Cause Of Leakage Research Articles

Analysis of cracking failures in water-cooled wall fins and thermal peaking unit mitigation strategies

Abstract The causes of leakage in the submitted superheater tubes were analyzed using the analysis of macroscopic morphology, chemical composition, and metallography. The analysis results indicate that the chemical composition of the failed superheater tube is within the standard range, and the metallographic structure is ferrite + pearlite, with no abnormalities in the metallographic structure. The main reason for the failure of water-cooled wall tubes and superheater tubes may be the formation of fatigue cracks on the inner and outer walls of the superheater tubes under cyclic stress. As the two fatigue cracks grow and converge, penetrating cracks form, ultimately leading to the initial leakage of the superheater tubes. In addition, the excessive depth of the weld pool in the fins of the superheater tube is another crucial factor that promotes accelerated cracking of the superheater tube. It is recommended that power plants reasonably regulate the temperature difference fluctuation rate of boilers to prevent similar failure accidents from occurring.

A study on radial oil seal leakage failure due to viscoelasticity under dynamic eccentricity

Purpose This study aims to investigate the causes of leakage in radial oil seals under dynamic eccentricity, elucidate the influence of operating parameters on leakage failure and develop methods for predicting and preventing such leakage. Design/methodology/approach Based on the principle of cam motion and considering viscoelasticity, develops a motion model of the compression and release of the shaft seal and proposes a method to determine its failure. In addition, this study quantifies the leakage gap and formulates a quantitative calculation model to accurately determine the location and shape parameters of the leakage gap. Findings Leakage gaps predominantly occur during the release phase of the shaft seal. Their presence can be identified by comparing the descending times of the seal and the shaft during this phase. An increase in rotation speed and eccentricity heightens the likelihood of gap formation, with both the dimensions and leakage rate of the gap increasing as these factors escalate. Eccentricity, in particular, has a more pronounced effect on gap formation. Originality/value This study clarifies the failure mechanisms of radial oil seals under dynamic eccentricity and introduces a criterion for identifying leakage gaps, providing valuable theoretical guidance for the design and optimization of radial oil seals. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0192/.

Using Artificial Neural Networks to Predict Leakage Location in Water Distribution Networks

One of the major types of water wastage in a distribution network is the leakage that occurs in pipes or other network components such as connections. Leaks in urban water supply networks impose many costs and workforce on governments and related organizations annually. If the cause of leakage is traced to the cracks and slits on various parts of a network, the amount of leakage from the location of the crack is said to be directly associated with the amount of pressure at that point. To trace leakage in water distribution networks, this study introduced a method based on hydraulics modeling and the inverse solution of flow equations to predict the location and amount of leakage in water distribution networks, by considering the values of the measured pressure in some network nodes. For this, a hydraulic model of the network under study was provided in the EPANET Hydraulic Analysis software, and the network analysis of various values and states of hypothetical leaks led to obtaining pressure values in the different nodes of the network via modeling water modeling under a steady state. Then, the artificial neural network, having been trained, was used to provide measured pressures in some network nodes at the testing hour as input data to the neural network to locate possible leaks in the water distribution network and to predict their approximate values. The findings were found to enjoy desirable accuracy. DOI: https://doi.org/10.52783/pst.835

