Journal of Loss Prevention in The Process Industries最新文献

Technological accidents triggered by natural disasters are called Natech accidents. Natech accidents have the impact of increasing the negative effects of disasters. One of the places at risk for a Natech accident is the Organized Industrial Zones (OIZs), where many industrial establishments are located. Although businesses within OIZs are evaluated in terms of security, Natech risk assessment is often ignored. This situation causes Natech accidents to occur. For these reasons, the study focused on evaluating OIZs regarding Natech risk. Many criteria such as electrical resources, natural gas, distance between buildings and so forth are taken into account in Natech's risk assessment. However, it is challenging to make clear decisions and predictions about these criteria due to the nature of the disaster. There is inherently uncertainty and confusion during and after a disaster. For this reason, using fuzzy sets to evaluate criteria is more appropriate. Therefore, the study uses Pythagorean fuzzy sets, which have a wider fuzzy evaluation area. This study also includes the evaluation of alternative sectors in terms of Natech risk. For this purpose, Pythagorean Fuzzy Analytic Hierarchy Process (PFAHP) and Pythagorean Fuzzy the Technique for Order of Preference by Similarity to Ideal Solution (PFTOPSIS) methods are used. OIZ in Gaziantep has the largest area compared to those in other cities in Türkiye, is chosen as the application area of the study. As a result of the study, it is determined that the release of hazardous substances and flammable criteria is the most crucial criterion, and the most dangerous sector in terms of Natech risk is the chemical sector.

Multi-spectrum infrared flame detectors are commonly installed in many oil and gas processing facilities for an early fire detection. Since these facilities are filled with equipment and piping, the visibility of flames from infrared flame detector is a critical factor for reliable and early detection. However, conventional methodology of fire mapping study does not consider the three-dimensional spread of flames. Therefore, this paper focuses on the responsiveness of multi-spectrum infrared flame detectors under the condition that flame is partially hidden by such obstructions.

A series of full-scale experiments was conducted to examine the responsiveness of infrared flame detectors to flames partially hidden by shielding objects. These experiments simulated various conditions seen in the oil and gas processing facilities.

The experiments have confirmed the relationship between the intensity of infrared energy and the obstruction ratio. Specifically, the infrared energy at a wavelength of 4.504 μm emitted from a flame hidden by shielding objects can be quantified using the obstruction ratio, the ratio of visible area of partially hidden flame. By using these indices, it has been clarified that the infrared energy emitted from a partially hidden flame at the location of an infrared flame detector can be estimated. The responsiveness of detectors depends more on the intensity of the infrared energy near 4.5 μm than on flame pulsation. Multi-spectrum flame detectors, commercially available and employed in this study, exhibited performance equal to or even more sensitive than what is stated in their data sheets. Quantitative evaluation of the responsiveness of flame detectors to partially hidden flames revealed in this study can contribute to the improvement of the fire mapping study for the realistic design evaluation in the oil and gas processing facilities.

The purpose of this study is to suggest systematic management measures by analyzing the risk of related part through FMEA of RPN index based on severity, occurrence, detection of 543,900 7 kW EV chargers installed until 2023 in South Korea and SI based on severity, detection and information score scale. To achieve this goal, this research investigated the current status of 7 kW EV chargers, and categorized the parts and assemblies of the investigated chargers. The failure mode of classified components was explored based on the 2016 edition of FMD, and the failure mode rate and information score of SI were referred to data contained in Nprd 2016, Eprd 2014; Fmd 2016. The identified failure mode, failure causes, and failure effects were described by domestic experts in EV charger-related sectors.

There were 4 risk factors (10%) felt under “Group A″, the upper 10% of RPN. Of these, inverter overheating ranked in the highest. Moreover, the analysis revealed one case of corrosion of the enclosure and overheating in the main board and communication board each. The effect of overheating was confirmed in these components excluding the enclosure. From the SI perspective, high values were obtained in 4 parts of AC/DC breaker, one of connector, and one of cable. Based on the extracted data, management strategies were suggested.

