scholarly journals Condition-Based Maintenance Strategies to Enhance the Durability of ETICS

2021 ◽  
Vol 13 (12) ◽  
pp. 6677
Author(s):  
Cláudia Ferreira ◽  
Ana Silva ◽  
Jorge de Brito ◽  
Ilídio S. Dias ◽  
Inês Flores-Colen
Keyword(s):  
Service Life ◽  
Condition Based Maintenance ◽  
Performance Criteria ◽  
Time Interval ◽  
Maintenance Strategies ◽  
Total Replacement ◽  
Remaining Service Life ◽  
The Impact ◽  
Maintenance Model

The increase of awareness with sustainability and the desire of reducing the energy consumption in the construction sector haved increased the application of External Thermal Insulation Composite Systems (ETICS) across Europe in the last decades. Nevertheless, the implementation of appropriate maintenance strategies is still neglected. The aim of this study is to analyse the impact of different maintenance strategies. For that purpose, a condition-based maintenance model, based on Petri nets, is used to evaluate three maintenance strategies: MS1—total replacement only; MS2—combination of minor intervention and total replacement; and MS3—combination of cleaning operations, minor intervention, and total replacement. In the end, a multi-criteria analysis is used to discuss the impact of the three maintenance strategies proposed, evaluating the remaining service life, the global costs over time, the ETICS’ degradation condition, and the number of replacements (end of service life) over the time horizon. For this purpose, a sample of 378 ETICS was analysed, based on in situ visual inspections, carried out in Portugal. The results from this study reveal that maintenance plays an important role to increase the durability of ETICS, and therefore their sustainability. Regular maintenance can promote the extension of the ETICS’s service life between 88% and 159% (between 15 to 27 years), improve the global degradation condition of the ETICS, and reduce the impact on users by reducing the number of deeper interventions. Further research is essential to optimise the maintenance strategies (time interval between inspections, stakeholders’ performance criteria, and environmental exposure).

scholarly journals Maintenance Modelling of Ceramic Claddings in Pitched Roofs Based on the Evaluation of Their In Situ Degradation Condition

2020 ◽  
Vol 5 (9) ◽  
pp. 77
Author(s):  
Cláudia Ferreira ◽  
Ana Silva ◽  
Jorge de Brito ◽  
Ilídio S. Dias ◽  
Inês Flores-Colen
Keyword(s):  
Service Life ◽  
Maintenance Strategies ◽  
Total Replacement ◽  
Remaining Service Life ◽  
In Situ Degradation ◽  
Maintenance Policies ◽  
And Performance ◽  
The Impact ◽  
Maintenance Model

Existing maintenance policies have several limitations, mainly due to the lack of knowledge regarding the durability and performance of buildings. Usually, the maintenance policies are insufficiently accurate, neglecting the risk of failure over time and the global costs associated with repairs. In this study, a condition-based maintenance model, based on Petri nets, is proposed to evaluate the impact of three maintenance strategies of ceramic claddings in pitched roofs (CCPR): MS1—only total replacement; MS2—composed of total replacement and minor intervention and MS3—composed of total replacement, minor intervention and cleaning operations. In this study, 146 CCPR were inspected in situ, with a total area of 43,991.6 m2. The remaining service life of the CCPR; the global costs over the claddings’ lifetime (considering inspection, maintenance, replacement and disposal costs); the claddings’ degradation condition and the number of replacements during the time horizon are used to evaluate the performance of the different maintenance strategies through a simplified multi-criteria analysis. The results show that the gains in performance, in terms of expected service life and durability, of the consideration of preventive maintenance actions (minor interventions or cleaning operations) outweigh the increase of the operation costs.

