Composite Pipes Research Articles

Interface Microstructure and Mechanical Properties of Nickel/Steel Bimetal Composite Pipe Fabricated by Explosive Welding

In this paper, the microstructure and mechanical properties at the interface of Incoloy825/X65 bimetallic composite pipe achieved by explosive welding were systematically studied. Results show that a periodic wavy bonding interface was formed between the Incoloy825 and X65 due to the jets caused by the high-impact stresses during explosive welding, which was beneficial for improving the bonding strength of the Incoloy825 and X65. Atomic diffusion and localized melting occurred near the interface during explosive welding. Some fine crystal grains were generated in the vicinity of the interface due to the strong plastic deformation and dynamic recrystallization, whereas some elongated grains growing in the perpendicular direction to the interface were found in the wider localized melted zone. Room temperature nanoindentation test showed that due to the existence of fine grains resulting from the recrystallization at the interface, the hardness of the interface was higher than that of the base metals. Voids and defects were prone to appearing in the vortex regions near the interface, where the weak point in the interface was located.

Pitting corrosion resistance of tempered N08825 alloy in the inner layer of bimetallic composite pipe

Pitting corrosion resistance of N08825 alloy in the inner layer of bimetallic composite pipe SA210A/N08825 tempered at 570∼720 ℃ was investigated in NH4Cl solution by scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical measurement techniques. The M23C6 precipitates, observed at the grain boundaries of inner layer alloy 825, exhibit a temperature-dependent behavior during tempering at 570∼720 ℃. The quantity of M23C6 precipitates and the pitting corrosion resistance change with the tempering temperature. When the tempering temperature increases from 570 to 660 ℃, the quantity of M23C6 precipitates increases, with the pitting potential (Ep) decreasing from about 499 ± 8.6 to 354 ± 6.7 mVSCE, the passive current density (ip) increases from about 1.9 ± 0.2 to 2.45 ± 0.3 μA cm-2, and the average number of pits on the specimen surface rises from 3 to 7. Conversely, when the tempering temperature increases from 660 to 720 ℃, the quantity of M23C6 precipitates decreases, leading to the Ep increases from about 354 ± 6.7 to 394 ± 14.6 mVSCE, the ip decreases from about 2.45 ± 0.3 to 2.34 ± 0.4 μA cm-2, and the average number of pits on the specimen surface decreases from 7 to 6. There is a strong relationship between the M23C6 precipitates and the pitting corrosion resistance. As the quantity of M23C6 precipitates increases, it results in the expansion of Cr-depleted zones on the specimen surface, the rise of passive film defects, and a subsequent reduction in the pitting corrosion resistance of inner layer alloy 825.

Enhanced dynamical stability of rotating composite pipes conveying fluid by a smart piezoelectric design

Enhanced dynamical stability of rotating composite pipes conveying fluid by a smart piezoelectric design

An Analysis of the Flexural Stiffness and Horizontal Bearing Capacity of CFRP Composite Pipe Piles in Marine Environments

Carbon-fiber-reinforced polymer (CFRP) is a composite material consisting of a resin matrix reinforced with carbon fibers. This study focuses on CFRP composite pipe piles as the subject of investigation, exploring the impact of substituting steel bars with CFRP bars on the bending performance of pipe piles through rigorous three-point bending tests. The attenuation of flexural stiffness in CFRP pipe piles under a chloride salt environment was anticipated. The lateral bearing capacity of CFRP pipe piles was calculated by introducing a stiffness degradation coefficient for the piles and utilizing the finite difference method. The findings of the analysis suggest that as the CFRP reinforcement replacement rate increases, the initial bending stiffness of the composite pipe pile experiences a corresponding decrease. After serving for 28.15 years, the steel reinforcement within the pipe pile commences rusting, resulting in a nonlinear decline in the bending stiffness of the composite pipe pile. As the service time of pipe piles increases, a higher replacement rate of CFRP reinforcement results in a slower attenuation of pile stiffness. Consequently, both the horizontal displacement at the top of the pile and the bending moment along the body of the composite pipe pile gradually increase over time. During the same service period, the higher the rate of CFRP reinforcement, the less noticeable the attenuation in the horizontal bearing capacity of the pile shaft.

