Safety of synthetic organic compounds is recognized as one of the most important recent problems of chemical industry. Legal safety control system applied to chemicals is meeting to keep safety as well as voluntary restriction by industry. Present situation and trend of Japanese and international regulation systems on chemical substances is reviewed. Variety and classification of chemical substances, legal control systems, basic factors of safety evaluation, testing and standards of biodegradability, accumulation and toxicity, industrial activities on safety control are generally discussed and surveyed.
As to the Prevention of Fire and Explosion, Japanese Chemical Industry is mostly controled by three acts. namely Compressed and Liquified Gas Control Act (CLGCA) by MITI National Fire Prevention and Control Act (NFPCA) by Fire Prevention Adm. (Japanese) Occupational Safety and Health Act (OSH Act) by Min. of Lab. Main articles of these three acts which closely related to Fire and Explosion are picked up and compared each other.
After a brief introduction to reactive chemical hazards, the examples of hazardous chemical reactions which seem to cause accidents were shown along with energy concentrating operations encountered in chemical plants and laboratories. It was demonstrated from some case histories that chemical laboratories are apt to catch fire at a big earthquake, and chemists' preparations for the earthquake were suggested. As the efficient methods for the estimation of reactive chemical hazards, the utilizations of case history, hazardous chemical data sheet and computation of reaction heat were suggested. Finally, test methods of reactive chemicals and prevention principles for reactive chemical accidents were briefly described with some references.
Some case histories in chemical process occurred due to unexpected reaction in the past twelve years in Japan were collected, classified and discussed. As the result, chemical accidents of this type were found to occur mainly in reaction process, in distillation process, in drying or storage process (in which the causes are mostly similar to spontaneous ignition phenomena) and in pipe lines. Causes of accidents in the reaction process can be classified into two large groups, in which one is due to the fault of temperature control and the other is concerned with the miss in composition control of the reaction system. The typical examples of the fault of temperature control are as follows breakdown of electric power supply, breakdown of temperature control instruments, infelicity of the positon of the temperature sensor, etc. And that of the miss in composition control are : breakdown of measuring instruments, mistake in feeding control of reactants or catalyst, fault associated with agitating operation, trouble in enlarging the scale of operation, etc. On distillation process, it is stated that special caution should be given to impurities such as catalyst or its derivative for recovery that may be carried forward with the crude distillate to the distillation process. In addition, some comments are given on how to investigate the course of accident.
We, Toagosei Chemical Industry, have buckled down seriously to the safety problem with making the best use of our experience of plant accidents happened in the past. With an explosion accident in 1952 as a momentum, our plant operation was standardized. Then, with an explosion accident in 1972 as a momentum, an expert committee for the prevention of plant accidents was institutionalized. By the said committee, the checking for causes of accidents is done as to each stage of research, engineering, and test operation. The check list is used for this purpose. Now, we would introduce the part relating to the explosion. Differential Scanning Calorimeter is effective for the checking against explosive chemicals of which counterplan is difficult to be set.
This paper contains a review of the current status of our understanding of accidental explosions and safety techniques in chemical plants. In the first section the unconfind vapour cloud explosions are discussed. Accidental release of combustible gases and liquids into the open air generates an unconfind vapour cloud. Notable incidents in the past have already shown that unconfind vapour cloud explosions are catastrophic. In the second section the accidental explosions of combustible gas in process equipment, such as reactors or pipelines, are described. The explosion hazard can be eliminated by addition of inert substance.
Presenting an example of safety assessment system for the chemical plant, the basic methods of evaluating potential hazards and Fundamentals of safe plant design, corresponding each stage of laboratory, pilot plant test and plant design, are discussed. The attitude of self-defence is essential for the loss prevention.
On December, 1976, the Bureau of Labor Standards, Ministry of Labor, Japan, issued the guidelines for safety assessment in chemical process plants. To prevent fire and explosion accidents in chemical industry, the guidelines indicates requirments of evaluating proper by the hazard degree of the plants on stage of designing in their constraction of modification, and taking safety precautions based on these hazard degree. The method to assess the hazard in the plants recommended to follow the next step. Step 1 : Arrangement and study of the relevant documentation. Step 2 : Qualitative evaluation- Inspection according to the check list. Step 3 : Qualitative evaluation. Step 4 : Safety precaution-Engineering and Management. Step 5 : Re-evaluation based on information of accidents. Step 6 : Re-evaluation by a fault tree Analysis.
This commentary provides an overview of the laws and regulations of Japan which govern the design of process plants, highlighting the fundamental four laws related to plant safety and those dictating the prevention of industrial pollution. This emphasizes that the intent of the laws in question is the prevention of disasters and accidents and that the complete understanding of the laws is an essential requisite for process plants planning and engineering.