Pipe Placement Research Articles

Deformation and Heat Transfer on Three Sides Protected Beams under Fire Accident

Fire accidents are common in oil and gas industry. The application of passive fire protection (PFP) is a costly solution. The PFP is applied only on critical structural members to optimise project cost. In some cases, beams cannot be protected from the top flange in order to accommodate for the placement of pipe supports and grating. It is important to understand the thermal and mechanical response of beam under such condition. This paper discusses the response of steel beam under ISO 834 fire protected, unprotected and three sides protected beams. The model validated against an experimental study. The experimental study has shown good agreement with FE model. The study revealed that the beams protected from three sides heat-up faster compare to fully protected beam showing different temperature gradient. However, the affects load carrying capacity are insignificant under ISO 834 fire.

Evaluation of Seismic Protection Methods for Buried Fuel Pipelines Subjected to Fault Rupture

Buried steel fuel pipelines are critical lifelines for the society and the economy, but are very vulnerable to earthquake-induced ground failure. Traversing seismic areas inevitably results to several pipe – fault crossings. Fault rupture forces a buried pipeline to undergo deformations that could be substantial and heavily endanger its integrity. Due to the grave consequences of a potential pipe failure, mitigating measures are commonly applied at pipe – fault crossings to reduce the effects of a potential fault activation. In this paper, a comparative review of several measures that are used in practice or have been proposed in the technical literature is presented. Numerical analyses are then carried out to compare the effectiveness of commonly used measures and to extract conclusions regarding their applicability. Results indicate that the most efficient among the evaluated measures are pipe placement within culverts and use of flexible joints. Trench backfilling with pumice is a moderately effective measure in terms of pipe protection, while steel grade upgrade, wall thickness increase and pipe wrapping with geotextile are found to be insufficient protection methods.

Energy, Power and Heat Flow of the Cooling and Fluid Systems in a Cutting Machine Tool

Cooling is one of the main tasks of fluid systems in cutting machine tools. Cooling systems are essential for controlling the thermo-elastic properties of the whole machine structure. The paper describes an experimental investigation of a modern machining center's cooling system. Additionally, a network-based simulation strategy is presented, which has been utilized for the theoretical analysis regarding the energetic properties and thermal impact as well as the evaluation of improved design concepts. These for instance focus on the optimum placement of pipes and individually controllable supply units.

Experimental and numerical studies on protection of buried pipelines and underground utilities using geocells

This paper presents the results of the laboratory model tests and the numerical studies conducted on small diameter PVC pipes, buried in geocell reinforced sand beds. The aim of the study was to evaluate the suitability of the geocell reinforcement in protecting the underground utilities and buried pipelines. In addition to geocells, the efficacy of only geogrid and geocell with additional basal geogrid cases were also studied. A PVC (Poly Vinyl Chloride) pipe with external diameter 75 mm and thickness 1.4 mm was used in the experiments. The vehicle tire contact pressure was simulated by applying the pressure on the top of the bed with the help of a steel plate. Results suggest that the use of geocells with additional basal geogrid considerably reduces the deformation of the pipe as compared to other types of reinforcements. Further, the depth of placement of pipe was also varied between 1B to 2B (B is the width of loading plate) below the plate in the presence of geocell with additional basal geogrid. More than 50% reduction in the pressure and more than 40% reduction in the strain values were observed in the presence of reinforcements at different depths as compared to the unreinforced beds. Conversely, the performance of the subgrade soil was also found to be marginally influenced by the position of the pipe, even in the presence of the relatively stiff reinforcement system. Further, experimental results were validated with 3-dimensional numerical studies using FLAC3D (Fast Lagrangian Analysis of Continua in 3D). A good agreement in the measured pipe stain values were observed between the experimental and numerical studies. Numerical studies revealed that the geocells distribute the stresses in the lateral direction and thus reduce the pressure on the pipe. In addition, the results of the 1-g model tests were scaled up to the prototype case of the shallow buried pipeline below the pavement using the appropriate scaling laws.

