ABSTRACT Risk assessment is the most significant factors in risk management. Earlier researches h... more ABSTRACT Risk assessment is the most significant factors in risk management. Earlier researches have shown that risk assessment is essential to achieve success in Engineering, Procurement and Construction projects(EPC). The occurrence of different risk can worsen the effects of each other such as the impact of political risks on economic risks. Although appointed methods such as Analytic Hierarchy Process (AHP), Fuzzy Synthetic, Interrelated Tree and Fuzzy AHP methods are commonly used in the industry sectors, yet these approaches seem powerless for evaluating the interactions and feedback between the aforementioned risks. As a result, an accurate assessment of the severity of risks cannot be determined. This study aims to assess the risks in EPC projects using Analytic Network Process (ANP) method. ANP approach is preferable in order to identify the problems of interdependence and feedback between various risk ranking alternatives. The method utilizes data that are collected through literature review, interview and a questionnaire distributed to EPC project experts. In this paper, the effects of risks on EPC project objectives such as cost, quality and time and probabilities of occurrence are assessed. Risks in EPC projects are divided into six groups: design risks, market risk, political risk, environmental risk, construction risk and political risk. The results have shown that political risks, and design risks are the most significant group of risks in EPC projects as compared to other group of risk. As a conclusion, ANP is found suitable in analyzing the feedback and interdependence between risks.
The impact of onshore oil and gas pipeline accident i.e., explosion varies depending on the pipel... more The impact of onshore oil and gas pipeline accident i.e., explosion varies depending on the pipeline location, transported product, proximity of residential areas and etc. Pipeline owner's reputation is threatened once an accident takes place, which influences stakeholders' perceptions consequently. This study focuses on prioritizing the importance of the reputation loss factors according to the experts' judgments. Twenty two reputation loss factors were identified from 10 major pipeline explosion post-accident case studies. Nine experts were interviewed to rate importance level of the reputation loss factors using 10-point Likert scale rating method. The significance difference was obtained by the implementation of statistical analysis. Relative Importance Index (RII) was used to identify the importance level of the factor and Analytical Hierarchy Process (AHP) method for prioritization process with the aid of Super Decisions software. Results show that all reputation l...
Pipelines play an extremely important role in the transportation of gases and liquids over long d... more Pipelines play an extremely important role in the transportation of gases and liquids over long distance throughout the world. Internal corrosion due to microbiologically influenced corrosion (MIC) is one of the major integrity problems in oil and gas industry and is responsible for most of the internal corrosion in transportation pipelines. The presence of microorganisms such as sulfate reducing bacteria (SRB) in pipeline system has raised deep concern within the oil and gas industry. Biocide treatment and cathodic protection are commonly used to control MIC. However, the solution is too expensive and may create environmental problems by being too corrosive. Recently, Ultraviolet (UV) as one of the benign techniques to enhance mitigation of MIC risk in pipeline system has gained interest among researchers. An amount of 100 ml of modified Baar's medium and 5 ml of Desulfovibrio vulgaris (strain 7577) seeds was grown in 125 ml anaerobic vials with carbon steel grade API 5L-X70 coupons at the optimum temperature of 37°C and pH 9.5 for fifteen days. This was then followed by exposing the medium to UV for one hour. Results from present study showed that UV radiation has the ability to disinfect bacteria, hence minimizing the risk of metal loss due to corrosion in steel pipeline.
International Journal of Biological Chemistry, 2015
In oil and gas industry, corrosion due to activity of microorganism is one of the main factors, w... more In oil and gas industry, corrosion due to activity of microorganism is one of the main factors, which contribute to catastrophic structural failure. Previous study always linked Sulfate-Reducing Bacteria (SRB) upon the mechanism of Microbiologically Influenced Corrosion (MIC), as the major contributors. In this study, mechanisms of SRB genus D. vulgaris in terms of bacterial growth under influence of environmental factors were investigated. The growth of pure strain ATCC 7757 and SRB isolated from the soil in suspected areas in Peninsular Malaysia were investigated by using turbidity measurement. Results from the study were analyzed statistically to show the significant influence due to various environmental factors. The results agreed that variation of each environmental parameter tested gives strong influence upon bacterial growth for SRB strain individually.
