Multilayer Pipes Research Articles

Decoupled Analysis of a Multi-Layer Flexible Pipeline Buried in Clay Subjected to Large Lateral Soil Displacement

Multilayered flexible subsea pipelines may experience significant lateral movements due to manmade and environmental geohazards. These pipelines incorporate several structural and protective layers to resist different loads, and may require additional protection such as trenching, rock placement, or burial. In practice, simplifications are considered due to the complexities and uncertainties involved in the multi-layer pipe structure and the surrounding soil, compromising the pipe structure or the soil behavior. These simplifications are applied either on the pipe by assuming a rigid section or on the soil by representing it as elastic springs, which may result in inaccuracies. This study proposes a decoupled methodology combining the Coupled Eulerian–Lagrangian (CEL) model for soil displacement with a small-strain finite element analysis of the flexible pipe. This approach aims to accurately capture cross-sectional deformations and local stresses due to soil movement while maintaining reasonable computational effort. A parametric analysis was conducted to assess the impact of several variables on failure risk. The deformed cross-section was then used for a collapse analysis to determine critical loads at maximum operational depth. The study showed that modeling parameters such as soil strength and internal diameter might significantly influence pipe failure and the risk of collapse.

Embedded passive guided wave tomography. Application to corrosion monitoring in multilayered pipes

Guided wave tomography techniques have been studied in the last decade to quantitatively image defects in waveguides such as plates or pipes. Recent developments based on the use of an autocalibration method, removing the need of a reference acquisition, enabled the absolute imaging of the structure and drastically reducing the sensitivity to environmental and operational conditions. Another interesting feat for the structural health monitoring (SHM) is the use of passive methods relying on the measurement of the ambient noise, related to the use of the structure and its environment, and signal processing based on a cross-correlation to recover signals equivalent to the ones measured when a sensor is emitting. Such system prevents from the need of cumbersome circuitry and energy consumption related to wave emission. It also enables the sole use of sensors that cannot emit waves or only with a poor actuation such as optical fiber sensors. A SHM system relying solely on Fiber Bragg Gratings (FBGs) in optical fibers can then be designed. Several FBGs can be enscribed in a single optical fibers, reducing further the size and weight of the system. The optical fibers being resistant to harsh environments such as extreme temperatures or ionizing environments and having a good integration capability, such a system meets the needs for an industrial application. This talk will hence show the principle of the passive guided wave tomography with embedded sensors in a structure. It will be exemplified in the case of a multi-layered structure, showing the possibility to apply this system in a large panel of cases.

Partnerships Crucial in Developing Nonmetallic Downhole Tubulars

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 23491, “Role of Ecosystem Partners To Make Nonmetallic Downhole Tubulars a Reality,” by Ahmed Aladawy, SPE, and Ameen Malkawi, SPE, Baker Hughes, and Omar El Shamy, SPE, Novel Non-Metallic Solutions. The paper has not been peer reviewed. Copyright 2024 International Petroleum Technology Conference. _ Nonmetallic (NM) downhole tubulars offer a longer lifetime than their steel counterparts while eliminating corrosion concerns and lowering total cost of ownership. Making them a reality, however, requires a rigorous ecosystem with multidisciplinary skill sets and technology expertise. The complete paper discusses the challenges that face the development of such tubulars starting from academia and research institutes to complement expertise and computer computational power and moving through to material suppliers and manufacturing facilities for pipe prototyping. NM Pipe Construction and Technology Status NM pipes also can include metallic elements, where a hybrid system of NM layers is incorporated into multilayered pipe structures that assume specific roles, similar to a metallic pressure armor layer in subsea flexible risers, jumpers, and flowlines. Another example is polymer-lined steel rigid pipes with glass-fiber reinforced epoxy (GRE), or a dual-layer thermoplastic-lined reinforced pipe (Fig. 1). Composite-based NM pipes can broadly be categorized into reinforced thermoplastic pipe (RTP) and reinforced thermoset pipe (RTR), with glass-fiber reinforced plastic pipe (GRP) and GRE considered a subset of RTR. RTP consists of thermoplastic matrices and layers that can soften after heating and can harden when cooled in a reversible process, thus having the potential to recycle. Because of the flexibility of thermoplastic polymer, RTP pipes up to hundreds of meters long can be spooled on reels and deployed through rigless operation, with reduced system cost and deployment time. This synopsis will concentrate, as does the complete paper, on RTP. RTP pipe design can be classified as unbonded, semibonded, or fully bonded. Essentially, three layers of constituents for RTP exist: the inner layer is a fluid barrier (liner), the second layer is a load-bearing component (reinforcement), and the outer layer is external protection (cover). Unbonded RTP pipe means that the layers are not heat-fused to one another during manufacturing and are free to move between layers. This type of RTP pipe usually is low to medium in pressure rating, especially with regard to collapse rating, but also is lower in manufacturing cost and is suitable in onshore applications for fluid transportation. To increase the pressure rating, semibonded RTP pipes can be considered if pipe thickness is a limitation. For offshore and downhole applications, however, where higher pressure and temperature ratings are required, fully bonded RTP pipes, more commonly known as thermoplastic composite pipes, are preferred to handle high burst and collapse-pressure requirements and more-consistent load transfer across the structure. All RTP types can be manufactured continuously into pipe lengths of hundreds of meters because of their flexibility, but fully bonded RTP may be limited to larger-bend radii than unbonded or semibonded RTP; consequently, a need exists to consider reel-size limitations or even carousels to wind long pipe lengths during manufacturing. Conversely, fully bonded RTP structures may be easier to model and analyze than unbonded pipe.

