Academic literature on the topic 'Chlorine attenuation'

ABSTRACT Perchlorate contamination can be microbially respired to innocuous chloride and thus can be treated effectively. However, monitoring a bioremediative strategy is often difficult due to the complexities of environmental samples. Here we demonstrate that microbial respiration of perchlorate results in a significant fractionation (∼−15‰) of the chlorine stable isotope composition of perchlorate. This can be used to quantify the extent of biotic degradation and to separate biotic from abiotic attenuation of this contaminant.

The marine environment in Kuwait is polluted with various hazardous chemicals of industrial origin. These include petroleum hydrocarbons, halogenated compounds and heavy metals. Bioremediation with dedicated microorganisms can be effectively applied for reclamation of the polluted marine sediments. However, information on the autochthonous microbes and their ecophysiology is largely lacking. We analyzed sediments from Shuwaikh harbor to detect polychlorinated biphenyls (PCBs) and total petroleum hydrocarbons (TPHs). Then we adopted both culture-dependent and culture-independent (PCR-DGGE) approaches to identify bacterial inhabitants of the polluted marine sediments from Shuwaikh harbor. The chemical analysis revealed spatial variation among the sampling stations in terms of total amount of PCBs, TPHs and the PCB congener fingerprints. Moreover, in all analyzed sediments, the medium-chlorine PCB congeners were more abundant than the low-chlorine and high-chlorine counterparts. PCR-DGGE showed the presence of members of the Proteobacteria, Spirochaetes, Firmicutes and Bacteroidetes in the analyzed sediments. However, Chloroflexi-related bacteria dominated the detected bacterial community. We also enriched a biphenyl-utilizing mixed culture using the W2 station sediment as an inoculum in chemically defined medium using biphenyl as a sole carbon and energy source. The enriched mixed culture consisted mainly of the Firmicute Paenibacillus spp. Sequences of genes encoding putative aromatic ring-hydroxylating dioxygenases were detected in sediments from most sampling stations and the enriched mixed culture. The results suggest the potential of bioremediation as a means for natural attenuation of Shuwaikh harbor sediments polluted with PCBs and TPHs.

In the actual project, many concrete structures not only suffer the loading of static force and the repeated loading but also affected by the corrosive effects of chemical substances in external environment, which makes concrete corrosion and damage become an unavoidable issue in engineering. The research on it at home and abroad is still in stage of theoretical exploration. This paper studied the attenuation of the residual strength of concrete under fatigue loading and corrosion of chloride, using self-designed experimental corrosion fatigue loading device. The results show that the corrosion of concrete by chlorine ion is unneglected, its influence is greater than mathematical superposition of alternating load and corrosion when they affect the concrete separately.

Two series of model compounds were devised to follow the attenuation of substituent effects with an interposed methylene group: short-chain aliphatic compounds 1 and derivatives of bicyclo[2.2.2]octane 5. In all compounds, chlorine atom acts as substituent and charged oxygen atom as the functional group; the interaction of both is measured by the reaction energy of the isodesmic reaction calculated at the B3LYP/AUG-cc-pVTZ//B3LYP/6-311+G(d,p) and/or B3LYP/6-311+G(d,p) levels. Attenuation of the substituent inductive effect with the distance is less steep than observed previously in solution. It depends also markedly on the conformation but cannot be reproduced, not even approximately, by the electrostatic formula. Only for simple regular conformations, it can be described approximately by an exponential function with the transmission factor for one methylene group equal to 0.74. The behavior of isolated molecules differs in this case distinctly from the reactivity in solution. Nevertheless, the significance of the two formulas, electrostatic and exponential, is similar in the isolated molecules and in solution. These formulas represent only two different, rather crude mathematical approximations and cannot be given any physical meaning.

