Four thermal spray coatings were subjected to high temperature corrosive environments of oil‐fired boiler conditions to compare their corrosion protection under simulated…
Abstract
Purpose
Four thermal spray coatings were subjected to high temperature corrosive environments of oil‐fired boiler conditions to compare their corrosion protection under simulated conditions. The coatings included FeCrAl, Tafaloy 45CT, which were arc‐sprayed, 50Ni‐50Cr and Cr3C2‐NiCr, which were coated by high velocity oxy fuel spray (HVOF) method.
Design/methodology/approach
The coating substrates used were SA213TP 347H, SA213 T11 and SA213 T22 alloys that are widely used as boiler tube materials. Specimens were covered with a synthetic ash mixture of 70 per cent V2O5‐20 per cent Na2SO4‐10 per cent NaCl and exposed to 550°C and 650oC°for 192 h (6 cycles). After high temperature corrosion tests, weight change curves were obtained; specimens were examined by metallographical techniques, scanning electron microscopy and EDX analyses.
Findings
Salt deposits attacked steels and coatings during the exposure. The corrosion rates were strongly affected by the composition of the scale formed adjacent to the steels and coatings surfaces. Austenitic steel was only bare material that experienced uniform corrosion in the tests. Ferritic steels were primarily attacked by grain boundary corrosion. Thermally sprayed coatings were mainly attached through oxides and voids at splat boundaries. FeCrAl and 50Ni‐50Cr were prone to spalling. Tafaloy 45CT is also a promising method for producing homogenous coatings. Cr3C2‐NiCr 80/20 coating remained mostly intact.
Originality/value
This paper provides useful information about corrosion behaviours of four coatings used for common boiler tubes. It shows with a practical explanation how the bare material and coatings react in corrosion simulated environments.
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Khushdeep Goyal, Hazoor Singh and Rakesh Bhatia
Molten sulphate-vanadate induced hot corrosion is the main reason of failure of boiler tubes used at high temperatures in thermal power plants. The hot corrosion can be…
Abstract
Purpose
Molten sulphate-vanadate induced hot corrosion is the main reason of failure of boiler tubes used at high temperatures in thermal power plants. The hot corrosion can be encountered by applying thermal spray coatings on the alloy steels. In this perspective, this paper aims to attempt to investigate the effect of carbon nanotubes reinforcement on Cr2O3 composite coatings on hot corrosion behaviour of ASTM-SA213-T22 steel in a corrosive environment of Na2SO4 – 60%V2O5 at 900°C for 50 cycles.
Design/methodology/approach
The coatings have been deposited with high velocity oxy fuel process. The samples were exposed to hot corrosion in a Silicon tube furnace at 900°C for 50 cycles. The kinetics of corrosion behaviour were analysed by the weight gain measurements after each cycle. Corrosion products were analysed with X-ray diffraction, scanning electron microscopy, energy dispersive and cross-sectional analysis techniques.
Findings
During investigations, the carbon nanotubes (CNT) reinforced Cr2O3 composite coatings on T22 steel were found to provide better corrosion resistance in the molten salt environment at 900°C. The coatings showed lower weight gain along with formation of protective oxide scales during the experiment. Improvement in protection against hot corrosion was observed with increase in CNT content in the coating matrix.
Research limitations/implications
The addition of CNT has resulted in reduction in porosity by filling the voids in chromium oxide coating, with interlocking of particle and has blocked the penetration of corroding species to enhance the corrosion resistance of the composite coatings. The corrosion rate was found to be decreasing with increase in CNT content in coating matrix.
Originality/value
It must be mentioned here that high temperature corrosion behaviour of thermally sprayed CNT-Cr2O3 composite coatings has never been studied, and it is not available in the literature. Hence, present investigation can provide valuable information for application of CNT-reinforced coatings in high temperature fuel combustion environments.
