3. Maintenance

The service life of the furnace's major components is calculated in years, based on 300 operating days per year, 24 hours a day, or 7,200 hours.

• Between 0 and 15 years of service (8% of cases), treads can be subject to breakage and cracking. After 15 years, spalling occurs in 5% of cases, while the risk of breakage or cracking is reduced to 2%.

  Overall, 85% of bandages have a life expectancy of 25 years.

• Standard ferrules have a lifespan of around 20 to 30 years; but ferrule corrosion phenomena, linked to the use of particular raw materials or fuels, can appear and lead to the replacement of ferrule sections within a few years.

  Similarly, careless furnace operation causes irreversible permanent deformations that can be likened to...