Pipe Thickness Research Articles

Research on Strain of Unequal Wall Thickness Pipeline of the X80 Pipeline under Lateral Load

X80 steel is a material with high strength and good toughness, which is widely used in long-distance natural gas pipelines. Pipelines will have different wall thicknesses, depending on the safety level requirements of different regions. Two sections of pipes with different wall thickness form unequal wall thickness of pipeline (UWTP) that is joined together by welding. UWTP pass through some geohazard areas, such as landslides. The frequency of landslides is extremely high in mountainous areas, which can seriously affect the safe operation of UWTP. In this paper, a model of a 12.8 mm wall pipe section and a 15.6 mm wall pipe section are linked by girth welds. The strain between the pipe section and the weld was quantitatively analyzed. The results show that the strain at the girth weld in the 3 o’clock direction of the pipe increases sharply. The strain in the 9 o’clock direction of the pipe is generally lower than the strain in the 3 o’clock direction. The strain value of the 12.8mm wall thickness pipe section is generally greater than the strain value of the 15.6mm wall thickness pipe section.

Hydrodynamic Load Effect on Composite Polymer Cold-Water Pipe Joint in Ocean Thermal Energy Conversion

The cold-water pipe in Ocean Thermal Energy Conversion (OTEC) is a very important part of the process of producing electrical energy. The cold-water pipe functions to convey cold water with a temperature of 5°C from a sea depth of >500 m to the sea surface. The cold water in the pipe is allowed to experience a temperature increase of <3°C so that it can be used to dilute the ammonia in the condenser. The use of polymer composites as cold-water pipe materials is a challenge because the hydrodynamic load from seawater currents fluctuates in a direction perpendicular to the position of the pipe. The pipe length reaches >500 m consisting of several pipes connected using the Friction Stir Welding method. This research was conducted to determine the effect of the hydrodynamic load of seawater currents on Friction Stir Welding (FSW) connections, the stress distribution in pipe joints, and the thickness of pipes that are safe to use as OTEC cold water pipes. In addition, simulations were carried out using Inventor software on pipes with a length of 500 m, a diameter of 4 m, and variations in thickness from 18 cm to 30 cm which produced von Mises yield stress and stress distribution at different joints at each pipe thickness. In pipes with a thickness of less than 20 cm, the stress and stress distribution are purely influenced by the hydrodynamic load of seawater currents. Meanwhile, in pipes with a thickness greater than 24 cm, the stress that occurs in the pipe is influenced by the current and weight of the pipe. In pipes with a thickness greater than 24 cm, the stress in the pipe is concentrated in the middle of the joint which is the critical part of the pipe and is the initial point of failure. It was found that at a pipe thickness of 22 cm, the stress was distributed almost evenly because the stress caused by seawater currents was reduced by the heavy load of the pipe. So, from the simulation of cold-water pipes with polymer composite materials that experience hydrodynamic loads from seawater currents varying in thickness from 16 cm to 30 cm, it is recommended to use a pipe thickness of 22 cm so that the pipe connection is safer as an ocean-based OTEC cold water pipe application.

Measurements of thickness of a steel operation pipe occurring in a salt cavern and its geometry: simulations and experiments

In this paper, the attempts of measuring the thickness of a steel operation pipe occurring in the salt cavern and its geometry using an ultrasonic probe in the stage of computer simulation and laboratory are presented. The pipe makes as an obstacle for ultrasonic waves. In order to resolve this task, we need to determine the thickness of the pipe and choose the appropriate resonant ultrasonic wave. Determination of the thickness of the industrial steel pipes was carried out using the resonant frequency of reflected ultrasound waves and the relationship coefficients. The thicknesses of the industrial pipes measured by the resonant ultrasound wave method are in good agreement with those measured using an electronic caliper. Measurements of the cavern geometry with presence of the operation pipe using the resonant frequency of ultrasonic wave were well verified in a physical model and will be able in application to determine the real salt caverns.

Myrmecia: Failure analysis and thermodynamic coupled simulation program for heat pipe in micro reactor based on MOOSE

The heat pipe cooled microreactor (HPMR) has become increasingly popular in the realm of research, largely due to its clean, efficient, and safe properties. This paper presents the development of Myrmecia, a simulation software built on the MOOSE framework. Myrmecia integrates the thermodynamic model and failure analysis model of a heat pipe, facilitating the assessment of the failure probability of a given heat pipe based on its thermodynamic parameters and design parameters. The verification of both models has been conducted. The findings demonstrate that increasing the wall thickness of the heat pipe leads to a reduction in its heat transfer capacity, while significantly decreasing the failure probability. Furthermore, appropriately elevating the initial temperature contributes to a decreased likelihood of a break event occurring in the heat pipe. Under the assumption of a fixed heat source/sink temperature, enlarging the inner diameter of the heat pipe exerts negligible influence on the failure probability, yet substantially enhances its heat transfer capability. In summary, various parameters of the heat pipe exert considerable influence on both its safety performance and heat transfer performance. Consequently, the trade-off between these two aspects represents a critical consideration for heat pipe designers.

