Papers by Keyword: Pipe

Abstract: Roll forming pipes for hydrogen infrastructure poses particular challenges for process design, especially with regard to geometric accuracy and the avoidance of forming defects that could compromise the integrity of the pipelines. Geometric accuracy is crucial to ensure uniform pressure distribution within the pipe. Conventional trial-and-error approaches to developing roll flower designs are time-consuming and cost-intensive, especially when working with high-strength steel grades. This work presents an integrated methodology for roll forming of monolithic sheet by incorporating real-world machine stiffness and experimental anisotropy. A finite element model was developed for S235 and S355 steels, validated through three-point bending and Digital Image Correlation (DIC). While database-derived models (JMatPro) underestimated yield stress by up to 30%, the experimental model precisely predicted strain distributions (error < 2%). A central novelty is the integration of in-situ 3D laser scans of the roll forming mill under load, allowing the simulation to account for elastic machine deflection. This enables the prediction of process-induced residual stresses, which are critical for the long-term integrity of pipelines against hydrogen-induced cracking.

Abstract: The article deals with the simple two-dimensional axis-symmetric mechanical model of the technological system of the operation to distribute a steel pipe into a steel pipe grid is considered. The pressure amplitude during pulsed flaring and explosion welding of pipes with pipe grids is given. For solution under the Wilkins method, the pipe was divided into quadrilateral elements. Further, the deformed state was analyzed at a number of characteristic points located on the pipe outer surface and the bushing inner surface. The graph shows the radial displacements of points on the pipe surface in the initial period of time. The non-simultaneity of the collisions and the out-of-phase oscillations indicate bending and bending vibrations of the pipe. The dependence of the node displacements on the bushing inner surface in the radial direction on the deformation time and the dependence of the point radial velocity on the outer contact surface of the pipe on the deformation time are also shown. The dependence of the displacement speed of the points of the nodes located on the sleeve surface on time in the initial period of the process is given. The stressed condition of the system elements is characterized by the occurrence of stress waves generated by pipe being struck and spreading in the bushing and pipe. The process of pipe fastening is analyzed using the model of a flat deformed state. The co-deformation of a pipe and a pipe board with a hexagonal hole arrangement is considered for the case if a single pipe needs flaring inside the pipe grid.

Abstract: Fracture analysis of crack is very essential to ensure the reliability and avoid the catastrophic failure of engineering components and structures since most of the failures start from the crack which leads to loss of life and economy. In the present study, extended finite element method (XFEM) is used to simulate the axial surface crack in bi-material pipe. Bi-material consists of two dissimilar materials with distinct properties. In this study, bi-material pipe consists of inner pipe made of steel alloy and outer pipe made of ceramic. An axial semi elliptical part through crack at different location is used for 3D linear elastic fracture mechanics (LEFM) analysis of bi-material pipe. Bi-material pipe is subjected to internal pressure and stress intensity factor (SIF) is computed at different location of crack front of semi elliptical surface crack using virtual domain extension approach.

Abstract: This study dealt with the rotary draw bending method most used for tube bending and investigates how applied bending such as normal bending, using mandrels or pressing with booster have an effect on machining accuracy, focusing on dimensional defects due to springback and flat deformation to the transverse plane. The study used particle swarm optimization (PSO) algorithms to investigate the optimal machining conditions for improving the accuracy of dimension and shape of a bent part. The following findings were obtained: The springback during applied machining using a mandrel, or using a mandrel and booster together, is almost the same as during normal processing; The flattening near the center of the bend in applied processing using a mandrel, or a mandrel and booster together, decreases more than with normal processing at mandrel protrusion L ≥ 4 mm, and the maximum can be suppressed to approximately 0.15%; When the sum of the springback and the flattening is taken as the objective function and the minimum value is obtained, the optimal solution is around L = 7 mm.

