Pipe Layer Research Articles

Thermal performance of a wooden pipe-embedded building envelope using a low-grade heat source in extreme cold climate conditions

A pipe-embedded wall can effectively reduce building energy consumption in winter. Most of the research on this concept to date has used traditional building materials such as concrete and brick. This paper reports on a wooden pipe-embedded wall allowing more flexible pipe locations, which can be used to reduce heat load in winter. An experimental assessment was developed to investigate the building assemblies thermal performance and the results were used to develop an understanding of its thermal energy saving potential, and as an input for the validation of a numerical model of same. A 3D computational fluid dynamics model of the pipe-embedded wall was developed and applied to assess the thermal performance of the wall under boundary conditions beyond the capabilities of the experimental assessment. Further, the influence of five parameters including the outdoor temperature and pipe positions were studied. A method was proposed for selecting the pipe layer's optimal location. The results show dual thermal impacts of the pipe layer: active heating and passive insulation. Using 8 °C water reduces internal surface heat transfer by 42.5 % under −20 °C outdoor temperature conditions. This is akin to an 18 °C outdoor temperature rise. Furthermore, another interesting result is that increasing the wall material thermal resistance can sometimes increase energy consumption. This study provides a reference for designing and optimizing net zero energy buildings in extreme cold climate conditions.

Mechanical Characteristics of Fiber-Reinforced Flexible Pipe Subjected to Axial Tensile Load

Fiber-reinforced flexible pipes are subjected to large axial tension loads in deep-water applications, which may result in the excessive deformation of the pipes. Owing to the anisotropy of the composite materials, accurately describing the tensile behavior of these pipes is difficult. Theoretical, numerical, and experimental methods are employed in this study to investigate the mechanical characteristics of a glass fiber-reinforced unbonded flexible pipe under axial tensile loads. Based on the load–strain relationship of each pipe layer, analytical equations considering the effect of anisotropy and radial deformation are first proposed to calculate the axial tensile stiffness of the pipe. A detailed numerical model is established to simulate the tensile behavior of the pipe. A prototype test is performed on a 4500 mm long sample using a tensile testing machine. The leading roles of outer tensile reinforcement layers in axial tensile capacity are illustrated by the strain energy of the pipe layers obtained by the numerical model. Subsequently, a comparison analysis of the mean fiber direction strains of the selected sections are performed between numerical and experimental results, which validates the numerical model. Additionally, the stress distributions of different pipe layers are discussed based on the results of the numerical analysis. Finally, the comparison of axial tensile stiffness results validates the accuracy of the analytical model considering radial deformation. This study proposes effective theoretical and numerical models to predict the tensile behavior of a fiber-reinforced flexible pipe, which provides useful references for the design and structural analysis of these pipes.

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.

AN INVESTIGATION INTO PROPERTY VARIANCES BETWEEN OUTER AND INNER HDPE PIPE LAYERS

Many studies devoted to plastic piping investigated mechanical properties as suggested by many standards; however very few of them were designed for surface roughness and hardness analyses in relation to microstructure. The objective of this research work is to establish property differences between inner and outer surface layers of a high density polyethylene pipe. Machined specimens are prepared from both sides of a pipe and subjected to mechanical testing, roughness and hardness measurements. It is found that local mechanical properties are in favor of the inner layer as a result of the fabrication process which produces residual stresses and imposes structural variations. On the other hand, the outer die-hardened pipe face develops higher roughness and higher shore hardness values. All methods used to obtain crystallinity provided acceptable measurements and indicated that the inner pipe layer is more crystalline because of slow cooling. Finally, it is shown that OIT results are in favor of the outer surface layer with 14% difference. This indicates that the inner surface layer is more vulnerable to thermal degradation compared to the outer one. Such results should improve the understanding of HDPE pipe behavior under combined outer and inner frictional effects during service operations. DOI: http://dx.doi.org/10.5755/j01.mech.25.2.22115

A Semi-Automatic Approach in GIS for 3D Modeling and Visualization of Utility Networks: Application for Sewer & Stormwater networks

