Members of the Society are presumably primarily interested in manufacturing, distributing and using fertilisers, and the fact that they have to use for these purposes engineering equipment is a necessary nuisance. Naturally the equipment costs money, breaks down, requires maintenance and forces people to think about these problems, but these are secondary to the main job, and I think it would therefore be better for me not to go into technical details but try and deal with my subject in the most general terms possible.
Metals, alloys and concrete have been the engineer’s standard materials for many years and it is only comparatively recently that plastics and some other non-metallic materials have started being used on an appreciable scale. As a consequence a great deal is known about metals, and through experience people have learned how to design and fabricate acceptable equipment in metals by avoiding well-known pitfalls. Discussing these materials in general terms is therefore not worthwhile, and going into the technological details which have novelty is not suitable for an audience with diverse interests. By contrast, experience and knowledge about plastics is not widespread, and it is possible to review certain aspects of the subject superficially and nevertheless say something worthwhile. This is particularly so at this point in time because during the next five or ten years members of the Society will find a gradual increase in the use of plastics in their equipment and they may like to know what is in store.
Bearing in mind that our interests in the equipment is not a primary interest, let us first agree in what we are interested. First, we are interested in the equipment doing its functional job, but having achieved this we are interested in comparing the available alternative pieces of equipment in terms of capital and running costs, including durability, maintenance etc. Normally our judgement is based on a comparative scale, and we only start criticising a piece of equipment when the economics associated with using it compare unfavourably with something else. All equipment is therefore to some extent unsatisfactory unless it costs nothing, does not wear out or require repair. Thus durability and especially corrosion are always good subjects to discuss, as well as initial costs.
C Edeleanu, MA, PhD. Imperial Chemical Industries Ltd, UK.
34 Pages, 12 Plates, 3 Figures, 2 Tables.