Pipeline integrity management programs address a wide range of threats to safe operations. Among ... more Pipeline integrity management programs address a wide range of threats to safe operations. Among these threats, external corrosion has been among the most dominant failure mechanism experienced by buried steel pipelines. External corrosion can be detected through a variety of assessment methods, including inline inspection (ILI) and external corrosion direct assessment (ECDA). In the absence of data from inspection, the corrosion rate can be estimated based on the use of buried corrosion coupons, corrosion probes and corrosion rate modelling using data derived from soil analysis. The objective of the paper is to design a methodology of the external growth modelling of corrosion on buried gas pipelines under various exposures to soil conditions. The technique can be used to generate field data so as to model empirically the corrosion dynamic in soil or for verification of corrosion data from laboratory testing. The potential model based on the proposed technique is highly potential t...
The oil and gas industry uses carbon steel pipelines as the basic element in transporting crude o... more The oil and gas industry uses carbon steel pipelines as the basic element in transporting crude oil and gas. These pipelines are subjected to deterioration due to several factors, including third party damage, material and construction defects, natural forces and corrosion. Deterioration of underground pipelines due to corrosion can lead to serious pipeline failures such as leakage and explosion. Hence, methods to repair such damage have been developed in order to extend the durability of pipelines. This paper reports on the current development of infill materials of epoxy grouts used for pipeline external repair. Assessment of the defects should be completed by pipeline operators to identify list of parameters including pipeline operating characteristic, geometries and materials of pipeline, and configuration and location of pipeline to make the best option of repair techniques. Therefore, selection of an appropriate rehabilitation system is crucial in preventing the future failure...
Risk assessment is the most significant factors in risk management. Earlier researches have shown... more Risk assessment is the most significant factors in risk management. Earlier researches have shown that risk assessment is essential to achieve success in Engineering, Procurement and Construction projects(EPC). The occurrence of different risk can worsen the effects of each other such as the impact of political risks on economic risks. Although appointed methods such as Analytic Hierarchy Process (AHP), Fuzzy Synthetic, Interrelated Tree and Fuzzy AHP methods are commonly used in the industry sectors, yet these approaches seem powerless for evaluating the interactions and feedback between the aforementioned risks. As a result, an accurate assessment of the severity of risks cannot be determined. This study aims to assess the risks in EPC projects using Analytic Network Process (ANP) method. ANP approach is preferable in order to identify the problems of interdependence and feedback between various risk ranking alternatives. The method utilizes data that are collected through literat...
Sulphate-reducing bacteria (SRB) as the main source of Microbiologically Influenced Corrosion (MI... more Sulphate-reducing bacteria (SRB) as the main source of Microbiologically Influenced Corrosion (MIC) mechanism has a dominant influence upon localized corrosion problems especially for internal piping. In this paper, corrosion behavior of high-strength carbon steel (API 5L X-70) under anaerobic conditions in the presence of SRB's bacteria was studied in batch reactor. The coupons were exposed to the SRB culture for 1, 3, 6, 10, 20 and 30 days at 22 0 C and 37 0 C along with a control set. Corrosion rate in SRB medium at 37 0 C showed a higher dynamic value compared to medium inoculated at 22 o C. The corrosion rate of the carbon steel also showed no correlation with the planktonic or sessile SRB cell numbers.
Risk allocation is a key to managing risks associated with the public private partnership... more Risk allocation is a key to managing risks associated with the public private partnership projects. Optimal risk allocation between the parties involved, namely public and private, is the essence of successful PPP project implementation. This study intends to identify and prioritize significant risk allocation criteria and barriers preventing the optimal allocation of risk to PPP projects in Malaysia. Due to interaction among criteria and barriers, this research has adopted analytic network process in order to decompose decision model into meaningful network and weight decision elements. Data has been collected through literature review, questionnaire and interview with PPP project experts. This study reveals that "Bear the risk at lowest price", "Control the chance of risk" and "Risk attitude" are three major optimal risk allocation criteria. "Different sets of information about project risk", "Lack of efficient risk allocation mechanisms" and "Lack of understanding the benefits of optimal allocation" are of three major optimal risk allocation barriers identified throughout the study. The outcome can be used to improve the implementation of PPP project in Malaysia by more rationally allocating risks between parties involved.