This paper presents a semi-automatic methodology proposed for 3D modeling of utility networks in GIS environment. The ModelBuilder in ArcGIS (ESRI) software is used for implementing this methodology, by developing two tools to automate the construction processes of 3D networks. The first presents a tool to create a 3D Manhole layer from points layer, and the second is a tool to create a 3D pipe layer. For both tools, a work algorithm has been built, in addition to designing user interfaces elements. These tools are stored in a Toolbox called “3D Manhole & Pipe.tbx”. The two previous tools were tested and applied to spatial data for a proposed residential area. The final 3D model of the residential area includes the sewage and stormwater networks, as well as other spatial data such as buildings, parks, roads, etc. This model is able to spot the intersection points in the network, visually or using the 3D analysis available in the software, allowing us to identify problems to be processed and resolved before starting a project, leading consequently to time and cost savings, effort and money. The proposed methodology is an easy and an effective way to build 3D network models (sewer, water..etc), and the developed tools allow the implementation of a set of necessary processes needed to build 3D networks.

Hull deflection in still water and in waves of a pipe layer barge

The evaluation of ship’s hull deflection in still water and in waves is an important step which has to be performed starting with early design stages. The different scenarios are depending on the loading cases to be considered as most dangerous ones which could appear during ship’s life time. The paper is focused on the evaluation of forces and moments in calm water and in waves, the last ones being a result of the motions and accelerations of a pipe layer barge in waves for a range of wave frequencies and heading angles. The static case is important due to the implications in the building process and docking. Consequently, the bending moments and shear forces in hogging and sagging conditions are evaluated. The dynamic case could have major implications during operational time when large dynamic forces and moments could lead to dramatic effects. The analysis has been performed and consists in the evaluation of Response Amplitude Operators (RAO) of motions and the induced forces and moments which are calculated based on a computer code using the potential theory. Then, hull deflections are evaluated using FEMAP-NX-NASTRAN.

Long-term performance of a polyamide-12-based fuel line with a thin poly(ethylene-co-tetrafluoroethylene) (ETFE) inner layer exposed to bio- and petroleum diesel

The long-term performance of a polyamide-12 (PA12)-based (bio)diesel fuel line/pipe with a thin poly(ethylene-co-tetrafluoroethylene) (ETFE) inner layer was investigated in “close to real” and high-temperature isothermal conditions with fuel on the inside and air on the outside of the pipe. The inner carbon-black-containing ETFE layer resisted fuel attack, as revealed by the small fuel uptake, the very low degree of oxidation, and the unchanged electrical conductivity, glass transition and melting behaviour. The properties of the ETFE layer remained the same after exposure to all the fuel types tested (petroleum diesel, biodiesel and a blend of 80% diesel with 20% biodiesel). Because of the presence of the ETFE layer on the inside, the fuel pipe experienced noticeable changes only in the outer PA12 pipe layer through migration of plasticizer, annealing and slight oxidation. The evaporation of plasticizer was found to be diffusion-controlled and it led to an increase in the glass transition temperature of PA12 by 20 °C. This, together with a small annealing-induced increase in crystallinity, resulted in a stiffer and stronger pipe with an increase in the flexural/tensile modulus and strength. The oxidation of PA12 remained at a low level and did not lead to an embrittled pipe during the simulated lifetime of the vehicle. This study reveals that fluoropolymers have a great potential for use as fuel-contacting materials in “demanding” motor vehicle fuel line systems.

INFLUENCE ANALYSIS OF THE ATTACHMENT COORDINATES RELATING TO THE CARGO OSCILLATIONS ON THE PIPE LAYING CRANE’S BOOM

Introduction . The work of a crane - a pipe-laying machine in difficult ground conditions has a significant influence on the process of performing the work and the mode of the machine operation. The unevenness of the microrelief is the main reason for the fluctuations in the load, often leading to emergency situations. Therefore, engineering solutions aimed at reducing the negative impact of cargo oscillations on the boom of a crane - a pipe laying - are considered in the article. Moreover, the necessity of a new engineering solution aimed at limiting the amplitude of load oscillations on a crane arm - a pipe laying - is substantiated. Materials and methods . The mathematical model is used in the research, where the crane - pipe layer is a hinged articulated link with elastic-viscous bonds superimposed on it. Additionally, the kinematics of the links are described by the method of homogeneous coordinates; the dynamics of the links are described by a system of Lagrange Equations of the 2nd type. Results . As a result, the following dependencies are constructed: the oscillation of the load from the coordinates of the attachment of the balancing rope to the boom and the load rope, for a range of boom with angles’ range from 30 ° to 80 °. Also the influence of the coordinates of the attachment of the balancing rope to the boom and the load rope on the oscillation of the load is determined for a fixed value of the length of the cargo rope. Discussion and conclusion . The estimation of the effect of the coordinates of fastening the balancing rope to the boom and the cargo rope on the oscillation of the load on the boom of the crane - the pipelayer is given.

