Technical Report

A Midwestern integrated mills #2 BOF Bogiflex drive was experiencing fires due to the large Bogi drive’s close proximity to the BOF vessel and the combination of an oil piping leaks or ruptures in the vicinity of hot slag. After several small fires and one major fire which caused substantial damage, The BOF maintenance super-intendent, decided to investigate the possibility of a fire resistant gear oil.

Water glycol fire resistant hydraulic fluids have been used successfully for many years in high combustion environments. But could a gear oil with fire resistance characteristics carry the extreme loads of a vessel tilt drive? The super-intendent, contacted Schaeffer Manufacturing Company, a specialty lubricant supplier with a reputation for innovation and cutting edge technology. Schaeffer began the development of a fire resistant, EP gear oil with adequate viscosity to maintain lubricant film and protect the gearing.

Typically, water glycol fluids are not considered to have adequate viscosity or film strength to carry extreme loads. Furthermore, typical EP packages are not readily emulsifiable in these types of base oils. Since protecting the gears during service was of primary concern to the mill, these design issues needed to be resolved before the lubricant could be submitted for testing.

In addition to load carrying ability, filterability and seal compatibility were issues of concern to the product design team. Typical base oils used in the development of fire resistant fluids often contain as much as 40% water. This makes them difficult to filter through traditional media and increases the likelihood of rust and corrosion. In addition to these issues, design team member Kyle Saxton says they were forced to “think outside the box”. “When a challenge like this presents itself,” said Saxton, “you really need a team of people working together to keep you from getting tunnel vision.” An autoignition point of 900o F was determined to be the minimum standard for acceptable fire resistance. After design and bench testing, a lubricant with the following typical characteristics was submitted for field tests:

After a review of the specifications by Xtek, the gear manufacturer, it was determined that the lubricant was sufficient to protect the gears. Maintenance personnel also performed some “not-so-scientific” tests of their own. At one point, an open pan containing the test lubricant was placed in front of the vessel during charging without incident. Everyone agreed that the new lubricant appeared to meet the prescribed criteria. On August 12, 1997, the first fire resistant gear oil was placed in service at a major BOF at this midwestern integrated mills #2 BOF.

The early results have been very positive. Since the installation of the Schaeffer’s #230 Fire Resistant EP 150, no fires have been reported near the Bogiflex drive. On several occasions, slag spills have produced enough material to ignite traditional high temperature gear oil, but the fire resistant product has refused to catch fire. Gear temperatures and oil analysis indicate that the gearing is being adequately protected.

Note: Ferrography tests available on request: