Regular inspections and overhauls of industrial furnaces and, above all, their brickwork are mandatory: "During the production of cement, abrasion causes erosion of the fireproof lining. In addition, there are stresses caused by temperature changes and thermochemical corrosion, which leads to damage and flaking in the brickwork," explains Bennet Röpke, Project Manager in charge of the development of the Quadriga at the M-Group. To maintain the brickwork, the plant operators or specialised service providers previously had to erect scaffolding inside the furnace. Deposits were then removed from the surface of the brickwork and damaged bricks were removed and replaced. This is physically demanding work which is not without danger for the specialised bricklayers due to poor visibility, high temperatures, falling bricks, dust and noise. It is also very time-consuming and costly. At a cement works, downtime costs of up to €200,000 can quickly arise - per day, it should be noted. Coordinating the various trades involved is another uncertainty factor.