Large Diameter Pipes Research Articles

Discussion on Construction Technology of Large Diameter and Long Distance Slurry Balance Pipe Jacking in Complex Geological Conditions

Discussion on Construction Technology of Large Diameter and Long Distance Slurry Balance Pipe Jacking in Complex Geological Conditions

Cracking analysis of massive concrete with large-diameter pipes during construction

This paper presented the results of a study on the cracking behavior of early age massive concrete with large-diameter pipes during construction. Material property tests were conducted to identify the time-dependent mechanical properties of the early age concrete made of P.O. 42.5 cement. A full-scale reinforced concrete block of 4.4×4.8×3m with pipes up to 508 mm in diameter was cast and monitored for the development of the temperature and strain of concrete. A three-dimensional FEM model was established based on user defined subroutine for the time-dependent mechanical and creep properties. The FEM model was verified based on the test results and was used for cracking risk analysis of massive concrete with different pipe layouts. It is found that a diameter to edge distance ratio or a diameter to spacing ratio of no more than 1/3 is sufficient to prevent additional cracking risk of concrete due to the presence of pipes.

Behavior and innovative design model on soil pressure at the top of large-diameter buried steel pipes

Existing design models of soil pressure at the top of buried steel pipes are limited to small-diameter pipes. This study aims to investigate the behavior and design model on the soil pressure for large-diameter pipes considering the pipe diameter, diameter-to-thickness ratio, and cover depth. The distribution and size of soil pressure are obtained from finite element models and compared with traditional design models. Sensitivity studies of soil parameters, trench parameters, and friction coefficients are discussed. Furthermore, an innovative design model of soil pressure for large-diameter pipes is proposed. The results indicate that the basic distribution pattern of soil pressure is the “inverted basin”/parabola for large/small-diameter pipes, respectively. Peak soil pressure typically appears in the pleura of pipes with great flexibility and deep cover depth. The modulus and Poisson's ratio of backfill and soil-soil friction coefficient have an influence range of within 10% for soil pressure, while trench parameters have a more significant influence. Prism load is too large at high cover depth, and Marston load is small at low cover depth. The proposed basin model for soil pressure adopts the form of “straight line + parabola” for distribution and “Marston + pleura” load for size, with high accuracy and strong adaptability.

Coupled response characteristics of cold water pipe and moored ship for floating OTEC plant

A floating Ocean Thermal Energy Conversion (OTEC) plant requires a large-diameter Cold Water Pipe (CWP) to be attached to a floating structure. For the design of the mooring system and the CWP, a coupled analysis of a floating body, mooring system and CWP should be employed due to the huge mass of the internal fluid in the CWP. The aim of this paper is to construct a simplified coupled response model to facilitate the preliminary stage of the design. The equations of equilibrium and motion are derived based on modeling as a two-dimensional floating body and an elastic pendulum. In order to verify the applicability for a practical design and limitation of the present model, a 100 MW ship-shaped platform, a spread mooring system and a CWP with an inner diameter of 12 m and a length of 800 m are configured. The results of the extreme analysis in the frequency domain with equivalent linearization of drag force by using the present model agree well with the time domain coupled analysis using OrcaFlex. Subsequently, the influence of the design parameters for CWP to the coupled responses is also clarified by a parametric study combining the bending stiffness, the linear density and the boundary conditions. The proposed model will facilitate the preliminary study with a large number of design trials, and a comprehension of the results of numerical simulations and model experiments.

Analysis of the change in the shape of large diameter pipes during assembly and welding

Studies have been carried out to assess the effect of residual stresses and deformations arising in the process of assembly and welding, as well as after metal cooling, on the shape of pipes. In the process of cooling, the weld and heat-affected sections are shortened, leading to a curvature of their generatrices, with the main change noted at the ends of pipes. To determine the stresses and strains in pipes, experimental and analytical studies and mathematical modeling were carried out at the assembly and welding site. Presented are the results of geometry measurements from the front and rear ends of pipe blanks and pipes with dimensions of 1420×25; 1420×21.6; 1420×18.7; 1420×15.7 mm of K60 strength class and 813×39; 813×37.4 and 813×39 mm of K65 strength class after step forming, assembly, welding and expansion, as well as the curvature of these pipes. The calculation of stress intensity along the entire perimeter of pipes 813×39 and 1420×25.8 mm before and after assembly on the assembly and welding mill was carried out. Pipes with a ratio of diameter to wall thickness of 90.4 of the K60 strength class had the largest deviation in ovality and curvature, and the smallest deviations were 20.8 and 22.3 of the K65 strength class. After welding of the external seams, the vertical diameter and the value of curvature increase, and after expansion they decrease. The total change in the ovality of pipes due to residual welding deformations is on average 0.5% for pipes with a diameter of 813 mm and 2% for pipes with a diameter of 1420 mm.