Moored offshore structures - evaluation of forces in elastic mooring lines

In most situations, the high frequency motions of the floating structure induce important effects in the mooring lines which affect also the motions of the structure. The experience accumulated during systematic experimental tests and calculations, carried out for different moored floating structures, showed a complex influence of various parameters on the dynamic effects. Therefore, it was considered that a systematic investigation is necessary. Due to the complexity of hydrodynamics aspects of offshore structures behaviour, experimental tests are practically compulsory in order to be able to properly evaluate and then to validate their behaviour in real sea. Moreover the necessity to carry out hydrodynamic tests is often required by customers, classification societies and other regulatory bodies. Consequently, the correct simulation of physical properties of the complex scaled models becomes a very important issue. The paper is investigating such kind of problems identifying the possible simplification, generating different approaches. One of the bases of the evaluation has been found consideringtheresults of systematic experimental tests on the dynamic behaviour of a mooring chain reproduced at five different scales. Dynamic effects as well as the influences of the elasticity simulation for 5 different scales are evaluated together. The paper presents systematic diagrams and practical results for a typical moored floating structure operating as pipe layer based on motion evaluations and accelerations in waves.

Recent Developments of HEP Pixel Detector Readout Chips

This article reviews the development of readout integrated circuits for hybrid pixel particle physics detectors. The 250-nm feature size chips in the presently operating ATLAS and CMS experiments are compared with the current state of the art in 130-nm feature size represented by the FE-I4 chip that will be used to add a new beam pipe layer for the ATLAS experiment in 2013 and the upgrade options of the CMS pixel readout chip. This includes a discussion of the array and pixel size, analog performance, readout architecture, power consumption, power distribution options and radiation hardness. Finally, recent work in 65-nm feature size as a means to continue the evolution of readout chip technology towards smaller feature size, higher rate, and lower power is presented.

Integrated Navigation and Positioning System

A unique integrated navigation and positioning system was developed by Systems Management, a unit of Sperry Division, for control of Saipem's new semi-submersible pipe laying ship Castoro Sei. Accurate ship's movement along a pre-surveyed route is provided for precision pipe laying in deep water. The navigation function measures vessel state in six degrees of freedom, and offers several modes of operation. Position reference selections may be made from a complement of microwave, UHF, and MF radio navigation systems; data from these systems are mixed with doppler water speed and gyrocompass information to derive navigation outputs superior to radio data or dead-reckoned data alone. A unique dead-reckoning mode, utilizing data obtained from the vessel's mooring lines, was designed and incorporated into the navigation function; this dead-reckoning feature is peculiar to a vessel propelled by mooring lines, such as a pipe layer, and significantly enhances the navigation function during chronic prolonged periods of radio navigation unavailability. The ship is controlled automatically with respect to the navigation position and attendant data sources, in six degrees of freedom, by computer generated commands. A control operator, sitting at a specially designed console, and utilizing graphic and alphanumeric navigation and control situation displays, may command a fully automatic ship's control sequence, or may “drive” the vessel semiautomatically using a joy stick for translation and a heading knob for azimuthal control. The concepts on which the navigation and positioning system were based are discussed, and the performance results of certain navigation at-sea trials are presented.

A Method of Measuring the Concentration of Certain Polymers in Dilute Aqueous Solutions

A technique has been devised for measuring the concentration of “Polyox” in dilute aqueous solutions. “Poly-ox”* is one of those polymers whose addition to water in low concentrations causes a reduction in skin friction (if the Reynolds number is sufficiently high) in turbulent flow through a pipe or boundary layer. (See, for example, ref. 1.) The analytical method is probably applicable to other polymers having this property, and it should be generally useful in this field of research. For example, in any experiment in which a polymer solution is injected at a point in a boundary layer, the method could be used to determine the distribution of polymer concentration at downstream sections. It is based on polarography, a well-established tool of chemical analysis of which an excellent account is given in ref. 2.