Effect of plenum chamber obstructions on data center performance

Cool air supplied from a raised floor plenum is the most common cooling technique employed in any electronic data center. Many factors lead to the presence of obstructions in the under-floor plenum chamber. However, detailed investigations on the effect of these obstructions on cooling system performance need to be carried out. We have performed CFD studies to quantify the effect of obstruction and perforated tiles on total CRAC (Computer Room Air Conditioning) flow rates as well as the distribution of flow through CRAC. We investigate various factors affecting the air flow distribution and the corresponding cooling with seven models. This paper describes these models and presents key results, compared with experimental data available from the relevant literature. The flow rates through perforated tiles obtained through simulations show good agreement with the measured values for three CFD models. It was observed that obstructions in the plenum chamber lead to decreased air flow rates by as much as 80%, thereby leading to an increase in the occurrence of hot spots. Further, we demonstrate that pipe placement in the plenum chamber is one of the important factors affecting data center performance and hence there is a need to further develop industry standards.

DEVELOPMENT OF A SYSTEM TO VALIDATE AND CERTIFY EQUIPMENT AND TECHNICIANS FOR UNDERGROUND PIPE INSPECTION

Storm water delivery systems are an integral part of transportation construction projects. Pipe placement is costly and time consuming, and when a system fails, the costs associated with repairing and replacing the system are significantly greater because of the existing infrastructure often built above the pipe. Several state departments of transportation in the U.S. have standard specifications for the inspection of newly-installed pipe, but no Department of Transportation has standardized operator training for laser profiling or closed-circuit television (CCTV) pipe inspection. This is significant because state-of-the-art systems for underground pipe inspection currently utilizes these two technologies. Likewise, standards do not exist for the certification of systems or operators for CCTV, laser profiling, or other technologies. Within this report are the findings of an ongoing project funded by the Florida Department of Transportation. This paper reports on pipe inspection in the U.S., the development of a field test for laser-and CCTV-based inspection systems, and practical exams for prospective operators of certified systems used in the inspection of underground pipe construction.

Characteristics Analysis of the Heat Exchange Rate according to Soil Temperature and Grout Material using Numerical Simulation

The ground source heat pump (GSHP) system has attracted much of attention, because of its stability of heat production and the high efficiency of the system. Performance of the heat exchanger is dependent on the soil temperature, the ground thermal conductivity, the operation schedule, the pipe placement and the design temperature. However, in spite of the many variables of these systems, there have been few research on the effect of the systems on system performance. In this study, analysis of the heat exchange rate according to soil temperature and grout material was conducted by numerical simulation. Furthermore, the heat distribution around the ground heat exchanger was presented on the different conditions of grout and underground temperature by the simulation.

Proper Design of Leachate Collection Pipe in Semi-Aerobic Landfill by Two Dimensional Simulation

Semi-aerobic method is a standard type of landfill currently used in Japan. Semi-aerobic landfill system enables to enhance the stabilization of landfilled solid waste utilizing the self-purification capacity inherent in nature. Although semi-aerobic method has been developed for about 20 years, the mechanism has not widely understood in many countries. The objective of this study is to make clear the influence of the laying condition (pipe diameter, pipe placement distance) of leachate collection pipe on the stabilization of landfill through numerical simulation, by use of landfill model constructed in this study with consideration of the interactions of microbial activity and the transport process such as gas transport, heat transport and material transfer between gas and liquid phases.

설계조건 변화에 따른 지중열교환기 길이 변화 연구

A ground loop heat exchanger for the ground source heat pump system is the important equipment determining the thermal performance and initial cost of the system. The length and performance of the underground heat exchanger is dependent on ground thermal conductivity, operation hours, ground loop diameter, grout, ground loop arrangement, pipe placement and design temperature. In this study we find out heat exchanger length with various design factor.

