Pipe Diameter Research Articles

ANALYSIS AND OPTIMIZATION OF WIND RESISTANCE PARAMETERS FOR LATTICE-TYPE HIGH-MODULUS SUPPORTS BASED ON THE OPTIMAL CRITERIA METHOD

Lattice high-molded support can generally be used for cast-in-place support for bridges, but for more than 50 meters of lattice high support, due to the wind, load and other factors, due to the support length and slenderness of the relatively large, relatively light and flexible structure and other characteristics of the role of the wind load is very sensitive. When the lattice high-molded stent construction is used in the typhoon area, it is easy to be damaged by the typhoon, and the structural design of the lattice high-molded stent and the construction of that technology are facing great challenges. In this paper, based on the new construction of a special bridge in Fujian, finite element analysis of four-legged and six-legged lattice bracing is carried out by ANSYS, and the effects of steel pipe diameter, number of columns, longitudinal and transversal spacing of bracing, and diagonal bracing structural parameters on structural performance are analyzed by using the coefficients of buckling stability and the coefficients of critical loading. The results of the study show that the main design variable for displacement sensitivity is the diameter of vertical rod; the main design variable for stress sensitivity is the diameter of diagonal rod; the main design variable for overall stability sensitivity is the diameter of diagonal rod; and the main design variable for overall stability sensitivity of total volume is the diameter of diagonal rod. And the optimal wind resistance parameters are: 4 lattice high-braced columns are selected, the section length should be controlled within 15m, and the total height should not be more than 70m, and the spacing of the columns is controlled between 7m and 8m. This study proposes a set of optimized design process method for wind-resistant lattice structure under the constraints of stiffness, strength and critical load factor, which improves the economy and ensures the reasonableness of the design, and can be used for the design of high-modular lattice bracket in typhoon area.

Effect of Solar Radiation and Soil Temperature on the Flow Characteristics in Above Ground and Underground Petroleum Pipelines

In this proposed study, all environmental factors affecting the aboveground and buried pipes, such as solar radiation and temperature, and soil temperature, have been studied on the characteristics of flow inside the aboveground and underground pipelines by building a mathematical model using MATLAB based on energy balance equations. From the mathematical model, the effect of solar radiation on the aboveground section of the pipeline is significate. During March and an inlet temperature of 34 °C, the pipeline outlet fluid temperature will rise to 50 °C. Other parameters affecting the aboveground section of the pipeline, such as ambient temperature and wind speed, have a much smaller effect on the fluid temperature, and the temperature difference is approximately 4 °C between the highest and lowest pipeline outlet fluid temperature. The result for the underground section of the pipeline showed that the main affecting parameter on the fluid temperature is the burry depth of the pipeline, the deeper the pipeline depth the lower the temperature variation and the lower fluid temperature can be seen, at 1 meter of bury depth the minimum and maximum fluid temperature was 18 °C and 36 °C respectively, and at 5 meters of bury depth, the minimum and maximum fluid temperature was 26 °C and 31 °C respectively. This study also checks different process parameters. Some of these are fluid flow, pipe diameter, and pipe material. The effect of the fluid flow and pipe diameter has a similar impact on the fluid temperature (while fixing all the other parameters), the higher the fluid flow or the smaller the pipe diameter resulted in a better heat transfer and more considerable temperature difference, and vice versa. The final process parameter, pipe material, had little to no effect on the fluid temperature variation.

Experimental investigation of flow characteristics of a jet in low atmospheric pressure conditions on the Tibetan Plateau

The indoor humidity of heated buildings on the Tibetan Plateau can be as low as 5%RH. Indoor air humidification is very important to people's life and health. Due to the low atmospheric pressure on the plateau, the air physical parameters and wet component diffusion characteristics are different from those of standard atmospheric pressure. This paper investigates experimentally the effects of horizontal and vertical wet jets with various initial velocities, pipe diameters, ambient temperatures, and moisture temperatures on the indoor temperature and humidity field. It is shown that low atmospheric pressure will lead to an increase in relative humidity nearly the jet outlet, but the effective moisture delivery distance becomes shorter and the actual moisture load increases. When the same relative humidity is reached, the specific humidity under low atmospheric pressure is about 1.5–2.5 times as that under standard atmospheric pressure. The average relative humidity of jets produced by the ultrasonic humidification source is 10% higher than the evaporative humidification source during the same time. During the actual humidification process, it is necessary to consider the balance between the initial velocity of the jet and the humidification distance and select the jet tube diameter according to the humidification space area. Additionally, choosing a jet with a temperature slightly higher than the ambient temperature can avoid reducing the indoor temperature. This study should be helpful to the plateau humidification jet characteristics and parameter selection.

