A flange, butt or lap bolted connection is a special part of an installation, structure or foundation. Despite the identical environment in which the entire installation (structure) is located, the corrosion exposure is different (more intense, dangerous) in the connection zone itself than in the rest of the area. This is due to the geometry and variety of materials from which the connection elements are made. An additional factor accelerating corrosion are stresses, which sometimes reach high values, which can, for example, initiate cracks in the steel and thus contribute to the creation of new areas of corrosion.