Theoretical Considerations of Joint Optimal Model for Water Allocation and Pipe Placement

Water shortage emerges and restricts the urban construction and the social-development due to the rapid expansion of the cities. Recent research mainly focuses on the water resources management or water distribution network management separately. In this paper, a joint optimal model for water allocation and water distribution network management is developed. In the first phase, a multi-objectives linear programming is used for the optimal allocation on multi-water resources for multi-users, in which cost and water conservation are regards as objectives. In the second phase, a non-linear model is proposed, which is solved by single-objective GA linking to EPANET hydraulic solver. The result of the first phase is a parameter of the objective in the second phase.

Maxi-HDD Pull Loads for Entry and Exit Points at Different Elevations

ASTM guidelines provide a procedure for estimating pull loads and stresses on polyethylene pipe as primarily a function of the drilled path and buoyant weight of the pipe in the drilled hole. The equations were initially developed assuming a level grade or that the horizontal directional drilling (HDD) entry and exit elevations are the same. In practice, however, it is not uncommon that there would be a finite grade or difference in elevation between the entry and exit points of the drilling operation. The equations and methodology have been expanded to address the placement of polyethylene pipe for the case of a nonlevel grade, including the installation of pipe with and without antibuoyancy measures. The theoretical model and associated results were primarily based on a particular generic borehole geometry, recognizing that specific trends and conclusions may differ somewhat for other possible bore paths. This paper therefore investigates an alternate generic geometry for traversing different entry and exit elevations, representing a reasonable bore path in many practical applications. The results help provide a better understanding of the factors influencing the pull loads in the maxi-HDD installation of pipelines.

Effect of Pipe Stiffness on Maxi-HDD Pull Loads

The ASTM standard F1962, Standard Guide for Use of Maxi-Horizontal Directional Drilling for Placement of Polyethylene Pipe or Conduit Under Obstacles, Including River Crossings, provides a procedure for estimating pull loads and stresses on polyethylene (PE) pipe as primarily a function of the drilled path and buoyant weight of the pipe in the borehole. Although the (capstan) effect of tension at route bends is reflected in the analysis, it is assumed that pipe bending stiffness effects may be ignored for the typically very flexible PE material. However, it is of interest to gain a quantitative understanding of the potential impact of such additional factors on the required pull force in somewhat stiffer pipe materials, such as polyvinyl chloride (PVC) or steel. The present investigation therefore focuses on an analytical means of estimating the associated frictional drag forces, allowing an appreciation of the possible importance of such effects and, as appropriate, an extension of the general ASTM F1962...

Maxi-HDD Pull Loads for Nonlevel Grade for Polyethylene Pipe

ASTM F1962, “Standard Guide for Use of Maxi-Horizontal Directional Drilling for Placement of Polyethylene Pipe or Conduit Under Obstacles, Including River Crossings,” provides a procedure for estimating pull loads and stresses on polyethylene pipe primarily as a function of the drilled path and buoyant weight of the pipe in the drilled hole. The original equations initially were developed assuming a level grade or that the horizontal directional drilling (HDD) entry and exit elevations were the same. In practice, however, it is not uncommon that there would be a finite grade or difference in elevation between the entry and exit points of the drilling operation. It is, therefore, of interest to extend the equations and methodology of ASTM F1962 to address the installation of polyethylene pipe for the case of a nonlevel grade. The primary source of drag corresponds to the frictional drag associated with the buoyant weight of the polyethylene pipe, which buoyancy also tends to pull the pipe upwards, opposite gravity, along sloped portions of the bore path. The effects on the pull load depend on the degree to which the drilled hole is free to drain slurry from the lowest access (entry or exit) point during the pullback operation, and the possible deployment of antibuoyancy measures (i.e., water ballast added to pipe interior). This paper addresses the installation of the pipe in the absence of antibuoyancy measures (i.e., no ballast). A subsequent paper will address the case with added ballast. This paper provides a better understanding of the factors influencing the pull loads in the maxi-HDD installation of pipelines.