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Sandeep Kumar, Rakesh Bhatia and Hazoor Singh
In Indian thermal power plants, the main cause of boiler tube failure is the presence of molten sulphates and vanadates, which deteriorate the tube material at high temperatures…
Abstract
Purpose
In Indian thermal power plants, the main cause of boiler tube failure is the presence of molten sulphates and vanadates, which deteriorate the tube material at high temperatures. To combat the hot corrosion failure of metals, thermal spray technology is adopted. This study aims to investigate and study the effect of hot corrosion behaviour of carbon nanotube (CNT)-reinforced ZrO2-Y2O3 composite coatings on T-91 boiler tube steel in a molten salt environment at 900 °C for 50 cycles.
Design/methodology/approach
A plasma spray technique was used for development of the coatings. The samples were exposed to hot corrosion in a silicon tube furnace at 900 °C for 50 cycles. After testing, the test coupons were analysed by X-ray diffraction, scanning electron microscopy/energy dispersive spectroscopy and cross-sectional analysis techniques to aid understanding the kinetics of the corrosion reaction.
Findings
CNT-based reinforced coatings showed lower weight gain along with the formation of protective oxide scales during the experimentation. Improvement in protection against hot corrosion was observed with increase in CNT content in the coating matrix.
Originality/value
It is pertinent to mention here that the high temperature behaviour of CNT-reinforced ZrO2-Y2O3 composite on T-91 steel at 900°C temperature in molten salt environment has never been studied. Thus, the present research was conducted to provide useful results for the application of CNT-reinforced composite coatings at elevated temperature.
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This paper aims to examine how neighborhood characteristics (income, population composition) and individual building attributes (ownership) affect the recovery period of…
Abstract
Purpose
This paper aims to examine how neighborhood characteristics (income, population composition) and individual building attributes (ownership) affect the recovery period of single-family housing and determine their correlations with property abandonment and changes in residential land use after natural disaster.
Design/methodology/approach
This empirical study focuses on Valley Fire, one of the California’s most destructive wildfires in 2015, and uses assessor, community, demographic and sales data to measure recovery of a panel of single-family houses located in Lake County in California between 2012 and 2020. Several regression and correlation models will be developed to test different hypotheses.
Findings
This study found that: Recovery period is longer than what expected in most existing literature; ownership status significantly affects recovery period; income level is not a significant factor for shortening the recovery period; and minorities may need more assistance for constant recovery. Findings of this research will help identify at risk communities to avoid uneven housing recovery and lower the rate of property abandonment.
Originality/value
Housing recovery is key to revitalizing communities following major natural disasters. The sociodemographic characteristics of each neighborhood have significant impact on the duration of recovery and possible property abandonment. Understanding how home and neighborhood characteristics affect recovery will help planners prevent long-lasting adverse effects of natural disasters.
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Despite the extensive research in project risk management and availability of several techniques and tools, quantifying uncertainty in project schedules remains a challenge…
Abstract
Purpose
Despite the extensive research in project risk management and availability of several techniques and tools, quantifying uncertainty in project schedules remains a challenge. Current risk analysis models suffer from several shortcomings that need to be addressed to provide more reliable and valid schedules. This paper aims to present a dynamic decision support system with the purpose of providing project managers with necessary tool for making real-time informed decisions.
Design/methodology/approach
The proposed approach incorporates the widely accepted critical path method (CPM) calculations in a Bayesian network (BN). BN is employed to conduct inferencing and causal analysis and provide probabilistic results, which can improve the decision-making process. Time parameters of each activity in the CPM network is modeled by a set of simulation nodes in the BN. Prior probability distribution of activities duration is extracted from experts using a fuzzy analytical solution.
Findings
The model proposed in this paper is able to address some key outstanding issues of current project scheduling techniques through: (1) modeling the causality among different sources of schedule uncertainty, (2) minimizing uncertainty in experts' evaluations, (3) assessing effects of unknown risk factors and (4) using actual activity data for learning the behavior of project and predicting crew productivity.
Originality/value
The purposed methodology provides a framework for the new generation of project schedule analysis tools that are better informed by available knowledge and data, and hence, more reliable and useful.
