Cement Pipe Research Articles

Towards more realistic stochastic modelling of leakage in water distribution systems

ABSTRACT A new stochastic model is developed to predict leak types and sizes in water distribution systems. By linking records of actual failures in water networks with new tools for stochastic modelling, the study provides more accurate estimates of network leakage behaviour. District metered areas (DMAs) have been adopted internationally as best practice for monitoring and controlling leakage, with the infrastructure leakage index (ILI) as the main performance indicator. The leakage exponent (N1), which quantifies the relationship between leakage rate and pressure, is a key parameter in describing DMA leakage behaviour. After analysing thousands of stochastic networks for different combinations of pipe material and ILI, the study found that different pipe materials have distinct leakage exponent distributions. Iron and asbestos cement (AC) pipes display N1 values close to 0.5, polyvinyl chloride (PVC) pipes have the highest N1 values, and polyethylene (PE) lies between PVC and iron/AC. The study further showed that current guidelines linking ILI to N1 for different pipe materials depart substantially from the observed results, indicating that these guidelines may need to be updated. The study provides a tool for more realistic modelling of leakage that offers valuable insights into the behaviour of leakage in different pipe materials.

ПОЛУЧЕНИЕ ФИБРОЦЕМЕНТНЫХ ИЗДЕЛИЙ С ИСПОЛЬЗОВАНИЕМ ХРИЗОТИЛА – ХРИЗОТИЛЦЕМЕНТНАЯ ПРОМЫШЛЕННОСТЬ

The article discusses the technology of production, the problems of the development of chrysotile and chrysotile cement industries in the countries of independent states. The article provides information on the composition and properties of natural chrysotile fibers, data on the quality of raw materials of cement and chrysotile fibers supplied to chrysotile cement enterprises, characteristics of suspension with them, semi-finished product and properties of solidified chrysotile cement products. The emerging requests of the manufacturers of chrysotile cement products (slate, chrysotile cement pipes) to the mining and processing enterprises of the countries of independent states on the quality of the supplied chrysotile fibers in connection with the apparent violations of the physical and mechanical properties of the slate products are considered.

Long-term influences of pipe materials on bacterial communities of matured biofilms (> 40 years’ old) in drinking water distribution systems

Pipe materials appear to play an important role in the development of biofilms in drinking water distribution systems. However, there is controversy as to whether pipe materials shape the composition and diversity of bacterial communities in biofilms. To investigate the long-term effects of pipe materials on biofilms, triplicate samples of mature biofilms on unplasticized polyvinyl chloride (PVC-U), grey cast iron and asbestos cement (pipe age > 40 years) were obtained from three areas of an unchlorinated drinking water distribution system in the Netherlands. Illumina sequencing was performed and 773 OTUs (730 OTUs-814 OTUs) were detected within the biofilms on the three pipe materials, all of which were dominated by Proteobacteria (36.2%-46.1%). Both the alpha and beta diversity results showed that the bacterial communities of the biofilms formed on different pipe materials were highly similar. The neutral community model revealed that the assembly of the biofilm communities was governed by environmental selection rather than neutral processes. Among the 142 shared OTUs between the water and biofilm samples, there were 25 enriched OTUs (e.g., OTU7, assigned as Nitrospira spp.), which accounted for 62.6% of the total sequences, while 16 OTUs were disadvantaged (e.g., OTU14 and OTU40, assigned as Hyphomicrobiaceae), accounting for 2.2% of the sequences. Based on the findings, we propose and discuss a harmonisation process by which biofilms with significant differences due to the pipe material harmonize over time resulting in biofilms with similar bacterial communities. Our findings provide valuable insights into long-term biofilm development, bridging an essential gap in our current understanding of the influence of pipe materials on biofilm communities. These findings also highlight the importance of long-term studies and point to a potentially masked harmonizing process during biofilm development over years/decades.

