Pipe Joints Research Articles

Effect of cuttings particle content on the tribological behavior of Fe/DLC at casing and drill pipe joints: A molecular dynamics study

The presence of cuttings in the drilling fluid can exacerbate the wear of drill pipe joints and casing. Diamond-like carbon (DLC) films have ultra-low friction coefficients and high wear resistance, which have excellent research prospects in reducing the wear between drill pipe joints and casing. To investigate the impact of varying particle counts at the interface between Fe bulk and DLC film, this work builds a pertinent molecular dynamics model. The results show that the interfacial friction increases with increasing particle content, which leads to more severe abrasive wear on the Fe bulk and prevents the amorphous structure atoms in the Fe bulk from recovering to a body-centered cubic crystal structure. On the contrary, the DLC film is difficult to be affected by the particle motion because of its good tribological properties. Simultaneously, more silica particles reduce the space for the movement of water molecules and ultimately weaken the lubrication ability of water molecules.

Wear resistance of carbide-containing deposited layers for drill pipe joints

Wear resistance of carbide-containing deposited layers for drill pipe joints

Application of Isogeometric Spline Finite Element Method to the Sealing Performance ofHigh-Pressure Pipe Joint

Application of Isogeometric Spline Finite Element Method to the Sealing Performance ofHigh-Pressure Pipe Joint

Drill pipe joints fatigue analysis and optimization under special working conditions

Recently, the number of ultra-deep and extended reach wells has continuously increased. The failure of the drill pipe is prominent when drilling. The thickened area of the drill pipe body and the position of the drill pipe joint often appear fatigued, especially the internal thickening zone for the nonlinear structure of the cast component. Fatigue failure occurred at the drill pipe joint due to non-linear contact between the male and female snaps. The fatigue life S-N curves show that the overall life of drilling with high-resistance torsion drill pipe is increased by 136% compared with API drill pipe, though the maximum stress value was reduced by 8.4%. The high-bend drill pipe has an overall life improvement of 174% over the API drill pipe. High flexural drill pipe reduces stress by 10% compared to the maximum value. At the same time, the drill pipe’s fatigue period and safety factor can be improved by adjusting the drilling speed and annulus pressure properly.

Investigation on Cracking Cause of Drill Pipe Joint Used in an Ultra Deep Well

The drill pipe joint cracked during service, resulting in joint failure. The geometric dimensions of thread, chemical composition and microstructure of the drill pipe joint were tested. The geometric dimensions, chemical composition and microstructure were found to comply with the standard requirements. The whole macroscopic fracture didn’t show obvious corrosion product. The tensile properties, Charpy impact properties, and Brinell hardness met the standard requirements. Microstructure of fracture was analyzed, which showed a typical erosion micromorphology with parallel arranged fatigue strips. Through simulation analysis, it was found that the location of cracking was the stress concentration area. The failure mechanism of the drill pipe joint was revealed. The stress concentration led to fatigue cracking at the drill pipe joint. After the fatigue crack penetrated through the wall thickness, the drilling fluid leaked from the inner wall to the outer wall. The flow rate of the leaking drilling fluid is significantly increased. And it is sprayingly leaked, which further leads to fan-shaped erosion damage of the cracked surface from the inner wall to the outer wall.

Use of DC Motor Control in Development of Pipe Welding Technology by Using the GMAW Process for Variation of Welding Nozzle Movement

Gas Metal Arc Welding (GMAW) welding technology is a welding method that is widely used in industry. A problem that often occurs is that it is difficult for a welder to control the speed of movement of the welding nozzle, which can affect the quality of the welding results. With welding tools that can control the movement of the welding nozzle, this problem can be overcome and increase the efficiency and productivity of the welding manufacturing process. The method for testing the quality of welding results is analyzed visually using the visual test and penetrant test methods. The use of GMAW welding tools for pipe butt joints using DC motor control to vary the movement of the welding nozzle is effective, making it easier for the welder and good welding results. Good welding results were obtained for setting the welding nozzle movement time in 1.4 seconds and 1 second for one left and right the movement cycle on a pipe joint rotating at a constant speed of 24 rpm. Setting the time for the welding nozzle movement in 0.6 seconds for one cycle of left and right movement produces poor welding in pipe joints that rotate at the same speed.

