METHOD OF NON-DETACHABLE SLEEVE-TYPE CONNECTION OF PIPES MADE FROM HIGH-STRENGTH CAST IRON WITH SPHERICAL GRAPHITE Russian patent published in 2003 - IPC

FIELD: erection of underground pipe lines made from high-strength cast iron with spherical graphite. SUBSTANCE: proposed method includes making circular projections on external surfaces of pipe ends which have form of triangle or trapezium in cross section. Then, sleeve is made from metal whose hardness is below as compared with hardness of pipes made from high-strength cast iron with spherical graphite. Sleeve is reduced to internal diameter at which circular projections of pipes run into metal and metal fills circular bores of pipes. EFFECT: enhanced strength of pipes. 2 cl, 1 dwg