Journal of Health and Safety at Work

Assessing safety risk in electricity distribution processes using ET & BA improved technique and its ranking by VIKOR and TOPSIS models in fuzzy environment

M. Omidvari

Introduction: Electrical industries are among high risk industries. The present study aimed to assess safety risk in electricity distribution processes using ET&BA technique and also to compare with both VIKOR & TOPSIS methods in fuzzy environments.

Material and Methods: The present research is a descriptive study and ET&BA worksheet is the main data collection tool. Both Fuzzy TOPSIS and Fuzzy VIKOR methods were used for the worksheet analysis.

Result: Findings revealed that overhead low and medium voltage power distribution networks had the highest risk among the other network types of transmission and distribution of electricity. Also, it was found that TOPSIS and VIKOR methods are appropriate to rank the safety risks with somehow similar results.

Conclusion: The height and electricity are of the main causes of accidents in electricity transmission and distribution industry which caused the overhead power networks to be ranked as high risk. Application of decision-making models in fuzzy environment minimizes the judgment of assessors in the risk assessment process.

Optimization of the calculation of hazardous zones boundaries for classification of hazardous area using risk-based approach

T. Ebadi

Introduction: Leakage from process equipment and the entrance of flammable fluids to surrounding atmosphere may cause flammable gas cloud. The coincidence of flammable gas cloud with ignition source could make flash fire or vapor cloud explosion that cause injury and fatality. The concept of reduction of confluence of flammable gas cloud and potential sources of ignition is known as hazardous area classification. Several standards have provided methods regarding hazardous area classification; however, of the disadvantages of them are lack of an accurate determination of hazardous areas due to potential leakage sources which is because of low flexibility in process condition variation and equipment layout and also not considering effect of weather conditions and cumulative effects of release sources.

Method: In this paper, risk-based hazardous area classification is optimized using parameters such as the number of influencing release sources and weather condition probabilities. In this method, the determining factor of hazardous area boundary is the probability of acceptable ignition for every specific location. This probability is calculated using quantitative risk assessment with PHAST RISK software version 6.7 on the gas boosting unit of a gas refinery as a case study.

Result: The results of this method showed the full dependency of hazardous area boundary to cumulative effects of potential sources of release and the prevailing wind direction and it also demonstrated that the suggested optimized method can consider wind direction probabilities and cumulative effects of potential sources of release in risk-based hazardous area classification calculation.

Conclusion: Comparing the results of this method with the usual method determines that this method has some advantages such as considering all sources of release and cumulative sources of release and considering wind direction probabilities in determining boundary of zone 2 which makes the hazardous area classification very precise and flexible.

Nobel method for xylene removal from air on nano activated carbon adsorbent compared to NIOSH approved carbon adsorbent

F. Golbabaei

Introduction: Volatile organic compounds such as xylene are one of the main air pollutants. Adsorption method are of the most common methods used in the control of volatile organic compounds. The aim of this study was to investigate the xylene removal from air through nano activated carbon adsorbent in comparison with NIOSH approved carbon adsorbent.

Material and Method: Xylene adsorption tests on nano activated carbon and activated carbon in static mode (batch) were done in glass vials with volume of 10 ml. Gas chromatography with FID detector was used for analysis. Various variables including contact time, amount of adsorbent, concentration of xylene, and temperature were studied.

Results: Absorption capacity of xylene at ambient temperature (25° C) in static mode and duration of 10 minutes for activated carbon and nano activated carbon was obtained 349.8 and 435 mg/g, respectively. Results of Scanning Electron Microscope (SEM) images of nano activated carbon showed particle size pf less than 100 nm. Furthermore, Transmission Electron Microscope (TEM) pictures showed particle size of 30 nm. XRD images also showed cube structure of nano activated carbon adsorbent.

Conclusion: The results showed that adsorption capacity at constant humidity increased by raising in temperature and contact time. What is more, nano activated carbon absorbent showed greater absorption capacity for xylene removal compared to activated carbon absorbent

The relationship between employees’ emotional intelligence and their job satisfaction using structural equation model in one of the oil industries in Tehran

S.A. Zakerian

Introduction: Emotional intelligence as the ability to understand and control feelings and emotions, and job satisfaction as positive attitudes of employees towards their jobs is amongst the effective indicators in the workplaces. Therefore, this research invetigated the effect of emotional intelligence of employees on their job satisfaction in one of the Oil refineries in Tehran.

Methods and Materials: This research is a practical and cross-sectional study. The statistical population consisted of 300 employees selected by stratified random sampling method. Bar-On questionnaire (90-item) and JDI questionnaire (70-item) were used in order to measure emotional intelligence and job satisfaction, respectively. LISREL8.72 software was employed to estimate causal effect between study variables and calculation of descriptive indices and comparison of variables were done by means of SPSS software version 18.

Results: According to results, there was a direct association between emotional intelligence of employees and their job satisfaction. In other words, the higher emotional intelligence, the higher rate of job satisfaction. Of the 15 sub-scales of emotional intelligence, Responsibility and Self-expression obtained the highest and the lowest scores, respectively. Furthermore, Supervisor and Salaries were ranked as the highest and the lowest valued subscales of job satisfaction. According to the results, employees job satisfaction level are improved in parallel to increase of education level and the maximum score of this variable was belonged to the age group of 30-45 years.}

Conclusion: Emotional intelligence, as a psychological variable, affects the worker's job satisfaction. Considering the direct relationship between these two variables, by training and increasing the emotional intelligence of employees, job satisfaction and consequently their efficiency and productivity can be improved in the workplaces.