A Novel Magnetic Flux Leakage Sensor System for Inspecting Large Diameter Pipeline

The magnetic flux leakage (MFL) type non-destructive inspection can be performed only when the metal object is sufficiently magnetically saturated. Therefore, since the general MFL sensor system used for pipeline inspection must sufficiently saturate the pipe, the weight and size of MFL sensor system are inevitably increased according to the diameter or thickness of the pipe. However, if the weight of the MFL sensor system is excessively increased, it is difficult to drive, and thus it is difficult to inspect a pipe having a large diameter. In this paper, the novel MFL sensor system which can be inspected large-diameter pipes without increasing the weight of the MFL sensor system is proposed and compared to the conventional MFL sensor system used for the pipe inspection. Since the proposed MFL sensor system is a system that saturates the pipe locally, it has the advantage of being able to inspect the pipe regardless of the pipe diameter.

Mechanical Analysis of DS in Horizontal Directional Drilling

In recent years, trenchless horizontal directional drilling (HDD) technology has developed rapidly towards the direction of large pipe diameter and long span. During construction, the buckling deformation and large drag torque of the drillstring (DS) are the key problems restricting the development of the HDD technology. In order to understand the buckling deformation law of the DS in horizontal directional drilling engineering, as well as the transfer and the distribution of the drag torque, and the relationship between the buckling deformation and drag torque, the dynamic model of the DS system in drilling engineering is applied to HDD engineering. The dynamics model of HDD at a long distance (5200 m) is established and calculated. The research indicates (1) when the buckling deformation of the DS is small, priority should be given to reducing the friction and torsion at the bending position; (2) excessive inlet thrust is the main reason for the buckling deformation of the DS, and the smaller the hole diameter, the more serious the buckling deformation; (3) severe buckling deformation of the DS will lead to an increase in the frictional resistance at the deformed part, and even local self-locking, resulting in the inability to continue to increase the weight on bit (WOB). The research results preliminarily reveal the relationship between DS buckling deformation and drag torque in ultra-long distance HDD engineering and point out the phenomenon law of drag torque and buckling deformation, which has reference value for the development of HDD technology.

Research on reduction of residual stress in girth welds of large-diameter natural gas pipes by ultrasonic

ABSTRACT Excessive residual stress of the girth weld in pipes will directly damage the pipe strength during its operation. Accurate measurement and effective reduction of the residual stress can ensure the safety of natural gas pipes during their service. In this paper, an X80-type large-diameter natural gas pipe section with girth welds is taken as the research object. The coercive force method is used to characterize the residual stress of the girth weld and its surroundings, and then the distribution law of the residual stress of the girth weld and its surroundings is obtained based on the measurement results of the Blind-hole method; the ultrasonic impact method was used to reduce the girth weld residual stress, and the effect of the ultrasonic impact method on the residual stress reduction was studied by comparing changes of the distribution characteristics of the coercive force in the girth weld and its surroundings before and after the residual stress reduction in the natural gas pipes. Lastly, the in-situ test specimen is made to carry out the uniaxial tensile test so as to study the effect of the ultrasonic impact method on the tensile mechanical properties of pipe welds. This study clarifies the influence law of the ultrasonic impact on the mechanical properties of weld toe materials, and provided technical theoretical guidance for the reduction of field residual stress in natural gas pipes.