Identification of Subsurface Water Pipe Based on Horizontal to Vertical Spectral Ratio (HVSR)

Disruption of water distribution through underground pipe is a frequent case. As a handling, a method that can detect disturbances from subsurface pipe is needed. Microtremor is one of the geophysical methods that can provide an overview of the subsurface. Processing is done with the HVSR method with input in the form of seismic waves in the time domain which is then processed using Geopsy software to get output in the form of dominant frequency values, amplification, and H/V spectrum. The data used in this study are primary data obtained from data acquisition with a total of 60 measurement points. The distance between points is given 5 dm with a measurement time of 10 minutes for each point. The study was conducted on pipe with empty, partially filled with water, and fully filled with water with a pipe diameter of 0,9 dm. The pattern in each pipe condition from the modeling results appears at a frequency of 0-10 Hz. The difference in the range of amplification values in pipe anomalies is due to different levels of water content which can be concluded that pipe filled with water have higher amplification than empty pipe and be showed in 3D modelling.

Simulation and analysis of hydraulic transition process based on mechanical hydraulics.

With the scarcity of water resources in various regions, the pressure on water supply projects is also increasing, which has led to a sharp increase in the water hammer effect in water supply pump projects. In response to this issue, the study proposes to apply a unidirectional pressure regulating tower based on mechanical hydraulic technology to water hammer protection in water supply pumps. In addition, the study also optimizes the calculation method of water hammer and designs one simulation software, which is used to simulate and analyze the proposed water hammer protection measures. The study first determines through simulation software that the optimal initial water level of the unidirectional pressure regulating tower is 2m and the optimal diameter of the make-up water pipe is 600 mm. Afterwards, simulation analysis is conducted on different water hammer protection measures, and it is found that the maximum pressure of the water hammer under the proposed protection measures is the lowest, at 14.8m, which was lower than the comparison measures. In addition, according to expert ratings, the average protective effect rating of protective measure 1 by relevant technical personnel is 9.4 points, which is better than the comparative measure. The above results indicate that through the simulation analysis of hydraulic transition process based on mechanical hydraulics, it can be found that the water hammer protection measures proposed in the study have good protective functions and can effectively reduce the water hammer effect in water supply engineering.

Development of the method for determining the deformation parameters and remidal stresses of metal in the manufacture of straight-seached pipes of large diameter using expansion

Since 2020, in Ukraine, LLC NVP «UKRTRUBOIZOL» began to operate a technological line for the production of large-diameter pipes (TVD) for main oil and gas pipelines with a hydromechanical expander. From 2023, interstate GOST 20295-85 and GOST 10706-76 ceased to be valid in Ukraine. Formulation of the problem. Ukrainian standards are needed. It is necessary to determine the rational values of the deformations and the effectiveness of the expansion to reduce the residual stresses in the metal of the pipes. Goal. Development of Ukrainian standards for TVD production and determination of the effect of expansion on residual stresses. Method. The method of cutting rings was used. The results. Developed and implemented with the participation of author: DSTU 9219:2023; DSTU 9218:2023 and TU 24.2–05757883–095:2022. Pipes with a diameter of 630 mm, with a wall of 8 mm, made of S335 steel and hot-rolled rolled sheet were studied. The opening between the longitudinal edges of the pipe blank after bending was 70-80 mm. For the ring after welding, the opening was 180 mm and for the rings expanded by 0.8%, 1.2% and 0.4% -58-53 mm. This indicates that the residual expansion stresses were much smaller than in the pipe after welding the seam, and the amount of expansion change from 0.4% to 1.2% does not affect the residual stresses. Scientific novelty. For the first time, for the JCOE technology of production of TVD from rolled hot-rolled sheet, the influence of expansion on residual stresses was determined experimentally. It was shown that the opening of the rings during expansion is significantly reduced. For the first time, the influence of the amount of expansion on the reduction of residual stresses was determined for the JCOE technology of TVD production. It is shown that deformations of 0.4-1.2% give the same opening of the rings after expansion. Practical significance. The obtained results can be useful for the personnel of steel welded TVD production enterprises and project organizations sn the design of oil and gas pipelines

