Hazards of materials of construction in machinery used for manufacture of explosives depend on the explosive which is being handled by the machinery. Thus one has to consider the combination material/explosive as well as material and explosive themselves, in assessing hazards. Several types of hazard can occur viz., due to sparks, friction, impact or heat. For a given material the most likely factors that will influence its hazard depend on the type of hazard, e.g. for spark hazards important factors are: static pick-up of material and explosive, conductive properties and spark confinements; for impact hazards: hardness, surface roughness, elasticity, presence of cavities, confinement offered and area of contact; for frictional hazards: hardness, friction coefficient and thermal conductivity. For purely thermal hazards, only flammability need be considered.
In impact and friction the chemical action between material and explosive may play an important role. In all cases the sensitivity of the explosives themselves to the particular type of action, has to be taken into consideration. In accidental mishaps the type of hazard is often a combination of impact and friction, and requires a special test method.
In this paper the literature on some aspects of all of the above hazards is reviewed. Experimental results of frictional and frictional impact tests are discussed from a theoretical point of view. A number of results of particular interest, e.g. for aluminum alloys, coated steel and non-metallic materials are presented.
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