Isotherapics prepared from toxic substances have been described as attenuation factors for heavy metal intoxication in aquatic animals. Herein, Artemia salina and mercury chloride were used as a model to identify treatment-related bioresilience. The aim was to describe the effects of Mercurius corrosivus (MC) in different potencies on Artemia salina cyst hatching and on mercury bioavailability. Artemia salina cysts were exposed to 5.0 µg/mL of mercury chloride during the hatching phase. MC 6cH, 30cH, and 200cH were prepared and poured into artificial seawater. Different controls were used (nonchallenged cysts and challenged cysts treated with water, succussed water, and Ethilicum 1cH). Four series of nine experiments were performed for 4 weeks to evaluate the percentage of cyst hatching considering all moon phases. Soluble total mercury (THg) levels and precipitated mercury content were also evaluated. Solvatochromic dyes were used to check for eventual physicochemical markers of MC biological activity. Two-way analysis of variance (ANOVA) with mixed models was used for evaluating the effect of different treatments and the simultaneous influence of the moon phases on the cysts hatching rate, at both observation times (24 and 48 hours). When necessary, outliers were removed, using the Tukey criterion. The level of significance α was set at 5%. Significant delay (p<0.0001) in cyst hatching was observed after treatment with MC 30cH, compared with the controls. An increase in THg concentration in seawater (p<0.0018) and of chlorine/oxygen ratio (p<0.0001) in suspended micro-aggregates was also seen, with possible relation with mercury bioavailability. Specific interaction of MC 30cH with the solvatochromic dye ET33 (p<0.0017) was found. The other observed potencies of Mercurius corrosivus 6 and 200 cH were not significant in relation to the observed groups. The results were postulated as being protective effects of MC 30cH on Artemia salina, by improving its bioresilience.

The progress of high-efficiency non-precious metal anode catalysts for direct seawater splitting is of great importance. However, due to the slow oxygen evolution reaction (OER) kinetics, competition of chlorine evolution reaction (ClER), and corrosion of chloride ions on the anode, the direct seawater splitting faces many challenges. Herein, we develop a perovskite@NiFe layered double hydroxide composite for anode catalyst based on Ba0.5Sr0.5Co0.8Fe0.2O3 (BSCF) and NiFe layered double hydroxide (NiFe-LDH) heterostructure. The optimized BSCF@CeO2@NiFe exhibits excellent OER activity, with the potential at 100 mA cm−2 (Ej = 100) being 1.62 V in the alkaline natural seawater. Moreover, the electrolytic cell composed of BSCF@CeO2@NiFe anode shows an excellent stability, with negligible attenuation during the long-term overall seawater splitting with the remarkable self-recovery ability in the initial operation stage, and the direct seawater splitting potential increasing by about 30 mV at 10 mA cm−2. Our work can give a guidance for the design and preparation of anode catalysts for the direct seawater splitting.

The goals of this work are as follows: (а) searching for a method of study of the In – Se system taking into account the specified problems and difficulties, (b) choosing a way for the instrumental implementation of this method, and (c) obtaining experimental evidence that this method and its implementation are promising. The choice of the In – Se system is related to the fact that indium selenides, layered structures and semiconductor phases with stoichiometric vacancies, are promising from the point of view of materials science. This choice is also related to the use of binary precursors for the synthesis of heterostructures based on CIS compounds.We studied the possibility of applying the auxiliary component method using the equilibrium with the participation of indium chloride vapours which were made to contact the condensed phases of the In – Se system. Equilibrium was achieved using high-temperature spectrophotometry of the vapour phase. The experiment had two stages. During the first stage we determined the absorption characteristics of the InCl3 vapour. During the second stage we studied the heterogeneous equilibrium of the unsaturated indium chloride vapour with several phases of the In – Se system. Over the course of the study, we determined the molar attenuation coefficients of the InCl3 vapour and plotted the temperature dependences of the value KP.It was found that the phase composition of the alloys significantly influences the position of the corresponding lines on the KP–T diagram, which proves the possibility of using the suggested auxiliary component method in its specific instrumental (spectrophotometric) implementation in order to study the In – Se system. We also showed the additional possibilities of using this method for plotting T-x diagrams of binary systems in such high-temperature areas where the binary solid phase is in equilibrium with the melt. This application of the method is related to the solubility of a vapour of an auxiliary component (chlorine in the form of indium chlorides) in the melts of binary phases (indium selenides).