Proactive exfiltration severity management in sewer networks: A hyperparameter optimization for two-tiered machine learning prediction

Effective management of aging sewer pipelines requires accurate analysis of sewer pipeline exfiltration. Previous research studies have not paid attention to proposing an index to represent the exfiltration severity. To this end, this study introduces a novel Exfiltration Severity Index (ESI) by considering the frequency and severity of defects captured from Closed-Circuit Television (CCTV) reports. To address the need for a proactive tool that automates the exfiltration estimation and reduces dependence on CCTV reports, we leverage Machine Learning (ML) and Deep Learning (DL) models to predict sewer exfiltration occurrence and severity. In this regard, our proposed methodology comprises a series of steps that start by computing the ESI of pipeline segments considering the frequency, type, and severity of defects. After that, physical, environmental, and climatic factors influencing pipeline exfiltration are gathered and aggregated to build predictive models. We compare the performance of six ML models and two DL models, developed in two tiers to predict exfiltration occurrence and severity, respectively. The hyperparameters of each model are optimized using GridSearchCV to enhance prediction accuracy. Among the eight algorithms, the light gradient-boosting machine performs best, with 71% and 85% accuracy in the first and second tiers, respectively. Furthermore, our study investigates the influence of various factors on pipeline exfiltration and reveals that pipe diameter and population have the most significant impact on exfiltration occurrence and severity. Our method provides a valuable tool for managing sewer pipeline exfiltration and can be utilized to prioritize sewer network maintenance and repair efforts.

Study on the Influence of Urban Water Supply Pipeline Leakage on the Scouring Failure Law of Cohesive Soil Subgrade

Urban water supply pipelines serve as vital lifelines for urban operations. However, the occurrence of underground pipeline leakage, caused by various factors, results in significant water loss and gives rise to safety hazards such as pavement collapse due to the erosive action of leaking water on the overlying soil. To conduct a more comprehensive investigation into the erosion characteristics of the leaking jet on the soil, this study employed a custom-built soil-test system to investigate the erosive effects of leakage from the water supply pipe network on the clay roadbed above. The study considered water flow rate, leakage port size, and leakage angle as influential factors. The experimental results demonstrated that reducing the water flow rate significantly enhances the soil’s erosion resistance. There is a positive correlation between the caliber of pipe leakage, pipe diameter, and the erosion rate of the soil cavity. Under identical conditions, the erosion rate of the specimen increased consistently with an increase in the leakage port angle. The study also investigated and summarized the curve depicting the formation of soil cavities. The aforementioned findings offer valuable insights for the implementation of reinforcement measures using fine-grained cohesive soil backfill in urban water supply pipelines.

Axial and azimuthal development of disturbance waves in annular flow in a horizontal pipe

Transformation of gas-liquid flow in a horizontal pipe is investigated during the transition from stratified to annular flow pattern. Using Brightness-Based Laser-Induced Fluorescence technique, spatiotemporal evolution of liquid film thickness is analyzed over the downstream distance range of about 900 mm (45 pipe diameters), starting from the inlet. The measurements are carried out for three values of azimuthal angle θ: 0 (pipe bottom), 90°, and 180°, to track the circumferential spreading of liquid film and disturbance waves. At large gas velocities, thin liquid film is dragged upwards before the formation of large waves. The disturbance waves are created at the pipe bottom and spread circumferentially as they propagate downstream, over the already-wetted pipe walls. At large enough liquid flow rates, the spreading disturbance waves reach the pipe ceiling and form full rings around the circumference. The frequency and velocity of the disturbance waves eventually become the same around the pipe circumference; the disturbance wave amplitude and the base film thickness decrease with θ. The base film is more uniform around the circumference compared to the wave amplitude. At lower liquid flow rates, the disturbance waves cover only a part of pipe circumference. Their edges demonstrate oscillatory circumferential spreading, which ends by deceleration and decay of the edges. The upper part of the pipe may be wetted by a thin base film layer, covered only with ripples, or remain dry. At low gas speeds and large liquid flow rates, occasional splashing of large waves over the pipe ceiling without pre-wetting by the thin film is possible; however, the remaining film drains downward and no stable annular film is maintained. Liquid droplets, entrained from the pipe bottom and depositing in the upper parts of the pipe, are gathered in trains of creeping pendant droplets at the very top part of the pipe; no continuous wetting is achieved due to droplet deposition.

