Search Results (14)

The implementation of a decentralized blue–green infrastructure (BGI) is a key strategy in climate adaptation and stormwater management. However, the integration of urban trees into the multifunctional infrastructure remains insufficiently addressed, particularly regarding rooting space in dense urban environments. Addressing this gap, the BoRSiS project developed the soil-pipe system (SPS), which repurposes the existing underground pipe trenches and roadway space to provide trees with significantly larger root zones without competing for additional urban space. This enhances tree-related ecosystem services, such as cooling, air purification, and runoff reduction. The SPS serves as a stormwater retention system by capturing excess rainwater during heavy precipitation events of up to 180 min, reducing the pressure on drainage systems. System evaluations show that, on average, each SPS module (20 m trench length) can store 1028–1285 L of water, enabling a moisture supply to trees for 3.4 to 25.7 days depending on the species and site conditions. This capacity allows the system to buffer short-term drought periods, which, according to climate data, recur with frequencies of 9 (7-day) and 2 (14-day) events per year. Geotechnical and economic assessments confirm the system stability and cost-efficiency. These findings position the SPS as a scalable, multifunctional solution for urban climate adaptation, tree vitality, and a resilient infrastructure. Full article

This study introduces an integrated Multi-Criteria Decision Making (MCDM) methodology combining the Analytic Hierarchy Process (AHP), Entropy Weight Method (EWM), and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) to optimize the selection of municipal water supply pipeline materials. A comprehensive evaluation system encompassing thirteen criteria across technical, economic, and safety dimensions was developed to ensure balanced decision-making. The method employs a weight determination model based on Jaynes’ maximum entropy theory to harmonize subjective AHP-derived weights with objective EWM-derived weights, addressing inconsistencies in traditional evaluation approaches. This framework was validated in a case study involving a DN400 pipeline project in Jiaxing, Zhejiang Province, China, where five materials—steel, ductile iron, reinforced concrete, High-Density Polyethylene (HDPE), and Unplasticized Polyvinyl Chloride (UPVC)—were assessed using quantitative and qualitative criteria. Results identified HDPE as the most suitable material, followed by UPVC and reinforced concrete, with steel ranking lowest. Comparative analysis with alternative MCDM techniques demonstrated the robustness of the proposed method in balancing diverse factors, dynamically adjusting to project-specific priorities. The study highlights the flexibility of this approach, which can extend to other infrastructure applications, such as drainage systems or the adoption of innovative materials like glass fiber-reinforced plastic (GFRP) mortar pipes. By integrating subjective and objective perspectives, the methodology offers a robust tool for designing sustainable, efficient, and cost-effective municipal water supply networks. Full article

Traditionally, acoustic methods for leak inspection are based on the measurement of the acceleration of the external pipe wall or of the acoustic pressure in the pipe. This work presents an alternative inspection methodology based on measuring the acoustic velocity vector in the fluid filling the pipe. Unlike the acoustic pressure, the acoustic quantity is very sensitive to the presence of a pipe wall defect. Such defects are important to detect before they develop into leaks, which can lead to the loss of water, environmental pollution and service disruption. A new sensor design is proposed to measure the acoustic velocity vector in a pipe. A model is presented to demonstrate the underpinning theory behind this new sensor technology. The results of this model are compared with experimental data based on measurements of the acoustic velocity in an exhumed section of ductile iron pipe. These sensors can be deployed on robots to autonomously monitor the deterioration of buried pipes to support proactive asset management at a low operational cost. Full article

Water hammer (WH) is a critical phenomenon in fluid-filled piping systems that can lead to severe pressure surges and structural damage. The characteristics of the pipe material, geometry, and support conditions play a crucial role in the fluid–structure interaction (FSI) during WH events. This study investigates the impact of various pipe parameters, including material, length, thickness, and diameter, on the WH behavior using an FSI-based numerical approach. A comprehensive computational model was developed based on the algorithm presented in Delft Hydraulics Benchmark Problem (A) to simulate the WH phenomenon in pipes made of different materials, such as steel, copper, ductile iron, PPR (polypropylene random copolymer), and GRP (glass-reinforced plastic). This study examines the influence of pipe parameters on WH performance in pipelines, utilizing FSI to analyze the phenomenon. The results show that the pipe material has a significant influence on the pressure wave speed, stress wave propagation, and the overall system response during WH. Pipes with lower modulus of elasticity, such as PPR and GRP, exhibit lower pressure wave speeds but higher stress wave speeds compared with steel pipes. Increasing the elastic modulus, pipe wall thickness, length, and diameter enhances the pipe’s stiffness and impacts the timing, magnitude of pressure surges, and the likelihood of cavitation. The findings of this study provide valuable insights into the design and mitigation of WH in piping systems. Full article

