FRP Pipe Research Articles

An Experimental Study on the Force Characteristics and Stability of an FRP Pipe Floating in Mud

Based on the occurrence of floating and fracture accidents of FRP pipes on muddy seabeds in practical engineering combined with the water intake and drainage project of the 2 × 660 MW coal-fired power plant in the second phase along the coast of Vietnam, a model test study was carried out. The laboratory simulated the FRP pipe conditions during the construction and operation periods by configuring different densities of silt. The experiment results obtained are as follows: the FRP pipes floated up in the mud during the construction period; the thickness of sediment deposition when the FRP pipes are lifted up, as well as the entire lifting process time and maximum force, are all within 2 h and 70 kN/m; after adopting a cover layer design section during the operation period, the FRP pipes in the silt remain stable while obtaining a maximum force of 15 kN/m; and based on the experimental results, an empirical formula for the stress on FRP pipes and was derived and measures for FRP pipe stability were proposed. The research results not only solve practical problems in water intake and drainage engineering but also provide technical support for the promotion and application of FRP pipes.

Compressive model and numerical simulation analysis of a low-weight and high-strength structure combined with a buoyancy material and FRP

ABSTRACT The requirements of low weight and high strength are often contradictory in the design and production of manned/unmanned submersibles. In this paper, a novel structure that combines fiber-reinforced composites and buoyancy materials was proposed to solve this contradiction. These two materials in this structure can cooperate and obtain good compressive properties and low densities. A theoretical model of the compressive strength of this combined structure is proposed. Compression experiments were carried out on six groups of samples. The experimental results show that the compressive capacity of the combined structure is greater than the sum of the compressive capacity of buoyancy material and FRP pipe. The stress distribution of the combined structure under uniaxial pressure is simulated through a finite element model. The numerical simulation results and theoretical predictions show good agreement with the experimental data.

Nonlinear analysis of axial-compressed corroded circular steel pipes reinforced by FRP-casing grouting

In this paper, ABAQUS software is used to carry out finite element simulation on the axial compression performance of corroded round steel pipe members reinforced by FRP casing grouting. Moreover, its working mechanism and failure mode are analyzed. A typical load-displacement curve of the component is obtained. Furthermore, the effect of FRP pipe thickness, grouting thickness, corrosion rate, concrete strength, and slenderness ratio on the mechanical performance of the component is explored. The research results indicate that the component load-displacement curve can be characterized by bilinear and trilinear models. The former corresponds to the overall buckling failure mode, while the latter corresponds to the strength failure mode for the bare ends of a round steel tube. After reinforcement, the component bearing capacity increases up to 166.83%. Moreover, the increase is positively correlated with FRP pipe thickness, grouting thickness, and corrosion rate. The component bearing capacity first decreases and then increases when modifying the slenderness ratio, while concrete strength has a minor effect on it. Moreover, the bending stiffness ratio equation and the stability bearing capacity correction equation of the axial compression reinforced components are proposed. The aforementioned provides reference suggestions for practical engineering applications of corroded steel structures reinforced by FRP casing grouting.

Energy Dissipation Analysis of FRP Concrete Steel Tube under Multiple Impact

In order to study the effects of wall thickness and impact times on the splitting tensile properties of FRP pipe concrete steel pipe, the dynamic impact test of FRP pipe concrete steel pipe is carried out by using the separated Hopkinson compression bar system with a diameter of 74mm. By changing the wall thickness and impact times, the variation laws of FRP concrete dynamic characteristics under different conditions are analyzed. The test results show that the increase of FRP pipe thickness greatly improves the load resistance of the specimen, the increase of FRP pipe thickness greatly improves the toughness and fatigue resistance of the specimen, and the energy absorption capacity of FRP pipe material is better than that of concrete; In terms of failure mode, the increase of FRP pipe thickness significantly enhances the protection ability of the specimen.

Study on the Lateral Impact Behavior of FRP-concrete-steel Tube Composite Structure

In this test, a 74mm diameter split type get-a-purkinson test device was used to impact the specimen. The relationship between the peak stress and the number of impacts, the air pressure and the thickness of FRP tube was studied by using the control variable method.The test results show that:Under the same air pressure, the elastic modulus of the specimen increases first and then decreases, and the peak stress decreases after the first impact, and then stays stable.The peak value of stress increases with the increase of air pressure. The increase of air pressure has a linear relationship with the peak value of stress.With the increase of FRP pipe thickness, the stress peak value will change greatly, and the stress peak value will increase more and more quickly with the increase of FRP pipe thickness.