TEMPERATURE DEFORMATION MODELING AND COMPENSATORS CHARACTERISTICS DETERMINING FOR CASES OF PIPE WELDED JOINTS AND EQUIPMENT OF COLLAPSIBLE PIPELINES

The article discusses the issues of determining the permissible deformations of U-shaped compensators for unloading from temperature stresses of straight horizontal sections of collapsible pipelines (SRT) connected by welding, used in centralized aircraft refueling systems. Comparative data on possible leaks through sealing joints of pipes with polyethylene heat-shrinkable couplings and welded joints are presented, as well as a method for determining the number of U-shaped compensators and their characteristics for straight horizontal sections of the SRT connected by welding. Modeling was carried out to establish the influence of various initial data on temperature deformations and the compensating ability of U-shaped compensators. Dependences are obtained for determining the compensating ability of U-shaped compensators without preliminary stretching (compression) by half of the longitudinal deformation, depending on the length of the departure and the width of the shelf for pipelines PST-100 and PST.

Hot Tool Welding of Pipelines from Polyethylene for Gas Supply with a Diameter of 90-315 mm

Purpose of research. GOST P 55276-2012 applied in the Russian Federation does not regulate concrete data on the choice of this or that procedure under various conditions of welding and standard sizes of the applied pipes, leaving it to the discretion of the consumer. Unlike the procedure of the welding with only low pressure which is well fulfilled and widely applied in domestic practice, the welding according to the procedure with the only high pressure allowing to reduce three times time of a welding cycle is practically not used and specially intended welding machines in Russia are not issued. In this regard this work is devoted to development of the modes of hot tool welding of abutting connections of pipes from polyethylene with a diameter from 90 to 315 mm for SDR 13.6 - SDR 9.0 with the only high pressure, to the choice of possible domestic welding equipment and experimental check of the developed modes.Methods. In this article for butt welding by the heated tool of pipes from polyethylene with a diameter from 90 to 315 mm, using a design technique, main parameters of welding procedure are determined with the only high pressure. When choosing the welding machine necessary for tube welding of the considered range on welding procedure with the only high pressure, by results of the carried-out analysis of technical datas of domestic welding machines and features of their operation capabilities it is preferred as the welding machine with the hydraulic drive "Native of the Volga Region of SSPT-315". For experimental check of the executed payment of parameters of the procedure of welding under the cyclogram with the only high pressure four joints of pipes with a diameter of 110 mm with thickness of a wall of 10 mm from PE-100 (SDR 11.0) have been welded and visual and measuring quality control of the executed connections and short-term tests of technological samples on axial stretching by the R-50 machine is made.Results. Mechanical tests of technological samples of all joints of the pipes from PE-100 with a diameter of 110 mm (SDR 11.0) executed on the SSPT-315 welding machine on welding procedure with the only high pressure have shown 100% - ny result of plastic nature of destruction at the size of lengthening from 500 to 600%.Conclusion. The high quality of experimental joints of pipes from PE-100 assumes a possibility of use of the SSPT- 315 machine for hot tool welding of pipes from polyethylene of everything of the range regulated by technical datas on welding procedure with the only high pressure.

Sealing performance and failure mechanism of rubber core for conical blowout preventer during the well shut-in process

Blowout preventer reliability is important for safe drilling operation. In order to study the sealing mechanism and failure mechanism of conical blowout preventer, a numerical model of conical blowout preventer was established based on the theory of large deformation of rubber, and the deformation law, stress distribution and sealing performance of rubber core in well shut-in operation were studied. The results show that there are stress concentrations in the contact area between the rubber core and the piston, the grooves in the middle of the adjacent support ribs, and the chamfered corner of the inner wall of the rubber core, the main form of failure at these locations is rubber cracking. Higher stress is present in the neck region of the upper plate and the back region of the lower plate of the support ribs. The inner wall surface of the rubber core gradually produces stripes of wrinkles, and the smaller the size of the sealed drill pipe, the more obvious the wrinkles are. When the drill pipe joint is sealed by the rubber core, there is a sealing buffer zone at the shoulder, and the contact pressure change abruptly. The lower portion of the rubber core’s inner wall serves as the primary sealing area. Increasing the piston displacement appropriately can enhance the sealing performance of the rubber core. The results can provide a theoretical basis for the optimization design of the conical blowout preventer.

