Service Life Of Pipes Research Articles

Experimental studies of bearing capacity of pipe steel of sewage systems

The results of experimental studies on the kinetics of crack growth, its relationship with the parameters of crack resistance and long-term strength of pipe steels of different service life and their structural and phase composition are presented. It was found that the value of the critical stress SK for all test steels increases with the increase in the service life, and the impact viscosity decreases, which indicates the structural embrittlement of the pipe steels associated with their sudden flooding. It is shown that the new 06G2BA steel, which is economically modified with a carbide-forming element (vanadium) and has a fine-grained structure and a low content of harmful impurities (sulfur, phosphorus), has the highest visco-plastic properties and resistance to brittle fracture. The microstrain of the α-Fe crystal lattice, as well as the quantitative decay of cementite and the redistribution of carbon between ferrite and pearlite, were evaluated by X-ray structural methods. 06G2BA steel is recommended for use in the construction of pipelines and, for example, bridge structures, which are constantly under cyclic loads with simultaneous contact with a corrosive-aggressive environment. The influence of the service life of water pipes on the hydrogen content and microcracks in pipe steels was determined. A diagram of the relationship between long-term and static strength depending on the hydrogen content in steels is recommended, which can be used by designers to rationally choose the type of steels with high crack resistance in aggressive technological environments. In order to extend the service life of pipe structures, it is necessary to use economically modified steels.

EFFECT OF BACK PRESSURE DURING DIRECT PRESETTING OF ALLOY LBTPN D16T

Pipes made of high-strength aluminum alloys with protector thickeners in the middle and at the ends are actively used in the construction of wells for oil and gas. Their light weight and sufficient strength make it possible to build wells of greater depth from lower lifting capacity installations. In addition, aluminum alloy pipes of keyless construction are widely used in cases where there is a high content of carbon dioxide and hydrogen sulfide. This design and material make it possible to significantly increase the service life of pipes in aggressive, corrosive environments. In order to increase the production speed of pipes, it is proposed to use the technology of direct compression with back pressure. You can simulate the manufacturing process using this technology of LBTPN (alloy drill pipe of increased reliability) using a specialized software complex DEFORM, which was done. These aluminum pipes are used in the development of ultra-deep gas and oil wells, as well as horizontal and inclined extended reach wells. LBTPNs were also used in the drilling of ultra-deep Kola, Kryvyi Rih, and Ural wells. It is possible to use compressed pipes with back pressure if the design depth of the well is more than 3000 m. During pressing in the plastic deformation focus, stress transformation is observed: normal growth and drop of tangents and, therefore, a decrease in their total impact; increased level of hydrostatic pressure, all components of deformations and, therefore, also their total impact. Unlike the non-backpressure process, when present and under its action in the gage zone, there is a significant decrease in longitudinal tensile forces, as a result it is possible to carry out the process with higher values of alloy flow rates. Also, pipes made of aluminum alloys of a lock-free design are widely used in cases where there is a high content of carbon dioxide and hydrogen sulfide. This design and material can significantly increase the service life of pipes.

Study on the relationship between microstructure and properties of heavy-wall X70 pipeline steel with different processing directions

The neglect of microstructure and anisotropy in the design of subsea pipeline steel can seriously affect the pipe service life and lead to fracture failure. In this work, experimental and representative volume element (RVE) model results were used to analyze the effect of differences in the microstructural characteristics of heavy-wall ferritic/bainitic dual-phase (DP) ×70 pipeline steel in the transverse and rolling directions on the mechanical properties. The results showed that blocky bainite with an aspect ratio 1.9 in the transverse microstructure induced the ferrite to produce strain localization, decreasing the plasticity. Banded bainite with an aspect ratio of 4.4 in the rolling direction was more prone to activate the dislocation slip system, which enhanced deformation compatibility by limiting the ferrite deformation space through plastic deformation at low strain levels. The dislocation wall type of the rolling direction promoted the production of back stress (long-range internal stress) and reduced the strain gradient at the interface. The dislocation arrangement in the transverse direction was transformed from a mixed type to a dislocation wall type during cyclic loading, and the back stress was dynamically saturated by grain size. Higher forest hardening in the transverse direction increased strength and hardening rates, while higher back-stress hardening in the rolling direction promoted plasticity. The results reveal the relationship between microstructural characteristics difference and mechanical properties and back stress evolution to provide a theoretical basis for designing the heavy-wall ×70 pipeline steel.

