Application Special 2 1/2" ANSI simple chain used for conveying in a mine.
Failure mode No. 58 pin suffered a fatigue failure.

The joint was extremely dry and showed no signs of lubrication. The joint showed heavy galling with the presence of surface corrosion products. Subsequent investigation revealed that the chain had been running in water, but more significantly that the user had opened out the holes of the no. 58 joint to make assembly easier. This caused the fatigue failure experienced.

Solution Provide a better lead in the pin to enable the user to assemble more easily. Reconsider lubrication regime.