critical information needed to properly design the driving force required to perform the expansion process. Furthermore, accurate analysis of the contact of the threaded connection is necessary for estimating the sealing capacity of an expandable casing section after expansion. The 3D Finite Element Method has been used to numerically simulate the expansion process fora given expandable casing section. The principal results obtained from this numerical analysis include: 1) maximum value and distribution of equivalent plastic strain after expansion within the casing, 2) deformed casing shape, 3) maximum value and distribution of contact force at contact surface between pin thread and box thread, and 4) variation in values of the driving force of the mandrel cone during the expansion process.

Abstract: The development of ultra-deep drilling and extended reach drilling present many critical challenges for the threaded connections. The reliability of threaded connections must be evaluated to ensure the structural and sealing integrity of drillstring in critical applications. Three-dimensional finite element analysis of threaded connections has been performed in this paper. Different types of loading composed of make-up torque, working torque, tension and bending loading are applied to the model. The makeup characteristics of threaded connections have been analyzed, and the reliability of threaded connections under severe conditions has been evaluated. The results show that von Mises stress distribution over threaded connections is highly uneven, tooth nearby two ends was bearing the most of load. It shows that ultra-deep drilling case is even more challenge than extend reach drilling case in the threaded connections, the reliability evaluation of threaded connections is important in those challenging drilling.

Abstract: The intensity of the joint in the bottom chord would affect the quality of the whole bridge because that the force of the bottom-through bridge is transferred mainly through the bottom chord, and the members of the truss connect each other by using the thread. In this paper, the bottom chord around the tapped holes is reinforced by composite material , and the stress on the bottom chord is analyzed before and after the reinforcement using the finite element analysis method, and the stress distributions in the directions of X,Y and Z on every layer of the composite material under the bilateral reinforcing condition are extracted and compared. The results show that: Reinforcing the bottom chord around the tapped holes using the composite material can change the stress level of the bottom chord effectively, helping to improve the quality of the construction of the steel bridge and the effect of the bilateral reinforcing is better than the unilateral reinforcing and providing certain reference for the security of the steel truss bridge

Abstract: This work presents a study of a fatigue test and a finite element analysis on an arch bridge stainless steel suspender with threaded connections. A suspender which had a diameter of 70mm was tested under axial tensile loads range from 430kN to 700kN. The suspender was sudden failure from the thread root of the first loaded tooth in the pin after 1546609 cycles. Then, a two-dimensional axisymmetric modeling ignoring the helix angle of the thread was established with finite element software ANSYS to perform a stress analysis of the threaded connection. The stress concentration factors (SCFs) at the root of the teeth of pin were investigated under the applied external loading. The conclusive results had been drawn from the analysis including the location and the value of maximum SCF in the pin. Finally, the location and the value of the maximum von Mises stress were given. The results showed that the location of the fracture surface was consistent with the location of the maximum von Mises stress.

Abstract: Based on the axisymmetric and 3-D finite element models, the axial-load and stress distributions on each thread of the threaded connection have been studied. The effect of helix and the elastic-plastic behavior of the material at the thread roots have been explored. Simulation results indicate that the axial-load and stress distributions obtained from the axisymmetric finite element model show good agreement with the results of 3-D analysis in both elastic and plastic states with the same mesh density. So the axisymmetric model can be used to study the axial-load and the stress distributions of the threaded connection subjected to axial-load. The axial-load and stress distributions in threads are very sensitive to the applied load. With increasing the applied forces, the axial-load and stress distributions over teeth become homogeneous eventually.