Pipe Material Properties Research Articles

Probabilistic assessments of running ductile fractures in dense-phase and supercritical CO2 pipelines

Running ductile fracture (RDF) is a severe failure mode of high-pressure pipelines. Dense-phase and supercritical CO2 pipelines are particularly susceptible to RDF due to the unique characteristics of the depressurization process resulting from a fracture of the pipeline. The present study carries out probabilistic analyses of RDF in dense-phase and supercritical CO2 pipelines. The well-known Battelle two-curve method is employed to establish the limit state function for RDF by comparing the arrest pressure with the saturation pressure. The arrest pressure is computed using the Battelle through-wall crack model with the adjustment recently proposed in the literature. The saturation pressure is computed based on the one-dimensional isentropic decompression assumption and a rigorous equation of state. The first-order reliability method is employed to evaluate the probabilities of RDF in hypothetical CO2 pipelines designed per DVN-RP-F104 with representative pipe attributes and initial operating conditions by considering uncertainties in the relevant pipe geometric and material properties. The analysis results indicate that the probability of RDF can vary by several orders of magnitude depending on the pipe attributes and initial operating conditions. Furthermore, the results shed light on the key uncertainties associated with the pipe geometric and material properties that influence the probability of RDF.

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.

BOILER SUPERHEATER PIPE FAILURE ANALYSIS THROUGH CORROSION RATE AND MECHANICAL PROPERTIES TESTING


 
 
 
 Superheater is a subcritical boiler component that functions to reheat saturated steam at constant working pressure so that it becomes saturated steam. This study aims to (1) analyze failures in superheaters, (2) test mechanical properties of superheater pipe materials, (3) calculate corrosion rates in superheater pipes with weight loss methods, (4) provide preventive maintenance solutions to minimize superheater pipe damage.
 The method used in this study is a qualitative approach with the type of experimental study. The method of failure analysis in this superheater pipe is by testing mechanical properties, calculating the corrosion rate of the superheater pipe and providing maintenance solutions.
 The results of this study are (1) the failure that occurs in this superheater pipe is the occurrence of corrosion and leakage, (2) after heat treatment with a temperature of 8500C on the superheater pipe material, the hardness value increases to 148 BHN, the impact value also increases to 43.26 joules and the phase that occurs in this material is ferrite and pearlite which shows the specimen is increasingly tenacious, (3) the corrosion rate that occurs in the superheater pipe is 0.0489 mmpy, (4) the workable maintenance solution is hardening to increase the durability and service life of the superheater pipe.
 
 Keywords: Superheater, Noise, Mechanical Properties, Heat treatment.
 
 
 

Internal flow effects in OTEC cold water pipe: Finite element modelling in frequency and time domain approaches

In this study, a Finite Element Model (FEM) was developed to analyse the stability of an Ocean Thermal Energy Conversion (OTEC) Cold Water Pipe (CWP). The general equation describing the pipe dynamics was adapted from a previous study and modified to consider the non-linear drag force. The flow field and change in the flow direction were imposed by varying the coefficient of the centrifugal force to 0, 0.5, and 1. The pipe material properties were varied using GFRP, PE, ABS, and HDPE. Pipe length was varied from 600 to 1000 m with a 100 m increment. Initially, the analysis was performed in the frequency domain, yielding Eigen frequencies in complex numbers. Subsequently, the analysis was conducted in the time domain using the Newmark time-scheme method to produce dynamic responses for each time increment. The critical fluid velocities obtained from the frequency-domain analysis were verified in the time domain. The results showed that the critical velocities obtained from the frequency- and time-domain analyses were in good agreement. The critical velocity in the fixed configuration was slightly higher than that in the pinned joint by approximately 3%–5%. The existence of the centrifugal force strongly influenced the critical velocity, depending on the observed modes. We found that GFRP is the most suitable material for the OTEC CWP.

