Chlorine leakage from bonnet of a valve in a bullet—a case study

This paper deals with the accidental release of chlorine from bonnet of a valve in a bullet installed in a chloro-alkali industry, and the probable causes of the accident and the ensuing sequence of events. Emergency procedures are also discussed. Finally, in the conclusions reached at some useful recommendations, which has been drawn for industrial facilities handling chlorine.     

Application of mindfulness-based stress reduction to a stress management intervention in a study of a mining sector company

Purpose. The aim of this article was to check whether mindfulness-based stress reduction (MBSR) is an effective intervention in reducing work-related stress in the case of workers in a copper mine. Methods. Sixty six employees were randomized to the experimental group (32 participants) or to the control group (34 participants). Work-related stress was measured using the job content questionnaire (JCQ) and mental health was measured using the general health questionnaire (GHQ-28) Experimental manipulation was 40-h MBSR training. Results. Multivariate repeated-measures analysis of variance revealed a significant increase of JCQ decision latitude (F?=?17.36, p?<?0.001) and social support (supervisor F?=?9.00, p?<?0.004; coworker F?=?5.61, p?<?0.020), and a significant decrease in GHQ-28 anxiety (F?=?5.28, p?<?0.079) and depression (F?=?3.95, p?<?0.048) due to the intervention. Conclusions. The study confirms that MBSR can be effective in reducing stress resulting from the external risk (and/or imagined fear) of losing one’s health or life. The use of MBSR could be recommended in health and safety activities in difficult and dangerous work conditions, such as mining, to promote workers’ well-being.     

一起化肥厂爆炸事故的原因分析

某县化肥厂合成车间分析室突然发生爆炸,当班的2名化验员当场死亡,经济损失较大.爆炸冲击波将整个钢筋水泥(20m2)的分析室夷为平地,一块重约70kg的砖垛被抛至30m以外;离爆炸中心方圆60m以内的建筑物玻璃全部震碎.     

Ignition of a dust layer by a constant heat flux

In real conditions, the surface temperature of an equipment enclosure covered with a combustible dust layer can significantly rise due to insulating properties of the dust layer. To assess this effect, the measurements of minimum ignition temperature of dust layer at constant temperature of the heated plate t_{t min} (standard method) and the same ignition temperature at constant rate of heat generation t_{h min} for two coal dusts were made. Dust layers of thickness between 5 and 50 mm were tested. For each dust, t_{t min} was higher than t_{h min} for every tested thickness of the layer. The difference was biggest for thin layers and decreased with increase of the layer thickness. The results suggest a deficiency of the standard procedure of measuring minimum ignition temperature of a dust layer.     

The Airline Lifesaver: a 17-year analysis of a technique to prompt the delivery of a safety message

INTRODUCTION: The Airline Lifesaver (AL) is a 13.3 cm x 9.8 cm card any passenger can deliver to the attendant of a commercial airline in order to prompt the delivery of an important safety message. In particular, the AL requests the following safety--belt reminder be added to the regular announcements given at the end of the flight-"Now that you have worn a seat belt for the safest part of your trip, the flight crew would like to remind you to buckle-up during your ground transportation." METHOD: The AL card was handed to 1,258 flight attendants over a 17-year period and compliance with the request for the safety message was systematically tracked. Slightly more than one-third of the AL cards (n=460) included an incentive for making the announcement. RESULTS: Without the incentive, compliance to give the buckle-up reminder was 35.5% of 798 flights. With the incentive, compliance was significantly higher (i.e., 53.3%). IMPACT: The validity of the AL intervention is discussed with regard to its: (a) relevance to cognitive dissonance and consistency theory, and (b) broad-based applicability as a component of community-wide efforts to facilitate a safety-focused culture. The 17-year study also demonstrated a practical and cost-effective application of a behavior-based incentive program.     