Effect of recycled material on failure by slow crack growth in multi-layer polyethylene pipes

Among polymer materials, high-density polyethylene (HDPE) is one of the most demanded polymers for packaging as well as in sectors with higher material requirements, such as the plastic pipe industry. The extensive use of HDPE means it is often present in municipal waste. Therefore, there is a high potential for reprocessing and exploring new applications for recycled HDPE, aiming for a circular economy. In the plastic pipe industry, recyclates have found practical use in non-pressure applications. However, the high structural and loading requirements do not allow using it for pressurized pipes yet. The presented study is focused on the possible utilization of recycled HDPE in pressurized pipes in the form of a layer in a multi-layer pipe with two protective layers made of virgin HDPE. The performance of the pipes is assessed based on numerical simulations, coupled with lifetime estimations. The lifetime assessment is based on linear elastic fracture mechanics using experimentally measured slow crack growth (SCG) rates in the virgin and recycled HDPE grades. Thanks to the numerical models, it was possible to describe damage by SCG of the multi-layer pipe as well as to find the dependency of the pipe performance on the thickness ratio and material properties of the layers.

IMPACT OF STRUCTURAL DEFECTS ON THE RELIABILITY OF POLYMER PIPES REINFORCED WITH METAL BELTS

Reinforced Thermoplastic Pipes (RTP; or Flexible Composite Pipes) are multilayered pipes that consist of inner, outer polymer shell and reinforcement layers. Although there are different types of reinforcement, due to widespread use in oil gathering systems in Russia, we consider steel strip reinforced pipes in this paper. While developing RTP manufacturers state constructive characteristics after conducting analytical analysis and experimental investigations. Final characteristics values are then published in technical regulations documents. Deviation from these values weaken strength of pipeline.As a result of conducted research it was shown that a thinning of a reinforcement strip by 0,1 mm leads to decrease in a burst pressure by 16 %. Similar effect on the pipe reliability has a deviation of the winding angle.

Assessment of the stressed-strained state of a reinforced transport pipe under the combined effect of ambient temperature and static loads

The object of this study is a reinforced three-layer transport pipe, which is subjected to the joint action of ambient temperature and static loading of the road subgrade soil. The analytical model for assessing the stressed-strained state of reinforced three-layer pipes, under the combined action of temperature and static loads, has been improved using the theory of elasticity. The stressed-strained state of the reinforced pipe was assessed taking into account the values of the joint action of temperature and loads from vehicles, the physical and mechanical parameters of structural materials, and the geometric parameters of the pipe. As a result of the calculation of the reinforced multilayer pipe, it was found that the maximum movements that occur on the outside of the defective pipe are 0.64 mm, the metal pipe – 0.75 mm, and in the concrete mortar (fine-grained concrete) – 0.69 mm. It was established that under the combined action of ambient temperature and static loads from the road subgrade soil, ring stresses are maximum. They are 151 MPa. Axial stresses are also high – 141 MPa. At the same time, the maximum radial stresses are the smallest – 37.4 MPa. It has been established that a small difference in displacements occurs on the contact of structural materials of the reinforced pipe. However, the magnitude of the stresses is high. The maximum difference in ring stresses was 73 MPa, while the difference in radial and axial stresses was up to 1.0 MPa. It has been established that to restore the bearing capacity of damaged reinforced concrete pipes, it is possible to use the repair technology by the method of "sleeving". It involves pulling a metal pipe into the middle of the layer damaged with concrete mortar remaining between the concrete defective and the new metal pipes.