A circumferential SH wave piezoelectric transducer array for damage detection in large-diameter pipes

Abstract Torsional or longitudinal wave-based inspection is an effective method for rapid defect screening in pipes, but it has difficulty to locate the circumferential position of a defect due to the axially symmetric properties of torsional and longitudinal modes. In order to overcome this problem, several flexural-wave-based focusing methods have been proposed while multiple mode propagation associated with dispersion has to be taken into account in them, which increases the complexity of identifying defects in practical applications. In this work, based on our recently developed bidirectional SH wave piezoelectric transducer (BSH-PT), a fundamental circumferential shear horizontal (CSH0) wave linear phased array was proposed for in-situ defect localization in large-diameter pipes. Firstly, the working principle of the BSH-PT array was presented and its performance on defects detection was assessed by simulations using the total focusing method (TFM). Then, experiments were conducted to examine the array’s performance. Results showed that the proposed BSH-PT array can detect multiple defects simultaneously at varied frequencies. Finally, a method for eliminating the mirrored artifact was proposed and then validated by both simulations and experiments on pipes. Considering the quasi-nondispersive character of CSH0 wave and the desirable performance of the BSH-PT on exciting and receiving pure CSH0 wave, the proposed CSH0 wave phased array may be useful in structural health monitoring (SHM) of large-diameter pipes such as pressure vessels and oil tanks.

Turbulent heat transfer of highly buoyant supercritical CO2 flow in various horizontal pipes

Supercritical CO2 (sCO2) is considered as an ideal heat transfer fluid for power cycles adapted to a wide range of heat sources. This paper employs computational approach based on Reynolds-Averaged Navier-Stokes (RNAS) modelling to study highly buoyant turbulent sCO2 flow and heat transfer heated in various horizontal tubes with diameter of 4.57 mm, 13.39 mm, and 22.14 mm. The conditions with relatively high ratio of heat flux q to mass flux G are simulated. The chosen AKN k − ε low-Reynolds number turbulence model is rigorously validated against experiments and DNS covering a wide range of operation conditions and exhibits quite satisfactory consistencies on the strong buoyancy reproductions of horizontal supercritical flows. With sCO2 heat transfer data presented, details about the coupled turbulent flow characteristics have been discussed. It has been observed that in various size horizontal geometries, not only the local sCO2 heat transfer along the tube top surface, but also the overall performance within the liquid-like region near Tpc is greatly degraded by the strong buoyancy, and the deterioration regime expands with decreasing pipe diameter. For the highly buoyant horizontal sCO2 flows, a backflow vortex appears near the top wall then a second velocity peak forms which locates further into the core flow section for larger diameter pipes; The radial velocity profile of the top wall has been flattened even distorted into “half-M” shape that the turbulence statistics decline remarkably then the turbulent activities and thermal advection are attenuated. With sCO2 heated into the gas-like regime, the heat transfer recovers because of the reduced buoyancy effects.

Bauschinger Effect, Masing Principle and Hencky Theorem for Bending Moment at Repeated Alternating-Sign Bending of Steel Sheet

In the production of the large-diameter thick-walled steel pipes (with a diameter of 1020-1420 mm and with a wall thickness of up to 32-48 mm from the high-strength steels of the strength class K50-K65) under the SMS Meer technology for the main gas-and-oil pipelines, the steel sheet is bent several times sequentially during the technological transitions from one press to another. At the elastoplastic alternating-sign bends of the sheet, the yield strength of the bending moment of the sheet changes from one bend to another, which causes great difficulties for the metallurgical technologists when they calculate the curvature of the tube’s wall and the final diameter of the pipe. To solve this problem, we propose the new analytical method for calculating the bending moment and curvature of a steel sheet under the low-cycle alternating-sign bending.

Practical analysis of cleaning water supply pipeline using air and water flushing technology

To ensure the safety of water quality, pipe network cleaning and security management are put forward higher requirements. Traditional single-phase water flushing pipe technology requires high velocity and large flow rate of water, which does not suitable for large-diameter pipes. Air and water flushing pipes are new pipeline cleaning technology, which has high efficiency, good washing effect, and can save a lot of water. The principles of airwater flushing large-diameter, large-deviation-elevation, and many- ups-and-downs pipes are described in this paper. Based on the two-phase flow theories, it analyzes complex hydraulic characteristics and control parameters for flushing pipeline. Combine with engineering practice, air and water flushing diameter of 800 mm pipeline in Shanghai city and flushing pipe parameters are introduced. The air and water flushing effect and water resource consumption reduction are analyzed, as well.