With the help of computational fluid dynamics (CFD) technology, this research focuses on the quantitative effects of the explosion venting area (S), static opening pressure of the vent (P_stat) and dust cloud concentration (C_D) on the explosion overpressure, high-speed airflow and high-temperature flame in the explosion venting zone. The results show that the explosion disaster along the explosion venting zone in general shows an oscillating fluctuating trend of attenuation, and the closer to the explosion vent explosion disaster is more serious. The increase of S will enhance the nonlinear change of explosion disaster, and the change law of explosion overpressure is completely opposite to that of high-speed airflow and high-temperature flame. With the increase of P_stat, the coupling effect of air intake pipe and dust collector is strengthened, which further aggravates the spread of explosion disaster. The change of C_D has both promoting and restraining effects on the spread of explosion disaster. The maximum overpressure (P), maximum wind speed (V), maximum flame speed (Fs) and maximum flame distance (Fd) in the explosion venting zone are 0.022 MPa, 494.5 m/s, 112.9 m/s and 10.9 m, respectively, and the venting safety distance is more than 11 m. In addition, the degree of impact on explosion disaster is in the following order: P_stat > A > C_D. This research can provide a reference basis for the effective prevention and control of the composite disaster external the explosion vent induced by dust explosion inside the dust collector.

The flue gases such as SO₂, SO₃, and CO₂ generated during the purification process of sulfur-containing natural gas need to be treated to a certain concentration before they can be discharged into the atmosphere. The flue gas unit of a purification plant in Sichuan adopts the new Cansolv flue gas treatment process. After running for a period of time, the Venturi scrubber experienced severe corrosion failure, resulting in equipment shutdown and significant economic losses. This paper utilizes an actual failed device as a case study to analyze the corrosion environment of the Venturi scrubber. It conducts a comprehensive failure analysis, encompassing material mechanical properties, metallographic analysis, and failure microstructure analysis, aiming to elucidate the reasons behind the Venturi scrubber failure. Systematic analysis shows that the manufacturing materials used in this scrubber meet all design requirements. However, flue gas at temperatures reaching 280 °C enters the scrubber tower at a flow rate exceeding 10 m/s. The dissolution of acidic gases leads to a significant drop in the pH of the cooling water to 1, manifesting evident signs of erosion corrosion and intergranular corrosion on the material surface. These observations suggest that erosion and intergranular corrosion in high-temperature acidic environments are the predominant factors contributing to the corrosion failure of the Venturi scrubber.

Aircraft fuel tanks experience sub-atmospheric pressure during flight, and so do fuels during storage and transportation at high altitudes. Additionally, chemical processes commonly operate at non-atmospheric pressure. Flash points measured at sub-atmospheric pressure are lower than those measured at the standard atmospheric pressure of 101.3 kPa, signifying that ignitable liquids at sub-atmospheric pressure are more hazardous than those at 101.3 kPa. This study developed a model for predicting the influence of pressure on flash points on the basis of basic thermodynamic characteristics; this model was validated against experimental data obtained from the literature for six single-component and multiple-component liquid fuels at sub-atmospheric pressure. The proposed model effectively predicts closed-cup flash points, with small deviations in the range 0.18 °C–1.25 °C. However, because the model's assumption of vapor–liquid equilibrium was violated in the experiments, the predicted open-cup flash points did not agree well with their experimental counterparts, with the deviations in the range 1.11 °C–12.55 °C. Nevertheless, the trends predicted by the model agreed with those in the experimental data. Furthermore, standard flash point test method (such as ASTM D56-22, ASTM D93-20, and ASTM D7094-17) are based on a linear formula for correcting flash points measured at pressures other than 101.3 kPa. When the ambient pressure is approximately 101.3 kPa during flash point testing, the slope value of the correction formula should be changed from 0.25 to 0.20.