Analisis Tegangan pada Jalur Pipa dengan Pemindahan Penopang Akibat Longsor

Landslide that has done in the Chevron, Minas oil field area on 4A-54 pipeline section, resulted the failure at one of pipe supports of 12in and 8in pipe diameter. The Action is planned to remove pipe support number 2 which affected a landslide, and move pipe supports number 1 and 3 that is closer to pipe support number 2. For this reason, action is being taken to redesign the piping system so that the pipe line can function safely. Allowable piping design criteria are used based on the maximum distance between pipe supports and maximum stress based on ASME B31.3 standards not greater than 20,000 Psi. Based on the calculation results, the allowable maximum distance between 12 in pipe supports is 16.064 m. Base on stress simulation, the maximum combined tension and torsion stress on the pipeline at that distance is 17606.44 Psi, 12% less than the allowable stress. The combine stress in the pipe produce displacement of pipe in the x-axis direction of 0.074 m and -0.95o.

A Gas Flow Measurement System Based on Lead Zirconate Titanate Piezoelectric Micromachined Ultrasonic Transducer.

Ultrasonic flowmeter is one of the most widely used devices in flow measurement. Traditional bulk piezoelectric ceramic transducers restrict their application to small pipe diameters. In this paper, we propose an ultrasonic gas flowmeter based on a PZT piezoelectric micromachined ultrasonic transducer (PMUT) array. Two PMUT arrays with a resonant frequency of 125 kHz are used as the sensitive elements of the ultrasonic gas flowmeter to realize alternate transmission and reception of ultrasonic signals. The sensor contains 5 × 5 circular elements with a size of 3.7 × 3.7 mm2. An FPGA with a resolution of ns is used to process the received signal, and a flow system with overlapping acoustic paths and flow paths is designed. Compared with traditional measurement methods, the sensitivity is greatly improved. The flow system achieves high-precision measurement of gas flow in a 20 mm pipe diameter. The flow measurement range is 0.5-7 m/s and the relative error of correction is within 4%.

Levelized-cost optimal design of long-distance CO2 transportation facilities

With the need to develop carbon-neutral technologies and reduce greenhouse gas emissions to avert climate change, carbon capture, storage and utilization (CCS/CCUS) techniques have emerged as effective pathways to achieve these targets. Despite being a critical aspect of CCS/CCUS chains, carbon dioxide transport is an astonishingly under-researched domain. This study presents an efficient and robust computational model to cost-optimally design of long distance carbon dioxide transport pipelines (trunk) connecting a source-sink pair. Several physical and topographical conditions have been accounted for to propose optimal design solutions for different case studies. This involves right-sizing of pipes and booster stations and placing the latter at the right locations. The implications of uncertainties in modelling of the costs have also been studied. The model is very flexible and general in the sense that it can work with a variety of cost models and design constraints. Further, unlike most studies, an appropriate hydrodynamic model for pressure and density calculations has been incorporated. Genetic algorithm and interior point methods have been employed to find optimal design parameters that minimize the “per ton levelized transportation cost”, and their performances have been compared. Results demonstrate that pipe diameters and elevation changes have the most significant impact on the pressure drop, optimal design parameters and the cost. Lastly, several improvements have been made over our previous study in this domain.

Cooling Strategy Optimization of a Permanent Magnet Synchronous Motor

In this study, 250 kW, 9 phase, outer rotor types of Permanent Magnet Synchronous Motor (PMSM) are taken into consideration. To optimize the cooling efficiency of the motor, firstly, the motor geometry is obtained, and the e-magnetic model of the geometry is validated with the manufacturer`s data. Secondly, by using the validated e-magnetic model, the cooling system of the motor was analyzed by using the thermal model of the Motor-CAD. The thermal model is also validated with the real-time experiments which are held on an electric bus at constant speed experimentally. For finding the best cooling strategy for the motor, after validation, the effect of the mass flow rate, the type of the cooling refrigerant, the cooling pipe diameter size, and the change of torque are analyzed on the validated model. The results showed us that mass flow rate and torque have a significant effect on winding temperature, and the Taguchi method showed that [mass flow rate (A)=50 l/min, pipe diameter (B) = 17.7 mm, number of turns (C)=20, type of fluid (D)= EGW50/50, torque (E)=2000 Nm] is the best cooling design parameters for the cooling strategy of the considered PMSM.