Hazards associated with pressure relief devices in hydrogen systems

Hydrogen is increasingly being used as an alternative renewable energy carrier because of its potential to reduce carbon emissions in transportation and heavy industry. Nevertheless, this transition necessitates establishing an infrastructure for storage, transporting, and distributing hydrogen. This infrastructure is typically equipped with pressure relief devices (PRD) to protect systems from uncontrolled pressure increases. Without PRDs, a substantial pressure increase has the potential to rupture equipment and lead to a hydrogen release, which could lead to fires, explosions, and significant damage. However, recent incidents have shown that these PRDs can also be the root cause of leaks and releases. Therefore, there is a need to understand the conditions when PRDs increase the risk versus when these devices effectively mitigate the risk. This paper presents the first comprehensive analysis of past hydrogen incidents involving PRDs and considers when these components succeed and when they fail. We then analyze a diverse, representative subset of events involving PRDs using a root cause analysis (RCA) methodology known as Tripod Beta. Further, we introduce a taxonomy breakdown of the root causes of these incidents. Finally, we provide conclusions related to the observed root causes. The most frequently observed failure modes leading to PRD incidents are 1.) spurious operations of PRDs and 2.) high input to the PRD from components upstream of the PRD, which then activate PRDs. When comparing PRD-mitigated events to PRD-initiated events, we found that PRDs initiated more events than they mitigated; however, it is yet to be seen if this is an artifact of poor (success) data reporting or a true prevalence of PRD activations which undermines their value as a protective feature. The use of Tripod Beta shows that using systematic approaches to incident investigation and analysis provides more causal insight into risk mitigation than simply documenting the occurrence of a single failure. To understand the risk tradeoff that PRD offers, we need more rigorous assessments for the risk & reliability of these components. The results of this study motivate research, design and operational changes, and upcoming codes and standards developments to ensure the continuous, safe, and reliable operation of hydrogen systems.

Analysis of the causes of waste heat boiler leakage in large-scale chemical plants

A waste heat boiler is a kind of high-temperature and high-pressure heat exchanger in a large chemical plant, and its safe operation is directly related to the production efficiency and safety risk of a chemical plant. In this paper, the leakage failure analysis of a waste heat boiler in an ethylene plant is carried out, and the analysis methods such as field observation, macro observation of fracture, metallographic analysis, micro observation of fracture, phase analysis, and energy spectrum analysis are adopted respectively. The results show that the direct cause of the leakage of the waste heat boiler is the thinning of the wall thickness of the heat exchange tube caused by alkali corrosion, which leads to the overload and fracture of the heat exchange tube. The pits on the outer surface of some heat exchange tubes are caused by mechanical reasons, which are related to this leakage and closure. The corrosion failure of heat exchange tubes is widespread, which has a great influence on safety production and serious consequences. Through this comprehensive analysis, the failure mechanism is clarified, which can provide a reference for the maintenance of similar equipment. At the same time, preventive measures are put forward from the aspects of technology, structure, and detection to reduce the occurrence of similar accidents.

Electrolyte Leakage in Cylindrical Lithium-Ion Batteries Subjected to Temperature Cycling

In transportation and operation, lithium-ion batteries can be exposed to environments where the temperature exceeds 75 °C, compromising seal integrity and leading to electrolyte leakage and safety issues. Standards introduced by regulatory bodies require temperature testing, including temperature cycling tests. This study examines cylindrical battery electrolyte leakage due to temperature cycling between 25 °C and 80 °C through capacity tests, electrochemical impedance spectroscopy, computed tomography scans, and thermal analysis. Different thermal expansions among battery cap elements were identified as the cause of leakage. The thermal test parameters and requirements in the UN Manual of Tests and Criteria Section 38.3 were reviewed, revealing the 72 °C upper-temperature limit and the 24 h storage period after temperature cycling fail to effectively qualify lithium-ion batteries for real-world applications.

Left atrial appendage occlusion: On the need of a numerical model to simulate the implant procedure.