The creation of industrial production of the sub-industry of plastic pipes at the enterprises of the POLYPLASTIC Group

A historical sketch of the development of plastic pipe production in the Russian Federation is presented. The data on the production of pressure pipes of large diameter up to 1600 mm, non-pressure pipes for sewage, with a diameter of up to 2.5 m, pressure reinforced pipes based on cross-linked polyethylene and thermoplastics are presented. The trends in the development of the production of various types of pipes are characterized and data on the specifi cs of their application are given. The technological features of enterprises are analyzed, highlighting the preferred categories of pipes produced by the enterprises in the highest quality categories.

ИССЛЕДОВАНИЕ ИЗНОСА СЕГМЕНТОВ ЭКСПАНДЕРА ПРИ КАЛИБРОВКЕ ТРУБ БОЛЬШОГО ДИАМЕТРА

In metallurgical industries, expensive tools are used, which often have complex geometries. The performance of such tools directly affects the economic performance of the production. One of these tools is the expander segment. This tool is used in the process of calibrating large diameter pipes obtained according to the JCOE, UOE, RB-forming schemes. The calibration process is the last stage of shaping, which consists of the gradual deformation of the pipe billet using segments that have a certain set of mechanical and geometric properties. At each stage, the segments give a rounded shape to the pipe, correcting straight sections, ovality and other geometric irregularities of the billet. The main load of the process falls on the expander segments. In this paper, we study the wear of segments in the process of calibration of large-diameter electric-welded pipes. To predict wear, CAE models of the calibration process were built in a specialized software package MSC-Software, with the help of which an analysis of possible wear, its magnitude, position and nature was carried out. A technique is proposed for assessing the wear of expander segments using 3D scanning, digitizing the data obtained and constructing a 3D map of deviations from the reference model. An analysis of finite element modeling and experimental studies showed that CAE models with high convergence predict zones and features of the wear distribution of expander segments. It is shown that modeling with a high degree of certainty can be used to assess the performance of tools, both new and already in operation. Based on the experimental data, an equation was obtained to determine the wear of the expander segments. According to the obtained equation, a nomogram was constructed, which makes it possible to predict the wear of the expander segments depending on the stresses that arise in the tool during calibration and the number of processed pipes. Evaluation and accounting for the wear of the working surface of the expander segments make it possible to predict deviations in the geometric parameters of pipes in the process of expanding.

Wave Spectrum Characterization in Turbulent Stratified Air-Water Flows in a Large Diameter Pipe

Wave Spectrum Characterization in Turbulent Stratified Air-Water Flows in a Large Diameter Pipe

Effect of Interfacial Area Modeling Method on Interfacial Drag Predictions for Two-Fluid Model Calculations in Large Diameter Pipes

Effect of Interfacial Area Modeling Method on Interfacial Drag Predictions for Two-Fluid Model Calculations in Large Diameter Pipes

Methane-air explosion pressures in cylindrical interconnected containers with different dimensions

The characteristics of methane-air explosion in interconnected containers with different dimensions are studied in this paper, and the prediction models are established. The explosion apparatus consists of two cylindrical containers and a connecting pipe, and three structure parameters are selected as influencing factors for the experiments. The explosion pressure, the maximum rate of pressure rise and pressure growth index under different conditions are compared by changing the volume ratio (<italic>V</italic>₁/<italic>V</italic>₂), the length of the pipe, and the inner diameter of the pipe. During the experiment, the combustion and explosion of gas developed from the main container to the auxiliary container. Under different size effect conditions, the maximum explosion pressure in the secondary container was always higher than the maximum explosion pressure in the primary container. The maximum explosion pressure and the maximum rate of pressure rise in the primary and secondary containers both increase with increasing pipe length. With an increase in the pipe diameter, the maximum explosion pressure and the maximum rate of pressure rise both decrease gradually. When the volume ratio changes, the parameters such as the maximum explosion pressure are also affected by the volume changes of the containers at both ends. Therefore, the explosion parameters in both connected container do not show a single development trend with the increase of the volume ratio. For practical application, in order to reduce the explosion intensity and protect the device, large-diameter pipes should be used and the volume ratio should be reduced.

