Abstract: A pneumatic pipe plug for the sealing of pipelines of various nominal diameters can be inserted through connections of relatively small diameters in a wall of a pipeline and is intended for high working and dynamic pressures in order to ascertain good sealing, whereat the plug is also conceived in a way to be resistant to mechanical damages that could occur when inserting the plug into or removing it from a connection in the wall, said connection being often sharp-edged. The pipe plug of the invention is conceived as a tube element (1) in the sense of an ellipsoid of revolution, whereat the thickness of a wall (8) of the element (1) becomes thinner towards the centre and the wall can also contain a gummed cord (9) running in several, preferably two layers so that, with respect to the longitudinal axis of the element (1), one cord (9) lies obliquely to one end and another cord (9) to another end for an angle a measured from the central line and amounting to 0-20° C.

Abstract: A method is provided for the continuous processing of coarse-grained waste rubber into a secondary rubber raw material, in which coarse-grained waste rubber having a particle size of 0.5 to 15 mm, preferably approx. 4 to 6 mm, in a layer of a thickness not exceeding the largest dimension of a single grain is exposed to a thermoshock without the access of oxygen at a temperature of 200.degree. to 900.degree.C., preferably 600.degree. to 800.degree. C., for a time of 5 to 200 seconds, preferably about 30 to 60 seconds, depending on the size of the particles and the desired structure of the product.

Abstract: A method of separating rubber from metal, which includes obtaining a metaontaining rubber body, impeding the access of oxygen to the rubber, exposing the body to high-frequency electromagnetic field to cause the metal to glow and the border layer of the rubber on the metal-rubber contact to be thermally degraded and carbonized, and magnetically separating the rubber from the metal, and apparatus for carrying out the method.

Abstract: A method of separating rubber from metal which includes covering a metal-taining rubber body with an inert powdered agent, exposing the body to high-frequency electromagnetic field to cause the metal to glow and the border layer of the rubber on the metal-rubber contact to be thermally degraded and carbonized, removing the powdered agent and magnetically separating the rubber from the metal, and apparatus for carrying out the method.