Vapor flow resistance characteristics in ultra-thin flat heat pipes

Miniaturization of electronic devices drives the development of ultra-thin flat heat pipes (UTFHPs). As the thickness of the heat pipe decreases, the microchannel effect of the vapor chamber exacerbates the deterioration of the vapor flow. The vapor flow resistance, which is often neglected in the conventional theory due to its extremely small effect compared to the liquid flow resistance, becomes a critical factor limiting the heat transfer performance of UTFHPs. To provide a theoretical basis for the design and performance evaluation of UTFHPs, this paper investigated the effect of the wicking structure and working fluid on the vapor flow resistance of UTFHPs based on theoretical derivations, numerical calculations, and experiments. The results indicate that conventional analytical theory is no longer applicable when the total thickness of the heat pipe is less than 1 mm. The vapor flow resistance obtained using the conventional equation is significantly smaller than the experimental results, which is caused by several factors: raised momentum loss at the wall and gas-liquid interface due to the growth of the velocity gradient in the boundary layer; exacerbated flow instability due to the mixing between the vapor and the working fluid; enhanced fluctuating effects on the flow channel due to the presence of the wicking structure. A dimensionless flow resistance coefficient equation was proposed with the vapor Reynolds number and the channel height ratio. An experiment was conducted to verify the accuracy of the flow resistance correlation. The difference between the experimental results and the calculated values is less than 15 %.

Application on Welding Technology of Thick Pump Pipes

Application on Welding Technology of Thick Pump Pipes

A Pulsed Eddy Current Sensor for UAV Deployed Pipe Thickness Measurement

A Pulsed Eddy Current Sensor for UAV Deployed Pipe Thickness Measurement

Numerical analysis and deformation prediction of a novel large-area vapor–liquid hybrid coplanar aluminum flat heat pipe

With the further reduction of the thickness of flat heat pipe, vapor–liquid coplanar flat heat pipe (CFHP) has been proven to be an effective method for thermal management system of electronic devices in limited spaces. The large-area, thin, and lightweight CFHP was of great importance for achieving thermal control of high-power outdoor telecommunication equipment. Thus, a novel large-area vapor–liquid hybrid coplanar aluminum flat heat pipe (HCFHP) was proposed in this work. Initially, a simplified three-dimensional numerical model was constructed to assess the thermal–hydraulic performance of HCFHP. Comparisons were made between the velocity, pressure, and temperature profiles of HCFHP and CFHP. The simulation results revealed a significant enhancement in the heat transfer performance of the optimized HCFHP structure. Notably, the total thermal resistance of HCFHP was reduced to 0.0567 K·W−1, representing a remarkable 94.144 % reduction compared to CFHP. Additionally, to meet the strength and deformation requirements of HCFHP under high saturated vapor pressure, thermal–mechanical coupling was considered. A fitting formula was developed to predict the maximum deformation of the thin plate between circular support structures within HCFHP. The mechanical simulation results were in excellent agreement with the formula calculations, with a mere 0.063 % relative error. This novel large-area vapor–liquid hybrid coplanar aluminum flat heat pipe could be a practical and highly efficient solution for thermal control of high-power telecommunication equipment.

Issues of laser welding technology of the ends of heat exchange pipes in pipe gratings.

The paper shows that the reliability and service life of shipboard heat exchangers largely depends on the quality of fixing heat exchange pipes in pipe grids. The methods of fixing pipes in a pipe grid depends on many factors: the type of heat exchanger, the material from which the pipes and pipe grids are made, the thickness of pipes and pipe grids, technological capabilities taking into account the chosen design, etc. One of the most effective ways of fixing pipes in the tube grids of heat exchangers is welding. Welds are characterized by strength, manufacturability, and provide a high service life of the joint.
 In the article, it is proposed to use laser welding to perform welded joints. Laser welding provides a high focused energy density concentrated on a very small area with relatively low energy input and heating of adjacent metal layers. In laser welding, there is no strong ionizing radiation, the magnetization of the workpieces does not affect the laser beam, which is relevant when welding magnetic materials. The effect of laser radiation is highly local, carried out in the air, including in the environment of protective gases. Thanks to this, laser welding can be used without problems to connect large-sized metal structures.
 The laser beam is easily transported with the help of mirror optical systems or through a light guide and is directed to hard-to-reach places. At the same time, reliable and operational control of the laser welding process with adjustable energy characteristics is provided. The article describes the technological equipment that can be used for welding heat exchange pipes and pipe gratings.