Fracture failure of oil-collecting steel wire reinforced thermoplastic composite pipe

A steel wire-reinforced thermoplastic composite pipe (SRTP) used as an oil connecting experienced fracture failure after 1.8 years’ service. In this paper, we conducted through on-site working condition investigation, visual physical inspection, analysis of the inner lining structure composition, physical and chemical properties analysis, thermal analysis, and mechanical analysis, and morphology analysis. The lining material of the SRTP exhibited significant swelling, which reduced its performance, and operation at high temperatures (>75°C) accelerated this process. Due to the swelling of oil and the permeation of CO2 and H2S, the oil and acid gases penetrated the interlayer of the composite pipe and accumulated in the annular space, continuously corroding and weakening the steel wire. This process gradually reduced its load-bearing capacity and pressure resistance. It is recommended that non-metallic pipes should be selected according to the service conditions to ensure that the materials are consistent with the design requirements.

Solvolysis and oxidative liquefaction of the end-of-life composite wastes as an element of the circular economy assumptions

In pursuit of sustainable development, recycling composite waste is a crucial challenge as well as an opportunity to support the progress towards eco-friendly materials management and circular economy practices. The current study brings together two modern recycling techniques solvolysis and oxidative liquefaction to recycle five types of composite waste materials including wind turbine blades (WTBs), composite pipes, personal protective equipment (PPEs) used in the medical sector, photovoltaic (PV) panels and municipal solid waste (MSW). Following a well-structured experimental design for each type of waste the solvolysis was performed at a temperature range of 100–190 °C, process time within the range of 1–3 h, and catalyst (TBD) concentration within the range of 0.015–0.025 mol, end with ethylene glycol and 1-methyl-2-pyrrolidinone in a 1:1 M ratio, while depending on the material evaluated, the oxidative liquefaction process was conducted at temperatures between 250 and 350 °C for WTB and between 200 and 300 °C for PPE, MSW, and PV. Oxidant concentrations, reaction time and pressure (15–45%, 30–90 min, 20–40 bar for WTBs, 30–60%, 45 min, 30 bar for remaining waste types) were studied in addition to highly variant waste-to-liquid ratio from 5 to 25% for WTB, 3–7% for PPE and MSW, and 12.5–37.5 for PV. Prior to experimental investigation, surface morphologies and chemical studies of the waste material were performed by scanning electron microscope (SEM) and Fourier transform infrared FT-IR spectroscopy, while after experimentation total polymer degradation (TPD) was calculated and liquid products were analysed through gas chromatography with flame ionisation detection (GC-FID). Following the solvolysis, 50–60% TPD was obtained, allowing for the recovery of glass fibres (GF) with average lengths of 50–60 mm and a maximum length of 650 mm. This allowed for the recovery of GFs with average lengths of 50–60 mm and a maximum length of 650 mm. In the case of oxidative liquefaction, total polymer degradation of 72–100%, 52–100% and 55–100% was achieved, depending on the investigated waste, i.e. WTB, PPE and MSW, respectively. The yield of oxygenated chemical compounds depended upon the types and composition of waste, but acetic acid was the main acid while WTB, PPE, and MSW, the liquid samples contained phenol also. Involved chemistry and possible degradation pathways of complex composite wastes are discussed in detail to enhance the recycling process and material recovery.

Research on the impact mechanism and parameter optimization of RTP structure layer fusion process

Fiber-reinforced thermoplastic composite pipes (RTP) possess a complex multilayer structure. Apart from the melting process of the reinforced layer, the melting process between the inner and outer layers and the reinforced layer is equally crucial. Factors such as heating time, heating temperature, and pipe diameter significantly influence the degree of tight bonding between these layers. The purpose of this study is to investigate the influence mechanism of the fusion process between the three main layers of RTP and to perform parameter optimization analysis. First, Box-Behnken response surface method and finite element analysis were used to obtain the softened layer thickness under different parameters and to couple the influence mechanism of process parameters on the softened layer thickness. Then, single parameter sensitivity analysis was used to reveal the influence mechanism of each parameter change on the softened layer thickness of the pipe, and then the coupling analysis of the process parameters was carried out. The analysis results show that the softened layer thickness is most sensitive to the change of heating temperature, followed by heating time and pipe diameter. Finally, the optimal parameter combination was obtained through the expected function method, and experiments were conducted on finished pipes.

