EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

Industrial furnaces are subject to extreme heat stress, chemical reactions and abrasive reactions. At the bosh and stack levels of blast furnaces, cooling staves are subject to severe abrasive wear. The staves if worn may cause water leaks, chilling of the furnace and/or catastrophic explosion. Thus, techniques have been developed to monitor the remaining stave thickness so that timely maintenance can be carried out. Traditionally, ultrasonic techniques (UT) cannot be used to measure the remaining stave thickness due to the multi-layer nature of the furnace, unless ultrasonic rods were preinstalled in the inlet/outlet pipes of the staves for fixed point measurements. In 2013, there was a break-through in the non-destructive testing methods for stave thicknesses. A technique known as the Low Frequency Pulsed Ultrasound (LFPU) was developed. The technique was tested on a medium size furnace on both cast iron staves and copper staves. The measurement results were verified by the conventional UT tests at designated copper rod inserts. Soon after this pilot project, there have been requests for the LFPU measurements from around the globe. This paper shows the comparison of the conventional UT tests and the advanced LFPU tests. A case study of the inspection performed at Novolipetsk MK is addressed.