Keywords: Ammonium nitrate safety, Risk evaluation, Legal safety requirements, Accident prevention, Safety in practice.
SAFETY IN WORKS
1. SAFETY OF PRODUCTS AND RAW MATERIALS.
Introduction.
Today, where public opinion and political interest are concentrated on environment-control, there is in industry an extra stimulation to take all the necessary safety measures to prevent accidents. This concerns also the fertiliser industry, which has grown very fast in the last decades. This growth has also resulted in more and more concentrated products, such as liquid ammonia, fertiliser-grade ammonium nitrate and concentrated compound fertilisers.
Larger quantities of products of more hazardous character are being stored in the fertiliser industry and in its distribution networks than in the past. For this reason a chapter is included concerning risk evaluation. This subject is rather new and has become over the last five years more and more the basis of the safety regulations. Past safety rules for storage and tanks for dangerous goods consist generally of safety measures or construction rules to prevent an accident.
Risk evaluation attempts to give a picture of the situation should a calamity occur in spite of all these preventive measures. By the aid of this prognosis precautions such as evacuation, protection of fire brigade against detonation, etc. can be planned in advance. Moreover such an analysis helps to convince the responsible people of the need for such safety measures. In general risk evaluation starts people thinking.
The following hazardous raw materials and products are distinguished in fertiliser industry:
- liquid ammonia
- ammonium nitrate, nitrate-containing fertilisers
- acids such as phosphoric acid, sulphuric acid and nitric acid.
- solutions containing ammonium-nitrate, e.g. AN-H2O, AN-NH3-H2O etc.
Because of the length, it was decided to restrict this paper to the treatment of the safety aspects of ammonium-nitrate and nitrate-containing fertilisers. It is suggested to devote one or two special papers to the other items.
G Perbal, UKF, Netherlands
18 Pages, 5 Figures, 26 Refs.
2. SAFETY SYSTEMS AND LEGAL REQUIREMENTS
Background.
The necessity for safety in the working environment is determined by economic, humanitarian and legal requirements. The material aspects of plant and substances has been covered. These can be analysed, weighed, measured and readily controlled. Safe systems of work however involve people with their human fallibilities and the law has had to be invoked in an attempt to enforce a measure of control on the activities of people. The historical basis of English law is still the ancient Common Law of England, as modified and extended by the judiciary. In the course of time it was found that industrial technology had outstripped the ability of Common Law to cater for all the problems of the 19th and 20thcenturies. The involvement of legislation became necessary and has resulted in a considerable body of Statute Law. At the present time the Factories Act, 1961, and the consequent regulations are of prime importance to industry and impose minimum standards.
Concluding remarks.
The field of accident prevention is rapidly becoming more complex. Problems of plant design and possible hazardous materials occur more frequently. Concern for the health of people and the quality of the environment are increasingly with us. Codes of practice, national and international, proliferate, usually advisory in character, but these standards are increasingly taken as the standards required, for example the code on noise, without being specific legal requirements. Having said this the patterns of injury and damage still indicate that the basic requirements are still essentially those of good house-keeping and well organised procedures.
V P England, Fisons Ltd., United Kingdom.
13 Pages, 2 Figures.
3. SAFETY IN DESIGN AND OPERATION
Synopsis.
It was felt that the most useful way of covering this topic was to take a practical case which would be of fairly general. interest in the fertiliser industry. The paper therefore deals with safety aspects of the design and operation of Nitrigin Eirean’s (NET's) new CAN/AN prilling plant.
With this type of process there are two aspects of safety to be considered:
a) General safety standards for dealing with corrosive or toxic fluids such as ammonia, nitric acid and ammonium nitrate and for the solids handling and bagging operations. The Paper seeks to highlight some of the more important and universally applicable conditions in this area.
b) Safety in process design to ensure that decomposition of ammonium nitrate does not occur, in particular that it does not occur in an enclosed space where an explosion could result.
NET have adopted what we would call a "common sense" approach to this problem. Certain combinations of temperature, pressure, residence time, pH, concentration or level of impurities are needed to produce decomposition. There is no virtue in spending money to eliminate one of these variables if the other variables needed to produce decomposition are absent anyway. What is necessary is that in normal operation, a number of these variables should have to change to produce a decomposition situation. Process and instrument design must therefore be such as to prevent this happening. Also the process operators must have adequate training to appreciate the significance of all changes in process variables.
The application of this philosophy to the design and operation of such items as the neutraliser, the concentrators and the 99.8 % AN pumps is discussed.
J F Killeen, Nitrigin Eirean Teoranta, Ireland.
14 Pages, 3 Figures, 1 Table.
Discussion 13 Pages.
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