Nearly 250,000 sites with past and present potentially polluting activities need urgent remediation within Europe. Major pollutants include organochlorines (OCls), e.g. chlorinated ethenes (CEs) and hexachlorocyclohexanes (HCHs), mainly used as industrial solvents and pesticides, respectively. Due to improper handling and disposal, OCls contaminants are present in the soil or groundwater surrounding sites, where they have been produced or used. CEs and HCHs can undergo degradation by microorganisms indigenous to the soil or groundwater. Therefore natural attenuation (NA), relying on the in situ biodegradation of pollutants, is considered as a cost effective remediation strategy, yet it requires accurate monitoring methods. Compound specific isotope analysis (CSIA) is a powerful tool to provide information on the extent of degradation and, when combining two isotope systems (2D-CSIA), such as carbon (δ13C) and chlorine (δ37Cl), on reaction mechanisms. The diagnostic reaction-specific isotope enrichment factors (εC and εCl) were determined in laboratory experiments for the anaerobic degradation of PCE, TCE (Paper II) and α-HCH (Paper III) by mixed bacterial cultures enriched from CEs and HCHs contaminated sites, respectively. The related mechanism-specific εCl/εC ratios were calculated as 0.35 ± 0.11 (PCE), 0.37 ± 0.11 (TCE) and 0.52 ± 0.23 (α-HCH). These values are smaller than previously reported values for pure cultures. This is explained by the microbial community composition changes observed during degradation of PCE and α-HCH, which also reflect the variability of the microbial community at the field level. Furthermore, εCl/εC ratio might be bacteria specific. These values allowed the estimation of the extent of contaminant degradation at the respective study sites (Paper III and IV). Application of both isotope systems (δ13C and δ37Cl) led to comparable estimates. However the choice of representative ε values is crucial for an accurate assessment. These studies show that CSIA is useful to quantify in situ degradation of OCls contaminants and identify reaction pathways, by combining δ13C and δ37Cl.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.

Le géoradar, ou Ground Penetrating Radar (GPR) en anglais, est une méthode non destructive couramment utilisée pour l'auscultation des ouvrages en béton. L'intérêt de cette méthode réside sur sa capacité à ausculter rapidement des très grandes surfaces, elle est de plus en plus employée en Génie Civil. Habituellement, cette méthode est utilisée en Génie Civil pour la localisation les aciers de renforcements, ou bien pour l'estimation de l'épaisseur d'enrobage du béton. Toutefois, la méthode GPR peut aussi être utilisée pour l'auscultation du béton. En effet, le béton est un matériau diélectrique poreux qui peut modifier la propagation des ondes électromagnétiques (EM). Les résultats les plus récents présentent la capacité du GPR à évaluer la teneur en eau. Cependant, le GPR pourrait très bien aussi être utilisé pour la détection des ions chlorure présents dans la solution interstitielle du béton, car comme les chlorures modifient la conductivité du béton ils sont susceptibles d'atténuer les ondes électromagnétiques. Néanmoins, seulement quelques études ont été menées dans ce domaine. Par conséquent, dans cette étude, nous proposons d'utiliser les ondes EM du géoradar pour estimer conjointement la teneur en eau et la teneur en chlorure du béton pour différents corps d'épreuves. Pour cela, plusieurs séries de corps d'épreuves sont utilisées avec des modes de contaminations par les chlorures différents. Une procédure de mesure de la vitesse à partir de l'analyse des signaux réfléchis est proposée. On démontre que la vitesse des ondes EM est essentiellement affectée par la teneur en eau alors que l'atténuation est sensible à la fois à la teneur en eau et à la teneur en chlorures. Ensuite, dans un second temps, nous testons différents modèles de permittivité pour prédire les mesures de constante diélectrique et du facteur de pertes évalués à partir des mesures par GPR ou de résistivité électrique
Ground Penetrating Radar (GPR) is an usual nondestructive testing method for the assessment of concrete structures. The benefit of this method lies within its ability to assess quickly a large scale of concrete surface. Generally, GPR is used for the localization of reinforcements or for the thickness measurements. However, GPR can be also used for the diagnosis of concrete because concrete is a porous dielectric material which can modify the propagation of the electromagnetic (EM) waves. Most common results present the ability of GPR to assess moisture. But, GPR could be also used to detect the presence of chlorides into the interstitial concrete solution as chlorides can modify the concrete conductivity and altered the electromagnetic signal waves. However, only few studies have been carry-out on that field. Therefore, in this study, we propose to use GPR electromagnetic waves to evaluate both the water content and the chloride content inside the interstitial concrete solution of several tests concrete samples. So, several groups of concrete samples with the same formulation will be conditioned for different chloride contamination modes. Thereafter, a velocity measurement process will be proposed from the reflected signal wave analysis. In that process, we will show that the velocity is only affected by the water content while the attenuation strongly affected by both the water content and the chloride content. Furthermore, we will test several permittivity models to predict the dielectric permittivity and the loss factor estimated from the concrete samples measurements with the GPR device and the electrical resistivity device

