Abstract: A sealing device for inner surfaces of hollow bodies such as pipes, containers, or the like which have adhering thereto contaminated or activated material. The sealing device comprises two supporting plates arranged in spaced relationship and substantially parallel to each other while extending in a direction perpendicular to the axis of the hollow body to be sealed. Of these two plates, the outer one is provided with a filling connection and with a discharging connection. The two supporting plates are adapted by means of pull elements to be tightened against a yieldable seal which is positively guided and is arranged along the circumferential rim of the hollow body.