Application of a predictive safety model in a combustion testing environment

A predictive safety model for accident prevention and system failure, called Continuous Hazard Tracking and Failure Prediction Methodology, is applied at the Marshall Space Flight Center's promoted combustion test chamber. It combines the underlying principles of work sampling, control charts, and multivariate analysis. The sampling is performed to observe the occurrence of conditions which may be becoming hazardous in a given system. These building blocks of hazards, which we have called dendritics, could result in an accident, system malfunction, or unacceptable risk conditions. The data collected is plotted to generate the appropriate control chart, which depends on the characteristics of the given system and the protection desired. Based on the pattern of the control chart, a system ‘under control’ is not disturbed whereas a system ‘out of control’ is investigated for potential conditions becoming hazardous. Then appropriate steps are taken to eliminate or control these conditions in order to maintain a desired safety status of the system. The continuously running characteristic of this model allows for the verification that the corrective measures taken to ameliorate the ‘out of control’ conditions were satisfactory or whether more proactive action is required. The results provided by the predictive model were validated with historical safety data.     

Thermal effects of a sonic jet fire impingement on a pipe

Although the effects of jet fires are often limited to rather short distances, if their flames impinge on a pipe or a vessel collapse can occur in very short times. In such cases, the heat flux on the affected equipment is very high and wall temperature can increase very rapidly. This can happen in parallel pipelines, if a release occurs and impinges on another one. Nevertheless, jet fire impingement has been scarcely studied. In this communication the results obtained from an experimental set-up are presented. Sonic jet fires impinged on a pipe containing stagnant air or water. The temperatures of the flames impinging on it were measured for the worst case (flame front-bright zone), as well as the evolution with time of the pipe wall temperature at different locations. Initial temperature increases up to around twenty °C/s were registered for the air inside, with maximum values of up to 600 °C reached in 2.5 min, and 800 °C in approximately 9 min. In the case of pipe containing water, in the zone of the wall in contact with the liquid the heating rates were much lower, the maximum temperature reached being up to approximately 150 °C. From the temperatures of the jet flames and of the pipe, the heat fluxes reaching the pipe and the corresponding heat transfer coefficients were obtained. The results obtained emphasized that safe distances are essential in pipelines, together with fire proofing and other safety measures.     

Smoke control of a fire in a tunnel with vertical shaft

The aim of this research is to find the optimum smoke extraction rate through the ventilation shaft in case of a fire in a long road tunnel. Furthermore, it is also investigated whether the current emergency ventilation design practice using a vertical shaft can limit the smoke propagation from a fully loaded gasoline tank lorry fire. For this research, scaled model experiments were carried out using a 20 m- long model tunnel with a vertical shaft. A CFD modeling tool was also extensively utilized to investigate the extremely dangerous situation in which a fully loaded gasoline tank lorry is burning inside a long road tunnel.     

A rigorous test of a model of employees' resource recovery mechanisms during a weekend

Employees' recovery from the effects of occupational stress can be affected by their actions during time away from work. Conservation of resources theory argues that a key to an effective stress recovery process is the replenishment of resources during off‐work time (a weekend in the present study). We test a model of the stress recovery process during a weekend whereby two recovery mechanisms (weekend activities and recovery experiences) improve two personal resources (self‐regulatory capacity and state optimism), subsequently affecting psychological outcomes (work engagement and burnout) at the start of the next workweek. Employees (n = 233) from various jobs responded to online surveys before and after a weekend. Controlling for pre‐weekend resource levels and psychological outcomes assessed on Friday, the two weekend stress recovery mechanisms (weekend activities and recovery experiences) contributed to improving or maintaining self‐regulatory and optimism resources on Monday. Of note, psychological detachment may result in less rather than more of the resource of state optimism on Monday. Monday resource levels were linked to improved work engagement and burnout. As proposed by conservation of resources theory, employees can benefit from participating in activities that replenish resources necessary to meet work demands upon returning to work after a weekend. Copyright © 2016 John Wiley & Sons, Ltd.     