Shear mechanical response and deformation failure of F-type socket joint in a rectangular pipe jacking tunnel under different geologic conditions

The shear mechanical properties of F-type socket joints in rectangular pipe jacking tunnels are currently unknown. To investigate the shear mechanical response and deformation failure of the F-type socket joint in rectangular pipe jacking tunnels under different foundation coefficients, a laboratory joint test and numerical simulation method were used, considering the structural features of the joint. The results showed that the deformation process of a joint subjected to shear consists of four stages: gap closure, elastic growth, shear strengthening, and yield failure. The ultimate shear capacity of the joint increases by 25% to 34% for every 3 mm increase in the steel ring thickness. The chamfer yield damage area comprises approximately 15% of the steel ring. The joint concrete crack first appears at the top of the socket joint, and the concrete damage area accounts for about 40% of the whole pipe section. The failure characteristics of the joint are primarily manifested as drum and warp of the steel ring or cracking of the weld, and the concrete at the joint is crushed. In practical engineering, the weld should not be located at the chamfer. The steel ring at the chamfer needs to be locally strengthened, and the chamfer and the reinforcement at the top and bottom need to be increased to improve the bearing capacity of the concrete.

Accelerated testing of soft soldered, small-diameter, thin-walled CuNi pipes subjected to cyclic internal pressure loading

Small-diameter, thin-walled pipes have applications in a wide range of industries including high-energy physics, heat transfer, nuclear, medical and communications. However, there are currently no standards that exist for permanently joining these components either via welding (melting the base material) or soldering. As such it is difficult to determine the likely performance of a thin-walled pipe connection. Porosity is largely inevitable in soldered joints and is a determining factor in the performance of a connection.This study focused on characterisation of failure initiation and propagation within soft soldered CuNi thin-walled pipe joints under cyclic internal pressure loading. A step-stress accelerated life testing regime (SSALT) was developed to simulate the loads the joints would experience over their operational lifetime, in a shorter timescale.10 soldered joints were studied in total, with varying levels of porosity within the soldered joints prior to testing. Pressurised Nitrogen gas was used to internally pressurise the samples, with cyclic loading between atmospheric conditions and a prescribed maximum pressure value.The results of the SSALT showed that the soldered samples experienced early failure through crack initiation and propagation through the solder. Cracks, or failures, were seen to initiate from existing voids, or porosity, within the soft-soldered joints.From this work, it can be concluded that the performance of soft-soldered joints under cyclic, internal pressure loading is strongly influenced by the presence of voids that are created during the manufacture of such soldered connections.

The Design and Mechanical Study of the Pipe Joint Structure in a High-pressure Hydraulic System

Pipe joints are important connecting devices and weak links in high-pressure hydraulic systems, and their rational design is of great significance for ensuring the safety of hydraulic transmission systems. In accordance with the requirements of high-pressure hydraulic oil systems, a 70 MPa high-pressure oil pipe structure was designed, and strength and sealing analyses were conducted by using the finite element module in SolidWorks simulation. The results showed that the stress distribution in various parts of the pipe joint was relatively uniform and achieved an elastic-plastic sealing effect. The radius of curvature on the outer wall of the pipe is a key factor in joint design, and the connectivity performance of the joint can be adjusted by the axial displacement of the connector. The sealing tests demonstrated that the pipe design meets the structural strength and sealing performance requirements for use at 70 MPa. The research findings provide references for optimizing the design, manufacturing, and installation of pipe joints in high-pressure hydraulic systems.

COMPARATIVE ANALYSIS AND SIMULATION OF WELDING MODES DURING THE CONSTRUCTION OF THE MAIN PIPELINE USING AUTOMATED TECHNOLOGIES

In the present work, the technology of laser welding of the circumferential joints of pipes of the main gas pipeline was studied on the basis of the existing certain experience of its application at the facilities of the gas transmission system and an assessment was made of the possibility of using it as an alternative to automatic arc welding during construction and repair and restoration work. An analysis was made of the use of laser radiation for orbital welding of main pipelines, which showed that the use of this technology makes it possible to increase the productivity of the welding process, to obtain more favorable structures in the seam and in the transition zone, and to ensure a high level of mechanical properties and weld density. Temperature and deformation conditions in the zone of the welded joint help to reduce the likelihood of hot and cold cracking.Modeling of a pipeline section with welded joints made by automatic arc welding and laser welding (hereinafter referred to as LS) was carried out. When modeling welded joints, their geometric parameters for the compared welding technologies were taken into account, as well as the area and volume of the deposited metal, which theoretically correspond to natural values. Loads were applied to the pipe section with a welded seam, imitating three types of mechanical tests: tension, compression and bending, which occur in the case of thermal deformations and soil subsidence during pipeline operation.In the course of the study, stresses were determined in the cross section of a welded joint obtained using two welding technologies, which show the level of mechanical properties of the weld. A comparative analysis and evaluation of the operational reliability of the main gas pipeline with welded joints made by modern automated welding technologies has been carried out.