Investigation of long-term rupture pressure in PEX-AL-PEX composite pipes

One of the most vital parameters in PE-X/Al/PE-X composite pipe production is the tolerated internal long-term hydrostatic pressure. Composite pipes rupture pressure depends not only on operating temperature and time but also on the layer's dimensions (inner polymer, outer polymer, and Aluminum layer), mechanical properties of layers, and welding types of the aluminum layer. In this research, the long-term life behavior of PEX multi-layer pipes until 1000 h was experimentally measured for different diameters and welding types. The hoop and radial stress of the pipe layers are calculated analytically, based on the classical elasticity theory. Also, by presented equations, the tolerable pressure of each layer can be defined as a function of long-term hydrostatic pressure, size, and mechanical properties of the Aluminum and Cross-linked Polyethylene layers in the pipe. The results show that the pressure bearing by the Aluminum layer is 84%–91% of pipe hydrostatic pressure. Meanwhile, the PE-X outer layer pressure bears less than 3% of the hydrostatic pressure, and the rest bears by the PE-X inner layer. The K coefficient is introduced as a pipe design parameter to show the relationship between the Aluminum tensile stress and the Aluminum layer hoop stress. In addition, by employing the Artificial Neural Network (ANN), the rupture pressure-time diagram for geometrical pipe parameters was predicted accurately with an acceptable fitting parameter R-squared more than 0.99.

Detecting and locating delamination defect in multilayer pipes using torsional guided wave

Detecting and locating delamination defect in multilayer pipes using torsional guided wave

Analytical solutions for multilayered pipes with temperature-dependent properties under non-uniform pressure and thermal load

In this study, we present an analytical method for multilayered pipes with temperature-dependent (T-D) properties under non-uniform pressure and thermal load based on thermoelasticity theory. We propose a slice model to obtain the temperature, displacement, and stress fields for the pipe. The results obtained using the proposed method were shown to be in good agreement with those produced using the finite element method and those reported in previous studies. Parametric studies were conducted to determine the effects of the surface temperature, T-D material properties, layer thickness ratio, and pressure distribution on the thermomechanical responses of a sandwich pipe. The results showed that the effects of the T-D material properties on the thermomechanical responses became more significant as the surface temperature increased. Finally, the proposed method was applied to the thermomechanical analysis of a coated steam dual pipe system. The results showed that hoop stress played a significant role in determining the structural safety of the system.

On Some Thermoelastic Problem of a Nonhomogeneous Long Pipe

The paper deals with the thermoelastic problem of a multilayered pipe subjected to normal loadings on its inner surface and temperature differences on its internal and external surfaces. Two types of nonhomogeneous pipe materials of pipe are considered: (1) a ring-layered composite composed of two repeated thermoelastic solids with varying thickness and (2) a functionally graded ring layer. The ring-layered pipe with periodic structure is investigated by using the homogenized model with microlocal parameters. A homogenization approach is proposed for the modelling of the FGM pipe. The analysis of obtained circumferential, radial and axial stress is presented in the form of figures and discussed in detail. It was shown that the proposed approach to the homogenization allows us to correctly calculate the averaged characteristics in the representative cell (the macro-characteristics) and also the characteristics dependent on the choice of the component in the representative cell (the micro-characteristics) for both microperiodic composites and functionally graded materials.