Analysis of factors driving water main breaks across 13 Canadian utilities

Deterioration of water infrastructure is a global challenge that jeopardizes water system ability to deliver water safely. While various factors affect watermain failure, previous studies have focused on common pipe attributes or general protection strategies. The main objective of this study is to examine the relationship between pipe break characteristics and system properties. Comprehensive data from thirteen Canadian water systems (over 60,000 failures) are examined with correlation and chi-squared analyses. Joint and fitting failures are most likely for pipes aged 20 years or less, and universal joints are most associated with joint failure. Pipes in clay and sand soils are more likely to break due to improper bedding and differential settlement, respectively. Furthermore, in the summer, accidental breaks of asbestos cement pipes are more likely, as are failures of pipes with collar joints and coal tar lined pipes. By exploring these relationships, the paper provides insights into opportunities for reducing water main failure, through improved design, maintenance and rehabilitation.

Molecular detection of Borrelia sp. in Ornithodoros cavernicolous (Acari: Argasidae) in midwestern Brazil

Ticks are obligate hematophagous parasites that can transmit to vertebrate hosts several pathogens, including viruses, bacteria, protozoa and helminths. Among these agents, some Borrelia species some Borrelia species cause disease in humans and other vertebrate hosts; therefore, they have medical and veterinary health importance. To gather additional information on Borrelia species in Brazil, the current study aimed to detect the presence of these species in Ornithodoros cavernicolous ticks collected in September 2019 from cement pipes that are used by bats as shelter in a farm located in the midwestern region of Brazil. DNA samples obtained from 18 specimens of O. cavernicolous were subjected of two polymerase chain reactions, targeting a segment of the Borrelia fla B gene. Of the samples tested, only one (6 %, 1/18) showed amplification. The nucleotide sequence of the amplified DNA showed more than 97 % (293/300) identity with a sequence of a Borrelia sp. detected in blood collected from a bat from Macaregua Cave, Colombia, and more than 97 % (292/300) detected in lungs from vampire bats from northeastern Brazil. The deduced amino acid sequences were identical to each other. Phylogenetic analysis indicated that these sequences formed a group of Borrelia species (putatively associated with bats) that is closely related to sequences of Borrelia species of the Lyme borreliosis group. Further investigations should be carried out in order to determine whether the sequence of the Borrelia sp. we found belongs to a new taxon. It will also be of great importance to determine which vertebrate hosts, besides bats, O. cavernicolous ticks can parasitize in order to investigate whether the Borrelia sp. we found may be transmitted and cause disease to the other vertebrate hosts.

Fiber-Reinforced Cement Pipes as Simulants for Deteriorated Asbestos Cement Pipes in Rehabilitation Studies

Fiber-Reinforced Cement Pipes as Simulants for Deteriorated Asbestos Cement Pipes in Rehabilitation Studies

An investigation of fatigue response of well cement under cyclic loading and impact on zonal isolation performance

Cyclic bottomhole pressure fluctuation is very prevalent in modern well construction and enhanced petroleum recovery applications and poses a great challenge to annular seal integrity and successful zonal isolation, even in cases where the cement seal exhibits excellent initial quality. Thus, annular sealants must be designed to mitigate or minimize the deleterious effects of cyclic pressure fluctuations on the annular seal. Optimal cement designs for this purpose require a proper understanding of damage modes and mechanisms associated with a cyclic pressure regime, as well as the impact of the cement mechanical integrity evolution on the leakage of the cemented annulus. Using four cement formulations with distinct mechanical and microstructural properties, we investigated the mechanical integrity evolution and leakage characteristics of cemented pipe specimens subjected to confinement pressure fluctuations. Via microscopic inspection of the cement/pipe interface after pressure cycling and permeability measurements during pressure cycling, we attempted to correlate cement properties with leakage and suggest a recommendation for optimal cement design and successful zonal isolation in wellbores subjected to cyclic pressure. Test data indicate that under high enough pressure variation, interfacial cracking at the cement pipe interface is unavoidable and the cement seal's ability to maintain zonal isolation will be dependent on the microstructural morphology and microscale mechanical resilience of the cement formulation. Stiffer conventional cements also appear to have a higher chance of leakage through non-interfacial fractures than their more flexible counterparts. Latex cements show great promise for effective zonal isolation under cyclic bottomhole pressure conditions and should be studied in more detail.