Sulphate-reducing bacteria (SRB) represent themselves as a class of anaerobic bacteria that can r... more Sulphate-reducing bacteria (SRB) represent themselves as a class of anaerobic bacteria that can reduce sulphate to sulphide for obtaining energy. This paper is aimed to detect sulphatereducing bacteria activities using rapid detectable culture media. Two different strains of sulphate-reducing bacteria were used in this study, namely ATCC 7757 and local bacterial strain of SRB isolated from underground sample. Both strains were tested on three recommended culture media of modified Baar"s, Postgate B and Postgate C. All three medium contained lactic acid which served to be as carbon source. The results showed that modified Baar"s medium is the best medium for the growth of ATCC 7757 while Postgate C medium is recommended for the local SRB bacterial strain.
This paper investigated the performance of low frequency ultrasound radiation in mitigating the m... more This paper investigated the performance of low frequency ultrasound radiation in mitigating the microbiologically influenced corrosion (MIC) by mechanically inhibiting the planktonic sulfate-reducing bacteria (SRB) growth in modified ATCC broth number 1249 medium.
Consequence assessment is an integral part of the risk assessment process. There are many types o... more Consequence assessment is an integral part of the risk assessment process. There are many types of consequences loss due to pipeline failure such as asset loss, environmental loss, production loss, and human health and safety loss (HHSL). This paper studies the comparison of HHSL between rural and urban areas due to pipeline failure subject to corrosion. The damage area of the explosion was calculated using Aloha software by considering the details of the selected sites such as atmospheric and demographics conditions. The HHSL was calculated using a mathematical equation of quantitative risk assessment in terms of the number of fatalities or injuries or both. The results of the assessments from rural and urban areas were then compared with one another to identify any significant dissimilarity. This study shows that there was a possibility to improve the decisive value of risk by implementing the proposed approach in consequence assessment in Malaysia.
Microbiologically influenced corrosion (MIC) is caused by the presence of sulfate-reducing bacter... more Microbiologically influenced corrosion (MIC) is caused by the presence of sulfate-reducing bacteria (SRB) and is of great concern to the heavy metal industries. Inhibitors and biocides are commonly used to control the problem. Nevertheless, the solutions are too expensive and may create environmental problems by being corrosive to metals. Ultrasound wave exposure is one of the potential alternatives to biocides for the mitigation of MIC risk in pipeline system. In this work, a combination of ultrasound wave and green biocides of glutaraldehyde and ethanol has been proposed to exterminate SRB in a medium. An amount of 100 ml of Desulfovibrio vulgaris (ATCC7757) broth number 1249 was grown in 125 ml anaerobic vials at 37˚C for one day followed by exposure to various mitigation methods. Results from the study show that a combination of ultrasound and biocide can effectively reduce the dosage of biocide during corrosion treatment. The effectiveness of mitigation based on ultrasound-biocide combination is better than the treatment based solely on biocide whereby the extermination of SRB was found 10 times more effective according to the reduction of cell numbers of planktonic's SRB. Ultrasound technique can provide a feasible alternative as an effective assist to chemical inhibitors and biocides for controlling MIC in a more eco-friendly manner.
This study investigates how sulfate-reducing bacteria (SRB) influence the process of microbiologi... more This study investigates how sulfate-reducing bacteria (SRB) influence the process of microbiologically induced corrosion (MIC) of carbon steel by measuring corrosion potential using open-circuit potential (OCP) measurements. MIC is mainly influenced by D. Vulgaris, formerly known as D. Desulfuricans, deposited as Spirillum Desulfuricans, which produces D(-)-lactate dehydrogenase. The manufactured strain ATCC 7757 and pure colony of SRB isolated from the Baram and Sg Ular areas in Malaysia were used in this experiment. An evaluation of SRB growth was performed during the test in the inoculated medium anaerobically at 37°C with pH 7.5. The results showed that the corrosion potential E oc in manufactured ATCC was the highest as compared to the SRB isolated from site. These results indicated that ATCC could be the reference to predict the metal corrosion due to high corrosive product of H 2 S generated during metabolic activity.