A novel procedure to determine the hoop mechanical properties of pipe materials using ring elongation testing technique

In this study, experiments including axial tensile tests and ring elongation tests, as well as analytical analyses were developed to determine the mechanical properties of ASTM A106 Grade B seamless carbon steel (A106-B) pipe material. Ring elongation tests were performed on the ring specimens to determine the mechanical properties of the A106-B pipe material in the hoop direction. Whereas axial tensile tests were carried out on standard axial tensile specimens to determine the axial stress-strain behavior of the A106-B pipe material. The axial stress-strain curve of the A106-B pipe material was used as a reference to validate the ring elongation test results. Besides, Analytical analyses using curved and straight beam formulas were developed. Directly from the ring elongation tests experimental results, both the curved and straight beam formulas accurately predicted the young's modulus and hoop yield strength of the A106-B pipe material. Moreover, the A106-B pipe material's plastic stress-strain behavior in the hoop direction was also successfully determined directly from the ring elongation test results with high accuracy.

Improvement of burst capacity model for pipelines containing surface cracks and its implication for reliability analysis

This paper presents the improvement of a widely used burst capacity model for steel oil and gas pipelines that contain longitudinal external surface cracks, namely the CorLAS model, through the addition of a correction factor that is quantified by the Gaussian process regression (GPR). The correction factor is assumed to depend on four non-dimensional input features that characterize both the crack geometry and pipe material properties. A database consisting of 212 full-scale burst tests of pipe specimens that contain longitudinal surface cracks is established based on the open literature, which is employed to train the GPR model and evaluate its performance. It is shown that GPR is highly effective in improving the accuracy of the CorLAS model predictions. The improvement is further shown to have a marked effect on the time-dependent probability of burst of pipelines containing growing surface cracks through two hypothetical pipeline examples: when employing the CorLAS model, the probabilities of burst are significantly higher, exceeding those obtained using the improved CorLAS model by more than one order of magnitude.

Thermo-mechanical vibration and stability behaviors of bi-directional FG nano-pipe conveying fluid

This work focuses on the thermo-mechanical modeling of a size-dependent pipe made of bi-directional functionally graded (FG) materials and conveying fluid through its inner wall. The material properties of this FG nano-scale pipe along radial and axial directions are assumed to be separately varying according to the power-law and exponential distributions. The governing equations of the FG nano-scale pipe are derived according to nonlocal strain gradient theory and Hamilton’s principle, and interactions between the size-dependent pipe and its inner fluid are revealed via size-dependent constitutive relation. The frequency response of the pipe and its critical flow velocity are calculated via generalized differential quadrature method. After validation of the proposed model by comparing with previous works, a detailed parametric study is conducted to fully examine the coupling effect of material distribution and various parameters including small size, aspect ratio, boundary constraint, temperature change and flow velocity on the frequency response of the FG nano-pipe. Simultaneously, the critical flow velocity of inner fluid under which the divergence phenomenon appears is also predicted and physically explained in detail. Numerical results show that bi-directional FG design is especially beneficial to improve the stability of FG nano-pipe, which can provide a guide to design advanced micro/nanofluidic devices for bio-engineering applications.

Roughness-controlled cell-surface interactions mediate early biofilm development in drinking water systems

Bacterial colonization onto interior pipe walls is ubiquitous in drinking water systems, with the inevitable consequences on water quality safety. However, the mechanisms of how physicochemical properties of pipe materials interfering with cell-surface interactions and subsequent biofilm colonization in drinking water systems have not been fully unveiled. In this study, we investigated initial biofilm colonization onto polyvinyl chloride (PVC), polyethylene (PE) and stainless steel (STS) coupons having various surface roughness during one week incubation in bench reactors. Results display that increased surface roughness encouraged biofilm formation particularly on plastic materials. With the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) modeling analysis, the increment in surface roughness enlarged superficial area and hydrophobicity that reinforced van der Waals force and acid-base bacteria-surface interactions, thereof facilitating biofilm initialization and consequent accumulation. Meanwhile, the PVC and PE coupons attracted around six-fold and four-fold adhesive cells in contrast to the STS ones with the roughness of ∼1.50 µm, respectively. Unlike the STS that induced hydrophilic (repulsive) interactions, plastic materials encouraged hydrophobic (attractive) acid-base interactions and bacterial surface adhesion, accordingly contributing to ensuing colonization. Increasing ionic strength (1–100 mM) further stimulated initial colonization associated with compressed electrical double layer and decreased electrokinetic potential that reduced the energy barriers for bacterial cells. These findings reveal that early biofilm development is a pipe material and roughness-controlled process, which provide new insights into the mechanistic understanding of the ever-growing biofilms in drinking water systems.