Application and research of titanium alloy oil drill pipes

The complex and harsh drilling environment has put forward higher requirements and standards for future drilling tools. Compared with other drill pipes, titanium alloy drill pipe has a series of characteristics such as high specific strength, excellent corrosion resistance, fatigue resistance, and non-magnetic, making it be the first choice of material for oil and gas drilling in unconventional deep well, deep sea and other harsh environments. This paper discussed the design and microstructure properties of titanium alloy drill pipes in terms of alloy composition, service performance as well as pipe body processing and joint connection. Combined with the development of the application and standards of titanium alloy drill pipe, the prospects of the development and application of titanium alloy drill pipe in unconventional drilling operations such as deep wells and ultra-deep wells were foreseen, in order to provide support for promoting the application and development of titanium alloy drill pipe in the oil fields.

Identifying some regularities of the heat transfer in the welded joint of SUS304 pipe using a numerical approach

In this study, an investigation into the impact of heat transmission in the welded junction of SUS304 pipe has been carried out with the use of a numerical method. An investigation was carried out by employing ANSYS’s static structural tools in conjunction with the software package’s thermal transient analysis. Based on the heat flow on the welding point, where the temperature reaches 507 °C within 200 mm of the end of the welded pipe, an examination into the efficiency of heat transfer has been carried out. This analysis was based on the heat flow on the welding point. As the total heat flux approaches 7.02e6 W∙m–2, studies have been conducted on the topic. There have been three types of directional heat flux measurements made (X, Y, and Z), with the numerical findings indicating that the X direction produces the most variable heat flow readings. These checks were performed in a variety of settings. These were chosen as the correct paths to go since they led directly to the source of the warmth. whereas the Z-axis permits the minimum amount of heat flow throughout the board. The damaged area identified on the trees that were still standing was factored into the calculation. To calculate the amount of residual stress, the Von Mises stress was applied repeatedly during the whole procedure. This tactic ended up being employed. Due to the tension caused by the pipe’s increased bending radius, the piece of pipe located 200 mm from the pipe’s distal end is the most vulnerable. The value was calculated to be 2.49e6 Pa when the temperature was increased to 500 °C.

Assessment Framework for the Maintainability of Sewer Pipeline Systems

The maintainability of sewer infrastructure systems is vital for public health, environmental protection, and the overall well-being of communities. However, maintenance and repair activities for sewer pipelines are often constrained, leading to challenges in effectively managing such infrastructures. To address these challenges, this study assessed the maintainability of sewer pipelines. A total of 15 defects were identified and categorized into structural, hydraulic, and quality defects after a comprehensive literature review was conducted and sewer pipeline experts were interviewed. Each failure caused by these defects was categorized as a pipe collapse associated with structural defects, sewer system overflow (SSO), odor, and groundwater contamination associated with quality defects. Apart from assessing the defects, the study identified potential solutions. After that, the obtained data were analyzed to determine the relative significance of each probability identified and its impact on four parameters, economic, social, environmental, and detection difficulty, using the relative importance index (RII), while the risk value index (RI) was applied to prioritize the defects. Furthermore, a data reliability assessment was utilized to evaluate internal consistency. The findings indicate that the probability of joint defects in the structural category caused by weaknesses in welded joints due to the misalignment of plastic pipes or joints, especially spigot and socket joints for rigid pipes, was the highest (RII = 0.733). Additionally, the ranking showed that the dumping of FOG had the highest priority, with an RI value of 0.535. This study offers a comprehensive maintainability framework that can be utilized by agencies assessing their current sewer infrastructure systems, in particular Arab Gulf countries including Saudi Arabia, which is the subject of this study.

A study on as-welded microstructure and mechanical properties of thick-walled 9Cr3W3Co1CuVNbBN martensitic steel weldment

A systematic study on the microstructure evolutions and their relationships with mechanical properties of thick-walled 9Cr3W3Co1CuVNbBN martensitic steel pipe joint welded by narrow-gap automatic argon arc welding was carried out. The results showed that a narrow equiaxed grain zone (EGZ) and a significantly wide inter-critical zone (ICZ) were formed in the heat affected zone (HAZ) due to the larger grain size and lower VN precipitates in base metal (BM). The refined grains formed in WM and the higher solid solubility of C, Cr and W in EGZ and ICZ were the main factors leading to their higher hardness than that of BM. The decrease of dislocation density in over-tempered zone (OTZ) immediately adjacent to ICZ not only significantly improved the impact toughness of HAZ, but also led to a significantly lower hardness than that of BM. Nevertheless, the room/high temperature tensile fracture of the welded joints occurred in the BM zone, which was attributed to the cross-sectional shrinkage of the OTZ restrained by the nearby high hardness region ICZ, and the preferential formation of cavities near the coarse Cr23C6 carbides in BM.