This study defines the interrelationship between turbidities and cell number counting efficiency ... more This study defines the interrelationship between turbidities and cell number counting efficiency for the growth of one of the microbiologically influenced corrosion (MIC) species in a medium. The metabolism activities during bacteria growth can accelerate the corrosion process and shorten the reliability of pipelines. Thus, the investigation of MIC species’ development and metabolic activities is significant. An experiment was performed on sulfate-reducing bacteria (SRB) that practiced the medium as the substance to grow. Desulfovibrio vulgaris, a strain of SRB, was cultured in a postgate C medium to measure the bacteria survival using two different measurement methods. The medium was modified to pH 7.5 at 37°C and placed in anaerobic vials. During 24 hours of incubation, samples were retrieved, and the value of turbidity and cell numbers was measured. Based on the SRB growth graph pattern, the amount of bacteria cell numbers was increased parallel to the value of the medium’s turbidity in respect to time. Both values (turbidity and bacteria cell numbers) dramatically increased from hour1 to hour24. The results supported that the turbidity value was positively correlated with bacteria cell numbers.
In the past two decades, public private partnership has been one of the
prevailing ways for the d... more In the past two decades, public private partnership has been one of the prevailing ways for the development of infrastructures in Malaysia. However, it involves many risks and uncertainties due to a large amount of investment and long concession period. It is very important to recognize and find out the ways to cope with the critical risks that are related to the investments made in PPP projects for the foreign investors. The aim of this article is risk ranking associated with the PPP projects using risk matrix. First, the paper reviews the current literature, consultation and a written survey distributed to the panel of experts to identify common risks in PPP projects . The risks identified from the literature were classified according to the type of risk. From the results, it was found that the critical risks associated with the PPP projects include the third party tort liability, interest rate volatility, construction cost overrun and the change in law. This research study is supposed to provide awareness and highlight the management of the risks associated with the PPP risks in Malaysia.
ABSTRACT Risk assessment is the most significant factors in risk management. Earlier researches h... more ABSTRACT Risk assessment is the most significant factors in risk management. Earlier researches have shown that risk assessment is essential to achieve success in Engineering, Procurement and Construction projects(EPC). The occurrence of different risk can worsen the effects of each other such as the impact of political risks on economic risks. Although appointed methods such as Analytic Hierarchy Process (AHP), Fuzzy Synthetic, Interrelated Tree and Fuzzy AHP methods are commonly used in the industry sectors, yet these approaches seem powerless for evaluating the interactions and feedback between the aforementioned risks. As a result, an accurate assessment of the severity of risks cannot be determined. This study aims to assess the risks in EPC projects using Analytic Network Process (ANP) method. ANP approach is preferable in order to identify the problems of interdependence and feedback between various risk ranking alternatives. The method utilizes data that are collected through literature review, interview and a questionnaire distributed to EPC project experts. In this paper, the effects of risks on EPC project objectives such as cost, quality and time and probabilities of occurrence are assessed. Risks in EPC projects are divided into six groups: design risks, market risk, political risk, environmental risk, construction risk and political risk. The results have shown that political risks, and design risks are the most significant group of risks in EPC projects as compared to other group of risk. As a conclusion, ANP is found suitable in analyzing the feedback and interdependence between risks.
The impact of onshore oil and gas pipeline accident i.e., explosion varies depending on the pipel... more The impact of onshore oil and gas pipeline accident i.e., explosion varies depending on the pipeline location, transported product, proximity of residential areas and etc. Pipeline owner's reputation is threatened once an accident takes place, which influences stakeholders' perceptions consequently. This study focuses on prioritizing the importance of the reputation loss factors according to the experts' judgments. Twenty two reputation loss factors were identified from 10 major pipeline explosion post-accident case studies. Nine experts were interviewed to rate importance level of the reputation loss factors using 10-point Likert scale rating method. The significance difference was obtained by the implementation of statistical analysis. Relative Importance Index (RII) was used to identify the importance level of the factor and Analytical Hierarchy Process (AHP) method for prioritization process with the aid of Super Decisions software. Results show that all reputation l...
Pipelines play an extremely important role in the transportation of gases and liquids over long d... more Pipelines play an extremely important role in the transportation of gases and liquids over long distance throughout the world. Internal corrosion due to microbiologically influenced corrosion (MIC) is one of the major integrity problems in oil and gas industry and is responsible for most of the internal corrosion in transportation pipelines. The presence of microorganisms such as sulfate reducing bacteria (SRB) in pipeline system has raised deep concern within the oil and gas industry. Biocide treatment and cathodic protection are commonly used to control MIC. However, the solution is too expensive and may create environmental problems by being too corrosive. Recently, Ultraviolet (UV) as one of the benign techniques to enhance mitigation of MIC risk in pipeline system has gained interest among researchers. An amount of 100 ml of modified Baar's medium and 5 ml of Desulfovibrio vulgaris (strain 7577) seeds was grown in 125 ml anaerobic vials with carbon steel grade API 5L-X70 coupons at the optimum temperature of 37°C and pH 9.5 for fifteen days. This was then followed by exposing the medium to UV for one hour. Results from present study showed that UV radiation has the ability to disinfect bacteria, hence minimizing the risk of metal loss due to corrosion in steel pipeline.