Modeling Large Diameter Industrial Pipe Insulation Performance

As previously presented, reducing industrial noise emission utilizing jacketed pipe insulation is critical to reducing noise in industrial spaces. The ISO 15665 standard defines a testing process for measurement of the acoustical performance of installed and jacketed pipe insulation systems. To provide a cost-effective method for evaluating various types of multilayered jacketed pipe insulation a model was developed. The model accurately estimates the performance of single, and multilayered, jacketed pipe insulation. Validating the use of the model to very large pipe diameters is highly desirable as the cost to test is significantly higher than testing the medium or small diameter pipe insulation. The estimated insertion loss result from the model is compared to validation testing results for large diameter jacketed pipe insulation are reported herein.

Simulation modeling of non-stationary thermophysical processes when monitoring the reliability of main oil pipelines in the Arctic

The use of modern complexes for calculating the designed pipeline systems and for predicting their behavior for a period of more than ten years is necessary in modern conditions of the constantly developing hydrocarbon market and the development of new northern territories for greater oil production. It will allow avoiding accidents and environmental disasters that have become more frequent in recent years due to the deterioration of existing equipment. The article presents a method for monitoring the main reliability parameters of underground oil pipelines, taking into account changes in soil foundations, mainly in the Arctic zone of the Russian Federation. An oil pipeline section is considered as an object for monitoring of heat engineering processes and their influence on the reliability of the system. We describe the main results of calculations of the oil pipeline section and simulate changes in soil foundations. We used a multilayer pipe with polyurethane foam insulation and coating for the calculations to improve the reliability characteristics. This pipe has showed the best results of modeling in comparison with the design pipe.

Development of multi-layered sewer pipe plug — 2nd report: Tensile strength of protective sheet bonded by seams

Since Japanese sewer system is becoming obsolete, it is necessary to reinforce and repair the system without stopping sewer functions. In this study, a multi-layered sewer pipe plug consisting of a protective sheet and inner and outer rubber balls is focused to be installed and removed conveniently at the construction site. In this paper, a suitable testing method and the strength of the protective sheet are discussed experimentally by changing the specimen geometry providing slit and seams. It is found that the slit specimen is most desirable to obtain the standard tensile strength of UHMWPE cloth named Izanas cloth. It is found that the seamed strength is [Formula: see text] MPa, which is about 17% of the standard tensile strength [Formula: see text] MPa.

Development of multi-layered sewer pipe plug — 1st report: Ruptured test and stress analysis of protective sheet

In recent years, the sewer system in Japan is becoming obsolete. It is, therefore, necessary to reinforce or repair without stopping sewer functions by applying a suitable water stopping method. In this study, a multi-layered sewer pipe plug consisting of a protective sheet and inner and outer rubber balls is focused since it can be installed and removed at the construction site in a short time conveniently. This sewer pipe plug has several advantages dealing with various diameters compared to the conventional type. In this study, the rupture test is conducted to improve the water stopping performance. The fractured position of the protective sheet of the sewer pipe plug is investigated experimentally. It is clarified that the maximum stress around the flange portion can be reduced by decreasing the flange inner diameter.

Development of multi-layered sewer pipe plug — 3rd report: Tensile strength of protective sheet bonded by adhesive

Since the sewer system in Japan is becoming obsolete, it is, therefore necessary to reinforce or repair without stopping sewer functions by applying a suitable water stopping method. In this study, a multi-layered sewer pipe plug consisting of a protective sheet and inner and outer rubber balls is focused since it can be installed and removed at the construction site in a short time conveniently. Four types of adhesively bonded structures are investigated experimentally by changing bonding processes and adhesives. It is found that the main and base adhesive joint is the most suitable since the pressurized adhesive strength [Formula: see text] MPa is 30% of the standard tensile strength of the protective sheet [Formula: see text] MPa.

Prompt Determination of the Mechanical Properties of Industrial Polypropylene Sandwich Pipes.

A simple and prompt method to determine the mechanical properties of industrial multilayer extrusion polypropylene pipes for a gravity sewer network is suggested. The engineering formulas included for calculating the permissible thickness and relative position of a foam core in the pipes are based on a linear-elastic approximation and the rule of mixtures. The applicability of the approximation was justified experimentally during investigation of the effective tensile characteristics of single- and multilayer pipes and each layer specimen by using traditional tests and finite-element calculations. The results obtained were used to formulate engineering recommendations for calculations of this type.