A Value Engineering Analysis of Head Loss in Pumping Mains

With net zero carbon emissions targets approaching over the next 20 to 30 years, the water industry must act now to develop energy efficient techniques and designs to reduce emissions and reduce the carbon footprint of water utility providers. There is also the potential for significant energy and therefore financial savings to be realised from the adoption of more energy efficient designs approaches. Water utility providers account for a significant proportion of national electricity consumption. The purpose of this research is to determine if, over the long term, opting for a larger diameter pipe at design stage can lead to significant financial and emissions savings for water utility providers when considering pumping mains. Pumping mains are widely used throughout the water and wastewater industry where a gravity solution is not possible. 72 hypothetical water main design scenarios were analysed and the long term financial and environmental impact of each hypothetical water main was assessed. It was found across all design scenarios that larger diameter water mains were capable of delivering the same rate of flow of smaller diameter pipes at a much reduced velocity and requiring reduced pumping power. It was concluded that pumped mains of larger diameters can ultimately be more energy efficient and cost effective over the long term when selected in favour of smaller diameter pumped mains in otherwise identical design scenarios.

Online monitoring of oil wear debris image based on CNN

Image monitoring of oil wear particles is currently only applicable to microflows and is susceptible to bubble interference. This paper develops an optical oil-monitoring system that can be used for large-diameter pipes with high flow rates. A shallow and wide observation cell with an equivalent diameter of Φ5 mm is designed to allow a theoretical maximum monitoring flow rate of about 8 L/min, which is a significant improvement over current image monitoring of generally less than Φ2 mm pipes. A low-magnification (0.8X – 5X) stereoscopic microscope head is used to improve the field of view and depth of field, and a high-speed camera is used to increase the flow range that can be monitored. A set of experimental platforms is also constructed to produce bubbles and wear particles separately. Images of the wear particles and bubbles are then collected for subsequent training and verification of image classification algorithms. A motion object extraction algorithm based on background differences and the Otsu method is used to extract debris and bubble images, and a convolutional neural network (CNN) algorithm is used to distinguish between bubbles and debris. Compared with the traditional morphological feature extraction method, histogram of oriented gradient (HOG) feature extraction method, k-nearest neighbor (KNN) classification algorithm, and support vector machine (SVM) classification algorithm, the CNN algorithm eliminates the tedious process of feature extraction and selection, and has better classification results. The experimental results show that the system can effectively collect wear particle and bubble images and classify them, and the classification accuracy can reach 91.8%.

ULTRASONIC MEASUREMENT TECHNOLOGY IN AUTOMATED CONTROL OF WATER RESOURCES

Control of water resources is becoming an important strategic issue. That is why authorities set the goal for wa-ter agencies to manage the availability of water and create regulations to its rational use. The main point in water control is measurement. There are three important aspects of measurements of water resources: at water extraction from nature, at the consumption and at custody transfer. Control of water consumption sometimes is based not on measurements, but on preliminary estimation, for example, by pumping.&#x0D; Ultrasonic measurement technology as a key feature of automated control of resources has a potential role in this market. In contrast to mechanical (turbine) meters, ultrasonic meters have a priority because they also give a possibility to realize smart metering. In contrast to electromagnetic meters, which also measure with high accuracy and realize smart functions, ultrasonic meters much more suitable for rough water, wastewater and sewage. Such water resources are usually poorly controlled, which means that no one knows their exact cost.&#x0D; Measurement is mandatory to control cost and for billing. Accuracy is important issue, especially when we say about measurements in large pipe diameters. There is practically no alternative to ultrasonic flow meters. Market of diverse meters concentrated on diameters under 400 mm. For larger diameters, only ultrasonic meters are in use. They have many chords, difficult algorithms for data processing. Thus, they are applicable over a very wide flow range.&#x0D; In this paper, we discover transit-time ultrasonic flow meters to understand features of their measurement theory taking into account all factors affecting their work. This article describes errors inherent in these flowmeters during measurements.&#x0D; As far as accuracy is significantly important in billing, the cost of 1% measurement error in consumption of water resources for small (DN50÷DN150 mm) and large (DN200÷DN1200 mm) pipe diameters has been evaluated and analyzed. The losses from the installation of low-quality metering devices are demonstrated and discussed.