Impact of a shock wave on a structure on explosion at altitude

The number of explosive attacks on civilian buildings has recently increased and the pattern of damage inflicted on structures when an explosion takes place at altitude remains quite difficult to predict. The primary aim of the work reported here was to enhance the understanding of how blast waves from an explosion at altitude interact with the ground and with a structure. Small-scale experiments were conducted using a propane–oxygen stoichiometric mixture as explosive. This approach is original because it models high-explosive detonation in terms of gaseous charge explosion using TNT equivalents. Several non-dimensional laws are expressed and validated by experiments. These relationships allow determination of the propagation of a blast wave and its interaction with a structure as a function of the position of the explosive charge when the explosion occurs at altitude. Then, from knowledge of the blast loading, using Hopkinson's scaling law and TNT equivalents, we can predict the interaction of blast waves with the ground and a structure on a real scale. Simulations were performed using the Autodyn code, and good correlation with the experimental results was obtained.     

Development of a FRAM-based framework to identify hazards in a complex system

System-based approaches such as Functional Resonance Analysis Model (FRAM) are developed to model the complex interactions of system variables and their performance variabilities that may lead to a hazardous scenario in a complex system. However, they have limitations to be applied in process industries for hazard identification since they are heavily based on qualitative analysis and expert elicitations. To overcome the limitations of the system-based hazard identification, the study developed a FRAM-based framework to integrate a human performance model, an equipment performance model, and a first-principle based chemical process model into a hybrid simulator, which will be able to aid hazard analysis in the process industries. The simulator is capable of simulating the performance variabilities of the functions through the aggregation of mathematical models within a complex system, which can be used to simulate potential hazard situations and identify the corresponding interactions. Interaction analysis is conducted by applying association rule mining to the simulated data. The impact of the interactions among upstream functions on the performance of downstream functions can be identified by interpreting the rules, whose antecedents contain upstream functions and consequents contain downstream functions.     

The Driver Behaviour Questionnaire as a predictor of accidents: a meta-analysis

Introduction

Through a meta-analysis, this study investigated the relation of errors and violations from the Driver Behaviour Questionnaire (DBQ) to accident involvement.

Method

We identified 174 studies using the DBQ, and a correlation of self-reported accidents with errors could be established in 32 samples and with violations in 42 samples.

Results

The results showed that violations predicted accidents with an overall correlation of .13 when based on zero-order effects reported in tabular form, and with an overall correlation of .07 for effects reported in multivariate analysis, in tables reporting only significant effects, or in the text of a study. Errors predicted accidents with overall correlations of .10 and .06, respectively. The meta-analysis also showed that errors and violations correlated negatively with age and positively with exposure, and that males reported fewer errors and more violations than females. Supplementary analyses were conducted focusing on the moderating role of age, and on predicting accidents prospectively and retrospectively. Potential sources of bias are discussed, such as publication bias, measurement error, and consistency motif.

Impact on Industry

The DBQ is a prominent measurement scale to examine drivers’ self-reported aberrant behaviors. The present study provides information about the validity of the DBQ and therefore has strong relevance for researchers and road safety practitioners who seek to obtain insight into driving behaviors of a population of interest.     

Investigation of a filter explosion

At about 10 o'clock on a summer morning in 1987, an industrial filter used to purify an electrolytic plating solution exploded at a printed wiring board manufacturing plant. An investigation team used the failure modes and effects analysis technique to identify potential failures that could have caused the explosion and to reconstruct the most probable sequence of events that led to the accident. This paper describes the investigation and its results.     

Ergonomic evaluation of a new truck seat design: a field study

A postural evaluation of commercial licensed truck drivers was conducted to determine the ergonomic benefits of a truck seat prototype in comparison with an industry standard seat. Twenty commercially licensed truck drivers were recruited to perform a 90-min driving task. Postures were assessed using accelerometers and a backrest and seat pan pressure mapping system. Subjective discomfort measurements were monitored using two questionnaires: ratings of perceived discomfort (RPD) and the automotive seating discomfort questionnaire (ASDQ). Participants reported significantly higher discomfort scores when sitting in the industry standard seat. Participants sat with more lumbar lordosis and assumed a more extended thoracic posture when seated in the prototype. Pairing the gluteal backrest panel with the adjustable seat pan also helped reduce the average sitting pressure on both the seat pan and the backrest. The prototype provided several postural benefits for commercially certified truck drivers, as it did for a young and healthy population.     