DEVELOPMENT OF INNOVATIVE PILE FOUNDATION DESIGNS ON SUBSIDENCE SOILS

New technical solutions for the elimination of negative friction forces in the construction of pile foundations on subsidence soils are considered. The friction forces arising between the subsidence soil and the side surface of the pile, according to the Amonton-Coulomb law and the theoretical justifications of B.V. Deryagin, are presented as the sum of a term depending on adhesion and the product of the coefficient of friction by normal pressure. There is some function approximating the total friction force along the side surface of the pile. Differentiating this function, we obtain a formula that determines the change in soil pressure on the side surface of the pile, which varies with the depth of the pile location in the subsidence soil. To sharply reduce the forces of negative friction, the author has developed the design of a pile foundation made of asbestos cement pipes. Studies have shown that in these piles, the forces of negative friction are reduced by 20-30 %, compared with concrete piles manufactured in factory conditions. The author has developed two variants of the method of building a pile foundation on subsident soils, in which the role of antifriction lubricant is performed by a layer of humbrine. Humbrin is a waste of the technology of purification of technical oils. This waste accumulates in large quantities in the landfills of oil refineries. The author has proposed a new design of a pile foundation, in which recycled tires are used as an outer shell to remove the forces of negative friction. Experimental studies have shown that even with vertical deformations of the tire screen of more than 0.04 m, the amount of pile precipitation turned out to be negligible, only 0.02 mm. The author also developed a pile foundation erected on subsident soils. This pile foundation has an external cylindrical shell. In the gap between the cylindrical shell and the side surface of the pile there is a spiral-wound elastic rubber rolling harness. When the surrounding soil subsides, the outer cylindrical shell moves vertically down the rolling spiral bundle, removing negative friction from the side surface of the pile. In addition, the rolling spiral elastic harness also performs the function of a seismic isolator.

Thermal performance analysis of coaxial borehole heat exchanger using liquid ammonia

The non-water working fluid is crucial to evaluate and optimize the thermal performance of the coaxial borehole heat exchanger (CBHE). An unsteady heat transfer model is built to evaluate the thermal performance of CBHE using different working fluids. Liquid ammonia, among other eight fluid candidates, is selected as an effective non-water working fluid because of lower injection pressure (5 MPa), a lower pressure loss (2.45 MPa), a better thermal performance (Outlet temperature and thermal power are 0.9 °C and 27.17 kW higher than that of water, respectively), a higher coefficient of performance (7.34) and a low cost than other fluid. Moreover, when a double-layered insulation pipe structure insulates 88.9% of the top of the central tube, the thermal power can be 8.41 times that of an uninsulated case. A high flow rate (23 m³/h) can provide a thermal power 15.35 times that of the 1 m³/h flow rate, but with an extra pressure loss of 3.38 MPa. Moreover, the effect of cement sheath, pipe size, injection temperature, injection pressure, and periodic shut-in operation is analyzed and optimized by analyzing the engineering and economic factors. This paper provides a theoretical basis for the future application of CBHE.

Modelling of Water Distribution Network for Hayin Banki, Kaduna State

Water distribution systems are designed to adequately satisfy the water requirement for domestic, commercial industrial and firefighting purpose. A spatial database of the water distribution systems (WDS) for Hayin-Banki was created in a Geographic Information System (GIS) environment (ArcGIS), drawing inputs data from water supply and demand. Environmental Protection Agency Network (EPANET, 2.0) was used to analyze the WDS to explore its reliability in current and future scenarios. Mapping of the existing 12.270 km long distribution network revealed that the total length of ductile iron pipe (DIP) is 11.12 km and asbestos cement (AC) pipes is 1.15 km. Running the analysis identified supply gaps, which includes deficiencies in the distribution system (small diameters pipes, system losses) resulting to negative and very small pressures. Running simulations with EPANET and geospatial techniques was used to solve the identified deficiencies.

Nest microclimate and heat stress in African Penguins Spheniscus demersus breeding on Bird Island, South Africa