Influence of operating hours of water pipes in aggressive mediums to degradation of structural steel

Ruining the design of water pipelines can lead to negative economic and environmental consequences. The usual scientific, technical and technological developments to ensure reliable corrosion-mechanical resistance and durability of water pipelines are not sufficiently systematic, so there is no need to report the reasons, minds and mechanisms of corrosion-mechanical servicing. Laboratory and experimental investigations were carried out in relation to the operation of structural steels on the structure and instead of schoolhouses. The causes and mechanisms of degradation of metal structures due to routine operation in chemically aggressive technological media were studied. X-ray diffraction studies have established that, with increasing service life of pipes, the surface metal balls adsorb a significant amount of gases. It manifests itself especially strongly in the area of corrosion defects (stains, pittings). During regular operation, the metal walls of the pipes are heavily flooded, which leads to a hardening, increased hardness and decreased ductility. There is a significant change in the mass fraction of cementite in the metal, which indicates a decrease in the value of the material and a decrease in its resistance to corrosion-mechanical damage. Such research is a pioneer in the corrosion-mechanical resistance of metal and its degradation during heavy use in the presence of significant pressures and in the immediate presence of aggressive media.

Influence of Temperature and Long-Term Operation on Metal Durability of Pipelines of Hydrotechnical Structures

The paper considers the issue of the influence of ambient temperature and service life on the endurance of pipe steels of underground pipelines. The results of numerous experimental studies allowed us to draw the following conclusions. An analysis of the experimental data indicates that for all the studied steels, the endurance decreases with decreasing air temperature, mainly down to-20... -30 °C. This can be explained by the embrittlement of the metal, i.e. a decrease in the plastic properties of the pipeline metal structure. In addition, it can be seen from the given data that low-alloy steels 48KhN, 09G2S, 10GS have the highest endurance. Weak endurance is mainly typical of grade 20 carbon steel. Experimental studies show that with an increase in the service life of pipes, their endurance decreases, and this tendency is inherent in all the studied steels. Studies of the endurance of pipe steels under complex stress states show that static torsional stresses close to the yield strength, when tested in the air, do not reduce fatigue life. Although the corrosive environment significantly reduces the cyclic strength of steel under shear stresses up to τcr=05τY, the conditional limit of corrosion fatigue is not lower than when tested for corrosion fatigue under the action of only alternating stresses in a symmetrical cycle. It could be considered that the torsional stress in the pipeline system does not exceed 10 MPa. In that case, their influence on practical calculations on the endurance of pipes of underground pipeline systems can be neglected.

Maintenance robot for remote assembly of protective jackets on live gas risers

Combining high-rise robotics research and polyurethane (PU) repair techniques presents new opportunities and unique challenges for utility pipe maintenance. Aiming at solving the complex pose alignment issue of robots and control PU curing, this paper automates the repair process by assembling protective jackets with PU foam. A wire-hoisted robot was equipped with anchors and a twin-gripper mechanism for workspace definition, along with a manipulator that positioned a pair of mirrored end effectors to perform surface polishing, jacket installation, and PU curing onto the pipe. Consequently, the robot pose was stabilized. The jacket pair was assembled onto the pipe with high precision, yielding high-quality repair, a success rate >96%, short cycle time, and low material wastage. This research may inspire innovative automation approaches for building maintenance, while utility companies can deploy the robot system for sustainable pipe service life.

