Abstract: A device for internally cladding an outer tube with an inner tube by means of an explosion process. The device includes an outer tubular fixture (1) in which a workpiece in the form of the outer (2) and the inner (3) tubes can be placed; at least one end of the tubular fixture (1) is connected to an expansion chamber (7, 10); and a sealing cap (6) of easily destructed material is located between a respective expansion chamber (7, 10) and the workpiece. The sealing cap or caps (6) is/are intended to retain a liquid pressure-transmitting medium (5), preferably water, in the inner tube (3) prior to detonating an explosive substance (4) placed within the inner tube (3).