International Journal of Biological Chemistry, 2015
In oil and gas industry, corrosion due to activity of microorganism is one of the main factors, w... more In oil and gas industry, corrosion due to activity of microorganism is one of the main factors, which contribute to catastrophic structural failure. Previous study always linked Sulfate-Reducing Bacteria (SRB) upon the mechanism of Microbiologically Influenced Corrosion (MIC), as the major contributors. In this study, mechanisms of SRB genus D. vulgaris in terms of bacterial growth under influence of environmental factors were investigated. The growth of pure strain ATCC 7757 and SRB isolated from the soil in suspected areas in Peninsular Malaysia were investigated by using turbidity measurement. Results from the study were analyzed statistically to show the significant influence due to various environmental factors. The results agreed that variation of each environmental parameter tested gives strong influence upon bacterial growth for SRB strain individually.
Pipeline integrity management programs address a wide range of threats to safe operations. Among ... more Pipeline integrity management programs address a wide range of threats to safe operations. Among these threats, external corrosion has been among the most dominant failure mechanism experienced by buried steel pipelines. External corrosion can be detected through a variety of assessment methods, including inline inspection (ILI) and external corrosion direct assessment (ECDA). In the absence of data from inspection, the corrosion rate can be estimated based on the use of buried corrosion coupons, corrosion probes and corrosion rate modelling using data derived from soil analysis. The objective of the paper is to design a methodology of the external growth modelling of corrosion on buried gas pipelines under various exposures to soil conditions. The technique can be used to generate field data so as to model empirically the corrosion dynamic in soil or for verification of corrosion data from laboratory testing. The potential model based on the proposed technique is highly potential t...
The oil and gas industry uses carbon steel pipelines as the basic element in transporting crude o... more The oil and gas industry uses carbon steel pipelines as the basic element in transporting crude oil and gas. These pipelines are subjected to deterioration due to several factors, including third party damage, material and construction defects, natural forces and corrosion. Deterioration of underground pipelines due to corrosion can lead to serious pipeline failures such as leakage and explosion. Hence, methods to repair such damage have been developed in order to extend the durability of pipelines. This paper reports on the current development of infill materials of epoxy grouts used for pipeline external repair. Assessment of the defects should be completed by pipeline operators to identify list of parameters including pipeline operating characteristic, geometries and materials of pipeline, and configuration and location of pipeline to make the best option of repair techniques. Therefore, selection of an appropriate rehabilitation system is crucial in preventing the future failure...
Risk assessment is the most significant factors in risk management. Earlier researches have shown... more Risk assessment is the most significant factors in risk management. Earlier researches have shown that risk assessment is essential to achieve success in Engineering, Procurement and Construction projects(EPC). The occurrence of different risk can worsen the effects of each other such as the impact of political risks on economic risks. Although appointed methods such as Analytic Hierarchy Process (AHP), Fuzzy Synthetic, Interrelated Tree and Fuzzy AHP methods are commonly used in the industry sectors, yet these approaches seem powerless for evaluating the interactions and feedback between the aforementioned risks. As a result, an accurate assessment of the severity of risks cannot be determined. This study aims to assess the risks in EPC projects using Analytic Network Process (ANP) method. ANP approach is preferable in order to identify the problems of interdependence and feedback between various risk ranking alternatives. The method utilizes data that are collected through literat...
Sulphate-reducing bacteria (SRB) as the main source of Microbiologically Influenced Corrosion (MI... more Sulphate-reducing bacteria (SRB) as the main source of Microbiologically Influenced Corrosion (MIC) mechanism has a dominant influence upon localized corrosion problems especially for internal piping. In this paper, corrosion behavior of high-strength carbon steel (API 5L X-70) under anaerobic conditions in the presence of SRB's bacteria was studied in batch reactor. The coupons were exposed to the SRB culture for 1, 3, 6, 10, 20 and 30 days at 22 0 C and 37 0 C along with a control set. Corrosion rate in SRB medium at 37 0 C showed a higher dynamic value compared to medium inoculated at 22 o C. The corrosion rate of the carbon steel also showed no correlation with the planktonic or sessile SRB cell numbers.