Online surface inspection systems have gradually found applications in industrial settings. However, the manual effort required to sift through a vast amount of data to identify defect images remains costly. This study delves into a self-supervised binary classification algorithm for addressing the task of defect image classification within ductile cast iron pipe (DCIP) images. Leveraging the CutPaste-Mix data augmentation strategy, we combine defect-free data with enhanced data to input into a deep convolutional neural network. Through Gaussian Density Estimation, we compute anomaly scores to achieve the classification of abnormal regions. Our approach has been implemented in real-world scenarios, involving equipment installation, data collection, and experimentation. The results demonstrate the robust performance of our method, in both the DCIP image dataset and practical field application, achieving an impressive 99.5 AUC (Area Under Curve). This presents a cost-effective means of providing data support for subsequent DCIP surface inspection model training. Full article

In the current investigation, a vertically continuous casting technique was used to produce a ductile iron pipe. The ductile iron was austempered, and the tribological behavior of austempered ductile iron (ADI) was examined under various service conditions. The finding demonstrated that ADI’s tribological behaviors were significantly affected by normal loads and sliding speeds. Spheroidal graphite was preferential to be transferred from the matrix to the tribosurface in ADI under high normal loads, and high sliding speed accelerated the formation of the graphite lubricating layer on the tribosurface. Consequently, ADI’s friction coefficient dropped with the increase in normal load and sliding speed. When compared with the friction coefficient, the wear rate of ADI displayed a similar tendency in that it increased with an increase in normal load and reduced with an increase in sliding speed. The worn surface indicated that adhesive wear at low sliding speeds and abrasive wear at high sliding speeds were the primary wear mechanisms for ADI. Full article

Sewer pipeline failures pose significant threats to the environment and public health. To tackle these repercussions, many deterioration models have been developed to predict the conditions of sewer pipes, most of which are based on CCTV inspection reports. However, these reports are prone to errors due to their subjective nature and human involvement. More importantly, there are insufficient data to develop prudent deterioration models. To address these shortcomings, this paper aims to develop a CCTV-based deterioration model for sewer pipes using Artificial Intelligence (AI). The AI-based model relies on the integration of an unsupervised, multilinear regression technique and Weibull analysis. Findings derived from the Weibull deterioration curve indicate that the useful service life for concrete and vitrified clay pipes are 79 years and 48 years, respectively. The regression models show that the R² value for vitrified clay sewer pipes, concrete sewer pipes, and ductile iron sewer pipes are 71.18%, 71.47%, and 81.51%, respectively, and 73.69% for concrete stormwater pipes. To illustrate the impact of various factors on sewer pipes, sensitivity analyses under different scenarios are conducted. These analyses indicate that pipe diameter has a significant influence on sewer pipe deterioration, with little impact on stormwater pipes. These findings would guide decision makers in identifying critical pipes and taking necessary precautionary measures. Further, this provides a sound basis for prioritizing maintenance actions, which would pave the way for designing sustainable urban drainage systems for cities. Full article