Left atrial appendage occlusion (LAAO) is a percutaneous procedure to prevent thromboembolism in patients affected by atrial fibrillation. Despite its demonstrated efficacy, the LAA morphological complexity hinders the procedure, resulting in postprocedural drawbacks (device-related thrombus and peri-device leakage). Local anatomical features may cause difficulties in the device's positioning and affect the effectiveness of the device's implant. The current work proposes a detailed FE model of the LAAO useful to investigate implant scenarios and derive clinical indications. A high-fidelity model of the Watchman FLX device and simplified parametric conduits mimicking the zone of the LAA where the device is deployed were developed. Device-conduit interactions were evaluated by looking at clinical indicators such as device-wall gap, possible cause of leakage, and device protrusion. As expected, the positioning of the crimped device before the deployment was found to significantly affect the implant outcomes: clinician's choices can be improved if FE models are used to optimize the pre-operative planning. Remarkably, also the wall mechanical stiffness plays an important role. However, this parameter value is unknown for a specific LAA, a crucial point that must be correctly defined for developing an accurate FE model. Finally, numerical simulations outlined how the device's configuration on which the clinician relies to assess the implant success (i.e., the deployed configuration with the device still attached to the catheter) may differ from the actual final device's configuration, relevant for achieving a safe intervention.

Reliability sensitivity analysis for water hammer-induced stress failure of fluid-conveying pipe

The water hammer, resulting from sudden valve closures or similar operations, is a primary cause of leakage and damage in fluid-conveying pipe systems. This work aims to investigate the reliability sensitivity of fluid-conveying pipes under the water hammer. A reliability model for the fluid-conveying straight pipe, involving uncertainty and fluid-structure interaction, is developed based on the stress-strength interference theory. Then the method of characteristics is employed to analyze the nonlinear behaviors of the pipe. To avoid excessive model evaluations, the Kriging surrogate strategy is used to evaluate rapidly the statistics of nonlinear responses. Furthermore, the Kriging model coupled with the single-loop Monte Carlo simulation is presented for estimating reliability sensitivity indices. The accuracy of results is verified by the Monte Carlo simulation. The results reveal that the proposed method is feasible for the reliability sensitivity analysis of fluid-conveying pipe under the water hammer. Moreover, the wall thickness has the most obvious influence on stress failure, followed by the inner radius, while the pipe length, Young's modulus, density of the pipe material, and Poisson ratio show a low effect. This work can not only guide the safety design of pipe but also enrich the theory and application of statistical analysis and reliability sensitivity evaluation for liquid-conveying pipe systems.

Application of natural language processing for spill reduction in an exploration and production company

Spill reduction is a key focus for exploration and production (E&P) companies to protect people, the environment, and to maintain oil production. Learning from previous incidents enable companies to identify ways to lower the severity and frequency of spills. Root cause failure analysis (RCFA) is a key element in process safety management, and this is often focused on high severity incidents because of the time required to properly conduct the analysis. Incidents that have lower severity occur more frequently, but typically less time and resources are spent analyzing these events. Learning from lower severity, high frequency events can be useful in improving process safety programs and reduce spill frequency and impacts because the data set is more representative of the big picture. Natural language processing (NLP) is applied to identify causes and contributing factors of spills and leaks associated with E&P activity to reduce the frequency and severity of these events. Reviewing incident reports allow us to identify trends and areas of improvement, and NLP can be used to process the data quickly and improve data quality. Incident reports are typically free text that includes a description and cause of the event. One challenge with free-text descriptions is that further analysis and interpretation is needed in order to effectively analyze, trend, and learn from the available data. In addition, identifying the causes and contributing factors of a spill accurately can be time intensive. Two natural language processing methods, rule-based entity extraction and a machine learning model approach have been utilized to analyze a greater number of incident reports, which enables us to pinpoint causes of leaks, reduce the frequency of spills, and mitigate the impact of these events. This paper presents the challenges associated with learning from incident reports, particularly spills, and offers solutions that natural language processing can provide to improve data quality and contribute to spill reduction efforts in the context of an exploration and production company.