Analytical calculation method for the axial equivalent elastic modulus of laminated FRP pipes based on three dimensional stress state

In engineering design, the axial equivalent elastic modulus of laminated FRP pipe was mostly calculated by the average elastic modulus method or the classical laminated plate theory method, which are based on relatively simplified assumptions, and may be not accurate enough sometimes. A new analytical calculation method for the axial equivalent elastic modulus of laminated FRP pipe was established based on three-dimensional stress state. By comparing the results calculated by this method with those by the above two traditional analytical methods and the finite element method, it is found that this method for the axial equivalent elastic modulus fits well not only for thin-walled pipes with orthotropic layers, but also for thick-walled pipes with arbitrary layers. Besides, the influence of the layer stacking on the axial equivalent elastic modulus was studied with this method. It is found that a proper content of circumferential layer is beneficial for improving the axial equivalent elastic modulus of the laminated FRP pipe with oblique layers, and then can reduce its material quantity under the premise that its axial stiffness remains unchanged. Finally, the meso-mechanical mechanism of this effect was analyzed. The improving effect of circumferential layer on the axial equivalent elastic modulus of the laminated FRP pipe with oblique layers is mainly because that, the circumferential fibers can restrain the rigid body rotations of the oblique fibers, which tend to cause the significant deformations of the pipe wall units and the relatively low axial equivalent elastic modulus of the pipe.

Composite helical micro pile’s bearing capacity

It is proposed to use two options of piles’ bearing capacity calculation based on existing Russian codes. Calculation of pipe’s section for an axial load is proposed either. Results of these calculations are compared to the site tests made earlier. Comparison of test results with calculations makes clear that existing methods for helical piles calculation are too conservative. Calculated soil’s bearing strength is 6 times lower than test results. Calculation method of pipes’ FRP sections is proposed. Existing fiberglass section bears almost double of the soil’s capacity. Optimization is proposed. Research provides results of bearing strength installed to weak clay helical fiberglass micro pile. Pile was designed, produced and provided by Composite Group LLC. Pile is made with pultruded fiber reinforced polymer pipe and screw produced with cast iron. Screw is glued to the FRP pipe by epoxy. In addition rivets strengthen connection detail. This structure is stable for corrosion, ground electricity. FRP screw pile has small weight and high strength. All the benefits and disadvantages of the composite piles are described below.

Active SHM for composite pipes using piezoelectric sensors

Composite materials, in addition to the high specific mechanical properties, have properties enabling their applications in high-pressure, high-temperature (HPHT) and corrosive environment as occurs in deep water. Their use for manufacturing pipelines and offshore risers can provide relevant performance advantages over steel such as lower weight, improved fatigue capacity, corrosion resistance and higher strain limits. However, composite materials are more complex to use in design than metallic materials due to their anisotropic properties and lack of accurate failure prediction models. Thus, a continuous in-situ and in real-time Structural Health Monitoring (SHM) of composite components would be necessary and useful to promote their use in a wider range of operational conditions. In this work, an FRP pipe sample was instrumented with Piezoelectric Wafer Active Sensors (PWAS) used either as passive receivers or as transmitters of guided waves for active health monitoring in pitch-catch configuration. The propagation properties of guided waves in glass fibres reinforced composites were studied by developing MATLAB scripts, running FE simulation and experiments. The numerical and experimental signals were post-processed in MATLAB by Short Time Fourier Transform (STFT) in order to evaluate their frequency and time-frequency content. Furthermore, the guided waves were used to detect artificial defects imposed on the structure identifying their location. Several testcases were studied to find out the limitations and the most suitable conditions of using guided waves for defects monitoring in a composite pipe. The work proposes effective methods for pipe structural health evaluation by non-destructive techniques and ultrasonic guided waves.

Bursting Analysis Of GFRP Composite Pipline Used In Oil & Gas Applications

The goal of this trial study was to research the impacts of low speed effect stacking on the weight bearing limit of the E-Glass and Epoxy Composite Pipe. In this investigation we are looking at the Burst Test Results of both PVC Pipe and FRP Pipe. The examples were loaded up with water and exposed to blast test until particular spillage disappointment is watched.

The research of penetration testing in the FRP pipe applications

In this paper, for the first time will be introduced to the penetrant metal nondestructive testing technology in FRP pipe non-destructive testing, glass fiber reinforced plastic are verified through the SEM surface sine qua non of penetrant testing. Through the prefabricated crack, glass fiber reinforced plastic materials available to the nondestructive testing methods for crack detection. By penetrant testing of glass fiber reinforced plastic, partial fluorine polyethylene and rigid polyvinyl chloride (PVC) for inspection, to find obvious crack.

