Abstract: A lightweight insulating polymer concrete formed from a lightweight closed cell aggregate and a water resistance polymeric binder.

Abstract: It is necessary to determine welding temperature as precisely as possible in order to properly control the high-frequency welding of longitudinal pipes. Changes in welding temperature are proportional to alterations in the welding current that flows through the edges of the skelp. Magnetic-field sensors can be used to directly and precisely determine alterations in the current and hence changes in the temperature. Voltages induced in the sensors can be processed into setting signals to correct the high-frequency welding generator and disruptions in the current used to generate signals to mark the site of failure on the pipe for subsequent rejection.

Abstract: It is necessary to determine the effects of welding pressure in order to control the high-frequency welding process in the manufacture of pipes with longitudinal seams. It has been discovered that measurements of the height of the welding bead provide an approximation that is satisfactory for determining the mass of the bead, which is proportional to welding pressure in known pipe geometry. The height of the bead is transmitted by an optical system to the diode matrix of a commercially available diode-matrix camera. The results are processed to control welding pressure.