Investigating attitude toward safety isuues among agricultural Jihad professionals with an emphasis on safety training

M. Bijani

Introduction: Agriculture is amongst the hazardous activities with a high rate of occupational injuries. Safety training is proved to have positive effects on reduction of agricultural users’ occupational accidents. In this sense, agricultural experts and extension agents play an important role in safety training programs. Thus, the purpose of this study was to investigate attitude of Agricultural Jihad Organization professionals toward safety.

Materials and Methods: This descriptive study was implemented by survey research design. The study population was 230 individual selected by Tackmans' Table, using proportionate stratification sampling method from Agricultural Jihad Organization professionals in Khuzestan and Ilam provinces. A questionnaire validated by a panel of experts and its reliability within a pilot with Coronbach Alpha's coefficient (α=0.75), was used for data collection. Data were finally analyzed by SPSS software version 22.

Results: The mean (SD) of safety attitude score was 4.04(0.77) out of 5, and overall attitude of 71.23 percent of the respondents toward agricultural safety were at "good" and "moderate" level. Of the components of experts' safety attitude "spending on safety is a worthwhile investment" and "the necessity of formulation of agricultural safety legislation by executers" had the first and second priority, respectively. There were significant differences in safety attitude considering gender and job tenure. However, no significant difference was observed regarding marital status, occupational group, and witnessing agricultural accidents. Furthermore, the association between safety attitude and "age" and "education" was positive and significant; but no significant correlation was found between number of educational courses and safety attitude.

Conclusion: Considering the importance of safety training, identifying the factors pertinent to agricultural experts' safety attitude would help safety experts to develop and implement strategies in order to reduce occupational accidents in this sector.

Risk assessment in gas and oil pipelines based on the fuzzy Bow-tie technique

P. Heyrani

Introduction: Nowadays, gas and oil account for 60 percent of world energy resources. Transporting crude oil and its products are accomplished through a number of ways among which pipelines are of the utmost significance. Considering the extent of pipelines in installation and residential areas and also high potential for damage, the safety of these pipes and application of risk management principles have undeniable importance. Bow-tie risk assessment method is one of the ways to determine safety level. The tool is a qualitative and semi-quantitative method the data of which are implemented by specialists and experts via conducting surveys.

Method and material: In the present study, Bow-tie technique was employed having been combined with fuzzy logic in which Likret Scale was applied to quantify the qualitative (verbal) data to reduce the uncertainty of risk evaluation of Amaak No.10 gas pipeline and Bongestan No.12 petroleum pipeline. In this way, factors affecting the pipeline safety were at first, recognized through the checklists. Then, the risk evaluation of pipplines was conducted using the mentioned method.

Results: The results of the study showed that third party damages, initial defects in materials, and constructing pipeline with failure possibility of 0.0484 stood at the highest in terms of importance (equivalent to 12.32%) in destroying oil and gas pipelines. In addition, the toxic impacts and environmental damages with occurrence possibility of 0.00327 were the most striking consequences of gas and oil leakage based on event tree analysis.

Conclusion: Considering the recognized factors leading to destruction of pipelines and their most notable outcomes, instructions on how to control and reduce the potential consequences were suggested, with emphasis on the removal of the most probable causes.

Studying the causes of high chromium concentration in the leather production process at Tehran Charmshahr industrial complex

M. Mahdiabadi

Introduction: Harmful effects of environmental pollutants and their environmental impacts necessitate revention of the pollution emission from various industries. Leather industry is one of the most polluting industries, with chromium compounds as an important contamination, widely used in the tanning process. The present study aimed to determine the causes of high chromium concentration from leather production process in Charmshahr industrial complex in Varamin city.

Methods and material: Continuous sampling was done from the wastewater in each plant for six months and the contaminations resulted from different stages of leather products were investigated. In this regard, for determining the chemical quality and pollution load of wastewater from tannery process, following parameters were examined: PH, Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Dissolved Solids (TDS), Chromium (III), and Chromium (VI). Analysis of data was conducted by SPSS and Excel softwares. The t-test was used for comparison with standards at significance level of P<0.05.

Results: The results indicated the existence of toxic pollutants such as Cr⁺³ and Cr⁺⁶in leather wastewater, the relatively high level of organic loads with low biodegradability, high levels of COD, BOD, TDS and finally the complexity of the treatment of wastewater.

The study of whole-body vibration effects on the passenger’s comfort commuting in Tehran metro system

A. Solaimanian

Introduction: Whole-body vibration is one of the factors which may have adverse effects on the comfort of passengers and crew of rail transportation vehicles. In this study, the probable impacts of whole-body vibration were explored on the convenience of the passengers of Tehran metro.

Material and methods: Planning, measurement, and pre-analysis calculations were mainly done based on ISO guidelines No. 2631-1, 4. Moreover, measurements and calculations were done using SVAN 958 sound & vibration analysis and Microsoft Excel software, respectively.

Results: Average calculated RMS acceleration values on the levels of seat cushion, seat back, and legs were 0.57, 0.44, and 0.64 m/s² on the dominant axes, and total r.m.s acceleration in all these three levels equaled to 1.02 with the standard deviation of 0.11 m/s². Mean Vibration Dose Value (VDV) of total exposure in the minimum and maximum exposure durations were 6.44 and 9.63 m/s ^1.75, respectively.

Conclusion: Calculated amounts of dominant axes were mainly ranked as “relatively unpleasant” in the convenience limits of ISO 2631-1, but the total calculated amount of exposure based on WRMS was at “unpleasant level”. The measured VDV amounts were mostly on the z axis, as the dominant one.