Contributed by Bob Kozickie, Technical Sales Support Manager
The criteria for removing alloy chain from service includes excessive wear, elongation, nicks and gouges, and bent links but one additional consideration is exposure to excessive heat. Manufacturers’ recommendations are to remove alloy chain from service due to excessive high heat exposure. A major indicator of this exposure is a visible discoloring of the steel to a variety of blue hues progressing eventually to a grey or dark grey color. Once the alloy chain has transformed into these stages, removal may be necessary based on the application.
OSHA, ASME, NACM, and manufacturers’ recommendations are all in agreement that alloy chain is required to be removed from service once the chain has been exposed to temperatures in excess of 1000° F. There is further agreement, in a published chain heat exposure chart, which shows that alloy chain must be used at a reduced working load limit while at temperatures between 400° and 1000° F. There is also a permanent reduction in capacity which must be applied to the chain for the remainder of the service life of the chain based on the exposure temperature.
The technical explanation is the fact that alloy chain will begin bluing at varying shades between 560° and 790° F. The bluing is an indication that the chain has seen excessive heat but maybe not have exceed