Parametric Dependency and Trends of HDD Pull Loads

The required pulling loads on pipes installed by horizontal directional drilling (HDD) are related to the route characteristics and various implementation parameters, some of which are directly controllable. The application of ASTM Standard F1962, Standard Guide for Use of Maxi-Horizontal Directional Drilling for Placement of Polyethylene Pipe or Conduit under Obstacles, Including River Crossings, has been conveniently employed to perform a parametric study to help understand the dependency of the pull loads on these variables and the corresponding installation characteristics. The results provide useful information to help focus on the more significant parameters that affect the pull loads, thereby helping to ensure successful installations. Some of the results are as expected, including the effectiveness of antibuoyancy techniques for dramatically reducing the required pull loads; other trends are less obvious. While the ASTM F1962 methodology is intended to be applicable for the placement of polyethylene pipe, the conclusions and guidelines may reasonably be extrapolated to other types of pipe.

Urban Water Demand Management in ASEAN Countries: Challenges and Solutions

ASEAN member countries face significant challenges in managing urban water demand given rising populations, urbanization and water scarcity. Depending on country circumstances, they have responded to these challenges with both short term and long term solutions including tariff solutions, management solutions, technical/engineering solutions, institutional/regulatory solutions and leadership, public education and community involvement. Short term solutions include reducing commercial losses, checking on meter accuracy and reducing pressure. Long term solutions include pipe placement programs, shifting towards economic valuation of water service, performance and process benchmarking and 100% metering. Other long term institutional solutions include more effective regulation, private sector participation and financial restructuring of water utilities. Pushing these solutions forward require continuing capacity building programs including formal training, staff exchange, advisory services, twinning arrangements and networking and leadership development. Singapore can play an important role in this process.

Conceptualizing lateral preferential flow and flow networks and simulating the effects on gauged and ungauged hillslopes

One of the greatest challenges in the field of hillslope hydrology is conceptualizing and parameterizing the effects of lateral preferential flow. Our current physically based and conceptual models often ignore such behavior. However, for addressing issues of land use change, water quality, and other predictions where flow amount and components of flow are imperative, dominant runoff processes like preferential subsurface flow need to be accounted for in the model structure. This paper provides a new approach to formalize the qualitative yet complex explanation of preferential flow into a numerical model structure. We base our examples on field studies of the well‐studied Maimai watershed (New Zealand). We then use the model as a learning tool for improved clarity into the old water paradox and reasons for the seemingly contradictory findings of lateral preferential flow of old water where applied line sources of tracer appear very quickly in the stream following application. We evaluate the model with multiple criteria, including ability to capture flow, hydrograph composition, and tracer breakthrough. We generate output ensembles with different pipe network geometries for model calibration and validation analysis. Surprisingly, the range of runoff response among the ensembles is narrow, indicating insensitivity to specific pipe placement. Our new model structure shows that high transport velocities for artificial line source tracers can be reconciled with the dominance of preevent water during runoff events even when lateral pipe flow dominates response. The work suggests overall that preferential flow can be parameterized within a process‐based model structure via the structured dialog between experimentalist and modeler.

Water flow patterns in subsurface flow constructed wetlands designed for on‐site domestic wastewater treatment

Bypass flow in subsurface flow constructed wetlands, which may be related to several wetland characteristics, reduces detention time and may result in inadequately treated wastewater. Subsurface flow constructed wetlands, 23 m wide by 4.8 m long and containing a gravel matrix, were used to investigate the impact of wetland depth, inlet pipe location, loading volume, and plants on water flow. Flow patterns were determined using blue dye or bromide as tracers. The blue dye adsorbed to the gravel and was not an effective tracer for following water movement Water dispersed as it flowed through the wetland, and approximately two pore volumes of added water were required to displace approximately 99% of the bromide tracer added as a pulse. In 17 and 25 cm deep wetlands, water flow was uniform with depth, and inlet depth had little influence on water flow patterns. Water flow in a 40 cm deep wetland was not uniform with depth for either inlet pipe placement The presence of plants caused preferential water flow around root masses, thereby, limiting their potential to interface with wastewater. Water mixing by dispersion from the surface to deeper depths may enhance aeration. Bromide was first detected in effluent after only 05 pore volumes of tap water had been added. This indicates that detention time for some wastewater would be less than expected, since plug flow is usually assumed in subsurface flow constructed wetlands. This occurrence should be considered for time‐dependent treatments, such as fecal coliform and biological oxygen demand reduction.