A Novel Investigation on Microstructural Analysis of a Rupture GRE Composite Pipe for Underground Fire Water System

This study investigates how underground fire water systems using Glass Reinforced Epoxy (GRE) pipes are affected by aging. Over time, GRE pipes can degrade, potentially reducing their expected lifespan. The study compared damaged and undamaged areas of pipes to assess how damage impacts their structural integrity. Microscopic and chemical analyses (SEM and EDX) were performed on pipe samples from different locations of the pipe. Mechanical testing (following ASTM standards) was conducted beforehand. Analyses revealed that as damage increased (closer to damaged area), the levels of carbon (C) and oxygen (O) changed significantly with the weight percentage exposed 45.62% difference and 11.62% difference, respectively, as compared with the undamaged area. This suggests that the epoxy resin degrades with age, releasing these elements. Additionally, the presence of foreign objects around the pipes can affect how they bear loads. These findings highlight the importance of understanding how aging and surrounding conditions can influence the performance of GRE pipes in real-world fire water systems.

Design of explosively welded Fe–Al multilayer laminated composite pipes: A critical microscopy analysis of stand-off distance and post-weld heat treatment effects on interface properties

This study examined the microstructure and mechanical properties of explosively welded (EXW) Fe–Al multilayer laminated composite pipes, specifically SS321/AA1050/AA5083, with varying stand-off distances (SD) and post-weld heat treatments (PWHT). Findings revealed that higher collision forces at higher-SD produced a wavy interface with finer grains at the AA1050/AA5083 interface. In contrast, lower-SD yielded a smooth, flat interface. At the SS321/AA1050 interface, collision energy resulted in the formation of an uneven composite reaction layer comprising multiple intermetallics. Analysis of the SS321/AA1050 interface revealed that an increase in the PWHT temperature results in diffusion toward the reaction layer, transforming the unevenly Al-rich and Fe-rich phases into a uniform Al85(Fe,Cr,Ni)15 solid solution. The increase in the fraction of this phase made the reaction layer more brittle. At the AA1050/AA5083 interface, PWHT at higher temperatures caused a significant hardness decline extending further from the interface in samples with higher-SD. On the SS321 side of the laminated composite, higher SD resulted in higher kernel average misorientation (KAM) and increased hardness. Despite a decrease in hardness after PWHT at 350 °C, the hardness gradient from the matrix to the interface in laminates with higher SD remained relatively unaffected, whereas the lower SD counterparts experienced a noticeable stress relief.

Internal Corrosion Control Strategy of Oil Gathering and Transportation Pipeline

Abstract Internal corrosion and perforation of metal pipelines is the main reason for failure of gathering and transportation pipelines in a western oil field. The content of Cl-in the transport medium of the oilfield is between 24910-118051mg/l, the total salinity is between 65404-39363mg/l, the reduced sulfur content is between 6-36mg/l, and the number of SRBS is between 20-300 /ml, which are the main factors leading to corrosion in the pipeline. Through investigation, demonstration and field test, the internal corrosion control technology system of pipeline has been formed, which includes internal extrusion coating, internal penetration, 32MPa high pressure flexible composite pipe, polyethylene lined FRP composite pipe technology. The internal corrosion control strategy has been popularized in oil field, and the effect is good.