EPANET MODEL CLEAN WATER NETWORK CALLIBRATION USING MODIFIED ROUGHNESS C NUMBER HAZEN WILLIAM METHOD

The Epanet model in clean water pipelines is intended for time efficiency in calculating hydraulic behaviour. Calibration of the water pipe network is to compare the simulation results of the model to actual field observations and to see that the model that has been made is truly valid and reliable as a tool to determine the hydraulic behaviour of the network system when a change input into the system is given (e.g. the addition of pipelines and number of customer tapping debits). The pipe roughness coefficient (C) is a number that indicates the amount of energy loss due to friction between the flowing fluid and the pipe wall. The increasing age of the pipe will cause the pipe wall roughness to increase, and the energy loss will be even more significant. This research aims to calibrate the pipe network model by adjusting the C value of the actual pipe roughness coefficient according to the installed age. An initial simulation model was carried out by entering the standard pipe C value in the Hazen Williams energy loss equation in the Epanet link/pipe properties. Then a simulation is carried out by modifying the value of C according to the pipe's service life. For 600 mm steel pipe, change the C value from 150 to 87 (pipe age >30 years), HDPE 315 mm pipe changes in C value from 140 to 100 (pipe age >10 years) and 25-50 mm PVC pipe from 140 to 100 (pipe age >10 years). From the simulation results of the Epanet model-field observations, the average compressive height was obtained for five observation nodes.of 2 tails was performed paired sample test the pressure height value of the model-observation. Before modifying the value of C, the paired mean difference test results showed a significant difference between the simulation results of the model on field observations with a model significance value of 0.004, which means <0.005. There is a considerable difference between the simulations and observations, and the model is considered invalid. However, after modifying the value of C according to the actual age of the pipe, a paired sample test T average value of the compression model-observation was 0.098 > 0.005), which means that there is no significant difference between the simulation and observation. This means that the model made is quite valid. Product moment correlation between the model simulation height - field observations, the value of R = 0.967, the relationship is robust between the two results.

Study of Causes of Plastic Pipe Failures

It has been observed that critical failures and loss of function occur in a shorter period than specified service life during operation of polypropylene pipes in hot water systems. The paper analyzes the failure causes of polypropylene pipes in closed loop hot water systems, and provides recommendations for increasing their service life. It has been established that the primary factors responsible for ageing and failure of polypropylene pipes during operation are medium temperature, stress due to internal pressure, water composition. It has been observed that a combined influence of the above mentioned factors provides a synergistic effect. We developed the recommendations for increasing a pipe service life, including close monitoring and recording of energy carrier temperature and pressure; changes in specifications for propylene pipes, including the recommendation for using random propylene pipe grades with high thermal oxidation stability in hot water systems.

Long-term testing methods for HDPE pipe - advantages and disadvantages: A review

High-density polyethylene (HDPE) has become a material of interest for culverts and drainage pipelines as a result of its numerous advantages. The issue of service-life expectancy of HDPE pipes made with recycled versus virgin resins has been the focus of research studies over the past several years. A number of recent studies have confirmed that HDPE is durable with an extended service-life performance of over 100 years. Nevertheless, exposure criteria, such as environment and service conditions, could affect pipe service life. Consequently, giving specific figures on the durability of HDPE pipes needs to be clearly addressed. Such concerns were raised by Quebec’s Ministry of Transportation (MTQ) to assess the durability of HDPE pipes made with recycled or virgin resins taking into consideration exposure conditions in northern climates. This paper provides an overview of the research on the main factors and mechanisms that affect HDPE pipe lifetime. Methods for predicting the lifetime durability of HDPE pipes—including the creep rupture strength, stress crack resistance, and oxidation—are introduced, emphasizing the advantages and disadvantages of each technique. Studies conducted on the fatigue performance of the pipes are highlighted. Moreover, an overview of studies on the use of HDPE pipes manufactured with recycled resins for transportation infrastructure applications is also presented.

A Front-Line and Cost-Effective Model for the Assessment of Service Life of Network Pipes

In any water utility, a reliable assessment of the service life of the network pipes is a key piece within the big puzzle of assets management. This paper presents a new statistical model (basic pipes life assessment, BPLA) to assess the service life of pipes, to locate the pipes on the failures bath curve and to forecast the expected failures in future years. Its main novelties are the processing of pipe information (is that information what is adapted to the classical maintenance engineering and not the other way back) and the definition of two different time variables that can be analyzed in parallel. The first novelty makes the model less demanding in terms of data and software tools than others currently available, and the second one allows to get all the results after one single stage of calculation. To show its usability, the BPLA has been applied to a pipe network that supplies water to 500,000 citizens for which two years of failure records are available. Procedures and results have been compared to the well-known Weibull proportional hazard model (WPHM), with final relative errors lower than 10% and 15% on each particular result.