Heighting and Distance Accuracy with Electronic Digital Levels

A Leica NA3000 electronic digital level, one of the newly-introduced heighting equipment, was evaluated for vertical and horizontal distance measurement. A well protected 170 m long 17-section test line was first established for this purpose using geodetic surveying techniques. The test instrument was then used to remeasure the line. Two approaches were followed. In the first, closed loops were run from one end of the line to each of the pegs on the line and back to the starting point in an out-and-back manner. Misclosure errors of loops were then computed and compared to known levelling standards. In the second approach, heights of some pegs on the line were re-established several times with the instrument erected on the one end of the line. Standard deviations of height measurement of each peg were then computed and compared with known standards. The results showed that in the first approach, the test instrument was able to achieve accuracy values commensurate with first order class I levelling standards as set out by the U.S.A.-based Federal Geodetic Control Committee (FGCC), i.e. better than ±3.0k mm. In the second approach, for distances up to 64 m, standard deviations better than ± 60 microns could easily be obtained. Again, this is within the requirements of first order class I levelling standards. Overall, therefore, it can be said that digital electronic levels, as exemplified by the Leica NA3000 model, could be used to support high accuracy levelling operations being them of the geodetic or ordinary type.The distance measuring stage of the test showed that, for up to 64 m from instrument station, the test instrument is capable of measuring distances to accuracy values better than 1/2000. This is sufficient accuracy for some localized survey works, e. g. site preparation in construction industry, pavement maintenance surveys, sewer pipe placement and monitoring etc. where distance errors of a few centimeters in several tens of meters are tolerable.

Optimal thermal-insulation placement of district-heating pipes and their support baffles in air-filled trenches

Steady-state conductive-convective heat transfers across a relatively cold, horizontal, rectangular cavity enclosing two relatively hot, horizontal pipes have been determined experimentally. By employing the displacement ratios of the two pipes (designated ‘h’ for the hot one and ‘w’ for the warm one relative to the mean temperature of the enclosure) as variables, the optimal configuration, i.e. that which achieves the minimum steady-state rate of heat loss from the hot pipe for the considered conditions was deduced to occur when the two pipes were placed one above the other at E h = 0·70 and E w = 0·03, and half-way between the vertical walls. The effective resistance of the air in the cavity can be further enhanced via the insertion of two pairs of low-conductivity, radial baffles, each supporting one pipe. The optimal angles of inclination for the baffles for this purpose were achieved at Θ h = ±48° and Θ w = ±60°.

Far Field Acoustic Radiation From an Expansion Chamber

A method is presented for the assessment of the effect of several system parameters on the radiated and transmitted acoustic fields of an expansion chamber with a flexible side wall. The approach is based on a previously developed model of a three dimensional cavity in an otherwise one dimensional acoustic transmission line. The acoustic field within the cavity is represented in terms of the cavity acoustic normal modes. The flexible side wall is represented in terms of its natural modes of free vibration. Computations are made and results presented to assess the effect on the acoustic output of parameters such as side wall thickness, side wall stiffness, inlet pipe length, and inlet and outlet pipe placement. It is concluded that radiation from the side wall can occur at significant levels at certain plate resonances and at cavity internal resonances. Reduction of radiation is achieved by thickening of the side wall and by adding appropriate stiffeners. Success in reduction of radiated noise requires an understanding of the entire coupled system.