Isotopic methods have been developed over the last 10 years as a method for determining chemical interactions of chlorinated solvents. These methods are especially promising for. This study attempts to employ and develop compound specific isotopic analyses of TCE and cDCE, along with chemical data, to characterize the degradation of TCE in a fractured bedrock aquifers. The Smithville site is a contaminated field site with extremely high levels of TCE contamination that is currently undergoing monitored remediation. From December 2008 until April 2010 extended samples were collected from the site to provide additional data analyses including isotopic data. The redox conditions at the site are anoxic to reducing, with sulfate reduction and methanogenesis as dominant terminal electron accepting processes. Redox data indicates that well electrochemical conditions are highly variable within the site, including areas near the source zone that not very reducing. Documented changes in groundwater conditions to much more reducing environments indicate that oxidation of organic matter is occurring at the Smithville site in select wells. Chemical analyses of TCE, DCE, VC, ethene and ethane are employed determine whether reductive dechlorination was occurring at the site. Results of field testing indicate that many wells on site, especially in the proximity of the source zone, dechlorination products were found. The isotopic data had a high range in both carbon and chlorine isotopes. Chlorine isotopic data ranges from a δ37Cl(TCE) of 1.39 to 4.69, a δ37Cl(cDCE) of 3.57 to 13.86, a δ13C(TCE) of -28.9 to -20.7, and a δ13C(cDCE) of -26.5 to -11.82. The range in values indicate varying degrees of degradation throughout the site, with the same wells grouping together. Combined chemical, redox and isotopic data shows that degradation seems to be a removal process for TCE at the Smithville site. Concentrations of chemicals created as a result of TCE degradation verify degradation, especially in wells 15S9, R7 and 17S9. Historically production of DCE in significant amounts, above 1.0 ppb, was observed to only occur after 2003. In addition to this, DCE data shows that the percentage of DCE made up of cDCE is above 96%. This indicates that microbes most likely mediate the processes that formed DCE from TCE. The linear regression of the delta-delta plot for isotopic TCE data shows line that is likely a direct function of the carbon and chlorine isotopic fractionation imparted upon the original TCE released. The slope found is consistent with data collected from other studies though cannot be applied to determining the process directly given the range of variability in isotopic field data.