Underground pipelines are vital parts to urban water supply, gas supply, and other lifeline systems, affecting the sustainable development of cities to a great extent. The pipeline joint, which is a weak link, may be seriously damaged during natural disasters such as earthquakes. The failure of pipe joints can cause leakage accidents, resulting in system failure and interruption, and even some secondary disasters. Herein, based on uniaxial and plane tensile test results of a T-rubber gasket material, the assembly process and sealing performance of a T-rubber gasket joint of a ductile iron pipe are numerically simulated using the Ogden third-order strain energy density function to fit the material constant. The simulation accounts for severe nonlinearities, including large deformations, hyperelasticity, and complex contacts. The effects of the assembly friction coefficient, assembly depth, and radial clearance deviation of the socket and spigot on the seal contact pressure are analyzed. The results suggest that the entire history of the deformation and stress variations during assembly can be clearly visualized and accurately calculated. For the different friction coefficients, the assembly depth corresponding to the sliding friction condition of the spigot pipe was 74 mm, while the minimum pushing force required to assemble the T-rubber gasket joint of a DN300 ductile iron pipe was 6.8 kN at the ideal situation with a friction coefficient of 0. The effective contact pressure of the rubber gasket seepage surface under various operating conditions is much higher than the normal pressure of municipal pipelines, thus indicating that the rubber gasket joint exhibits the ideal sealing performance. Furthermore, a certain deviation, which is about 20 mm, is allowed for the assembly depth of the rubber gasket joint such that the axial displacement of the pipe joint can be adapted under an earthquake or ground displacement. Full article

In the present study, the effect of pipe materials on water quality as well as the microbial community was researched with static devices as well as dynamic ones. Five kinds of pipe materials (SP: steel plastic composite pipe, SS: stainless steel pipe, DI: ductile iron pipe, CI: cast iron pipe, GS: galvanized steel pipe) were chosen, and the soaking experiment was carried out with bench-scale devices. To further investigate the performance of pipe materials over a long term, a pilot-scale simulated drinking water distribution system was constructed, and the water quality parameters were monitored for six months. The pipe materials were ranked as SP, DI, and CI by the order of increasing turbidity, COD_Mn, and NH₃-N. Furthermore, the biofilm samples were analyzed via pyrosequencing and COG functional categories. The DI biofilm possessed the highest bacterial diversity with a Shannon index of 3.56, followed by SP (3.14) and CI (0.77). The presence of nitrate-reducing bacteria (NRB), iron-oxidizing bacteria (IOB), iron-reducing bacteria (IRB), and sulfate-reducing bacteria (SRB)was identified, and NRB composed the largest share in all pipe materials (13.0%–17.2%), with other redox bacteria making up a minor proportion (0.02%–1.52%). NRB and IRB inhibited the corrosion process while IOB and SRB enhanced it. Most dominant genera present in samples were derived firstly from soil or active sludge, indicating a turbidity problem due to soil contamination in the distribution network. Full article

Water pipe surface deterioration is the result of continuous electrochemical reactions attacking the surface due to the interaction of the pipe surface with environments through the time function. The study presents corrosion characterization at the surface and sub-surface of damaged ductile iron pipe (DIP) and galvanized steel (GS) pipes which served for more than 40 and 20 years, respectively. The samples were obtained from Addis Ababa city water distribution system for the analysis of corrosion morphology patterns at different surface layers. Mountains 8.2 surface analysis software was utilized based on the ISO 25178-2 watershed segmentation method to investigate corrosion features of damaged pipe surface and to evaluate maximum pit depth, area, and volume in-situ condition. Based on the analysis maximum values of pit depth, area and volume were 380 $\mathsf{\mu }$ m, 4000 $\mathsf{\mu }$m², and 200,000 $\mathsf{\mu }$m³, respectively, after 25% loss of the original 8 mm thickness of DIP. Similarly, the pit depth of the GS pipe was 390 $\mathsf{\mu }\mathrm{m}$ whereas the maximum pit area and volume are 4000 $\mathsf{\mu }$m² and 16,000 $\mathsf{\mu }$m³, respectively. In addition, characterizations of new pipes were evaluated to study microstructures by using an optical microscope (OM), and a scanning electron microscope (SEM) was used to analyze corrosion morphologies. Based on the SEM analysis, cracks were observed at the sub-surface layer of the pipes. The results show that uniform corrosion attacked the external pipe surface whereas pitting corrosion damaged the subsurface of pipes. The output of this study will be utilized by water suppliers and industries to investigate corrosion phenomena at any damage stage. Full article

