So-called decoking, in other words, the emptying of a container in which coke arising from the operation of a refinery is deposited and carried out using a decoking tool with a free mounting on the end of a drilling bar. The mounting is achieved using a sliding guide on a guide plate, coupled to the container. Distortions in the container and the guide plate therewith as a result of temperature variations during operation of the refinery which could lead to function disturbance of the drilling rod are avoided, wherein the sliding guide and the guide plate are arranged with a spring relative deflection by at least one spring element in the manner of a spring damper.