Development and application of an integrated system of dewatering and recharge for the deep foundation pit

A large amount of pumping in the deep foundation pit will reduce the groundwater level and lead to surface cracking, building settlement, ground collapse and spring water cut-off. And the groundwater recharge is a good control measure. An integrated system of dewatering and recharge for the deep foundation pit is developed, and it is mainly composed of a pumping system, an assembled water tank, a variable frequency pressure system, a cleaning and filtering system, a recharge pressure tank, a recharge well system and a central control system. This system can realize intelligent automatic control according to the monitoring data. It does not require staff to operate on site and can be remotely adjusted by computer or mobile phone. Taking a subway station under construction in Jinan as the background, the single well recharge test and the multiple wells recharge test were carried out. It can be found that with the increase of recharge pressure, the recharge volume gradually increases, but the increasing trend is smaller and smaller. The relationship between the groundwater level and the recharge volume is a logarithmic function. Blindly increasing recharge wells may not improve the overall reinjection volume, and the relationship between the number of recharge wells, the diameter of reinjection pipes and the maximum recharge capacity of the variable frequency pressure system needs to be comprehensively considered.

A study on pipe failure analysis in water distribution systems using logistic regression

Abstract This study presents a pipe failure analysis that aims to identify key factors affecting pipe failure in a pilot study area (PSA). For this purpose, pipe failures that occurred in the PSA were recorded for 2 years. Recorded pipe failures were integrated into the existing geographical information systems of the PSA and then visualized. Then, the logistic regression model that calculates failure probability with unbalanced and small- and medium-sized data was performed to analyze pipe failures. Pipe material, age, diameter, burst pressure, and average water pressure are the factors used in the study. The developed model achieved a success rate of 70.1%, suggesting that it can predict a considerable portion of pipe failures with a relatively satisfactory performance. Findings show that the failure probability of pipes with an age greater than 20 years is 1.675 times higher than that of pipes with an age less than 20 years. Moreover, polyvinyl chloride pipes are 5.265 times and high-density polyethylene pipes are 9.027 times more likely to fail than ductile pipes. Further research should delve into the impacts of the number of service connections, pipe lengths, and traffic load on pipe failures.

Numerical analysis of concentric jet impingement heat transfer to the concave surface of the cone

This work includes numerical investigation of concentric jet impingement heat transfer to the concave surface of 30° apex angle conical surface. Heat transfer results are represented in terms of nondimensional heat transfer coefficient Nusselt number along the slant edge of the cone. Turbulence intensity, static pressure distribution along slant edge of the cone, and velocity contours in the domain are also presented for a detail understanding of the flow behavior. Different geometrical parameters like diameter of pipe (10 mm, 14 mm, and 20 mm) and L/D (4.25, 6.25, and 10.25) are considered for heat transfer analysis. Jet Reynolds number is varied between 25000 and 82000 for each diameter and L/D case. It is observed that Nusselt number value is minimum close to the apex of the cone due to stagnation region, then increases with increase in the distance from the apex of the cone and becomes maximum due to maxima in the turbulence intensity and decreases with increases in the distance. Nusselt number value decreases with increase in the L/D. Nusselt number increases with increase in the jet Reynolds number. There is an insignificant influence of the diameter of pipe on Nusselt number for identical jet Reynolds number and L/D.

Genetic Algorithm Based Combinatorial Optimization for the Optimal Design of Water Distribution Network of Gurudeniya Service Zone, Sri Lanka

This paper brings an in-detail Genetic Algorithm (GA) based combinatorial optimization method used for the optimal design of the water distribution network (WDN) of Gurudeniya Service Zone, Sri Lanka. GAmimics the survival of the fittest principle of nature to develop a search process. Methodology employs fuzzy combinations of pipe diameters to check their suitability to be considered as the cost-effective optimal design solutions. Furthermore, the hydraulic constraints were implicitly evaluated within the GA itself in its aim for reaching the global optimum solution. Upon analysis, the results of GA approach delivered satisfactory design outputs.