Structural Impact in FPSO Life Extension: A Class Perspective

2013 ◽  
Author(s):  
Christiane L. Machado ◽  
Sudheer Chand
Keyword(s):  
Service Life ◽  
Oil And Gas ◽  
Structural Response ◽  
Oil And Gas Industry ◽  
Environmental Data ◽  
Life Extension ◽  
Element Analysis ◽  
Actual Performance ◽  
Remaining Service Life ◽  
The Impact

The Offshore Oil and Gas Industry has converted a large number of units from trading tankers and carriers into Floating Production, Storage and Offloading units (FPSOs). Several of these have been moored offshore Brazil during the last 15 years. Following the discovery of offshore pre-salt fields some years ago, demand for FPSOs has increased, and the forecasts for productive field lives have grown. The result of these developments is the need to extend the service lives of existing FPSOs. The main aim of this study is to investigate FPSO structural response to environmental conditions and functional loads, considering the actual available tools for numerical simulations and Rule requirements, which currently are basic requirements for design review for Classification. The procedure was developed from one selected FPSO converted from a trading Very Large Crude Carrier (VLCC) tanker approximately 15 years ago and includes investigation of the impact on hull behavior comparing the motion analyses of the production unit under environmental data and software capabilities available at the period of conversion and actual performance: variances in the environmental (sea scatter diagrams) datasets; updates to Classification requirements for defining offloading conditions, environmental loads, acceptance criteria and remaining fatigue life (RFL); and incorporating the most recent gauged thickness for primary structure. The selected FPSO was evaluated according to prescriptive Rule requirements and also using finite element analysis, taking into account the previous conditions of Classification approval as well as the actual requirements and available data. Structural analysis included one global model and some local refined models to address strength, buckling and fatigue capacity of the typical portions/connections of the hull. The comparisons performed from the results of these analyses are a crucial step toward understanding the structural capacity of the FPSO at the conversion stage, its performance during the last 15 years, and its remaining service life. Differences were tabulated and evaluated so that a more precise level of uncertainty could be achieved for predicting the estimated remaining service life, and consequently, a new and dedicated approach to investigate the existing FPSO fleet is being generated.

scholarly journals ASR: Practical investigative techniques and field monitoring systems used to assess ASR for service life modeling.

2019 ◽  
Vol 289 ◽  
pp. 08004
Author(s):  
Irene Matteini ◽  
Paul Noyce ◽  
Gina Crevello
Keyword(s):  
Service Life ◽  
Significant Risk ◽  
Field Monitoring ◽  
Alkali Silica Reaction ◽  
Material Degradation ◽  
Deterioration Mechanism ◽  
Investigative Techniques ◽  
The Impact

Alkali Silica Reaction (ASR) is a common deterioration mechanism affecting many concrete structures of any type and age. Initially identified more than 60 years ago (Stanton, 1930), this mechanism is based on the chemical reactions between certain siliceous minerals present in the aggregate and the alkalinity of the concrete in the presence of moisture (internal RH). While certain deterioration patterns are clearly associated with ASR, such as gel exudation, aggregate expansion, and characteristic cracking, the material degradation can often be misdiagnosed to the untrained eye. In addition, certain elements of a structure can be severely affected while neighboring elements of the same batch/ mix design do not bear signs of deterioration or impact. Thus far, in situ field monitoring of ASR affected structures is related to moisture measurements, electrical resistivity, expansion, service life models are based on fracture mechanics of the aggregate. The impact to the concrete is loss of integrity, decreased compressive strength, shear and tensile strength. Some observed structures have split, with such force, that the concrete structure had cracks greater than 25mm where steel retention bands have split. The authors of this paper were engaged in two instances to provide service life assessments for ‘corrosion related degradation’ on ASR affected structures. In all instances the elements which were assessed were structural, load bearing elements, which if failed could pose a significant risk to owner, user, or end recipient. The need to develop an assessment technique for monitoring and service life assessments which are practical and efficient is being developed. The paper will discuss the development of the approach, from visual indicators identifying condition hierarchies, to long term condition monitoring for various concrete parameters combined with laboratory testing (expansion and residual alkalis) and mathematical modeling. Three case studies will be presented to illustrate conditions and process.