Evaluation of Compatibility with Steel Pipe and FRP Pipe for OCTG

Evaluation of Compatibility with Steel Pipe and FRP Pipe for OCTG

Finite Element Analysis of FRP-concrete-steel Tubular Short Columns under Axial Compression

In order to study constraints performance of FRP-concrete-steel double skin short columns, use non-linear finite element analysis software ABAQUS, by selecting the appropriate material constitutive relationship and cell type, use the method of numerical simulation for FRP-concrete-steel tube short columns, structural analysis show that the numerical results agree well with the experimental results. Discussion on stress-strain relationship of various factors. FRP tube thickness, core concrete strength, diameter-thick ratio, hollow rate on short columns under axial compression. The results showed that the confinement properties of the double-walled, core concrete stress-strain curves exhibit characteristics of two-stage ,pipe diameter thick ratio major influence of the first stage, the intensity level of FRP pipe layers and strength of concrete mainly affect the second stage. The study concluded provides a reference for the combination column in the future.

EPC method for delamination assessment of basalt FRP pipe: electrodes number effect

EPC method for delamination assessment of basalt FRP pipe: electrodes number effect

Vibration analysis of composite pipes using the finite element method with B-spline wavelets

A finite element formulation using the B-spline wavelets on the interval is developed for modeling the free vibrations of composite pipes. The composite FRP pipe element is treated as a beam element. The finite pipe element is constructed in the wavelet space and then transformed to the physical space. Detailed expressions of the mass and stiffness matrices are derived for the composite pipe using the B-spline scaling and wavelet functions. Both Euler-Bernoulli and Timoshenko beam theories are considered. The generalized eigenvalue problem is formulated and solved to obtain the modal characteristics of the composite pipe. The developed wavelet-based finite element discretization scheme utilizes significantly less elements compared to the conventional finite element method for modeling composite pipes. Numerical solutions are obtained to demonstrate the accuracy of the developed element, which is verified by comparisons with some available results in the literature.

Screw joint parts for high pressure-durable FRP pipes

Screw joint parts for high pressure-durable FRP pipes

Design Method of FRP Pipe for Oil Well Frontier

New technologies such as the centrifugal winding method and improved GPI screw joints have expanded the application performance and research results of fiberglass reinforced plastic pipes over their long-term development. This study describes a strength design method for new oil well pipes, which are required for untapping deep oil wells as existing oil and gas fields become depleted. The durability of these pipes must exceed 30 years. Here, we quantified the withstanding pressure (100 MPa), depth (7000 m), heat resistance (250°C) and the pH of the corrosion resistance (pH = 2). We also propose a strength design method that specifies new OCTGs for a global standard; namely, the Global Oil & Gas Pipe Institute (GPI) standard.

Centrifugal winding method of high pressure FRP pipes design method of oil-well pipes

Centrifugal winding method of high pressure FRP pipes design method of oil-well pipes

Design Method of FRP Pipe of GPI Standard

Design Method of FRP Pipe of GPI Standard

Friction Head Loss Calculation for the FRP Pipes of Inverted Siphon Project

The problem that the actual operation flow rate of inverted siphon in Xinjiang can not meet the need of the design requirement has always been discussed. After comparing Cole Brook - White Formula, Jain,A.K Formula and Hazen-Williams Formula, and taking FRP pipes as the research object, this paper attempts to make use of different formulas to calculate friction loss of inverted siphon, compare and analyze the calculation results with the measured data of years of operation. Finally, it is proved that Hazen-Williams formula has relatively higher accuracy in calculating head loss and the frictional coefficient of friction to different diameters has been obtained, which can offer reference to the inverted siphon’s engineering design of FRP pipes.

The Finite Element Analysis for Mechanical Properties of Reinforced FRP Pipe Concrete under Axial Compression - Discussing the Impact of Reinforcement Ratio, Concrete Strength

According to the basic idea of the finite element method, using the finite element software ANSYS to establish the finite element model of the reinforcement FRP pipe concrete under axial compression, introducing the unit selection in the process of building model ,based on the principle of meshing boundary conditions and constitutive relations selected; The significant degree of the model verified by compare with the test results. Analyzed by finite element reinforcement ratio, concrete strength and other factors on the mechanical properties of concrete under axial compression reinforcement FRP pipe, the analysis of the results shows: The increase of reinforcement ratio to improve the point load of the specimens and improve the composite column ultimate bearing capacity, but the reinforcement ratio increase will reduce the binding effect of the FRP pipe; The whole component be improved the strength of concrete can improve the ultimate bearing capacity, but it reduces the mechanical properties of the specimens.