Erosion-corrosion failure analysis of the elbow pipe of steam distribution manifold

This work discusses a case study of the failure of rice condition plant boiler pipe fittings. The failure analysis was performed on the 45° and 90° API 5LX65 steel pipe elbows connected to a steam manifold in a boiler of a rice conditioning plant. Failure analysis was performed by visual observation, microscopic analysis, hardness measurements, and numerically by Computational Fluid Dynamics (CFD). It was confirmed that the mechanism of failure was due to erosion-corrosion. The results showed also that, erosion-corrosion at the outlet of the 90° and 45° elbows due to the maximum particle impact in the high pressure and high turbulence intensity region. Microscopic analysis of the 90° and 45° elbows showed that large pits and cuts were the main reason for leakage perforation. Erosion at the inner bend of the 90° and 45° elbows is lower than at the outer bend, which is related to the higher particle–wall impaction, pressure, and turbulence intensity. The main cause of leakage and wall thinning in both elbows is the development of limescale which leads to pitting corrosion and the formation of leaks at higher oxygen concentrations. The simulation results show that the maximum material removal rate in the 45° elbow is 42 % lower than in the 90° elbow, the erodent impaction and higher wall shear are liable for the development of the perforation near the exit of 90° and 45° elbows.

A case report on spontaneous intracranial hypotension

A 38-year-old lady with bronchial asthma, psychiatric illness, and a suicidal attempt 6 years ago presented with persistent headache for more than 2 weeks. She was diagnosed with recurrent sinusitis and migraine and was on treatment at a local hospital and referred to a higher center for persistent headache which was orthostatic in nature. Clinically, the patient was alert, oriented, and systemic examination was unremarkable. MRI spine showed extensive extradural collection separating the anterior dural sac from the bony canal extending from C3 to D1. CT Myelogram showed cervical dural leak anteriorly at C7-D1 and bony osteophyte impinging on the dural sac – likely cause of leak. Diagnosis of Spontaneous Intracranial Hypotension was made. As no improvement was noted with trial of conservative management, we proceeded with advanced imaging-guided Epidural blood patch repair, following which the symptoms improved.

Flange Leak Investigation on Kettle Heat Exchanger Operating at Low-Temperature Condition

A kettle-type evaporator heat exchanger (TEMA BKU) is utilized to cool natural gas on the tube side from −34 °C to −55 °C, using Multi-component Refrigerant (MCR) as the cooling medium on the shell side. During operation, the heat exchanger encountered recurrent leakage issues at the channel-tubesheet bolted flange joint, particularly during the cooling down process. The primary objective of this research is to identify the causes of leakage and to propose viable solutions for minimizing the risk of leakage. To achieve this, Finite Element Method (FEM) was employed as an investigative tool to analyze the mechanical factors contributing to leakage. Results from the FEM investigation indicate that the leakage in the bolted joint of the heat exchanger is attributed to reduce of gasket seating stress as an effect of bolts self-loosening, influenced by several factors such as bolts plastic deformation, flange stiffness characteristics, and uneven temperature distribution. The study also reveals that gasket seating stress decreases after each shutdown compared to the previous start-up due to plastic deformation on bolts and flange gasket surfaces after shutdown. The findings of this study provide critical insights into the mechanical behavior of bolted flange joints in heat exchangers and offer guidance for their improved design and maintenance, enhancing operational reliability.

Multi-objective maintenance strategy for corroded pipelines considering the correlation of different failure modes

Corrosion is the leading cause of leakage and burst failures in long-distances gas pipelines. Periodic maintenance is often used to extend the service life of the pipeline. The presence of multiple performance indicators with competing objectives needs to be taken into account for pipeline maintenance strategy. To address these challenges, this paper proposes an approach based on multi-objective maintenance optimization. The copula function is applied to characterize the correlation of failure modes (leakage and burst). With the aims to optimize availability and cost rate, a multi-objective maintenance optimization model is established, and it is solved with the non-dominated sorting genetic algorithm II (NSGA II). The results show that the Pareto frontier of multi-objective optimization can provide more feasible maintenance schemes. Moreover, the effects of major variables on the availability and cost rate are investigated. It is found that compared with other parameters, downtime cost has the greater impact on performance indicators. The proposed method can provide theoretical reference for pipeline integrity management, thereby ensuring that the pipeline is in a safe state during operation.

