Optimization of recertification intervals for PSV based on major accident risk

Overpressure is a major hazard in the process industry with the potential to lead to a major accident. Pressure Safety Valves (PSVs) are often used as the last layer of protection against such a hazard and require regular recertification in order to be dependable. The valve safely vents gas from a vessel when the pressure becomes excessive. It is often the practice in industry to apply one or two years as the normal recertification interval of PSV. However, experience from the Norwegian oil and gas industry is that the recertification process several times have caused leaks of gas. The process thus represents a certain risk in itself and the question is then whether the recertification intervals presently being used actually are optimal from a risk point of view? The objective of this paper is to look into this problem, applying typical data from an oil and gas installation. An optimal recertification interval will be calculated based on minimization of risk to personnel.     

LGH - 01型空气质量自动监测系统常见故障及维修

介绍了 LGH-01型空气质量自动监测系统,对使用该系统时出现的常见故障和排除办法提供了解决思路,并且提出了使用该仪器时应严格按规程操作,要加强巡检工作和注意用电安全等日常维护的注意事项.     

飞机维修活动中的快速上肢评价

维修是保证飞机能够正常、安全飞行的一个重要环节 ,而好的工作姿势可以确保维修人员高效、快捷、安全的完成维修任务。在维修活动中以上肢动作居多 ,因此 ,笔者主要介绍了一种在国外比较通行的工效评价方法———快速上肢评价 (RULA)。该方法可以用来快速识别工作中可能出现的上肢不利姿势 ,以避免发生上肢损伤。同时笔者还编制了相应的评价软件 ,使得评价工作变得更加方便、快捷 ,并利用该软件对飞机维修任务进行了实例评价。     

Analysis of Socioeconomic and Environmental Impacts of Waste Stabilization Pond and Unrestricted Wastewater Irrigation: Interface with Maintenance

The effluent from the waste stabilization ponds (WSPs) of the University of Nigeria, Nsukka Campus, is used for irrigation by poor rural farmers. There has been fear that the poorly maintained WSPs and the reuse practices are contributing to environmental degradation and health hazards. In this study the environmental and socioeconomic impacts of the WSPs and reuse were evaluated based on data collected from questionnaires and the literature. The engineering and agricultural properties of soil in the irrigated and nonirrigated areas were compared. Comparison of the health status of the farmers and nonfarmers, of consumers of crops irrigated with wastewater and nonconsumers was performed using Student's t test and the z-score test. The occurrences of diarrhea, typhoid fever, and malaria among the various groups were used as indices. Analyses show that the health status of the farmers and consumers is poorer than those of nonfarmers and nonconsumers at the 5% level of significance. Vegetable cultivation using WSP effluent is a means of sustenance to the farmers and provides an affordable means of satisfying their nutritional deficiencies. However, the poorly maintained WSPs create odor and mosquito nuisances, trap and destroy livestock, and flood nearby compounds with waste debris. At both 1% and 5% levels of significance, communities around the ponds (< 300 m) suffer malaria more frequently than those who live far away (> or = 300 m). Cost-benefit analysis argues in favor of improvement of WSP management and irrigation reuse of wastewater. Dredging of the ponds, training workers and farmers, and adopting appropriate maintenance and monitoring strategies will greatly enhance the socioeconomic status of the urban poor farmers.     

Maintenance-related major accidents: Classification of causes and case study

The potential for major accidents is inherent in most industries that handle or store hazardous substances, for e.g. the hydrocarbon and chemical process industries. Several major accidents have been experienced over the past three decades. Flixborough Disaster (1974), Seveso Disaster (1976), Alexander Kielland Disaster (1980), Bhopal Gas Tragedy (1984), Sandoz Chemical Spill (1986), Piper Alpha Disaster (1988), Philips 66 Disaster (1989), Esso Longford Gas Explosion (1998), Texas City Refinery Explosion (2005), and most recently the Macondo Blowout (2010) are a few examples of accidents with devastating consequences.Causes are being exposed over time, but in recent years maintenance influence tends to be given less attention. However, given that some major accidents are maintenance-related, we intend to concentrate on classifying them to give a better insight into the underlying and contributing causes.High degree of technological and organizational complexity are attributes of these industries, and in order to control the risk, it is common to deploy multiple and independent safety barriers whose integrity cannot be maintained without adequate level of maintenance. However, maintenance may have a negative effect on barrier performance if the execution is incorrect, insufficient, delayed, or excessive. Maintenance can also be the triggering event.The objectives of this article are: (1) To investigate how maintenance impacts the occurrence of major accidents, and (2) To develop classification schemes for causes of maintenance-related major accidents.The paper builds primarily on model-based and empirical approaches, the latter being applied to reports on accident investigation and analysis. Based on this, the Work and Accident Process (WAP) classification scheme was proposed in the paper.