Risk allocation is a key to managing risks associated with the public private partnership... more Risk allocation is a key to managing risks associated with the public private partnership projects. Optimal risk allocation between the parties involved, namely public and private, is the essence of successful PPP project implementation. This study intends to identify and prioritize significant risk allocation criteria and barriers preventing the optimal allocation of risk to PPP projects in Malaysia. Due to interaction among criteria and barriers, this research has adopted analytic network process in order to decompose decision model into meaningful network and weight decision elements. Data has been collected through literature review, questionnaire and interview with PPP project experts. This study reveals that "Bear the risk at lowest price", "Control the chance of risk" and "Risk attitude" are three major optimal risk allocation criteria. "Different sets of information about project risk", "Lack of efficient risk allocation mechanisms" and "Lack of understanding the benefits of optimal allocation" are of three major optimal risk allocation barriers identified throughout the study. The outcome can be used to improve the implementation of PPP project in Malaysia by more rationally allocating risks between parties involved.
Sulphate-reducing bacteria (SRB) represent themselves as a class of anaerobic bacteria that can r... more Sulphate-reducing bacteria (SRB) represent themselves as a class of anaerobic bacteria that can reduce sulphate to sulphide for obtaining energy. This paper is aimed to detect sulphatereducing bacteria activities using rapid detectable culture media. Two different strains of sulphate-reducing bacteria were used in this study, namely ATCC 7757 and local bacterial strain of SRB isolated from underground sample. Both strains were tested on three recommended culture media of modified Baar"s, Postgate B and Postgate C. All three medium contained lactic acid which served to be as carbon source. The results showed that modified Baar"s medium is the best medium for the growth of ATCC 7757 while Postgate C medium is recommended for the local SRB bacterial strain.
This paper investigated the performance of low frequency ultrasound radiation in mitigating the m... more This paper investigated the performance of low frequency ultrasound radiation in mitigating the microbiologically influenced corrosion (MIC) by mechanically inhibiting the planktonic sulfate-reducing bacteria (SRB) growth in modified ATCC broth number 1249 medium.
Consequence assessment is an integral part of the risk assessment process. There are many types o... more Consequence assessment is an integral part of the risk assessment process. There are many types of consequences loss due to pipeline failure such as asset loss, environmental loss, production loss, and human health and safety loss (HHSL). This paper studies the comparison of HHSL between rural and urban areas due to pipeline failure subject to corrosion. The damage area of the explosion was calculated using Aloha software by considering the details of the selected sites such as atmospheric and demographics conditions. The HHSL was calculated using a mathematical equation of quantitative risk assessment in terms of the number of fatalities or injuries or both. The results of the assessments from rural and urban areas were then compared with one another to identify any significant dissimilarity. This study shows that there was a possibility to improve the decisive value of risk by implementing the proposed approach in consequence assessment in Malaysia.
Microbiologically influenced corrosion (MIC) is caused by the presence of sulfate-reducing bacter... more Microbiologically influenced corrosion (MIC) is caused by the presence of sulfate-reducing bacteria (SRB) and is of great concern to the heavy metal industries. Inhibitors and biocides are commonly used to control the problem. Nevertheless, the solutions are too expensive and may create environmental problems by being corrosive to metals. Ultrasound wave exposure is one of the potential alternatives to biocides for the mitigation of MIC risk in pipeline system. In this work, a combination of ultrasound wave and green biocides of glutaraldehyde and ethanol has been proposed to exterminate SRB in a medium. An amount of 100 ml of Desulfovibrio vulgaris (ATCC7757) broth number 1249 was grown in 125 ml anaerobic vials at 37˚C for one day followed by exposure to various mitigation methods. Results from the study show that a combination of ultrasound and biocide can effectively reduce the dosage of biocide during corrosion treatment. The effectiveness of mitigation based on ultrasound-biocide combination is better than the treatment based solely on biocide whereby the extermination of SRB was found 10 times more effective according to the reduction of cell numbers of planktonic's SRB. Ultrasound technique can provide a feasible alternative as an effective assist to chemical inhibitors and biocides for controlling MIC in a more eco-friendly manner.