Optimization of Welding Process for 825 Bimetallic Composite Pipes Based on Corrosion Testing

Abstract In the process of welding bimetallic composite pipe ring joints, a problem arises where the outer layer of carbon steel dilutes the inner corrosion-resistant alloy lining, resulting in a reduction in corrosion resistance. Therefore, selecting the appropriate welding process and parameters is crucial. This study established manual, semi-automatic, and fully automatic welding processes for welding 825 bimetallic composite pipes, conducted simulated corrosion tests on weld joint ring seams under sulfur-containing conditions, and performed comprehensive evaluations of physical and chemical properties, as well as corrosion resistance. The research findings are as follows: (1) There is a phenomenon of softening in the heat-affected zone of bimetallic composite pipe ring seams. Among them, the fully automatic welding method exhibits significant fluctuations in weld joint strength, higher toughness in the weld and heat-affected zone, and higher hardness values with less variation compared to other welding methods. (2) Under the manual, semi-automatic, and automatic welding processes, the intergranular corrosion rates are 1.08 mm/a, 1.64 mm/a, and 1.11 mm/a, respectively, and the pitting corrosion rates are 0.41 g/m2, 0.25 g/m2, and 0.31 g/m2, respectively. The uniform corrosion rates are 0.0002305 mm/a, 0.0002183 mm/a, and 0.0002197 mm/a, respectively. (3) High-temperature solution heat treatment (above 980 ° C for 30 minutes) can effectively promote the dissolution of carbides into the matrix, improving the intergranular corrosion resistance of alloy 825. The research demonstrates that under sulfur-containing conditions, weld joints obtained using the fully automatic welding process developed in this study exhibit better physical characteristics and corrosion resistance. This can effectively prevent corrosion failures and leakage incidents.

Research and Application of Flexible Fracturing Manifold in Volumetric fracturing

Abstract In order to solve the problems of high pressure pipe valves in Volumetrictric fracturing, such as large demand of high pressure pipe and valve parts, high pressure manifold for fracturing complex connection, fracturing pipeline connections are complex, long fracturing construction preparation period. The economy and timeliness of pipeline connection seriously affect the speed and efficiency of Volumetrictric fracturing operations. This paper designed and developed the high pressure flexible composite pipe and carried out its performance evaluation test. Combined with Volumetrictric fracturing operation conditions, supporting functional modular manifold system, overcome flexible pipeline and rigid pipeline fast connection technology, flexible fracturing manifold system was formed. Through the large-scale field application in the unconventional reservoir Volumetric fracturing field, The flexible fracturing manifold is compared with the conventional high-pressure pipe valve connection and the single pipe universal connection, the flexible fracturing manifold can reduce the use of high-pressure pipe valves by 1/3, increase the efficiency of fracturing manifold connection by 50%, and reduce the labor intensity by 50%, enables efficient, reduce high pressure manifold connection points by 70%. The timeliness and safety of fracturing manifold connections have been greatly improved. Flexible fracturing manifold fundamentally change the connection mode of Volumetrictric fracturing high-pressure manifold, and realizes the speed and efficiency of reservoir transformation.

The effect of coordinated deformation on the microstructure and corrosion performance of 316L stainless steel/20# carbon steel composite pipes during hot compression

Through hot compression experiments under different deformation conditions (0.1 s−1 at 900 °C/1050 °C/1200 °C), the effect of coordinated deformation on microstructure evolution was studied, and the influence of different initial microstructures on corrosion performance was subsequently investigated. As a result, strain preferentially concentrated in 20#, resulting in dynamic recrystallization (DRX). Subsequently, grain refinement and DRX occurred in 316L. Additionally, the farther from the interface, the weaker the coordinated deformation effect. Compared to only 316L, the 316L in composite pipes has higher density of dislocations and low-angle grain boundaries. Corrosion resistance is related to the microstructure after coordinated deformation, decreasing with the increase in dislocation density, low-angle grain boundaries, and recrystallized grain size. At 1200 °C, the effect of coordinated deformation on 316L is significantly reduced. The passivation film resistance is 2.14 × 106 Ω·cm2, similar to that of only 316L. Therefore, appropriately increasing the hot rolling temperature and the thickness of 316L in the billet can reduce the effect of coordinated deformation on the DRX of 316L, thereby maintaining the pitting corrosion resistance of 316L.