Nonlinear Frequency Analysis of FGM Pipes Based on the Homotopy Method

Based on the homotopy analysis method, this paper studies the nonlinear vibration of FGM pipeline with pores under generalized boundary conditions. Based on the power-law distribution of FGM, the physical properties of the material are distributed along the radial direction of the pipe. For the mathematical model of the pores of the pipe, we choose Voigt model to describe the material properties of FGM pipes with pores. Based on Euler Bernoulli beam theory and the influence of von-Kármán nonlinearity, using Hamilton variational principle, the dynamic control equations and generalized boundary conditions of functionally graded fluid transmission pipelines with pores are established. The homotopy analysis method is used to solve the nonlinear vibration characteristics of functionally graded flow pipelines under generalized boundary conditions. The numerical results show that the translation spring has little effect on the critical velocity of instability, while the rotation spring can increase the critical velocity of instability, making the system more stable;In the nonlinear system, the viscoelastic coefficient does not change the critical velocity; pipe length, power-law exponent and porosity all affect the nonlinear free vibration of FGM porous flow pipeline.

Role of surface physicochemical properties of pipe materials on bio-clogging in leachate collection systems from a thermodynamic perspective

Bio-clogging in pipes poses a significant threat to the operation of leachate collection systems. Bio-clogging formation is influenced by the pipe materials. However, the relationship between bio-clogging and the physicochemical properties of different pipe materials has not been clarified yet, especially from a thermodynamic aspect. In this study, the dynamic bio-clogging processes in pipes of different materials (high-density polyethylene (HDPE), polyvinyl chloride (PVC), polypropylene (PP), and polyethylene (PE)) were compared, and their correlation with the physicochemical properties was investigated. Results showed that the bio-clogging in HDPE and PVC pipes was more severe than that in PP and PE pipes. In bio-clogging development, the predominant factor changed from the surface roughness to the electron donator parameter (γ−). In the initial phase, the most severe bio-clogging was observed in the HDPE pipe, which exhibited the highest roughness (432 ± 76 nm). In the later phase, the highest γ− (2.2 mJ/m2) and protein content (2623.1 ± 33.2 μg/cm2) were observed in the PVC simultaneously. Moreover, the interaction energy indicated that the bacteria could irreversibly and reversibly adhere to the HDPE, whereas irreversible adhesion was observed in the PVC, PP, and PE cases. The findings clarify the thermodynamic mechanism underlying bio-clogging behaviors and provide novel insights into the bio-clogging behaviors in pipes of different materials, which can facilitate the development of effective bio-clogging control strategies.

MECHANICAL BEHAVIOR OF COMPOSITIONS OF GLASS-FIBER REINFORCED PLASTIC MORTAR PIPES BASED ON THEIR FUNCTIONING

The experimental investigation on the mechanical parameters compositions of glass-fiber reinforced plastic mortar (GRPM) pipe is the basis of simulating and analyzing the mechanical characteristics of the complete structure of GRPM pipe. Due to the anisotropic material properties of GRPM pipe, the compressive property test is carried out, and the results show that the circumferential compressive strength(CCS) is 49.93Mpa, the axial compressive strength(ACS) is 40.79Mpa, the circumferential elastic modulus(CEM) is 4.84Gpa, and the axial elastic modulus(AEM) is 4.04Gpa. The difference between the CCS and ACS and EM is about 20%, as well as the CCS and EM are greater than the ACS and modulus of elasticity. Conclusions drawn from the tests provide an important basis for checking whether the materials meet the design requirements.

A simplified equation for the collapse pressure of sandwich pipes with different core materials

Sandwich pipe with high-pressure resistance and the adequate insulation performance is a potential deepwater offshore oil and gas development solution. This paper establishes a two-dimensional finite element numerical model for sandwich pipe collapse prediction under external pressure using the finite element software ABAQUS. The developed numerical model is validated successfully using experiments in the literature. Parametric modeling is implemented with the help of the scripting language Python. A total of 3125 FEM models are established to analyze the influence of the sandwich pipe's geometric parameters, material properties, and interlayer adhesion properties on the collapse strength. The results show that the sandwich pipe's geometric parameters and core layer materials significantly influence the collapse strength. In contrast, the change of steel pipe steel grade has less influence. Moreover, the interlayer adhesion properties can significantly improve the collapse strength of the sandwich pipe. Finally, based on the numerical simulation results, a simplified equation for the collapse strength of the sandwich pipe is proposed for different core layer materials under frictionless interlayer conditions, which has an average error of 6.98% under the present assumptions.

