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A farm-silo hoist used as the power source for a homemade barn elevator failed catastrophically from destructive wear of the worm. The hoist mechanism consisted of a pulley attached by a shaft to a worm that, in turn, engaged and drove a worm gear mounted directly on the hoist drum shaft. The worm and the worm gear were made of leaded cold-drawn 1113 steel and class 35-40 gray iron (nitrided in an aerated salt bath) respectively. The gearbox was found to contain fragments of the worm teeth and shavings that resembled steel wool. More than half of the worm teeth were revealed to be sheared off to almost half the depth. It was revealed on investigation that the drive pulley had been replaced with a larger pulley that generated more power than the gearbox could handle, causing failure by adhesive wear of the steel worm.

On attempting to manipulate or bend a boiler tube some 22 ft. long, sudden failure occurred at what appeared to be a butt weld in the tube. Externally, the weld reinforcement had been ground flush and the entire tube surface painted. Internally, the appearance and width of the heated band suggested that the weld had been made by the oxy-gas process. A lack of root fusion over most of its length was evident. Examination of the fracture faces, which were of crystalline appearance indicative of brittle behavior, indicated incomplete fusion of the weld root. Microscopic examination showed the deposit to possess a large grain size with a low carbon content disposed as carbides along the grain boundaries, a feature which would provide an explanation of the brittle behavior. Subsequent inspection showed that this tube was one of several of the batch ordered for retubing of a boiler and which had a 2 ft. length welded to one end to make up the length.

Operation handles produced from C45 steel showed many fine cracks at the flame hardened noses. The cracks ran from the corners of indentations caused by the tool during alignment. Metallographic investigation showed the nose was overheated during flame hardening. It was concluded that the numerous hardening cracks were caused by abrupt quenching from over-heating temperature and by local stress concentrations due to indentations of the tool caused during alignment.

During natural gas drilling in the EMS region in 1956, considerable numbers of longitudinal cracks and transverse fractures occurred in the connecting pieces of the bore rods. The connectors were screwed onto the rods by means of a fine thread and tightly joined with it by shrinkage at 530 deg C. The connectors were made of SAE 4140 Cr-Mo steel. The material for the rod pipes was Fe-0.4C-1Mn steel. Structural stresses played a role in the cracking. Iron sulfide formed on the fracture planes and flake-like stress cracks occurred in the steel. The hydrogen sulfide content of the gas was the cause of damage. Hydrogen liberated by reaction with the iron caused the formation of iron sulfide after penetration of the steel, which had an explosive effect during molecular separation under high pressure. This in turn caused the crack formation in conjunction with the external and residual stresses.

Eddy current inspection was performed on a vertical evaporator unit (that contained 180 tubes) used in a chemical processing plant. It was advised that the tube material was type 316 stainless steel. The shell-side fluid was condensate and gaseous methylene chloride, while the tube-side fluid was contaminated liquid methylene chloride. More than 100 tubes exhibiting severe outer surface pitting and cracklike indications near each tube sheet were revealed during eddy current inspection. It was observed that the indications correlated with rust-stained, pitted, and cracked areas on the outer surfaces. The cracking was revealed by metallographic examination to have initiated from the outer surface, frequently at pits, and penetrated the tube wall in a transgranular, branching fashion. The crack features were characteristic of chloride stress-corrosion cracking. A change in tube material was recommended to avoid future failures and loss of service.