Uncertainty in the life cycle greenhouse gas emissions and costs of HDPE pipe alternatives

High density polyethylene (HDPE) is a thermoplastic used in many engineering applications but one that imposes environmental burdens when produced and environmental costs at end-of-life (EOL). Replacing pristine HDPE with post-consumer recycled (PCR) HDPE or bio-based polymer (bio-HDPE) in long-lived goods could mitigate those impacts. We investigate cradle-to-gate and cradle-to-grave greenhouse gas (GHG) emissions and costs of four alternative resins, pristine HDPE, pristine/PCR HDPE, bio-HDPE and nanoclay-pristine/PCR HDPE composite, and their use in 100-year drainage pipe, respectively. We construct stochastic LCA models that combine service life prediction from experiments with parametric and scenario uncertainty modeling using Monte Carlo simulation and non-parametric bootstrapping. Results differ significantly on a resin versus pipe product basis owing to the functional unit requirement for meeting pipe service life, if governed by crystallinity and fracture energy, properties that call for greater quantities of material in recycled and nanoclay composite HDPE compared to pristine HDPE. The nanocomposite pipe has varying GHG emissions compared to all alternatives due to high mass requirement if assuming crystallinity and fracture energy govern failure, but this predicted mass may be reduced given that the nanoclay can prolong fracture time, which would reduce GHG emissions and pipe production cost. Despite a large GHG reduction relative to pristine HDPE, the bio-HDPE resin has the highest material production cost; however, considering life cycle costs, the incremental difference among all alternatives is small over a range of discount rates, rendering the bio-HDPE pipe a promising solution for addressing climate change in long-lived thermoplastic assets.

Estimation of corrosive and scaling trend in drinking water systems in the city of Azogues, Ecuador

The quality of drinking water flowing in a distribution network can possess corrosive characteristics that may cause the material degradation of pipes and accessories. This problem can result in reduction of the service life of pipes and create a major public health problem. The agreement between the physical-chemical water quality analysis and national standards are not enough to confirm the balance of the water quality in terms of corrosion. In order to predict pipe corrosion in water distribution system networks, the corrosive trend was evaluated using the Langelier (LSI), Ryznar (RSI), and Larson-Skold (LRI) indexes based on measurements of pH, temperature, total dissolved solids, alkalinity, calcium hardness, sulfate and chloride. This study was setup with 180 samples collected in six zones of the distribution network, from July to December of 2017, according to the standard methods for the analysis of drinking water. The results indicate a variation of the LSI from -1.22 to -1.68; RSI from 9.75 to 10.52 and LRI from 0.46 to 0.77. A linear model was fitted for each index to predict the corrosion with the water quality conditions of this study case. Therefore, the drinking water of the city of Azogues, Ecuador has a corrosive tendency from significant to severe. Corrosion indices were calculated to provide useful information on the water's corrosiveness. These results indicate the need to constantly monitor the corrosion rate in the distribution network and conduct a laboratory study to adjust effective parameters such as pH, in order to control corrosion.

Three-dimensional finite element analysis of residual stresses in circumferential welds of 2205/X65 bimetallic pipe

Corrosion has a great negative influence on the pipe service life, and high welding residual stress will accelerate corrosion and reduce the strength of the pipe. Traditional carbon pipe is highly susceptible to corrosion, especially in the oil transport industry, and the stainless steel pipe is expensive. So bimetallic steel is a good choice for high-pressure and corrosion-resistant pipe. Multi-pass butt-welded 2205/X65 bimetallic pipe in this article is simulated numerically in non-linear thermo-mechanical finite element method (FEM), a three-dimensional (3D) finite element model is developed, the temperature history and the residual stress distribution are plotted, and the results are compared with the available measured data to evaluate the accuracy of the finite element model. In addition, the stresses changing with weld pass and the effect of the welding speed on stress distribution are also studied. The results show that the tensile stresses after cooling are larger than the tensile stresses after pass four on the inside surface, and the compressive stresses after cooling are larger than the compressive stresses after pass four on the outside surface, and the position of the maximum stress is farther away from the weld center when the welding speed decreases.