Cast iron is primarily used in buried piping to transport water in the fire protection system of nuclear power plants; ductile cast iron is generally used for domestic nuclear power plants. In general, the fluid used as fire-extinguishing water in such fire protection systems is tap water, and corrosion inhibitors are not currently added. In this study, the synergistic effect of an adsorption barrier (monoethanolamine) and oxidized film in an environment with a corrosion inhibitor (tungstate) is examined, and the corresponding passivation properties are presented. An immersion corrosion test and electrochemical test in tap water to which only tungstate was added showed suppression of corrosion compared to molybdate at the same concentration. The polarization resistance value of a passivation film in tap water mixed with monoethanolamine and tungstate showed better results than that of the molybdate control. A surface analysis in mixed addition tap water also demonstrated that oxygen ions were sufficiently distributed, including at some spheroidized graphite sites, when tungstate was added compared to molybdate. In addition, the amount of tungsten ions adsorbed on the surface was larger than that of molybdenum ions, and it was confirmed that tungsten ions were evenly distributed over the entire surface. Full article

This article analyses the relation between the failures that occurred in the water supply network and the road traffic in the city of Cluj-Napoca in Romania. The calculations in this case study were made using the Autodesk Robot Structural Analysis Professional 2011 software. In the case study, the following types of pipes were analysed: steel, gray cast iron, ductile cast iron and high density polyethylene (HDPE). While in most studies only a few sections of pipelines, several types of pipelines and certain mounting depths have been analysed, the case study presented analyses the entire water supply system of a city with a population of 324,576 inhabitants, whose water supply system has a length of 479 km. The results of the research are useful in the design phase of water distribution networks, so depending on the type of pipe material, the minimum depth of installation can be indicated, so as to avoid the failure of the pipes due to road traffic. From this perspective, similar studies could also be carried out regarding the negative influence of road traffic on sewerage networks, gas networks and heating networks. Full article

Some forensic in situ investigations, such as those needed in transportation (for aviation, maritime, road, or rail accidents) or for parts working under harsh conditions (e.g., pipes or turbines) would benefit from a method/technique that distinguishes ductile from brittle fractures of metals—as material defects are one of the potential causes of incidents. Nowadays, the gold standard in material studies is represented by scanning electron microscopy (SEM). However, SEM instruments are large, expensive, time-consuming, and lab-based; hence, in situ measurements are impossible. To tackle these issues, we propose as an alternative, lower-cost, sufficiently high-resolution technique, Optical Coherence Tomography (OCT) to perform fracture analysis by obtaining the topography of metallic surfaces. Several metals have been considered in this study: low soft carbon steels, lamellar graphite cast iron, an antifriction alloy, high-quality rolled steel, stainless steel, and ductile cast iron. An in-house developed Swept Source (SS) OCT system, Master-Slave (MS) enhanced is used, and height profiles of the samples’ surfaces were generated. Two configurations were used: one where the dimension of the voxel was 1000 μm³ and a second one of 160 μm³—with a 10 μm and a 4 μm transversal resolution, respectively. These height profiles allowed for concluding that the carbon steel samples were subject to ductile fracture, while the cast iron and antifriction alloy samples were subjected to brittle fracture. The validation of OCT images has been made with SEM images obtained with a 4 nm resolution. Although the OCT images are of a much lower resolution than the SEM ones, we demonstrate that they are sufficiently good to obtain clear images of the grains of the metallic materials and thus to distinguish between ductile and brittle fractures—especially with the higher resolution MS/SS-OCT system. The investigation is finally extended to the most useful case of fatigue fracture of metals, and we demonstrate that OCT is able to replace SEM for such investigations as well. Full article

Pulsed Eddy Current (PEC) sensing is used for Non-Destructive Evaluation (NDE) of the structural integrity of metallic structures in the aircraft, railway, oil and gas sectors. Urban water utilities also have extensive large ferromagnetic structures in the form of critical pressure pipe systems made of grey cast iron, ductile cast iron and mild steel. The associated material properties render NDE of these pipes by means of electromagnetic sensing a necessity. In recent years PEC sensing has established itself as a state-of-the-art NDE technique in the critical water pipe sector. This paper presents advancements to PEC inspection in view of the specific information demanded from water utilities along with the challenges encountered in this sector. Operating principles of the sensor architecture suitable for application on critical pipes are presented with the associated sensor design and calibration strategy. A Gaussian process-based approach is applied to model a functional relationship between a PEC signal feature and critical pipe wall thickness. A case study demonstrates the sensor’s behaviour on a grey cast iron pipe and discusses the implications of the observed results and challenges relating to this application. Full article