Design and Calculation of Products from Composite Materials Using Software

This article analyzes six types of composite pipes that are good replacements for corrosive steel and metal pipes for oil, gas, and water. The analysis of the six samples of composite pipes was done using the software program Hoffman Engineering, which is intended for the design and calculation of various types of products made of composite materials. For the analysis of the six composite pipes, the same diameter and the same length were taken, and variable parameters are: the type of material from which the composite pipes are made (carbon/epoxy, carbon-glass/epoxy and glass/epoxy), and the angle of winding of the fibers (10º and 90º degrees). Using the Hoffman Engineering software package, an analysis of the durability of the six differently designed composite pipes at high internal pressure was performed. The same conclusion was obtained from all analyses: the high internal pressure resistance of composite pipes is highly dependent on the fiber winding angle and the type of fibers used. Composite pipes obtained with a fiber winding angle of 90º have twice the internal pressure resistance compared to composite pipes obtained with a fiber winding angle of 10º. Composite pipes based on carbon fibers have the highest resistance to internal pressure, then composite pipes based on hybrid materials (glass and carbon fibers) and finally composite pipes based on glass fibers. Finally, a comparison was made with the obtained laboratory results for the same composite pipes. The same conclusion was obtained from all analyses: the high internal pressure resistance of composite pipes is highly dependent on the fiber winding angle and the type of fibers used. The composite pipes obtained by this process are durable and resistant to very high pressures.

Frequency-domain axisymmetric and thermomechanical viscoelastic analysis of thermoplastic composite pipe

ABSTRACT Thermoplastic composite pipe (TCP), composed of polymers and composite laminates, shows significant potential for deep-water offshore oil field development due to its lightweight and high strength. However, current mechanical studies primarily focus on the elastic domain, ignoring the critical viscoelasticity of non-metallic materials. To solve this, we introduce a comprehensive theoretical model that incorporates viscoelastic properties under both axisymmetric and thermal loads, considering radial convective thermal gradients and axial heat conduction. This model accurately predicts TCP's mechanical behavior by using stiffness coefficients, differential geometry, and radial-axial temperature transfer curves. By applying the principle of elastic-viscoelastic correspondence, we obtain viscoelastic solutions in the frequency domain, showing strong agreement with Finite Element (FE) models particularly under cyclic loading. Viscoelasticity introduces larger equivalent axial stiffness and viscoelastic damping within complex structures, which become more obvious with temperature fluctuations.

Experimental investigation of material properties of GFRP pipe for numerical simulation of novel nuclear power plant cooling water intake system

The cooling systems of nuclear power plants are typically made of reinforced concrete water intake structures and special steel pipes, making them large, important structures that necessitate very expensive special productions. In the scope of this research, an innovative design for 4-meter diameter GFRP composite pipes used in nuclear power plant cooling systems was developed using the circular wrapping method. The composite GFRP pipe used in the study has a substantial embedment depth. For this reason, an innovative design was created using unique stiffening rings, and the impact of these rings on the overall behavior was investigated. The nonlinear numerical analysis model of the nuclear power station cooling system, which consists of three pipes with a diameter of 4 m, was then created with ANSYS finite element software using the determined material models, and the results were interpreted. As a result of the study, a composite GFRP pipe design that can be used as a cooling system in significant structures like nuclear power plants has been developed.

Parameter analysis and prediction of crack propagation for thermoplastic composite pipes under lateral pressure

ABSTRACT The research investigates the process of crack propagation in thermoplastic composite pipes (TCPs) with initial racks subjected to lateral pressure, through a combination of numerical simulations and experimental studies. In the numerical analysis, a TCP is subjected to lateral pressure, considering parameters such as initial crack length, initial crack angle, and lateral displacement. This analysis employs the extended finite element method (XFEM). The results reveal that crack propagation predominantly occurs perpendicular to the fibre winding angle. Moreover, it is observed that longer initial cracks result in lower crack initiation loads, while the final extent of crack propagation increases with the initial crack length. The experimental study considers three distinct initial crack angles and verifies the conclusions drawn from the numerical simulations. Furthermore, a crack propagation prediction model is developed that combines particle swarm optimization (PSO) with backpropagation (BP) neural networks. The predictive results demonstrate a high level of accuracy.