Centrifuge test of large-diameter segmented ductile iron pipes crossing strike-slip faults

Seismic ground faults are severe hazards for buried pipes. To explore and model the failure mechanisms of segmented pipes crossing faults, a centrifuge test of a socket-type ductile iron pipe crossing a strike-slip fault is conducted. In the test, a segmented ductile iron pipe with five segments is buried in a soil box. Then, at a centrifugal gravity level of 30.7 g, 60 mm ground displacements are applied through translation of half of the test soil box. Thus, a 2646.2 mm-diameter pipe with a length of 27.4 m subjected to a 1.84 m-long strike-slip fault is simulated. The responses of the joint deformation and the pipe strain are obtained. Results show that the joint deformation is the main response of the pipes subjected to strike-slip faults, the joint near the fault trace is vulnerable, the pipe strain is relatively small, and the peak pipe strain occurs at a certain distance from the fault. Lastly, a theoretical method is presented to obtain the joint deformation of the pipes crossing a strike-slip fault, and a good agreement between the test and theoretical results is observed. The test can be a benchmark for theoretical and numerical models. Meanwhile, the proposed theoretical method has clear physical mechanisms and can obtain the pipe joint deformation effectively.

Analytical method for deformation and stress calculation of bell-and-spigot joints in PVC-U pipes

The stable operation of water supply pipelines relies significantly on the structural safety of pipe joints. A novel analytical pipe joint structural calculation method based on the Novozhilov thin shell theory was proposed to calculate the deformation and stress of bell-and-spigot joints in unplasticized polyvinyl chloride (PVC-U) pipes under internal pressure. An equivalent stress index was established to investigate and evaluate the safety performance of pipe joints. The effects of various factors, including spigot insertion depth, the clearance between the bell and spigot, internal pressure, and different pipe nominal outside diameter (DN) and nominal pressure (PN) series, on the maximum equivalent stress of pipe joints, were thoroughly analyzed. The results indicate that the maximum equivalent stress under nominal pressure is located on the inner surface of the bell and consistently exceeds the design stress. The influence of spigot insertion depth on the maximum equivalent stress is minimal. However, as the clearance value between the bell and spigot decreases and the internal pressure increases, the maximum equivalent stress increases significantly. Pipes with smaller DN and PN series result in a higher maximum equivalent stress at the joint. The analytical method indicates that increasing pipe thickness and reinforcing the bell with continuous carbon fiber filament winding are two potentially effective methods to enhance the mechanical performance of the joint and reduce the maximum equivalent stress. This study's findings offer valuable theoretical support for designing and selecting joints in PVC-U pipelines.

Dynamic Modeling and Parameter Identification of Double Casing Joints for Aircraft Fuel Pipelines

Double casing joints are flexible pipe joints used for connecting aircraft fuel pipelines, which can compensate for the displacement and corner of the connected pipes and have complex mechanical characteristics. However, it is difficult to use sensors to directly measure the mechanical connection parameters of flexible joints. In this paper, we construct a coupling dynamics model and parameter identification of a double casing joint. Firstly, we analyze the structure and working principle of double-layer casing joints and establish the dynamics model of a single-layer flexible joint based on the transfer matrix method. Then, we deduce the coupling matrix of the inner and outer pipeline according to the deformation coordination conditions combined with matrix dimension extension. We establish the coupling dynamics model of flow–solid coupling of double casing joints. Furthermore, parameters such as equivalent stiffness and damping of each motion of the double casing joint in the casing unit are identified using the force-state mapping (FSM) method, and an analytical solution in the frequency domain under hammering excitation is given by the dynamics model. Finally, the dynamics test bench of the double casing joint for aircraft fuel is set up, and the free mode test of the double casing joint assembly is carried out. The results show that under free boundary hammering excitation, the theoretical and experimental frequency-domain response results are well matched, both obtaining seven main resonance peaks, and the maximum error is 9.45%, which shows the validity of the pipeline dynamics modeling method with a double casing joint.