Risk assessment can reveal the level of a safety situation which can be very important info for company safety management. Considering the multiple factors in risk assessment of a system and the vagueness nature of many factors, and using the benefits of the Petri-net in modeling and reasoning, a weighted fuzzy Petri-net (WFPN) based risk assessment approach which combines WFPN with the SPA-fuzzy method is proposed in this paper. The SPA-fuzzy method is utilized to establish the membership functions for fuzzy assessment, taking its advantage in comparing identity, contrary and discrepancy features of two different sets. In this study, the WFPN is redefined to model relationships between assessment factors, and the matrix-based fuzzy reasoning algorithm is provided to assess the factors in parallel. The application of the proposed risk assessment approach is illustrated by case studies: the risk assessment of a chemical storage tank area and the ignition accident assessment of hydrogen refueling stations.

The purpose of this study is to derive the risk of electric shock based on the KEC (Korea Electro-technical Code), which was fully implemented in Korea in 2022, and IEC-60479. Therefore, a sewage treatment facility, where the risk of electric shock due to leakage current is high due to the possibility of damage to the insulation parts of electrical equipment caused by high humidity and the presence of corrosive gases, was selected. The risk of electric shock was analyzed in the event of leakage current occurring in the electrical equipment at the selected facility. To achieve the objectives of this study, the grounding resistance of the facility was measured to observe the trends in the management state of the grounding resistance. The resistance values of protective conductors and grounding conductors connected to exposed conductive parts and extraneous conductive parts were also measured. Additionally, based on the KEC, the grounding system was analyzed, and the touch voltage occurring during electrical leakage was calculated. Based on this, the risk of electric shock was analyzed according to the current flow using IEC-60479. As a result of measuring the resistance values of protective conductors, it was found that some protective conductors exceeded 1[Ω]. In all facilities, the risk of electric shock in the AC-4.2 range (with a 50% or higher probability of ventricular fibrillation) was observed when electrical leakage occurred. Additionally, when assuming the implementation of equipotential bonding, the analysis of electric shock risk revealed AC-3 range (potentially reversible effects on the heart) in two locations, and AC-2 range (no generally perceived physiological effects) in all other sections. These findings emphasize the urgent need for on-site implementation of equipotential bonding in compliance with the KEC. Furthermore, resistance measurement and management of the protective conductors are necessary.

Gas pipeline leakage may lead to fire, explosion and gas poisoning, thus causing a large number of injuries and property damage. This paper focuses on the chain characteristics presented by the development process of city gas pipeline leakage, based on Markov chain theory, studies the disaster-causing process and the mechanism of disaster chain formation for the leakage, establishes the disaster chain, evaluates the pipeline operation status and quantifies the failure probability of gas pipeline leakage to determine the causes of the leakage. Subsequently, Pipeline Studio is applied to simulate the consequences of gas pipeline leakage to realize the risk analysis. The analysis is based on Markov chain theory to calculate the probability of leakage and disaster-causing causes, analyze the consequences of gas pipeline leakage, and realize the diagnosis of the causes of gas pipeline leakage accidents and the prediction of the accident development trend. Finally, using European gas pipeline accident data to prove the effectiveness of the method, the result shows that gas pipeline leakage accidents are mainly caused by third-party damage and corrosion, which is consistent with the real situation and provides a reference for risk analysis and accident prevention of gas pipeline leakage.

The explosion characteristics of pine sawdust mixed with typical inhibitors (calcium carbonate, calcium phosphate, ammonium phosphate) were investigated under different inerting ratios in a vertical flame propagation device. Different analytical analyses by TG-DTG-DSC and FTIR analysis were also coupled to understand the physical and chemical mechanisms of the treated samples. The results show that the flame propagation velocity and the peak pressure decreased by more than 50% for an inerting ratio of 60 wt%.

This work clarifies the suppression characteristics and mechanism of different inhibitors in the flame propagation of biomass dust and yields some insights into the prevention and mitigation of biomass dust explosions in industrial applications.