Failures of Steel Parts in Service

Presumably, the matter of failure of metal parts in service would arise very infrequently, in the thousands
of years mankind knew how to make use of metals, before the introduction of steam power. There is much evidence, however, that failures bean to occur with distressing frequency from the time steam was applied to marine propulsion, and to railway engines early in the ninetee-
nth century. Not that the steam of itself had anything
to do with the failures, but its use as a prime mover implies normal working stresses higher than those empl-oyed when man, animal, water, and wind power were the
sole means of making machinery go round. Not only were
higher stresses used after the introduction of the
steam engine, but the intermittent nature of the earlier prime movers would give place to long continued appli-cations of the reversed stresses imposed by a steam
drive.