Structural performance of buried pipeline undergoing fault rupture in sand using Taguchi design of experiments

Nonlinear structural response of buried continuous steel pipeline undergoing fault rupture deformation is studied in a systematic manner. A detailed and efficient analysis framework for design is proposed and explained with a case study. A three-dimensional nonlinear finite element (FE) model previously developed and validated by the authors is used for this study. Taguchi method for design of experiments is employed to evaluate the structural performance of buried pipeline. It is also used to identify the influence of different parameters such as, the fault crossing angle, faulting type, the operating conditions of the pipeline, geometry of the pipe cross-section and material properties of the pipe and soil on the structural behavior of buried pipelines. The proposed method can be successfully employed to derive peak strain demands as a function of fault displacements for a given set of input conditions in an efficient manner leading to an efficient and safe design solution to this problem. A case study involving NPS 24 steel pipeline with a maximum operating internal pressure of 9.1 MPa is also carried out. The method presented here is suitable for pipeline strain hazard analysis, applicable for major oil and gas transmission lines crossing seismically active faults. • An efficient design approach for oil and gas transmission pipelines crossing active faults is presented. • Only 18 analysis are carried out instead of a full factorial design of total 2916 possible combinations. • Overall, the analysis methodology will be useful in performing strain hazard analysis of pipeline fault crossings.

Numerical study on heat transfer performance of geothermal piles in a Brazilian sandy soil

The worldwide consumption of electric energy destined for air conditioners, expected to triple by 2050, can be lessened by geothermal piles, which transfer heat from the internal environment of buildings to the subsoil. This paper shows the influence of pile geometry and properties of soil, pile, and pipe materials on the heat transfer of a geothermal pile to the surrounding soil, to support design from the viewpoint of thermal performance optimization. A numerical model was developed with ANSYS CFX 19.2, a high-performance Computational Fluid Dynamics tool, and calibrated using data from a thermal response test performed in a saturated sandy soil in São Paulo, Brazil. A parametric analysis was carried out varying pile length, diameter, and slenderness; soil and pile material conductivities; degree of saturation; fluid inlet temperature; fluid flow rate; and pipe thermal resistance. Results show that the fluid inlet temperature is the most influential parameter on the thermal performance of the pile. Heat transfer grows when geometrical parameters (diameter and length) are increased mainly due to an increase in heat exchange surface area, whereas the normalized heat transfer rate per unit of surface area of the pile is practically unaltered. Higher soil, pipe and pile thermal conductivities improve thermal performance. The degree of saturation increases the thermal conductivity of the soil; however, the effect is not remarkable on the system’s thermal performance for saturation degrees higher than 20%. The fluid flow must be turbulent but increases above a certain flow rate do not improve the thermal performance.

Static and dynamic characteristics of post-buckling of porous functionally graded pipes under thermal shock

The study of thermal post-buckling characteristics of functionally graded pipelines is of great significance for promoting the application of functionally graded materials in spacecraft thermal protection design and marine pipelines. In this study, the static buckling of functionally graded pipes with porosity and the pseudo-linear vibration near the first buckling position of post-buckling are studied. Based on the modified power-law distribution, it is assumed that the material properties of porous FGM pipes change continuously and smoothly along the radial direction. For porosity, it generally occurs in the manufacturing process of functionally graded materials, so the classical Voigt model is selected to describe the material properties of functionally graded material pipelines with pores. Based on Hamilton principle, the nonlinear control equations and corresponding boundary conditions of the pipeline are derived. Firstly, the Routh-Hurwitz criterion is used to discuss the influence of temperature and porosity volume fraction on the critical flow velocity of instability, and then the post-buckling structure of the pipeline and the dynamic characteristics of post-buckling are discussed. The numerical results discussed the influence of important parameters such as power law index, porosity volume fraction and temperature on the buckling and post-buckling behaviors of the system.