Millions of people in low and middle-income countries worldwide receive water only for a small fraction of the time in a day through piped networks. Even though the percentage of the world’s population with access to piped water has increased, the number of individuals receiving water intermittently is projected to rise. Water supply systems are designed for a continuous supply of water to consumers with a standard demand pattern. However, an unforeseen increase in demand, reduced network capacity, ease of operation and climate change results in Intermittent Water Supply. Because the intermittent water supply goes through filling and draining cycles regularly, the water is not always safe to drink. Due to ageing infrastructure, poor management, and system operation, the amount of Unaccounted For Water in these cities is extremely high and leads to inequitable water distribution. The water supply in developing countries is insufficient to meet demand, and there is a significant imbalance between supply and demand. This thesis examines the influence of intermittently supplied piped water on water inequity, the impact on the quality of water delivered, and possible solutions to intermittent supply. A framework for understanding the effect of inequitable distribution due to intermittent supply is developed first. Economic and geographical characteristics of the DMA, such as insufficient infrastructure, high Unaccounted For Water, socio-economic status, and so on, all contribute to inequity in the intermittent water supply. The inequality in intermittent water supply between 10 divisions and 83 DMAs in the South division of Bangalore, India, are examined in this study. The inequity is divided into four categories, namely: (i) inequity in water sharing, (ii) inequity in time of supply, (iii) inequity in the duration of supply and (iv) inequity in alternate supply. The supply, UFW, and consumption data were collected for a period of 36 months. The presence of inequity in water sharing was indicated by the Lorenz curve and Gini coefficient. The Kullback-Leibler divergence, Cauchy-Schwarz inequality, and Euclidean distance among supply zones revealed inequity in supply time and duration. Inequity in the supply duration and an alternate source of supply was also discussed using the Lorenz curve and Gini coefficient. The current analysis revealed a severe disparity in all four categories, showing that the IWS with poor infrastructure leads to inequitable water distribution. It was also clear that, despite significant savings in UFW, inequity remained largely unchanged. The most efficient way to counter the inequity in IWS is to move towards a continuous system. We study this phenomenon of Intermittent Water Supply with the city of Mysore, India, as an example, understand the issues therein and address them with a systematic procedure to achieve Continuous Water Supply. It is essential to solve the problem of Intermittent Water Supply due to the adverse effects caused. IWS can create inequity at various levels: command areas, DMAs, supply and sub-supply zones. On the contrary Continuous Water Supply has additional benefits like improved water quality, increased customer satisfaction, and better supply and demand man- agement. To achieve CWS, we formulate a convex cost minimisation problem with appropriate penalties to i) maintain the reservoirs at the desired level, ii) obtain a periodic solution and iii) avoid frequent changes in the valve configuration. The network-wide problem formulation helps vii compensate local infrastructure limitations using the excess infrastructure available elsewhere in the network. We then optimally control the water inflow into the reservoirs and meet daily demand. We propose a Simultaneous Perturbation Stochastic Approximation (SPSA) based gradient algorithm on solving the optimisation problem. A hydraulic modelling toolkit EPANET is used to compute the flows in the water network. We then initialise the reservoirs to their desired target levels using a similar approach, starting from arbitrary initial levels. The proposed algorithm was applied to two water networks in Mysore, India. The essential contribution here is to verify the possible enhancement of water supply systems by network-wide control. Risks to water quality are exacerbated due to intermittency of supply, mainly due to intrusion and back-flow, as well as variation in bio-film, deposits, and microbial growth. Chlorine is a widely used disinfectant in the drinking water treatment process, mostly in developing countries, due to its efficiency and affordability. Therefore, assessing the effect of intermittency in the drinking water supply on chlorine decay is needed to ensure safe drinking water delivery through piped networks in these countries. In this work, field sampling for chlorine decay measurement was carried out in adjoining continuous and intermittent water supply networks in Bangalore, India. The two networks received water from the same source. The first-order model was used to calculate chlorine decay rate in different pipe segments distributed across the networks. The effect of network parameters such as pipe velocity, pipe material, and pipe diameter on chlorine degradation rate was investigated. Further chlorine decay rates in continuous and intermittent networks were compared, considering the influence of these network properties. The analysis indicates that decay rates varied significantly with velocity in both networks, with reactive ma- terials being more sensitive to velocity variation than non-reactive materials. Reactive materials had higher decay rates than non-reactive materials, and decay rates increased with a decrease in pipe diameter, concurring with trends found in previous literature. The comparison of decay rates across networks showed that the average decay rate in the intermittent network was 1.5 times higher than the average decay rate in the continuous network, indicating that intermittency in the water supply has a long-term effect on chlorine decay. Contaminants can infiltrate a water distribution network at any time or location due to the ageing infrastructure, accidental discharge, or malicious actors. Contaminants such as total coliform bacteria, organic compounds, and others create serious health issues in a large population served by the WDS. This is especially prevalent in intermittent water supply, and it can lead to a loss of faith in the water utility. The detection of intentional or accidental contamination in a water distribution system (WDS) is necessary to ensure that society has access to adequate safe drinking water. One of the techniques for detecting contamination in WDS is to install the sensor. In the literature, determining the best location for the sensor is still a work in progress. We proposed ”EQ-water,” a new method for identifying sensor location which works for both continuous and intermittent water distribution systems. The EQ-water is based on complex network theory and utilizes very little hydraulic information. We evaluated the proposed method’s performance on four real networks, BWSN 1, BWSN 2, JPN, and D2B Bangalore networks. Furthermore, we compared the results to all of the BWSN’s proposed approaches and existing complex network-based methods. We employed TEVA-SPOT to assess the methods’ performance on four different objective functions, as well as the cumulative objective function. EQ-Water has the best performance in BWSN 1, JPN, D2B Bangalore and average performance in BWSN 2. Utility boards in India are ill-equipped to deal with Unaccounted For Water (UFW) in intermittent water supply, with leakage being the primary cause of UFW. Conducting controlled independent experiments in the field to detect leaks or study water quality is a time-consuming process. It is relatively difficult to interfere with a running water supply to conduct experiments and collect measurement data. As a result, at our R&D centre in IISc, Bangalore, we developed an experimental water supply setup. Detecting leaks in intermittent water supplies have not been studied in the literature; thus, in this study, we created such scenarios and used a data-driven approach to detect leaks in laboratory conditions. The goal of the work is to create an intermittent supply in the lab that mimics the real-world water supply of Bangalore, south, and to introduce various leak scenarios. Using the proposed data analytic approach using a log-likelihood model in conjunction with CUSUM, we then use this data to train the model. The testing data results show that leaks in intermittent supply systems can be detected and localised.
IMPRINT initiative of Ministry of Human Resource \& Development and Ministry of Housing and Urban Affairs, Govt of India [Project code: 5786 and Sanction No: F.No.3-18/2015-TS-TS.I.] and Robert Bosch Center For Cyber Physical Systems