Theoretical and FEA investigation of the mechanical behaviour for offshore LCO2 floating hose

Injecting liquid CO2 (LCO2) into the seabed for storage utilizing an offshore platform to achieve offshore storage of CO2 is one of the effective measures to realize the reduction of CO2 emissions. To solve the difference in motion characteristics between the LCO2 carrier and the receiving platform due to wind and wave currents, floating hoses can be employed as the pipeline in the CO2 transportation. In this study, an LCO2 floating hose based on the structural form of steel wire reinforced thermoplastic composite pipe is proposed. A mechanical model for this hose is developed to analyze the tensile mechanical properties. It is verified that the method is reliable by comparing with the published experimental results of composite hose containing 4 layers of aramid fiber reinforced layers with a maximum error of 11.48%. A comparative analysis was also carried out by finite element analysis (FEA) with a maximum error of 10.67%. On this basis, the damage states of the hose under internal pressure, tension, bending and torsion load were investigated to analyze mechanical properties. The ultimate tensile load capacity, ultimate bending radius and ultimate unit torsion angle are 463 kN, 1.64m and 14°/m, respectively. The components most prone to failure under different loads were clarified. This study can provide technical reference for the design of floating hoses for offshore LCO2 storage and transportation.

Electrodeposition transition layer induced Cu/PPr hybrids

The high-performance metal-plastic hybrids have been widely applied in lightweight manufacturing. In this work, microstructures were prepared on the copper plate (Cu) surface using an electrodeposition process. Afterward, this microstructure was used to join with the pentatricopeptide repeats (PPr) to obtain Cu/PPr hybrids. The effect of electrodeposition process parameters on surface morphology was explored. The polyacrylic acid (PAA) content had the most significant effect on the surface morphology, and an increase in PAA content resulted in a shift from a lamellar to a granular structure. When the PAA content was 5 g/L, electrodeposition time was 300 s and the current density was 25 mA/cm2, the transition layer on the Cu surface was optimized, the roughness reached 164 nm, and the contact angle decreased to 2.41°. Meanwhile, the effect of molding temperature on the strength of the hybrids was explored, and the joining strength of the hybrids reached a maximum of 13.45 MPa when the temperature was 270 °C, which is 73.5 % of the strength of the PPr matrix. Further elevation of the molding temperature failed in the transition layer due to oxidation. The joining strength of the hybrids relies solely on the mechanical interlocking ability of the interface. The Cu/PPr hybrids provide design ideas for the practical production of copper-plastic composite pipes.

Analytical approach for lateral dynamic responses of offshore wind turbines supported by cement-soil composite steel pipe pile embedded in gassy marine sediment layer

This study aims to clarify and gain an insight into the lateral dynamic response of offshore wind turbines (OWTs) supported by cement-soil composite steel (CCS) pipe pile embedded in gassy marine sediment layer by developing an analytical approach. In the proposed approach, the CCS pipe pile-supported OWT system is divided into three parts including the tower part, the seawater-immersed steel pipe pile part, and the embedded CCS pipe pile part. The lateral dynamic behaviours of the CCS pipe pile-supported OWT system have been determined and then validated by solving the analytical solution of lateral displacement for the above three parts. Numerical discussions are finally conducted to analysis the influence of some physical parameters on the lateral displacement and the first-order natural frequency of the CCS pipe pile-supported OWT system. The main findings can be summarized as: (i) the offshore deep cement-soil mixing (ODCM) pile is an effective reinforcement method to reduce the lateral vibration of conventional steel pipe pile-supported OWTs; (ii) the increase in tower height and seawater layer thickness will have a serious negative impact on the lateral dynamic response of CCS pipe pile-supported OWTs; (iii) the increase in gas saturation of gassy marine soil will lead to a negative influence on the maximum lateral displacement of CCS pipe pile-supported OWTs.