Accurate prediction of pressure losses using machine learning for the pipeline transportation of emulsions

One of the significant challenges to designing an emulsion transportation system is predicting frictional pressure losses with confidence. The state-of-the-art method for enhancing reliability in prediction is to employ artificial intelligence (AI) based on various machine learning (ML) tools. Six traditional and tree-based ML algorithms were analyzed for the prediction in the current study. A rigorous feature importance study using RFECV method and relevant statistical analysis was conducted to identify the parameters that significantly contributed to the prediction. Among 16 input variables, the fluid velocity, mass flow rate, and pipe diameter were evaluated as the top predictors to estimate the frictional pressure losses. The significance of the contributing parameters was further validated by estimation error trend analyses. A comprehensive assessment of the regression models demonstrated an ensemble of the top three regressors to excel over all other ML and theoretical models. The ensemble regressor showcased exceptional performance, as evidenced by its high R2 value of 99.7 % and an AUC-ROC score of 98 %. These results were statistically significant, as there was a noticeable difference (within a 95 % confidence interval) compared to the estimations of the three base models. In terms of estimation error, the ensemble model outperformed the top base regressor by demonstrating improvements of 6.6 %, 11.1 %, and 12.75 % for the RMSE, MAE, and CV_MSE evaluation metrics, respectively. The precise and robust estimations achieved by the best regression model in this study further highlight the effectiveness of AI in the field of pipeline engineering.

Design Parameters Investigation on Sand Transportation Characteristics of V-Inclined Pipe Based on Eulerian–Eulerian Two-Phase Flow Model

During the operation of the water transportation pipelines in the upstream of the Yellow River, varying degrees of sand deposition often occur under a low flow rate. Taking into account the effect of different pipe inclinations, pipe diameters, and inlet sand content, the Eulerian–Eulerian two-phase model was applied in the numerical simulation of sediment-laden flow in a V-inclined pipe. The results indicate that there is a significant difference between a V-inclined pipe and horizontal pipe affected by gravity. Compared with the downward inclined pipe, sand deposition is evident in the upward inclined pipe. The high-velocity region moves upward and the asymmetry of the cross-sectional velocity increases. As the pipe diameter increases, the interaction between sand and the wall as well as the degree of turbulence decrease, so that the distribution of sand volume concentration across the cross section will be more uniform. Under different inlet sand content, the lowest point of the pipe experiences the most sand deposition, with sand volume concentration and velocity distribution across the cross-sections becoming uneven as inlet sand content increases. The location of the maximum liquid velocity varies from section to section. When the inlet sand content increases from 0.42% to 5%, the liquid velocity of the pipe cross-section no longer satisfies the rule of high velocity for middle and low velocity near the wall.

A Method for Predicting the Load Interaction between Reinforced Thermoplastic Pipe and Sandy Soil Based on Model Testing

This study aims to investigate the interaction between reinforced thermoplastic pipes (RTPs) and sandy soil. The mechanical properties of sandy soil in the South China Sea region were determined through shear tests to obtain fundamental data. Subsequently, a specialized experimental setup was designed and assembled to study the pipe–soil interaction, specifically measuring the lateral soil resistance of flexible pipes at varying burial depths. Data analysis revealed the relationship between soil resistance, lateral displacement, and initial burial depth. To simulate the mechanical behavior of the pipe–soil interaction, the coupled Eulerian–Lagrangian (CEL) method was employed for numerical simulations. The research findings indicate that the lateral soil resistance is influenced by the uplift height and accumulation width of the soil ahead of the pipe. Within a lateral displacement range of 0.5 times the pipe diameter (0.5D), the lateral soil resistance rapidly increases, resulting in a soil uplift along the circumferential direction of the pipe. This process not only enhances the load-bearing capacity of the pipe but also increases the accumulated soil resistance, consequently expanding the soil failure zone. Furthermore, the ultimate soil resistance exhibits an increasing trend with an increasing burial depth. Once the pipe reaches a certain burial depth, the uplift height of the soil reaches a critical state. To address the grid distortion caused by soil deformation, numerical simulations based on the CEL method effectively modeled the pipe–soil interaction forces under significant lateral displacements, exhibiting good agreement with the experimental results. This study provides a solution for investigating soil resistance in submarine pipelines, thereby contributing significantly to the design and performance prediction of underwater pipelines.