Summary Low-latitude penguins naturally breed in burrows dug in guano. This affords them a buffered environment that remains cool and humid, reducing the risk of hyperthermia while on land. As a conservation strategy, several versions of artificial housing units have been trialled at various breeding sites of African Penguins (Spheniscus demersus) around South Africa, where former guano exploitation forced many penguins to breed in exposed surface nests. While some units yielded a positive effect on breeding success by providing protection against predation, none of them have effectively mitigated the risk of heat stress in penguins or their eggs. Here, we investigated the microclimate of a recent double-layered design of ceramic artificial nests and compared that to natural burrows, exposed surface nests, and commonly used cement pipe nests, in austral summer 2021 on Bird Island, South Africa. We also recorded penguin behaviour during the hottest period at each of these nest types using remote camera traps to determine the onset of heat stress (panting). Double-layered ceramic nests out-performed all other nest types, including natural burrows, by remaining cooler throughout the day, with temperatures never exceeding 36.7°C. By contrast, all other nest types had multiple episodes where temperatures exceeded 40°C. Double-layered ceramic nests also maintained constant levels of high humidity (relative humidity [RH] >70%) throughout our study, whereas low humidity levels were observed in surface nests (RH ≈ 60%) and cement nests (RH <50%) during midday heat. We observed penguins panting at temperatures of 25°C in nest boxes, and at 22°C in exposed surface nests. This suggests that heat stress in African Penguins may occur much sooner than anticipated and that they are particularly vulnerable to hyperthermia as climate change-related global warming progresses. Fortunately, we are encouraged by the capacity of double-layered ceramic nest boxes to buffer environmental extremes and maintain suitable breeding conditions.

A comparison between multivariate adaptive regression splines and regressive convolution neural network with support vector regression for pipe burst rate prediction on limited dataset

ABSTRACT By accurate predicting of pipe bursts, it is possible to schedule pipe maintenance, rehabilitation and improve level of services in Water Distribution Networks (WDNs). In recent years, artificial intelligence techniques have been used vastly in pipe burst prediction. These techniques need big input dataset for deep learning but big dataset might not be available in old WDNs. This paper aimed to compare the performance of multivariate adaptive regression splines (MARS) and regressive convolution neural network with least square support vector regression (RCNN-LSSVR) for predicting of Pipe Burst Rate (PBR) with limited dataset. Pipes age, diameter, depth of installation, length, average and maximum hydraulic pressure are considered as effective parameters of PBR. Data collected from real-case study in Iran include 158 cases for polyethylene and 124 cases for asbestos cement pipes during 2012–2019. The results indicate that RCNN-LSSVR model has a great performance of PBR prediction on limited dataset.

Investigation of through-casing borehole acoustic reflection imaging with a dipole source: Modeling and field application

In view of most wells are completed by casing pipe in oil & gas exploration and development process, it is imperative to extend the application of borehole acoustic reflection imaging (BARI) from open to cased boreholes. To understand the characteristics of signals in borehole acoustic imaging, we study the radiated and reflected elastic waves in an open and cased borehole through numerical simulations. The results show that, for a broadband dipole source, the radiated SH-waves have the highest amplitudes and broadest radiation angles in the cased borehole, which is similar to the observation in an open borehole. It is believed that the cement and casing pipe would prevent to a certain extent the energy excited by the inner borehole sources from propagating into the outside formation. However, our modeling results clearly show the existence of the cement and casing will not influence the amplitude of the radiated SH-waves significantly. In fact, the decrease of the borehole radius, which is caused by cased borehole completion here, will increase the amplitude of the radiated SH-waves. As a result, the signal-to-noise ratio (SNR) of reflected waves relative to direct waves in the cased borehole is higher than that in the open borehole. Meanwhile, the cement bond quality does not heavily affect the SNR of the reflected waves and the SNR increases with the decrease of source frequency. Interestingly, as the cutoff frequency of the dipole flexural-wave mode in the cased borehole increases rapidly with the decrease of the formation S-wave velocity, the amplitude of the direct wave also decreases significantly. This results in an increase of SNR of the reflected waves, which is beneficial for extracting the reflected waves. The field data example certifies our theoretical analysis. Our results provide a theoretical foundation for the through-casing BARI with a dipole source.