Abstract: The current composite pipes such as E-glass have better properties compared to metallic pipes. However, these pipes are prone to failure during its service life. In contrast, natural fiber such as basalt fiber composite pipes has better mechanical characteristics compared to current composite pipes. Hoop tensile, longitudinal tensile and internal pressure loads were carried out through experimentally and numerically investigation on the basalt/epoxy and E-glass/epoxy pipe performance. The basalt/epoxy and E-glass/epoxy composite pipes have been manufactured with ±55^o winding angle using dry filament winding with impregnation of epoxy resin used Vacuum Infusion Process (VIP) technique and investigated. Basalt and E-glass composite pipes with winding angles of ±45^o, ±55^o, ±65^o, ±75^o were fabricated in order to assess the optimal winding angle which can resists the subjected loads. There were good agreement between numerical and experimental results have been recorded. For internal pressure test, the basalt pipes have more internal pressure carrying capacity more than E-glass by 2.41%. Through this investigation, can be concluded that the natural based fiber of basalt can be used as a suitable replacement than E-glass, has further advantages of being cheap, abundant, renewable and easily recyclable. The also possess high strength, excellent flexural stiffness to cost ratio and low thermal conductivity

Abstract: Welding is an important technology of joint in engineering structures. In addition to a residual stress influence to a quality of joint, an obstacle in welding analysis are complex phenomena including phase transformation, thermal cycle and microstructure kinetics. The influence appears in microstructure development, formation of defects and in transformation of metallurgy in a welded zone. This article experimentally defines thermal cycles and shows the results in study of peculiar properties of austenite decomposition kinetics when using the technology of laser-hybrid welding in combination with multiple arc automatic sub-merged welding. There defined the rates of cooling influencing the change of properties of welded joints from tube assortment steel of K60 strength class. We found that the result of impact of laser-hybrid welding process in a heat-affected zone is that the austenite decomposition in studied steels flows in martensite area generally. The hardness of seam metal and heat-affected zone of the studied steels is of range 350-360 HV, which increases a probability of crack-like, defects formation. We revealed the normative value of hardness, which can be provided if a metal cooling rate in laser-hybrid welding is about 20 °C/s.

Abstract: In this paper, there are presented theoretical fundamentals of a real-time health monitoring for a pipeline system. The calculation of the total stress is based on measuring of the real loadings in the form of time-varying strains in critical places of a pipeline system in its real operation. Presented unique deployment of the strain sensors allows to decompose the individual components of loading in cross-section including its vector´s characteristics. The presented monitoring system pursuing the dangerous operational states like an overloading, dangerous vibrations and the fatigue damage accumulation. Monitoring system provides the information about real state of the structure in-time and directly to an operator of service.

Abstract: The current cutting equipment and methods cannot meet the demand of offshore wind cut jacket. In order to solve this problem, we develop a new suit of offshore wind jacket intersecting line cutting equipment. In this paper, detailed structure and operating guide of the equipment have been presented. The characteristics and application range are also included. The new equipment is simple and practical.

Abstract: Metal pipes have a long history as fluid conduits, and are commonly joined with components such as elbows to form bent transport paths. However, with the increasing demands for economy and energy saving, pipes with reduced joints and thinner walls are desired. The number of joints can be reduced by a drawing and bending process that forms a bend section at any position in the pipe. However, this approach incurs problems such as wrinkling and flattening, especially under conditions of large bending angle, decreased bending radius, and thin pipe walls. In this research, applying vibrations to the mandrel was trialed as an approach for controlling the wrinkle depth and flattening. First, processing experiments were performed on thin walled pipes (wall thickness = 0.5 mm; outer diameter = 14 mm). The change of flattening and the number and depths of wrinkles were investigated in the presence and absence of vibrations. Next, simulations were performed using the commercial nonlinear finite element software. Through these simulations, the flatness and appearance of wrinkles were analyzed by modeling the behavior and distribution of stresses and strains in the processing process. The application of vibration to the mandrel appears to be a promising approach for controlling the wrinkling and flattening problems during pipe processing.

Abstract: In this study, a finite element analysis of the crack repair with composite wrap of circumferential through cracks in pipes subjected to bending moment is presented. Also, the evaluation of the long-term performance of composite repair systems has been addressed. The stress intensity factor is utilized as a fracture criterion. Finally, an attempt was made to provide industry with an overview of the current state of the art in composite repair technology and how the integrity of pipeline systems is being restored using composite materials. The obtained results show that the presence of the bonded composite repair reduces significantly the stress intensity factor, which can improve the residual fatigue life of the pipe. However, the main disadvantage of the technique of bonded composite repair in pipe is the impossibility to bond double sided composite wrap in order to equilibrate the stress transfer between the internal and external crack tip