Kajian Kes: Kebocoran Antara Tingkat di Bangunan Kediaman Bertingkat Malaysia

Building defects are a common issue in the construction industry. Defects of high-rise buildings, such as cracks and leaks, are often caused by poor workmanship, and insufficient and low-quality building materials. Other contributing factors to building defects are inadequate cooperation during construction, poor design and improper installation. Inter-floor leakage is a widespread matter in new homes, leaks are detected late and repeated leaks occur even after repairs have been carried out. Inter-floor leakage often occurs in new homes. Leaks are detected late and repeated ones occur even after repairs are carried out. This study aims to diagnose buildings with inter-floor leakage problems by using several diagnostic tools and techniques like visual, destructive and non-destructive tests. Experts use testing equipment to determine moisture and appropriate maintenance or repair. A case study is carried out on a residential unit with a leak in the ceiling due to a crack on the rooftop. The findings of the study can provide knowledge about building diagnosis to property owners and property managers, identifying the cause of leaks and enabling early detection of building defects and suggested repairs to prevent similar leaks from occurring. By utilizing diagnostic tools and techniques, owners and property managers can detect problems early, minimizing damage and expenses in the long run. Based on the study, existing cracks can be converted into expansion joints, white paint can be used on the walls to control heat, installed thermal insulation to control solar energy stress and waterproof membrane can be applied to prevent moisture penetration.

On Internal Erosion of the Pervious Foundation of Flood Protection Dikes

This work focuses on the mechanisms that trigger internal erosion of the pervious foundation of flood protection dikes. The origin of these permeable layers is generally attributed to the presence of a paleo-valley and paleo-channels filled with gravelly-sandy sediments beneath the river bed and dikes. These layers may extend into the protected area. Visual observations of leaks, sand boils and sinkholes in the protected area testify to internal erosion processes in the underground soil. Local geological conditions are part of the information to be sought to explain these processes: presence of permeable soils and position of interfaces. Results obtained on Agly dikes (France), using two classical geophysical methods (EMI and ERT), were analyzed using cored soils and showed that it is not enough to simply conclude to the presence of backward erosion piping. The possibility of internal erosion, such as suffusion or contact erosion, must also be considered as the cause of leaks, sand boils and sinkholes. As the results obtained are explained by the presence of a paleo-valley and paleo-channels beneath the river bed and dikes—commonly encountered in this context—the methodology presented and the results obtained are likely to be relevant for many dikes.

Pediatric urethrovaginal reflux: an underestimated cause of urinary incontinence and its successful management.

Urethrovaginal reflux (UVR) secondary to vaginal urine entrapment is an unnoticed cause of daytime urinary leakage in toilet-trained girls. Our aim is to emphasize the diagnosis of UVR as a cause of urinary incontinence, its predisposing factors, early detection, and treatment. A total of 25 girls aged between 9 and 14years presented with mixed daytime urinary incontinence from 2019 to 2021. They were evaluated by detailed history, vaginal examination, focused neurological examination, bladder diaries, urine analysis, uroflowmetry, and residual urine assessment. Micturating cystourethrography was also performed in those girls who did not show improvement with a conservative line of management. The parents of these girls were educated about the cause of leakage. They were treated with behavioral modifications, urotherapy, correcting toilet postures, and reverse sitting on the commode. Urethrovaginal reflux was found in 6 of the 25 girls (24%). Their ages were 9, 10, 10, 11, 12, and 14years respectively. Two girls (10 and 14years old) had a body mass index more than 25. They all had a typical history of a small quantity of urine leakage 5-10min (post-micturition dribble) after every void. At follow-up after 12 months, all of them were free from urinary incontinence. Urethrovaginal reflux should be considered in the differential diagnoses of girls with day-time incontinence. The key to diagnosis is an appropriate and detailed history as it is common for parents or girls to ignore symptoms or fail to report them. Proper voiding instructions and behavioral therapy often resolve the problem.