Application performances of two greenhouses with new types of backwall in Yangling, China

In order to investigate the application performances of the solar greenhouses with new types of backwalls (greenhouse W2, and greenhouse W3) and the ordinary clay brick backwall greenhouse (greenhouse W1), and provide a theoretical basis for the construction of solar greenhouses in Yangling Demonstration Zone, Shaanxi, China, two greenhouses with different new types of backwall were designed. One of the backwall was built with lightweight aggregate concrete block (greenhouse W2) and that of the other one was assembled with a row of sand-filled cement pipes (greenhouse W3). The tested greenhouses were constructed in Yangling Demonstration Zone. Based on the data collected on typical sunny and cloudy days, the indoor temperature, inside wall temperature, and the heat flow of the greenhouses with new types of backwalls were compared with those detected in the ordinary clay brick backwall solar greenhouse, and the tested results were numerically simulated. According to the comparison of the physiological indicators of tomatoes planted in the greenhouses and the construction costs, the greenhouse type with the best practicability was found. The results indicated that: The average air temperature in greenhouses W1, W2, and W3 and outside was 15.1°C, 15.9°C, 17.3°C, and −0.4°C on the night of a sunny day, and the air temperature in W3 was the highest. The average air temperature in greenhouses W1, W2, and W3 and outside were 9.5°C, 13.3°C, 11.0°C, and −5.5°C on the night of a cloudy day, the air temperature in W2 was the highest. In the depth of 0-330 mm from the interface of the backwalls, the walls were obviously affected by the solar radiation, and the temperature changed greatly. The wall temperature on the sunny days exhibited an ascending order of W1, W2, and W3, while on the cloudy days was in the ascending order of W1, W3, and W2. The wall of W3 absorbed the most heat during the daytime and released the most heat at night on a sunny day, while W2 exhibited the second most heat absorption during the daytime, however, it exhibited the highest heat release at night on a cloudy day, which were almost equaled to its heat absorption. Tomatoes in W3 grew well and exhibited the highest yield, and this greenhouse had the lowest construction costs. Comprehensively considering the physiological indicators of tomatoes and the corresponding construction costs of greenhouses, W3 has the best application performance in Yangling Demonstration Zone. Keywords: application performances, solar greenhouse, backwall, temperature DOI: 10.25165/j.ijabe.20221503.6097 Citation: Sun Y C, Wang H T, Zhu C M, Lyu H Y, Zhang X H, Cao Y F, et al. Application performances of two greenhouses with new types of backwall in Yangling, China. Int J Agric & Biol Eng, 2022; 15(3): 62–71.

CT Scans of Asbestos Cement Pipes as a Reference for Condition Assessment of Water Mains

The water distribution network of The Netherlands contains around 30,000 km of asbestos cement (AC) pipes, which constitutes around 25% of the total network. As a pipe material, AC has a relatively poor performance, and therefore is a high priority for renewal. To help decide an effective order of replacement, the water utilities need condition assessment techniques that help them determine which pipes have the highest risk of failure. In the presented work, X-ray computed tomography (CT) was used to measure the degradation of AC pipes taken out of the field. These scans provide a description of the pipe degradation with unmatched detail. The results are compared with strength tests performed on the same pipes, revealing that detailed knowledge of the complete pipe degradation is more important than previously assumed. Moreover, comparison of the CT results to those of a commercial, non-destructive inspection technique was used as a new avenue for validation of this technique, demonstrating its future usefulness for attaining the detailed measurement of pipe degradation required by water utilities.

Degradation of asbestos – Reinforced water supply cement pipes after a long-term operation

Potable water supply system in major countries still uses a large proportion of asbestos-cement (AC) pipes for fresh drinking water delivery. Generally, after installation and initial purging, the AC tubes are believed to self-passivate by calcite scale and bio-film, especially when conveying hard water. However, the overall performance of AC tubes after decades of operation is significantly reduced and is still mainly unknown. In the current research, we investigated the AC water supply tube after 56 years of operation with high-hardness conveyed water. Our results show that asbestos fibres are emitted from degraded AC pipes as a result of wall softening due to calcium leaching from hydrated cementitious materials, resulting in the loss of mechanical stability. Although the water pumped into the system is not considered aggressive, the seasonal variations of water temperature and chemistry results in an interplay of calcite scaling and Ca leaching, the latter being the dominating process. By comparing the experimental observations with the long-term chemistry reports of the water supplied through the pipes, a positive relationship was established between the temperature and quality of the conveyed water with the corrosion and the calcite scale formation, which are dictating the emission of the fibres into the drinking water. In addition to the health risks posed by asbestos, these processes have many adverse effects on drinking water supply, such as pipe malfunction and destruction resulting in water loss, reduction of hydraulic capacity, microbial proliferation, and water quality deterioration, a topic of interest for global water industries process.

