While working as a lube salesman in the Toronto area, I was called to visit a customer who had experienced a lube-related problem. Over the weekend, a welder had been working on a large gearbox that was drained of our oil – a conventional EP gear oil.
The workers made that old fatal mistake of thinking that an empty oil vessel is completely empty.
However, they soon found out their assumption was incorrect. As a result of the welding, the accumulated fumes in the gearbox exploded. The force was so great it broke the bolts holding the heavy inspection plate, which shot up and damaged the ceiling. Nobody was hurt, except for a bad case of ringing in the ears.
The box had to be scrapped. I have a hard time imagining that it was “bent,” but I distinctly remember being told that it was rendered useless.
To decrease the possibility of an explosion, it is a good idea to leave open to the air any tank or gearbox that previously held a lubricant.
Contributed by Tom Muckian, Manager of Technical Services, Whitmore Group
The maintenance personnel at a customer’s plant applied compressed nitrogen to a gearbox in an attempt to evacuate all of the used oil from the unit. Although the mechanics were trying to expedite the process, they failed to consider the consequences of over-pressurization.
The over pressurization resulted in a sudden, catastrophic, brittle fracture of the cast iron gearbox (see photo). To their amazement, nobody was hurt.
This incident, like other gearbox welding accidents, emphasizes the need to utilize documented proper procedures for all maintenance undertaken.
Contributed by David Krause, Parman Lubricants Corp.