Role of Surface Physicochemical Properties of Pipe Materials on Bio-Clogging in Leachate Collection Systems from a Thermodynamic Perspective

Role of Surface Physicochemical Properties of Pipe Materials on Bio-Clogging in Leachate Collection Systems from a Thermodynamic Perspective

Root cause analysis of liner collapse and crack of bi-metal composite pipe used for gas transmission

An underground gas storage company adopted bimetallic composite pipes for gas transmission. The pipelines were inspected with industrial camera, it was found that a large number of pipelines had liner collapsed, and some of collapsed liner had suspected cracks. In order to analyze the reasons for the collapse and cracking of the liner, visual inspection, non-destructive testing, material examination, crack analysis, bend fatigue test and pressure test were conducted. The results showed that the material properties of the bimetal composite pipe meet standard requirements. The external pressure test was imposed on Φ168 composite pipe, the liner collapse under the pressure of 1.76 MPa which is lower than the calculated value. The cause of collapse was analyzed from manufacturing process and service condition. There are micro-cracks around the main crack of the liner, the fracture showed fatigue striations and thickness thinning characteristic. The root cause of the liner collapse is that the water enters the interlayer during the manufacturing of bimetallic composite pipe, and the thermal expansion coefficient of base pipe and lining pipe is different. When external anti-corrosion coating was manufactured and temperature changed during operation, collapse tendency of the liner increased. The root cause of the crack of the liner is bending fatigue, and the load originates from pressure fluctuations during operation. In order to avoid such incidents, the online inspection should be performed for the effusion part of the pipeline to check whether the remaining wall thickness of the base pipe meets the requirements for safe operation. The carbon steel pipe with regular pigging was recommended for this application situation.

A stochastic model for the speed of leak noise propagation in plastic water pipes

A good estimate of the speed of leak noise propagation is necessary to pinpoint the location of a leak using acoustic correlators. Models currently exist for this purpose, but they do not consider uncertainties in the pipe geometry and the properties of the pipe and soil. Using the fact that leak noise propagates as a predominantly fluid-borne wave, this paper develops a stochastic model of the speed of leak noise propagation in plastic water distribution pipes that can account for these uncertainties. The model provides confidence limits for the estimate of this wave speed. It is based on the mean and standard deviation of the pipe geometry as well as the pipe and soil material properties, which have strong influence on the speed at which the leak noise propagates in the pipe. Numerical examples, using parameters from water supply systems found in the field, in which the pipe is made from Medium-Density Polyethylene (MDPE) and Polyvinyl Chloride (PVC) are presented to validate the model. Monte Carlo simulations for both in-air and buried pipes are presented to check the 99.7% confidence interval. To verify that the predictions from the stochastic models give realistic results, they are compared with some measurements from different sites, in which nominal properties and tolerances for the pipe and soil properties are assumed.

Performance analysis and modeling of parabolic trough based concentrated solar facility using different thermal fluid mediums

The significance of sustainable power source has expanded because of environmental change and worldwide cautioning concerns because of its renewing quality. Solar energy is the focal point of numerous examinations due to modern industrial applications and small scale local applications in emerging nations. Solar energy is being bridled, either specifically utilizing photovoltaic or secondarily utilizing concentrated solar power. This study aims to design and fabricate a small scale concentrated solar power (CSP) plant using linear parabolic trough. Linear parabolic trough collector is used because of high efficiency and exceedingly prescribed kind of CSP. The scope of this study is to develop a CSP plant and also study the properties of various thermal fluids and expect the best transfer medium. The study done in this research is based on carrying out a detailed energy balance scheme for a linear parabolic trough collector while observing twenty-six vital design parameters, including the geometric measurements and material properties of concentrator and receiver pipe, thermal fluids properties, and operating conditions. Modeling of the system is carried out for different thermal fluids that are deemed viable for use. It was found that the results obtained from the fabricated parabolic trough CSP were used to verify the model and compare with the theoretical results. The conclusions deduced from this study will help design both small and large scale applications of linear parabolic troughs.

Vibration analysis of post-buckled fluid-conveying functionally graded pipe

The vibration of post-buckled fluid-conveying pipe made of functionally graded material is analyzed. The pipe material properties are assumed to be graded in the thickness direction according to power-law distribution. An exact solution is obtained for the post-buckling deformation of the fluid-conveying functionally graded pipe with various boundary conditions. The linear vibration problem is solved around the first buckled configuration and the natural frequencies of the three lowest vibration modes are obtained. The influences of power-law exponent, initial tension, fluid density and fluid velocity on the static deflection and free vibration frequencies are studied.