Reduce Accident Risks Research Articles

Hazards in a Two-Stage Natural Gas Conversion Plant

Sections concerned with two-stage natural-gas conversion are amongst the commonest sources of emergencies in the manufacture of ammonia. The system contains hazardous substances in large volumes in combination with specific technology associated with the state of the working material and the high temperatures and pressures, so the plant in such a division belongs to the potentially hazardous class. Existing Russian legislation lays down that the design of such a section must necessarily involve considering quantitative hazard evaluations, i.e., accident risk estimation. There is only a very restricted volume of actual statistics on failu res in such equipment, while it is necessary to obtain quantitative estimates of hazards on the basis of accident prevention measures, so we chose the barrier diagram method. The results serve to compare various organizational and engineering measures to reduce accident risks. In such a section, natural gas purified from sulfur is used at 350‐370°C and 4.15‐4.20 MPa in a tubular oven, where it is mixed with steam in a steam‐gas ratio of 3.7:4.0. The mixture passes to a heater in the convection zone in the tubular ov en, where heat from stack gases is used to heat it to 510‐525°C. The mixture is uniformly distributed in the radiation zone over the vertically placed reaction tubes, where the reactions occurring are: CH 4 + H 2 O = CO + 3H 2 and CO + H 2 O = CO 2 + H 2 . The temperature of the converted gas at the outlet from the reaction tubes is 790‐800°C. The residual methane content in the dry converted gas after the oven is 9‐11%. The converted gas passes to tubes where it is additionally heated by 25‐30°C and passes to the other collector, which is lined with heat-insulating concrete and placed in a water jacket. Then the gas passes to the annular space in a mixer in the upper part of the methane convector in the second stage (shaft convector) at 465‐480°C. The free volume of that convector is located above a layer of catalyst, and part of the gas is burnt with atmospheric oxygen. The conversion is performed on a nickel catalyst at 990‐1002°C. The residual methane content in the converted gas is 0.35‐0.55%. The stack gases, after their heat has been utilized at 200°C, are discharged into the atmosphere [1, 2]. The barrier diagram method uses the definition of equipment failure combinations, various deficiencies in adjustment, and errors made by the staff (subsequently causes) that can lead to accidents. The graphical representation of the entire chains of initiating causes and the measures to eliminate them may be called the barrier diagram. The connections between the causes and their combinations are indicated by OR and & logic functions. Measures to prevent the causes are specified by the &‐NOR logic function. One of the main tasks in the method is to estimate the probabilities of various events arising. The frequencies of the initiating causes and the failure probabilities for protective measures are often very low, so one uses a special point system for representing the event frequencies. The points are specified from the formula p = ‐2 logh, where p is the number of points on the expert evaluation and h is the frequency with which failure causes arise. The probabilities (frequencies) of causes (events) for which one lacks reliable statistics are derived by expert estimation.

Economic Analysis of Accident Law

Accident law is the body of legal rules governing the ability of victims of harm to sue and to collect payments from those who injured them. This paper contains the chapters on accident law from a general, forthcoming book, Foundations of Economic Analysis of Law (Harvard University Press, 2003). The analysis is first concerned (chapters 2-4) with the influence of liability rules on incentives to reduce accident risks. Then consideration of accident law is broadened (chapter 5) to reflect the effect of liability rules on compensation of victims and the allocation of risk. In this regard a central issue is the roles of victims' insurance and of liability insurance, and how they alter the incentives inherent in liability rules. Finally, the administrative costs of the liability system, namely, the private and public legal costs of litigation, are examined (chapter 6). These costs are significant and thus bear importantly on whether use of accident law is socially desirable. It is emphasized that social intervention -- either to curtail use of the legal system or to encourage it -- may well be needed because the private incentives to use the system are generally different from the socially desirable incentives to do so.

Contingent Workers in High Risk Environments

Contingent workers, particularly independent contractors and temporaries, are increasingly performing high risk work across many industries. Based on a review of studies conducted in the mining and petrochemical industries, this article identifies the high risk factors associated with the use of contingent workers. The migration of contingent workers from peripheral (low risk) to core (high risk) tasks has been a major factor in increased accidents rates. Managers need to reduce accident risks from the use of contingent workers, create on-going relations with a limited set of contractors, orient strangers to the work setting, provide incentives for safe performance, create means for employing firms to monitor both contingent and core worker performance, and promote risk awareness at all organizational levels.

On Liability and Insurance

The question considered in this article is how liability rules and insurance affect incentives to reduce accident risks and the allocation of such risks. This question is examined when liability is strict or based on the negligence rule; and, if first-party and liability insurance are available, when insurers have information about insured parties' behavior and when they do not have such information. The conclusions are in essence that although both of the forms of liability create incentives to take care, they differ in respect to the allocation of risk; that, of course, the presence of insurance markets mitigates this difference and alters incentives to take care; and that despite the latter effect, the sale of insurance is socially desirable.