A simple model for predicting the release of a liquid-vapor mixture from a large break in a pressurized container

This paper presents a simple, accurate model for determining the amount and composition of a liquid-vapor release from a pressurized tank that develops a large break above the level of the liquid. Most models commonly used by the chemical industry assume that there is thermal- and mechanical-equilibrium between the liquid- and the vapor-phase (homogeneous equilibrium models, HEM). While this assumption is valid for releases though long pipes and nozzles, we found that it overestimates the total amount released during rapid discharges through large breaks in a vessel when there is insufficient time for the mixture to become homogeneous. We derived an analytical non-homogeneous, thermal equilibrium model that accurately determines the void fraction of the mixture at the time of the release, and the quantity of a release from a pressurized container. Our model is based on equations describing the transfer of interfacial momentum between the liquid- and the vapor- phases that develop during the quick depressurization of a vessel. The model’s predictions are verified by comparing them with actual measurements of the void fraction, and with the results of the RELAP5 model. Also, our model is used to determine emissions of nitrogen oxides and nitric acid in an actual rupture of a railcar tank. The results agreed with actual observations, whereas a homogeneous equilibrium model gave erroneous predictions.     

矿井主运输巷道供风管突然垮塌所引发的一起伤亡事故分析

对某矿山所发生的一起矿井主运输巷道供风管突然垮塌所引发的伤亡事故进行了分析,说明了工程质量与安全管理的关系.指出在矿山建设中,一定要重视质量管理.     

临近深基坑的高边坡稳定性动态监测及险情分析

结合工程实例对由基坑与边坡组成的复杂体系的变形特征及支护结构工作特性进行了研究.周边环境复杂的基坑采用桩锚支护结构,局部采用土钉墙;基坑南面侧壁紧邻高边坡,边坡支护结构采用锚喷体系,在基坑开挖过程中监测基坑支护结构顶部水平位移、深层土体位移以及锚索轴力,并重点监测边坡变形和锚索拉力.结果表明,桩锚支护结构能有效控制基坑变形,在基坑开挖过程中锚索轴力呈现波动增加或减小.降雨会导致边坡锚索轴力增加,相邻锚索张拉可导致锚索预应力损失达10%以上.在开挖过程中边坡某些部位多次出现变形过大并导致边坡出现险情.在分析研究结果的基础上提出了抢险及加固方案.     

Measuring limitations in activities of daily living: a population-based validation of a short questionnaire

Purpose. A newly developed questionnaire assessing limitations in activity of daily living (LADL–Q) that should improve assessment of LADL is tested in a large population-based validation study. Methods. This survey was paper-based. Overall, 16,634 individuals who were representative of the working population in the German-speaking part of Switzerland participated in the study. Item analysis was used the final version of the LADL–Q to four items per subscale that correspond to potential problems in three body regions (back and neck, upper extremities, lower extremities). Analysis included tests for reliability, internal consistency, dimensionality and convergent validity. Results. Test–retest reliability coefficients after 2 weeks ranged from 0.82 to 0.99 (Mdn?=?0.87), with no item having a coefficient below 0.60. The median item-total coefficients ranged between moderate and good. Correlation coefficients between LADL–Q subscales and three validated clinical instruments (Western Ontario and McMaster Universities osteoarthritis index, shoulder pain disability index, Oswestry) ranged from 0.63 to 0.81. In structural equation modeling the three subscales were significantly related with two important outcomes in occupational rehabilitation: self-reported general health and daily task performance. Conclusion. The new LADL–Q is a brief, reliable and valid tool for assessment of LADL in studies on musculoskeletal health.     

某炼油厂冷却循环水系统故障与危害性分析

根据采集的某炼油厂一年的冷却循环水系统的故障数据,采用故障模式影响及危害性分析方法对该系统的可靠性进行了分析.由该系统结构特点,划分了水冷塔、换热器、水冷塔风机、水泵、水管、阀门等7个子系统及19种故障模式,统计了各子系统的故障率,分析了系统的故障模式及其故障原因,计算了各子系统的危害度.结果表明水泵及水冷塔风机的危害度最高,换热器的危害度排第三,但其故障率排第四,说明在做故障分析时不能只统计故障率而不进行危害度分析.最后提出了相应的改进措施,经过一年的实际运行,效果明显.