Pipe breaks and estimating the impact of pressure control in water supply networks

The deterioration and fracture of water supply pipes present a major threat for the continuous provision of drinking water. The hydraulic pressure in pipes is an influential factor for the occurrence of pipe breaks. However, little evidence has been provided so far for the quantitative assessment of the impact of pressure control on reducing the number of pipe breaks. In this paper, we applied logistic regression with polynomial terms, and a sensitivity analysis to assess the potential impact of pressure control on reducing pipe breaks. A large dataset of historic pipe breaks was used to develop and validate the presented method. Cast iron and asbestos cement pipes were examined in detail. Results showed that pipe breaks could be decreased by 18% to 30% by reducing the mean pressure for the investigated cohorts of asbestos cement and cast iron pipes. Pressure range reduction could provide larger impacts on both pipe materials. These results indicate that proactively controlling the hydraulic pressure may have a potentially significant impact on the reliability and sustainability of water supply networks.

Cement Slurry Plugging Law and Optimal Plugging Flow Rate at a High Hydraulic Gradient

With the continuous development of coal and rock mass engineering, water inrush grouting has become an urgent problem in engineering disaster management. Herein, a theoretical model of the optimal plugging flow rate was established, and a comparative theoretical analysis was performed based on the results of indoor model tests. The particle incipient velocity was defined as the optimal plugging flow rate. The effects of hydrodynamic velocity, water‐cement ratio, grouting pressure, and fracture aperture on the cement slurry grouting plugging were studied, and the optimal threshold of the plugging flow rate was obtained for theoretical model verification. Results showed that, at a high hydraulic gradient, the plugging effect of the grout was mainly affected by the hydrodynamic velocity, water‐cement ratio, and grouting pressure (listed in the order of importance). When the hydrodynamic velocity was low, the difference in the slurry deposition thickness was large under different water–cement ratios and pipe diameters. When the hydrodynamic velocity was increased, the influence of various factors on the slurry deposition thickness decreased. Through a comparative analysis of the experimental and theoretical values, the optimal plugging velocity of pure cement slurry was 0.5–0.55 m·s−1 under different conditions, and the error between the experimental and theoretical values was less than 0.1 m·s−1, which confirmed the rationality of the proposed model.

Pipe pressure of mining wet shot crete flowing in pipes

In order to explore the pressure change law of mining wet shotcrete in pipes, the rheological model was built based on rheology principle, and the computational formula of rheological parameters of wet shotcrete was deduced with the linear regression. 100 m full-scale pipeline platform of wet shotcrete was designed and built to study the relationship of pressure and other factors including flow rate, water cement ratio, mix proportion, and pipe bends. Results show: pipe pressure increases with the increase in flow rate and declines with the increase in water-cement ratio, the pressure may fluctuate with a high water cement ratio which can cause cement overhydration and bleeding separation. It will be more beneficial to transport materials if the continuous grading and straight pipe were considered. According to the tests of mix proportion 1:1.5:2.25, the pressure drop is 0.032 MPa·m−1 and the bend pressure drop is 1.3 times higher than in the straight line. We also conclude that solid phase pressure is bigger than liquid phase pressure and they both decline along the pipe based on FLUENT simulation. Finally, the formula of on-way resistance used in mine production was deduced.

Using generalized additive models to investigate the environmental effects on pipe failure in clean water networks

Predicting pipe failures using statistical modelling benefits from detailed knowledge of the conditions and circumstances which influence such failures. Incorporating this knowledge into model building improves failure predictions. In this study, we model weather, soil and hydrogeological variables in a generalized additive model for five common pipe materials separately, using partial dependence plots to understand the partial effects of each variable on pipe failure. We show how severe temperatures are associated with high pipe failure. Cold temperatures and air frost and their interaction with soils represent the key factors for pipe failures during the winter for metal pipes. Warm temperatures, high soil moisture deficit and soil movement results in higher pipe failures in asbestos cement pipes during the summer. Warm temperatures, ground movement and soil wash out, and water demand are key factors for polyvinyl chloride pipe failure during the summer. Frost is a key factor influencing polyethylene pipes during winter. An understanding of the physical principals concerning pipe failures can enable the development of more accurate models, guiding network management plans to help reduce asset leakage through appropriate interventions.