Buckling behavior of sandwich pipe under external pressure and lateral load

The buckling propagation in deep-sea service sandwich pipes is prone to occur under the influence of third-party loads. Therefore, it is crucial to determine the carrying capacity of the sandwich pipes under combined loading conditions for safety. Currently, the predominant method for studying the carrying capacity of sandwich pipes relies on hyperbaric chamber tests, which fail to reflect adequately the buckling behavior under lateral loads. In this study, the finite element package ABAQUS was used to establish a finite element model that accounted for the lateral load on submarine sandwich pipes. It was solved for the maximum lateral load and compared the results with experimental tests, and then validated the accuracy of our numerical simulation method. This investigation focused on studying the buckling behavior of sandwich pipes under displacement control, and analyzed the relationship between buckling behavior and external pressure as well as lateral load. Furthermore, the comprehensive parametric studies were performed to analyze the impact of initial ovality, inner pipe thickness, and outer pipe thickness on the maximum lateral load of the sandwich pipe. The findings demonstrated that under coupled loads, sandwich pipes exhibited two types of buckling behavior: local buckling and buckling propagation. Moreover, as the external pressure increased, the buckling tendency in sandwich pipes transited from local buckling to buckling propagation. To enhance the capacity of sandwich pipes, there were two strategies proposed: increasing the thickness of the outer pipe and then reinforce the inner pipe to improve overall strength. Finally, based on an analysis of sandwich pipe applications up to 5000 m water depths, the sandwich pipe structure were proposed suitably for various water depths.

Loading capacity of welded hollow spherical joints strengthened by cone member

The Welded Hollow Sphere Joint (WHSJ) is frequently employed as a connection form in spatial grid structures. Structures don't retire immediately upon damage, necessitating reinforcement. However, effective solutions for reinforcing WHSJs still have shortcomings in practical engineering applications. Given this research context, a reinforcement scheme for WHSJs is proposed. Feasibility is confirmed through numerical simulation, showing that this reinforcement method is applicable to WHSJs with initial loads, enhancing their mechanical performance without being influenced by the initial loads. The study also initially uncovers the patterns of load-bearing capacity variation with geometric dimensions. Subsequently, an Artificial Neural Network (ANN) is used to predict compressive load-bearing capacity. It utilizes input variables such as sphere diameter (Ds), steel pipe diameter (Dp), reinforcement cone base diameter (Dt), sphere thickness (Ts), steel pipe thickness (Tp), cone thickness (Tt), and cone base angle (θ), with the output being the compressive load-bearing capacity of the welded hollow sphere joint post-reinforcement. Prediction errors are confined to within 10%. Using the Garson algorithm, the sensitivity analysis reveals that steel pipe thickness (Tp) and sphere thickness (Ts) play relatively significant roles in the prediction process.

Deformation features of trunk pipelines with composite linings under static loads

This paper considers the deformation process of a typical section of a steel trunk pipeline with a defective zone, strengthened with a carbon fiber composite lining, under the influence of stationary internal pressure. Defects in the form of thinning of the pipe thickness and cracks were investigated. The stressed-strained state of the structure at critical pressure was analyzed. The thickness of the composite lining was determined, at which the bandage compensates for the effect of internal pressure on the damaged section of the pipeline. Research was carried out numerically based on finite element modeling in the ANSYS software package. When studying the stressed-strained state of a pipe with a defect of an arbitrary complex shape under the influence of critical pressure, a compensating value was obtained. The result showed that a carbon fiber lining with a thickness of 17 % of the rated thickness of the pipe could completely compensate for the effects of internal pressure in the defect area. In this case, the stresses in the carbon fiber lining were close to minimal. When studying the stressed-strained state of a pipe with a large crack of arbitrary shape at critical pressure, a compensating value was also obtained. It has been established that to compensate for the concentration of internal pressure in the crack zone, the thickness of the composite lining should be at the level of 34 % of the rated thickness of the pipe. In this case, the deformation of the steel pipe in the area of the crack occurs in the elastic region. The exception is the crack tips, where plastic deformations are observed, and stresses arise up to 93 % of the ultimate strength of the pipe steel. At the same time, the stresses in the carbon fiber lining remain close to minimal. Thus, it is recommended to use carbon fiber linings with a thickness of 17 % or more of the rated pipe thickness to bandage damage constituting up to 75 % of the thickness of a steel pipe. To bandage cracks, it is recommended to use carbon fiber linings with a thickness of at least 34 % of the rated pipe thickness