Prediction of the Remaining Service Life of Superheater and Reheater Tubes in Coal-Biomass Fired Power Plants

2013 ◽  
Vol 856 ◽  
pp. 343-348 ◽  
Author(s):  
Mohammad Asgaryan ◽  
Nigel Simms ◽  
Shao Min Wu
Keyword(s):  
Service Life ◽  
Power Plants ◽  
Operating Conditions ◽  
Fireside Corrosion ◽  
Remaining Service Life ◽  
Boiler Efficiency ◽  
Early Failures ◽  
Oxidation Damage ◽  
Type Of Failure ◽  
The Impact

Burning biomass in power plants is believed to result in severe fireside corrosion of superheater/reheater tubing and cause unexpected early failures of tubes. Morover, higher operating temeprtures and pressures (to increase the boiler efficiency) will also increase the risk of fireside and steamside oxidation damage to the boiler tubing and lead to shorter component lives. Predicting the remaining service life of superheater/reheater tubes in coal-biomass fired power plants is therefore an important aspect of managing such power plants. The path to this type of failure of tubes involves five processes: combustion, deposition, fireside corrosion, steam-side oxidation, and creep. To fully understand the impact of new fuel mixes and changing operating conditions on such failures, an integrated model of all of these processes is required. This work has produced an integrated set of models and so predicted the remaining life of tubes based on the conceptual and mathematical frameworks developed.

scholarly journals Improving estimates of water resources in a semi-arid region by assimilating GRACE data into the PCR-GLOBWB hydrological model

2017 ◽  
Vol 21 (4) ◽  
pp. 2053-2074 ◽  
Author(s):  
Natthachet Tangdamrongsub ◽  
Susan C. Steele-Dunne ◽  
Brian C. Gunter ◽  
Pavel G. Ditmar ◽  
Edwin H. Sutanudjaja ◽  
...  
Keyword(s):  
Water Resources ◽  
Hydrological Model ◽  
Hexi Corridor ◽  
Accurate Estimation ◽  
Groundwater Depletion ◽  
Time Interval ◽  
Grace Data ◽  
The Impact ◽  
Semi Arid

Abstract. An accurate estimation of water resources dynamics is crucial for proper management of both agriculture and the local ecology, particularly in semi-arid regions. Imperfections in model physics, uncertainties in model land parameters and meteorological data, as well as the human impact on land changes often limit the accuracy of hydrological models in estimating water storages. To mitigate this problem, this study investigated the assimilation of terrestrial water storage variation (TWSV) estimates derived from the Gravity Recovery And Climate Experiment (GRACE) data using an ensemble Kalman filter (EnKF) approach. The region considered was the Hexi Corridor in northern China. The hydrological model used for the analysis was PCR-GLOBWB, driven by satellite-based forcing data from April 2002 to December 2010. The impact of the GRACE data assimilation (DA) scheme was evaluated in terms of the TWSV, as well as the variation of individual hydrological storage estimates. The capability of GRACE DA to adjust the storage level was apparent not only for the entire TWSV but also for the groundwater component. In this study, spatially correlated errors in GRACE data were taken into account, utilizing the full error variance–covariance matrices provided as a part of the GRACE data product. The benefits of this approach were demonstrated by comparing the EnKF results obtained with and without taking into account error correlations. The results were validated against in situ groundwater data from five well sites. On average, the experiments showed that GRACE DA improved the accuracy of groundwater storage estimates by as much as 25 %. The inclusion of error correlations provided an equal or greater improvement in the estimates. In contrast, a validation against in situ streamflow data from two river gauges showed no significant benefits of GRACE DA. This is likely due to the limited spatial and temporal resolution of GRACE observations. Finally, results of the GRACE DA study were used to assess the status of water resources over the Hexi Corridor over the considered 9-year time interval. Areally averaged values revealed that TWS, soil moisture, and groundwater storages over the region decreased with an average rate of approximately 0.2, 0.1, and 0.1 cm yr−1 in terms of equivalent water heights, respectively. A particularly rapid decline in TWS (approximately −0.4 cm yr−1) was seen over the Shiyang River basin located in the southeastern part of Hexi Corridor. The reduction mostly occurred in the groundwater layer. An investigation of the relationship between water resources and agricultural activities suggested that groundwater consumption required to maintain crop yield in the growing season for this specific basin was likely the cause of the groundwater depletion.

scholarly journals Predictive maintenance in nuclear power plants through online monitoring