This study investigates how sulfate-reducing bacteria (SRB) influence the process of microbiologi... more This study investigates how sulfate-reducing bacteria (SRB) influence the process of microbiologically induced corrosion (MIC) of carbon steel by measuring corrosion potential using open-circuit potential (OCP) measurements. MIC is mainly influenced by D. Vulgaris, formerly known as D. Desulfuricans, deposited as Spirillum Desulfuricans, which produces D(-)-lactate dehydrogenase. The manufactured strain ATCC 7757 and pure colony of SRB isolated from the Baram and Sg Ular areas in Malaysia were used in this experiment. An evaluation of SRB growth was performed during the test in the inoculated medium anaerobically at 37°C with pH 7.5. The results showed that the corrosion potential E oc in manufactured ATCC was the highest as compared to the SRB isolated from site. These results indicated that ATCC could be the reference to predict the metal corrosion due to high corrosive product of H 2 S generated during metabolic activity.
This study defines the interrelationship between turbidities and cell number counting efficiency ... more This study defines the interrelationship between turbidities and cell number counting efficiency for the growth of one of the microbiologically influenced corrosion (MIC) species in a medium. The metabolism activities during bacteria growth can accelerate the corrosion process and shorten the reliability of pipelines. Thus, the investigation of MIC species’ development and metabolic activities is significant. An experiment was performed on sulfate-reducing bacteria (SRB) that practiced the medium as the substance to grow. Desulfovibrio vulgaris, a strain of SRB, was cultured in a postgate C medium to measure the bacteria survival using two different measurement methods. The medium was modified to pH 7.5 at 37°C and placed in anaerobic vials. During 24 hours of incubation, samples were retrieved, and the value of turbidity and cell numbers was measured. Based on the SRB growth graph pattern, the amount of bacteria cell numbers was increased parallel to the value of the medium’s turbidity in respect to time. Both values (turbidity and bacteria cell numbers) dramatically increased from hour1 to hour24. The results supported that the turbidity value was positively correlated with bacteria cell numbers.
In the past two decades, public private partnership has been one of the
prevailing ways for the d... more In the past two decades, public private partnership has been one of the prevailing ways for the development of infrastructures in Malaysia. However, it involves many risks and uncertainties due to a large amount of investment and long concession period. It is very important to recognize and find out the ways to cope with the critical risks that are related to the investments made in PPP projects for the foreign investors. The aim of this article is risk ranking associated with the PPP projects using risk matrix. First, the paper reviews the current literature, consultation and a written survey distributed to the panel of experts to identify common risks in PPP projects . The risks identified from the literature were classified according to the type of risk. From the results, it was found that the critical risks associated with the PPP projects include the third party tort liability, interest rate volatility, construction cost overrun and the change in law. This research study is supposed to provide awareness and highlight the management of the risks associated with the PPP risks in Malaysia.
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Papers by Nordin Yahaya
prevailing ways for the development of infrastructures in Malaysia. However, it
involves many risks and uncertainties due to a large amount of investment and long
concession period. It is very important to recognize and find out the ways to cope
with the critical risks that are related to the investments made in PPP projects for the
foreign investors. The aim of this article is risk ranking associated with the PPP
projects using risk matrix. First, the paper reviews the current literature, consultation
and a written survey distributed to the panel of experts to identify common risks in
PPP projects
. The risks identified from the literature were classified according to the
type of risk. From the results, it was found that the critical risks associated with the
PPP projects include the third party tort liability, interest rate volatility, construction
cost overrun and the change in law. This research study is supposed to provide
awareness and highlight the management of the risks associated with the PPP risks in
Malaysia.
prevailing ways for the development of infrastructures in Malaysia. However, it
involves many risks and uncertainties due to a large amount of investment and long
concession period. It is very important to recognize and find out the ways to cope
with the critical risks that are related to the investments made in PPP projects for the
foreign investors. The aim of this article is risk ranking associated with the PPP
projects using risk matrix. First, the paper reviews the current literature, consultation
and a written survey distributed to the panel of experts to identify common risks in
PPP projects
. The risks identified from the literature were classified according to the
type of risk. From the results, it was found that the critical risks associated with the
PPP projects include the third party tort liability, interest rate volatility, construction
cost overrun and the change in law. This research study is supposed to provide
awareness and highlight the management of the risks associated with the PPP risks in
Malaysia.