Steel plant makes sound savings
20 Nov 2006
Acoustic monitoring when components or machines rotate at less than 80rpm
Vibration monitoring is fine for checking the condition of high-speed motors, fans and pumps. The equipment is cost-effective, easy to use and the data is easy to interpret. It is less effective when components or machines rotate at less than 80rpm and operate under fluctuating load conditions, or only move through a part revolution.
In contrast, acoustic emission monitoring equipment has a high sensitivity to machine faults and is also immune to audible noise and low frequency background vibration. However, many engineers are not fully aware of the benefits of acoustic emission monitoring systems, nor do their companies possess the necessary skills in-house to interpret the data from acoustics emissions monitoring.
Acoustic emissions are the high frequency stress waves generated by the rapid release of strain energy that occurs within a material during crack growth, plastic deformation or phase transformation. Systems, typically, use surface-mounted transducers to detect these stress waves, which lie within the 25kHz to 1MHz frequency range.
Corus Northern Engineeing Services recently helped Corus' Scunthorpe steel plant to save at least five weeks' production time by using acoustic emission monitoring to detect early signs of bearing stress.
The plant uses three Basic Oxygen Steelmaking (BOS) plant vessels, which convert molten iron from the blast furnaces into steel. Each vessel weighs 1,300 tonnes and is supported on two, 1.75-metre diameter spherical roller bearings.
The units are designed to tilt to various angles up to 150° from the vertical during the process for charging and discharging purposes and this produces high local contact loads that, over time, generate high residual stresses in the tilt bearings.
Delivery lead times for bearings of this magnitude can be as long as 12-18 months, with plant downtime for a planned bearing change requiring three weeks. The bearing cost of £60k-£80k per unit becomes almost insignificant in comparison with the overall production outage costs.
For such critical equipment, it was essential that Corus knew the exact condition of the tilt bearings and the trends that could predict their life expectancy. The method Corus developed to do this, Aquilla AE Pro, is based on acoustic emission principles using software developed by Corus Research Development & Technology, a division of 900 engineers and technologists with expertise in data analysis, condition monitoring and failure analysis.
At Scunthorpe, Aquilla AE Pro detected early signs of distress and an automatic review of trends enabled the remaining bearing life to be predicted.
In contrast, acoustic emission monitoring equipment has a high sensitivity to machine faults and is also immune to audible noise and low frequency background vibration. However, many engineers are not fully aware of the benefits of acoustic emission monitoring systems, nor do their companies possess the necessary skills in-house to interpret the data from acoustics emissions monitoring.
Acoustic emissions are the high frequency stress waves generated by the rapid release of strain energy that occurs within a material during crack growth, plastic deformation or phase transformation. Systems, typically, use surface-mounted transducers to detect these stress waves, which lie within the 25kHz to 1MHz frequency range.
Corus Northern Engineeing Services recently helped Corus' Scunthorpe steel plant to save at least five weeks' production time by using acoustic emission monitoring to detect early signs of bearing stress.
The plant uses three Basic Oxygen Steelmaking (BOS) plant vessels, which convert molten iron from the blast furnaces into steel. Each vessel weighs 1,300 tonnes and is supported on two, 1.75-metre diameter spherical roller bearings.
The units are designed to tilt to various angles up to 150° from the vertical during the process for charging and discharging purposes and this produces high local contact loads that, over time, generate high residual stresses in the tilt bearings.
Delivery lead times for bearings of this magnitude can be as long as 12-18 months, with plant downtime for a planned bearing change requiring three weeks. The bearing cost of £60k-£80k per unit becomes almost insignificant in comparison with the overall production outage costs.
For such critical equipment, it was essential that Corus knew the exact condition of the tilt bearings and the trends that could predict their life expectancy. The method Corus developed to do this, Aquilla AE Pro, is based on acoustic emission principles using software developed by Corus Research Development & Technology, a division of 900 engineers and technologists with expertise in data analysis, condition monitoring and failure analysis.
At Scunthorpe, Aquilla AE Pro detected early signs of distress and an automatic review of trends enabled the remaining bearing life to be predicted.