The Influence of Pipe Thickness on the Quality of Welded Joints

In this article, we aim to investigate the effect of pipe thickness on the deformation of welded joints in tubular structures. To this end, pipes with a diameter of 60 mm and a length of 215 mm will be utilized in both simulation and experimental processes. The Tungsten Inert Gas (TIG) welding method, known for its high-quality welds, will be employed to join the two steel pipes. The study will be conducted with four different pipe thicknesses: 2.5 mm, 3.2 mm, 4.0 mm, and 5.2 mm, to cover a wide range of thicknesses commonly used in industrial applications. In addition, to validate the accuracy of the simulation method, experimental tests will be carried out for selected simulated cases. The results of the study indicate that structures with thinner pipe walls exhibit higher residual temperatures and stresses, which leads to more deformation. Therefore, it is crucial to consider the pipe thickness when designing and welding tubular structures. After comparing the deformation results obtained from both simulation and experimental tests, we conclude that the simulation method is an effective tool for predicting the deformation of welded joints in tubular structures. By utilizing simulation methods, engineers can optimize the welding parameters and select the appropriate pipe thickness to minimize deformation and ensure the structural integrity of tubular structures.

Experimental Investigations on Cylindrical GFRP Composite Pipes under Compression Loading

In a wide variety of aerospace applications have the mechanical properties of a thin cylindrical shell are important. Thin cylindrical shell structures are used to store a small and large quantity of fluids and solids. Glass Fabric reinforced epoxy composite is used to prepare the thin cylindrical pipes with different diameters and varying thickness of the composite pipes. The additives as glass flakes are added with 5%, 10% and 15% of the resin content in the matrix. The rolled composites specimens are prepared with the stainless steel (SS) mould. Experiments are test on Universal Testing Machine under lateral compression test to study the breaking load and compressive strength of the specimens. The failure modes are also observed.

Very low-cycle fatigue failure behaviours of pipe elbows under displacement-controlled cyclic loading

In this study, quasi-static very low-cycle fatigue tests were conducted on pipe elbows at room temperature to investigate the effects of the pipe thickness, internal pressure, and material on the failure behaviours under large-amplitude cyclic loads. Three types of elbow specimens comprising two different materials and two different pipe thicknesses were used in the tests. Elbow specimens were subjected to displacement-controlled, fully reversed, in-plane mode cyclic bending with and without internal pressure. All specimens failed due to through-wall cracking of which the location and orientation depend only on the pipe thickness regardless of the internal pressure and elbow material. For thin-walled elbows of Schedule 40, the axial crack at flank was developed, whereas for thick-walled elbows of Schedule 160, the circumferential crack at intrados. The number of cycles to failure decreased with increasing internal pressure in thin-walled elbows. However, the effect of internal pressure on the number of cycles to failure was negligible in thick-walled elbows. Regardless of internal pressure level, stainless steel elbows were more resistant to failure, compared with carbon steel elbows of identical dimensions. Finally, the strain-based evaluation model considering the void growth and shrinkage effect was applied to predict fatigue failure location and cycles. Two parameters in the model, the multi-axial fracture strain locus and void shrinkage ratio, were determined from monotonic tensile test data and the fatigue life curve of the material. The predicted crack initiation site and orientation were consistent with experimental finding. For all cases, the predicted failure cycles were less but overall close to experimental data.

The impact of the nonlinear concrete behaviour on the required liner thicknesses of spray-repaired concrete pipes

Buried reinforced concrete pipes (including sewers, stormwater pipes and other gravity flow structures) that experience unsafe levels of deterioration are commonly rehabilitated using trenchless solutions, such as the application of cementitious liners. Cementitious liners are centrifugally cast onto the inner surface of the damaged pipes with a spinning head that travels along the length of the pipe. Once cured, the liner increases the strength of the damaged pipe to resist applied earth and surface loads. A design method previously proposed by the authors provides guidance for selecting the required liner thickness to rehabilitate deteriorated concrete pipes situated at deep burials. However, this design method considers the linear elastic behaviour of the soil and pipe materials. Neglecting the nonlinear effects of crushing concrete within the host pipe may impact the predicted liner thicknesses for repair. Thus, the current study evaluates the impact of incorporating nonlinear compressive material behaviour on the required liner thicknesses to repair damaged concrete pipes. The required liner thicknesses obtained from the nonlinear version of the design method for rehabilitations of several pipes selected from the ASTM C76-11 Standard experiencing varying levels of deterioration are compared to thicknesses obtained using the authors' linear elastic solutions. The comparisons indicated that considering the nonlinear material response of the concrete generates slightly larger estimates of required liner thickness. The discrepancies between the estimated liner thicknesses were observed to be insignificant for pipes experiencing cracking and losses of concrete cover, demonstrating that the linear elastic model is suitable for design purposes. However, for damaged pipes situated at deep burials experiencing losses of tensile reinforcement, the discrepancies between the liner and nonlinear calculations become more significant. It is recommended that the results of the linear elastic model be checked with the nonlinear model for the repair of pipes experiencing loss of tensile reinforcement, or for deeply buried pipes.

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.

Experimental study on the vibration characteristics of fluid–structure coupling in the transition process of flexible bending pipes

The flexible bending pipes with large aspect ratios are more likely to cause large vibrations in the extraction of offshore oil and gas resources, which can accelerate the fatigue damage of the pipes. In order to explore the characteristics of fluid–structure coupling vibration during the transition period after the flexible bending pipe starts to transport fluid, an experimental platform of flexible bending pipes fluid–structure coupling vibration was created. The strain and vibration displacements of the pipe were measured by a resistance strain gauge and a high-speed camera system, respectively. According to the measure results, the largest values of stress and strain both were discovered at the pipe's two ends, and the maximum values of vibration displacement and vibration velocity were found in the middle of the pipe. The phenomenon indicates that the two ends of the pipe are more prone to fatigue damage. Moreover, the dynamic response and dynamic characteristics of the pipeline during the transition process were investigated. In addition, the effects of fluid flow rate, pipe wall thickness and different pipes on the dynamic response and dynamic characteristics of the pipe were also investigated in the present work.

Local instantaneous heat transfer characteristics around a rising single Taylor bubble and the temperature response of relatively thick pipe wall under local constant heat flux

A novel non-intrusive thermal diffusion measurement (TDM) method is proposed to measure the flow rate of gas–liquid two-phase flows under the slug flow state in our previous research. To improve the measurement accuracy of TDM by clarifying the real-time correspondence between wall temperature change and Taylor bubble (TB) location, the local instantaneous heat transfer characteristics around a rising single TB and the corresponding temperature response of the pipe wall are further investigated in detail by using the CFD tool in this paper. During the passage of TB, the local heat transfer between the pipe wall and fluid was analyzed based on the dynamic velocity field and temperature boundary layer, and the temperature on the fluid–solid interface presents the opposite trend with the heat transfer coefficient. For the zone upstream of the heat flux center, the lag time and increase of the wall temperature become large and weak along the radial direction, respectively, whereas the lag time is independent of the axial location, TB velocity, and TB length. Meanwhile, the increase in wall temperature shows an upward trend with the TB length for short TBs but is the same for long TBs.

In-service welding of X70 steel gas pipeline: Numerical and experimental investigations

The in-service welding process is widely used to repair defective gas pipelines, which allows the damaged section to be repaired without interrupting gas flow. In this way, consumers and gas transportation companies will be able to minimize losses. In this study, a thermomechanical finite element analysis model was developed to examine the effects of pipe pressure, thickness, diameters, and welding heat input on temperature history and residual stress. The results were analyzed using the design of the experiment method (DOE). According to the results, these parameters significantly affect the thermal distribution and pipe yield stress at the welding point by 48.8%, 29.4%, 15.1 and 6.9%, respectively. On the basis of optimal conditions, in-service welding is conducted. Investigations were conducted on the microstructure, temperature distribution, and residual stresses induced during the in-service welding of API 5L X70 steel pipelines. As a result, it was determined that the HAZ microstructure consists primarily of ferrite, bainite, and M/A constituents, whereas the pipe microstructure undergoes fewer phase transformations. In order to validate the numerical model, mechanical tests, as well as hole drilling, were conducted to gather data, and a combination of equivalent carbon and T8/5 was used to determine hardness at various locations in the HAZ in order to determine which areas are susceptible to cold cracking. The numerical results and the experimental results were highly concordant.