Predicting Water Quality Impact After District Metered Area Implementation in a Full‐Scale Drinking Water Distribution System

Pressure management using district metered areas (DMAs) can reduce leakage and break frequencies and extend the service life of pipes in drinking water networks. Valves must be closed, creating DMAs, resulting in hydraulic changes and increasing the number of dead ends. A field study of five pilot DMAs was conducted using an enhanced sampling program. Water quality was measured at different locations inside and outside DMA boundaries before and after implementation. Overall water quality did not change following DMA implementation. However, water quality (chlorine residuals, turbidity, and metals) was degraded at locations with elevated water residence times such as created dead ends, sites outside DMA boundaries, and extremities. An approach based on the combination of hydraulic modeling and water quality was developed to predict trihalomethane concentrations in the DMA using measurements only from an inlet site. Utilities can use a combination of hydraulic modeling and targeted monitoring to predict water quality changes after DMA implementation.

Multiobjective Optimal Design of Sewerage Rehabilitation by Using the Nondominated Sorting Genetic Algorithm-II

Application of multiobjective optimization in sewerage rehabilitation management is not widespread due to the limitation of data collection and complex optimization process. Thus, a few researches in literature focused on sewerage rehabilitation optimization, and only considered two-objective optimization usually between the service life and the direct cost instead of a social cost. A sewerage rehabilitation multiobjective optimization decision support system (SRMOS) was developed for sewerage rehabilitation management in this study. The nondominated sorting genetic algorithm-II was used to design a set of Pareto surfaces with desirable rehabilitation effectiveness at the lowest cost by providing optimal plans comprising a construction method and substitute material. The SRMOS was applied to a real sewerage system to provide tradeoff solutions for three conflicting objectives, which are minimizing rehabilitation cost, maximizing pipe service, and minimizing traffic disruption. Compared with the experts' manual estimation, the plan derived from the SRMOS enables saving nearly 20 % of the rehabilitation cost. The contours of the rehabilitation cost show the equivalent relation between the traffic disruption and service life of pipes. The results indicate that increasing the number of objectives can make up the drawback of cost hard to be quantified and can also facilitate deriving practical plans for reference in decision-making.

Sustainable Reverse Osmosis application for wastewater treatment in the steel industry

The research work presented in this paper is related to water reuse and facility management concepts for the main circuits in different steel plants through the salt elimination techniques. In particular the study concerned two water circuits belonging to two integrated steelworks where high salts concentrations caused relevant problems. In the first circuit, the high chloride and carbonate concentration in the cooling water of the hot strip mill can affect the quality of the strips, due to the salt depositions on the strip surfaces, and causes corrosion of equipment. In the second circuit, the high content of chlorides and fluorides in the process waters of a Blast Furnace gas cleaning system causes corrosion of various components.In both cases tests were carried out to assess the possibility to apply Reverse Osmosis implementation and to evaluate the stability of its qualitative performance to the brackish water. The tests showed that pre-treatments are actually needed for colloids removal, and, consequently, to protect Reverse Osmosis membranes: in the first circuit, ultrafiltration, and in the second circuit conventional coagulation-flocculation-sedimentation system followed by sand filtration have been implemented.Results showed that, through Reverse Osmosis system, most salts, such as chlorides, fluorides, calcium, sulphates, etc. can be removed and other parameters, such as electrical conductivity, alkalinity and Total Dissolved Solids dramatically decreased. Accordingly significant results have been achieved, such as fresh water consumption and water discharged decrease, and the pipe service life improvement, due to the reduction of corrosion problems. The economic viability at industrial scale was also evaluated and their implementation resulted feasible.

