METHOD OF MANUFACTURE OF PRESSURE PIPES Russian patent published in 2003 - IPC

FIELD: manufacture of articles from precast concrete and reinforced concrete. SUBSTANCE: proposed method includes molding of external protective layer in mold with centrifuge switched on. Then, centrifuge is switched off and spiral reinforcement with longitudinal rods secured on its inner side is introduced. Centrifuge is switched on at higher speed and distance rod is placed inside, after which centrifuge is stopped and longitudinal rods are subjected to tension; then, distance rod is withdrawn and internal protective layer of concrete mix is formed. Then, longitudinal rods are subjected to heat treatment followed by tempering. EFFECT: reduced labor consumption. 2 dwg