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Nasir Bedewi Siraj, Aminah Robinson Fayek and Mohamed M. G. Elbarkouky
Most decision-making problems in construction are complex and difficult to solve, as they involve multiple criteria and multiple decision makers in addition to subjective…
Abstract
Most decision-making problems in construction are complex and difficult to solve, as they involve multiple criteria and multiple decision makers in addition to subjective uncertainties, imprecisions and vagueness surrounding the decision-making process. In many instances, the decision-making process is based on linguistic terms rather than numerical values. Hence, structured fuzzy consensus-reaching processes and fuzzy aggregation methods are instrumental in multi-criteria group decision-making (MCGDM) problems for capturing the point of view of a group of experts. This chapter outlines different fuzzy consensus-reaching processes and fuzzy aggregation methods. It presents the background of the basic theory and formulation of these processes and methods, as well as numerical examples that illustrate their theory and formulation. Application areas of fuzzy consensus reaching and fuzzy aggregation in the construction domain are identified, and an overview of previously developed frameworks for fuzzy consensus reaching and fuzzy aggregation is provided. Finally, areas for future work are presented that highlight emerging trends and the imminent needs of fuzzy consensus reaching and fuzzy aggregation in the construction domain.
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Giovanna Culot, Guido Nassimbeni, Matteo Podrecca and Marco Sartor
After 15 years of research, this paper aims to present a review of the academic literature on the ISO/IEC 27001, the most renowned standard for information security and the third…
Abstract
Purpose
After 15 years of research, this paper aims to present a review of the academic literature on the ISO/IEC 27001, the most renowned standard for information security and the third most widespread ISO certification. Emerging issues are reframed through the lenses of social systems thinking, deriving a theory-based research agenda to inspire interdisciplinary studies in the field.
Design/methodology/approach
The study is structured as a systematic literature review.
Findings
Research themes and sub-themes are identified on five broad research foci: relation with other standards, motivations, issues in the implementation, possible outcomes and contextual factors.
Originality/value
The study presents a structured overview of the academic body of knowledge on ISO/IEC 27001, providing solid foundations for future research on the topic. A set of research opportunities is outlined, with the aim to inspire future interdisciplinary studies at the crossroad between information security and quality management. Managers interested in the implementation of the standard and policymakers can find an overview of academic knowledge useful to inform their decisions related to implementation and regulatory activities.
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Ruchini Senarath Jayasinghe, Raufdeen Rameezdeen and Nicholas Chileshe
The reverse logistics supply chain (RLSC) for demolition waste management (DWM) is a complex process that inherits significant interdependent risks. However, studies on the RLSC…
Abstract
Purpose
The reverse logistics supply chain (RLSC) for demolition waste management (DWM) is a complex process that inherits significant interdependent risks. However, studies on the RLSC have not explicitly identified the risks of its inter-relationships by disentangling their effects on operational performance. Accordingly, this paper aims to identify and assess the inter-dependencies of the risks in the RLSC to improve quality-related operational performance.
Design/methodology/approach
A sequential exploratory mixed-method research approach, consisting of qualitative and quantitative methods, was employed. The qualitative approach involved 25 semi-structured interviews, whereas the 18 subsequent structured interviews were conducted with stakeholders in the entire RLSC as part of the quantitative method. These were used to identify the cause and effect relationships of the identified risks. The data were analysed using thematic analysis, and the Bayesian belief network (BBN) technique was used to develop a conceptual risk model.
Findings
In total 20 risks in four RLSC sub-processes, namely, dismantling and on-site process, off-site resource recovery process, marketing of secondary products and residue disposal, emerged. Among cause and effect relationships of identified risk factors, inferior quality of secondary products was found to have the strongest relationship with customer satisfaction. Under-pricing of dismantling job, improper landfill operations and inadequacy of landfill levy are independent risks that initiate other risks down the supply chain. The aggregate effects of these risks affect customer dissatisfaction of the end-product, as well as health and safety risks in on-site, off-site and residue disposal.