Fracture Failure of Oil-Pipes of Truck Diesel Engine Boost Compensator

Two fractured oil-pipes of truck diesel engine boost compensators were received for failure analysis. Fracture occurred at the connection location of the pipe end with its casing-pipe wherein the positioned spot-welding was conducted. Fatigue fracture is the main failure mode of the two pipes. The chemical composition and the microstructure and the tensile properties of pipe materials are in accordance with the specification. However, the wider spacing of fatigue striations on the fracture surfaces and the shorter service life of pipes indicate that the ultimate strength of the specified material does not meet practical operating load with greater stress amplitude. The fatigue cracks initiated because of stress concentrations resulting from the combined effect of geometry configuration and high stiffness by the positioned spot-welding at the connection location of the pipe end and its casing-pipe.

Effect of solution pH on crack initiation and propagation in glass-polyester pipes subjected to impact

The objective of this study was the determination of the influence of alkaline and acidic solutions on the impact properties of glass-polyester composite pipes. First, the impact test was performed on virgin samples (without the influence of any liquid) to obtain knowledge about the original material properties. Subsequently, the specimens were soaked in water and in alkaline and acidic solutions: sodium hydroxide, ammonium hydroxide, phosphoric acid, and nitric acid. The specimens were left in each liquid for 3, 10, 30, and 60 days at room temperature. The impact toughness and the crack initiation and propagation energies were recorded for all samples. A comparison of the results was made based on the pH values of the aggressive media, as well as based on the original impact properties and number of days of treatment. This way, the service life of pipes for transport of theexamined solutions could be predicted. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

ОЦЕНКА СОПРОТИВЛЕНИЯ ХРУПКОМУ И ВЯЗКОМУ РАЗРУШЕНИЯМ ТРУБ С ЛОКАЛИЗОВАННЫМИ ИЗМЕНЕНИЯМИ РАБОЧИХ СЕЧЕНИЙ

Background Analysis of existing approaches to estimation of pipeline safe service life shows that the literature has not enough information about adequate assessment of influence exerted by localized of the pipe wall shape and thickness distortions on safe operation characteristics (the number of load cycles before and during the failure). In particular, it is shown that the existing approaches to estimation of safe service life of pipes with localized distortions of shape (dents) may several times underestimate safe life of a pipeline. The fact makes necessary to study how localized mechanical effects influence on serviceability and safety of oil pipeline main elements. Aims and Objectives The present work is devoted to research and development of the methods of estimating the resistivity to brittle and ductile failure of pipes with localized changes in the net opening. Methods The work presents results of analysis of the stressed state of pipes with angular dents, using the boundary problem approach and the theory of thin shells of revolution. Results Proposed and justified is the method of calculating the strength factor of pipes with multi-parameter crack-like damages caused by interaction with rocky ground. Obtained results serve the base for calculation of predicted and remained life of pipelines and their basic elements.

Economic assessment of cured concrete by organic coating materials and double wall corrugated HDPE pipes in sewer networks

Resistance to deteriorations (especially corrosion) and initial price are important features in selecting the proper pipe materials for sewers. Among different types of pipe material used in Malaysia sewers, concrete and double wall corrugated high-density polyethylene (DWC-HDPE) pipes are more common. Laboratory tests were conducted using cylindrical concrete samples coated by polyurethane and epoxy materials to investigate their ability to protect concrete pipe against corrosion. Secondly, the cured concrete pipe price was compared to sewer construction costs. Economic analyses were carried out to compare the prices of cured concrete and DWC-HDPE pipe in various diameters. The results revealed that the coatings act as a barrier against the aggressive environment. Besides, their ability was proved to prolong concrete service life. In addition, the results showed that using the coatings to prevent or delay concrete networks’ deterioration (against corrosion) was at least 2 times more economical compared to sewer reconstruction. Furthermore, it was concluded that DWC-HDPE pipe larger than 600 mm is not economical to be used for sewers due to well performance of designed coatings on extending the concrete pipe service life. Finally, mathematical models were developed to assist engineers or designers to accurately select the proper pipe based on desired variables.