Influence of Cement Return Height on the Wellhead Uplift in Deep-Water High-Pressure-High-Temperature Wells.

In oil and gas production in deep-water high-pressure–high-temperature (HP–HT) wells, wellhead uplift may cause the seal failure of wellbore integrity. Aiming at the oil and gas production stage in deep-water HP–HT wells, we considered the influence of cement sheath cementation and developed a model for calculating the height of wellhead uplifts, and simulation experiments for wellhead uplifts were carried out under the condition of the double pipe string at different cement return heights and multilayer pipe string coupling cementing and noncementing based on a self-developed HP–HT wellhead uplift simulation device. The results show that the elongation of the double pipe string under the condition of a cement return height of 100% is reduced significantly compared with that under the condition of a cement return height of 50%. Also, the maximum elongation of the multilayer pipe string under the condition of coupling and cementing is significantly reduced compared with that under the condition of noncementing. These show that cement sealing has a binding effect on wellhead uplifts. The error between the calculated and the experimental results is less than 10%; thus, the model can be used to predict the wellhead uplift height under different working conditions and provide technical guidance for designing scientific measures to prevent wellhead uplifts.

Real-Time Predictive Temperature Measurement in Oil Pipeline: Modeling and Implementation on Embedded Wireless Sensing Devices

In pipeline management, the advent of Internet of Things (IoT) technology enables effective pipeline maintenance with the deployment of embedded sensing units, the basic requirement of which is to make accurate and real-time measurement. Practically, it is impossible to directly measure the internal temperature of the pipe by laying conventional sensors in the oil. This work proposed a novel indirect testing framework to perform real-time and accurate temperature monitoring in oil pipes by solving the inverse problem based on pipe wall's temperature field. The contribution includes three aspects: 1) A rigorous theory was developed to validate the principle of equivalence for heat transfer in pipes. A single-layer boundary-equivalent diffusion model with effective thermal parameters exhibited excellent performance in predicting temperature change in a multilayer structure by simulation. 2) We established a microprocessor-enabled predictive temperature measurement modality to precisely determine the time-dependent temperature evolution in a multilayer composite pipe based on explicit analytical expressions. 3) The correctness and applicability of the modality were verified experimentally on a real oil pipe and a commercial device. The results show that precision of the predictive measurement modality reaches 0.3 K and 0.002 K/s for stable and linear-rising internal fluid temperature, respectively.

Propagation characteristic of axial and circumferential interface waves and detection of the interlaminar defect in multilayered pipes

This paper focuses on the dispersion characteristic of interface waves and the detection of interlaminar defects in multilayered pipes. The interface waves propagating along axial and circumferential directions are simplified as strain problems of planes (r, z) and (r, θ), respectively. The axial interface wave is well suited to axial localization of the defect, just as the circumferential interface wave is to circumferential localization. The dispersion curves and wave structures in generalized forms are built based on double- and treble-layered examples. Both interface waves converge to the Stoneley wave velocity at high frequency, while energy is concentrated on the interface. An experimental system is built. Theoretical and experimental group velocities are compared. The results indicate that the average relative errors of these two interface waves are 0.47% and 0.53%, respectively. An interlaminar crack is detected effectively both in axial and circumferential directions, revealing that interface waves hold great potential for non-destructive evaluation.

Exact solution for infinite multilayer pipe bonded by viscoelastic adhesive under non-uniform load

An analytical solution is presented for an infinite multilayer pipe bonded by viscoelastic interlayer subjected to racial loads non-uniformly distributed along the circumferential direction in order to investigate its time-dependent behavior. The elasticity equations in the polar coordinate are used to describe the stresses and displacements in each pipe layer. The viscoelastic property of the interlayer is modeled by the standard linear solid model considering the strain memory effect. By means of the Fourier series expansion method, the general solution of stresses and displacements is derived out with unknown coefficients, which are further determined by using the analytical Laplace transformation method. The present solution obtained can be used as the benchmark to validate other solutions such as finite element solution for the same problem. The comparison study shows a trend of the finite element solution converging to the present one as the mesh becomes refined; however, such a finite element model is time-consuming. The influences of load distribution, geometry and material parameters on the time-dependent stress and displacement fields in the pipe are discussed detailedly.