Research limitations/implications
This study only identify the cause and effect relationships of the identified risks within the RLSC for DWM operations. It has not targeted a specific construction material or any secondary production, which could be practiced through a case study in future research.
Practical implications
The results encourage the investigation of RLSC process quality by maintaining the relationship between recycler and customer to enable a safe workplace environment. Hence, the role of relevant practitioners and government is inseparable in supporting decision-making. Future research could discuss the impact of those inter-related risks in relation to time- or cost-related operational performance criteria.
Originality/value
This study contributes to the field through presenting the first major study on the identification and assessment of the inter-dependencies of the risks in the RLSC in South Australia. The RLSC process mapping had been identified as a tactical and operational management approach. However, the risk management process is a strategic management approach. Therefore, the integration of both process mapping and the risk management approaches in one platform is germane to construction management research.
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Christopher Amoah and Linda Bikitsha
Emerging construction companies often liquidate due to their inability to institute strategies to handle their business risks. This study investigated the skills and strategies…
Abstract
Purpose
Emerging construction companies often liquidate due to their inability to institute strategies to handle their business risks. This study investigated the skills and strategies adopted by emerging contractors to overcome business risk factors to make their businesses sustainable.
Design/methodology/approach
A qualitative research approach was adopted for the study. Semi-structured interview questions were used to solicit information from emerging contractors within the Construction Industry Development Board (CIDB) Grade one (1) to four (4) in the Gauteng Province of South Africa. The data gathered were analysed using qualitative content analysis to identify the main themes.
Findings
The study's findings indicate that emerging contractors face business risk factors that impact their project execution hugely. Thus to overcome these risk factors, they implement various strategies to curtail the risk they encounter in their businesses. These strategies include; human resource management (employing experienced and skilled labour and training of staff); communication management (with other employees about set goals); financial management (effective pricing of tender documents); procurement management (ensuring materials are available as and when necessary in their projects) and quality management (ensuring effective work supervision); among others.
Research limitations/implications
Although the study concentrated on the emerging construction firms in the Gauteng Province of South Africa, the findings may be applicable in other provinces and beyond South Africa.
Practical implications
In order for emerging contractors to prevent the collapse of their businesses, there is the need to be educated on effective project risk management to identify potential business risk, the mirage associated with the notion of the construction business profitability, effective tender pricing and strategic business partnership. These strategies, if well thought, will help sustain their businesses and growth in the construction industry.
Originality/value
The study has identified the management strategies used by emerging contractors to sustain their businesses in the construction industry. Thus, the finding will guide both emerging contractors who are already in the construction business and those planning to enter the construction market.
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Rashed Alotaibi, M. Sohail, F.T. Edum-Fotwe and Robby Soetanto
Many construction projects exhibit poor performance in terms of fulfilling predetermined schedules and financial objectives. Project control systems (PCSs) have been used to…
Abstract
Purpose
Many construction projects exhibit poor performance in terms of fulfilling predetermined schedules and financial objectives. Project control systems (PCSs) have been used to enhance construction project performance; however, a comprehensive framework regarding the key determinants of PCS effectiveness is lacking.
Design/methodology/approach
Herein, the determinants for effective PCSs that can improve construction project performance were comprehensively identified by evaluating existing studies. A systematic strategy following the preferred reporting items for systematic reviews and meta-analyses protocol was employed to search for and select relevant studies, followed by a qualitative synthesis.
Findings
The significance of incorporating and managing many factors associated with PCS for effective project delivery was elucidated. The study synthesized 12 key determinants and 29 sub-determinants of PCS effectiveness in project delivery and grouped them into organizational, human, technological and operational categories. Out of the four categories examined, operational aspects received the most references, underscoring their critical role in PCS effectiveness, while human-related dimensions received the least amount of attention in the reviewed research, accounting for 4%. This also revealed a significant gap in the research addressing the interactions between all PCS aspects.
Originality/value
Understanding of the variables influencing PCS effectiveness in construction project delivery was enhanced, and a framework for future PCS research in five dominant areas was created.