2013 ◽  
pp. 42-50
Author(s):  
H. M. Hashemian
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Online Monitoring ◽  
Predictive Maintenance ◽  
Condition Based Maintenance ◽  
Maintenance Strategies ◽  
Plant Safety ◽  
Generation Costs ◽  
Reactor Internals

The nuclear power industry is working to reduce generation costs by adopting condition-based maintenance strategies and automating testing activities. These developments have stimulated great interest in online monitoring (OLM) technologies and new diagnostic and prognostic methods to anticipate, identify, and resolve equipment and process problems and ensure plant safety, efficiency, and immunity to accidents. This paper provides examples of these technologies with particular emphasis on a number of key OLM applications: detecting sensing-line blockages, testing the response time of pressure transmitters, monitoring the calibration of pressure transmitters online, cross-calibrating temperature sensors in situ, assessing equipment condition, and performing predictive maintenance of reactor internals.

Hydrophobierung des Betons - Ökologische und ökonomische Aspekte / Water Repellent Treatment of Concrete - ecological and economical aspects

1997 ◽  
Vol 3 (3) ◽  
pp. 293-314
Author(s):  
C. Haag ◽  
A. Gerdes ◽  
F .H. Wittmann
Keyword(s):  
Service Life ◽  
Penetration Rate ◽  
Ecological Impact ◽  
Chloride Ion ◽  
Life Time ◽  
Performance Criteria ◽  
Water Repellent ◽  
Concrete Element ◽  
The Impact ◽  
Required Service

Abstract The use ofdeicing salts on roads may lead to chloride ion induced corrosion. This deterioration mechanism has become one of the most frequent reasons for repair measures within the planned service-life of concrete structures. One way of reducing the risk of chloride ion induced corrosion is the prevention of the penetration of dissolved chloride into the concrete. By water repellent surface treatment the water and chlorid penetration rate can be substantially slowed down. As the water repellent treatment has a limited service-life and its performance and durability depend on many parameters, no standard performance criteria for the water repellent treatment could be defined yet. This study compares the economical and ecological impact of a water repellent treatment with the impact of repair measures. Results are meant to be used to define standard performance criteria. These criteria must take into consideration not only the performance with respect to the reduction of chloride penetration rate, but also garantee the required durability.The expected life-time of an untreated reinforced concrete element can be estimated by modelling the mechanism of chloride ion induced corrosion. Based on this value the frequency of repair measures within a planned service-life of 100 years can be determined. Comparing the ecological and economical impact of a water repellent treatment with the corresponding impact of repair measures allows us to the formulate performance criteria concerning the durability and the minimum required service-life of a water repellent treatment. The water repellent treatment has to prevent repair measures within the planned service-life of a structural concrete element. Technical criteria concerning the performance of a water repellent treatment within the minimum required service-life can be formulated.

A Possible Basis for Nondestructive Characterization of Ropes of Nylon 6

1997 ◽  
Vol 503 ◽  
Author(s):  
H. Jiang ◽  
M. K. Davis ◽  
R. K. Eby ◽  
P. Arsenovic
Keyword(s):  
Tensile Strength ◽  
Service Life ◽  
Fiber Diameter ◽  
Structural Parameters ◽  
Crystal Form ◽  
Nylon 6 ◽  
Remaining Service Life ◽  
Nondestructive Characterization ◽  
Fractional Content

ABSTRACTPhysical properties and structural parameters have been measured for ropes of nylon 6 as a function of the number of use operations. The fractional content of the α crystal form, sound velocity, birefringence, tensile strength and length all increase systematically and significantly with increasing the number of use operations. The fractional content of the γ crystal form and fiber diameter decrease with use. These trends indicate that the measurement of such properties and structural parameters, especially the length, provide a possible basis for establishing a reliable, rapid, and convenient nondestructive characterization method to predict the remaining service life of nylon 6 ropes.

In situ Quantification of the Impact of Episodic Enhanced Turbulent Events in Large Phytoplankton

2011 ◽  
Author(s):  
Percy L. Donaghay ◽  
Jan Rines ◽  
James Sullivan
Keyword(s):  
The Impact
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