One of the main challenges facing the potable water production industry is deterioration of the quality of raw water. Drinking water that does not meet quality standards is unfit for consumption. Yet, this quality is a function of various factors, key among them being quality of the raw water from which it is processed. This is because costs related to potable water treatment are related to the nature of raw water pollutants and the degree of pollution. Additionally, survival of aquatic species depends on self-purification of the water bodies through attenuation of pollutants, therefore, if this process is not efficient it might result in dwindling of the aquatic life. Hence, this chapter presents spatial and temporal water quality trends along uMngeni Basin, a critical raw water source for KwaZulu-Natal Province, in South Africa. As at 2014 the basin served about 3.8 million people with potable water. Results from this study are discussed in relation to uMngeni River’s health status and fitness for production of potable water treatment. Time-series and box plots of 11 water quality variables that were monitored at six stations over a period of eight years (2005 to 2012), were drawn and analysed. The Mann Kendall Trend Test and the Sen’s Slope Estimator were employed to test and quantify the magnitude of the quality trends, respectively. Findings showed that raw water (untreated) along uMngeni River was unfit for drinking purposes mainly because of high levels of Escherichia coli. However, the observed monthly average dissolved oxygen of 7 mg/L, that was observed on all stations, suggests that the raw water still met acceptable guidelines for freshwater ecosystems. It was noted that algae and turbidity levels peaked during the wet season (November to April), and these values directly relate to chlorine and polymer dosages during potable water treatment.

Abstract In this paper, we propose a novel gradient index metamaterial lens to focus elastic wave energy in polymer pipes. We investigate multi-mode focusing of guided ultrasonic waves in a poly-vinyl chloride (PVC) pipe by designing and integrating an embedded gradient index (GRIN) lens within the pipe wall. The metamaterial lens is composed of equally spaced cylindrical brass inserts embedded into the pipe wall. All the inserts are of same height which is equal to the half-thickness of the pipe. Insert diameters are varied in circumferential direction to realize hyperbolic secant distribution of refractive index around the circumference of pipe. We explore focusing of three pipe wave modes commonly used for guided wave inspection of pipelines namely, L(0,2), L(0,1) and T(0,1), using a single lens design. We further verify the lens performance through numerical simulations estimating the amplification of wave energy in focal regions of the GRIN lens for these three modes. We also estimate attenuation of guided waves propagating in PVC pipe through experimental measurements.

Fitness-for-service (FFS) assessments are quantitative engineering evaluations which are required to be preformed periodically in accordance with the published codes and standards to demonstrate the structural integrity of in-service components. This report summarizes the results of nondestructive in-service-inspection (ISI) of pressurized components conducted for condition assessment of the Dakhani Gas Processing Plant of Oil and Gas Development Corporation Ltd. (OGDCL) for the first time since its commissioning in December,1989. The non-destructive evaluation of the plant was required because of concerns for occurrence of sulphide-stress-cracking. Hydrogen embrittlement, hydrogen-including-cracking, weight-loss-corrosion, sulphur-stress-corrosion due to determental service conditions at Dakhani having low PH, High H2S, high chlorides and pressure of CO2. The results have shown that microstructural changes associated with first and second stage of hydrogen attack have occurred in almost all of the pipe joints and pressure vessels. Hardness of some vessels has even exceeded the NACE limit of 220 HB. Effect of second stage of hydrogen attack are dominant in pipe joints, resulting in loss of hardness and strength because of decarburization. The results based on ultrasonic attenuation monitoring also indicate degradation of components. Random rounded indications have also been observed in some pipe joints during X-Ray radiographic testing that could serve as sites for failure initiation. The corrosion-under-insulation is observed for joints of piping spreading over a significant length. Localized corrosion and pitting is also observed in some locations of pressure vessels and piping. Ultrasonic thickness gauging has shown a significant variation in thickness for dish end and shell of some pressure vessels as well as for various joints of piping. In absence of periodic ISI data for the plant and keeping in view the results of non-destructive evaluation summarized above, the end-of-life (EOL) assessment of pressure vessels and piping is not possible and operation of the plant should be continued with a degree of caution. Any estimate of safe life assessment of the plant made at this stage would require revision on the basis of observed level of degradation through essential periodic in-service monitoring. In order to cope with the situation, it is recommended that monitoring of further degradation of microstructure and hardness along with flaw growth should be carried out after a period of 8x103 hours. Necessary remedial measures for rectification of flaws are requested. Non-destructive strain gauging is recommended to estimate data for safe life assessment of pressure vessels. Thermographic scanning of on-line in-service insulated pipelines is proposed for monitoring corrosion-under-insulation during plant operation.