The vanishing threat: Stealthy malfunction of closed suction system

This case report presents a rare case of a mechanical ventilation leak that was initially missed by clinicians in a patient with a myxoedema coma. Despite all efforts to investigate the causes of the leak, including a bedside lung ultrasound and chest radiograph, the leak persisted. It was eventually discovered that the rhythmic inflation and deflation of the polythene covering the closed suction system was causing the leak. The closed suction system was replaced with a new one, and the tidal volume was restored, resulting in the resolution of the leak alarm. The volume leak alarm and low volume alarm are important indicators of potential problems during mechanical ventilation, and close suction system malfunction is a potential cause of volume leak that should be considered in mechanically ventilated patients. Regular monitoring and appropriate management of these alarms and potential causes can help prevent complications and optimize patient care. Keywords: Mechanical ventilation, volume leak alarm, closed suction system, and myxoedema coma.

Metallurgical investigation of leakage observed in welded interface of Pilot pressure distributor of liquid stage for aerospace application

Pilot Pressure Distributor (PPD) system is used in liquid fuel stage of launch vehicles for the pressurized flow of liquid propellant. The PPD system is fabricated out of AISI304L austenitic stainless steel. The system consisted of adaptor and plumbing lines is welded together using Gas Tungsten arc welding technique. The distributor system is subjected to hydro test at 120 bar pressure and then post- harnessing command line leak check is carried out after the hydro test. During the leak test at 60 bar with snoop solution, a frothing leak is observed at PPD distributor weld joint. A pressure drop of 6 bar was also observed over a duration of 10 min. The leaked PPD distributor was dismantled from the assembly and subjected to detailed metallurgical investigation to identify the root cause of leakage. The metallographic analysis revealed leakage in PPD distributor attributed to the lack of fusion in the weld joint.

Leakage, diffusion and distribution characteristics of refrigerant in a limited space:A comprehensive review

The leakage and direct emission of high GWP HFC refrigerants in refrigeration, air-conditioning and heat pump systems increase the greenhouse effect, which pose huge threats to the ecological environment and the human health. Meanwhile, some alternative refrigerants with excellent environmental performance have different degrees of flammability. When the flammable refrigerants catastrophically leak from the refrigeration system into a limited space, it is easy to cause an explosion accident, the safety of people and property in the space is greatly threatened. In addition, the operating conditions of refrigeration systems, thermophysical properties of the refrigerants, obstacles and ventilation conditions of the space have a great impact on the process of refrigerant leakage and diffusion, the explosion risks formed in the external space have certain differences. To promote the security application of the alternative refrigerants, the leakage, diffusion, and distribution characteristics of the refrigerants from both theoretical and experimental aspects were reviewed in this work. The potential causes of leakages and common types of leakage holes in refrigeration systems were summarized, and the advantages and disadvantages of the existing leakage and diffusion theoretical models were concluded. The impact of the micro-sized leakage of the refrigerant on the internal of the system was discussed. The diffusion and distribution of the refrigerants in the external space after they catastrophically leaked from different types of systems were analyzed, and the influence of different parameters on the refrigerant distribution and the explosion risk based on the catastrophic leakage was also presented. The future work was prospected. The review is expected to provide a valuable reference for the safety risk assessment of the flammable refrigerants.

Leakage Analysis of Steam Condensate Pipe Elbow

The cause of leakage of a steam condensate pipe elbow has been carried out by means of chemical composition analysis, fracture surface analysis and numerical simulation. The results show that the inner wall of the pipe at the socket welding of the downstream pipe elbow of the steam trap is not enough smooth, and the inner diameter suddenly changes, resulting in a sudden increase in the flow velocity, which increases the erosion-corrosion rate of the pipe wall, and finally leads to the elbow leakage.