CONTROL OVER WELDING OF PIPELINES FROM HIGH-STRENGTH PIPES WITH CONTROLLED HEAT INPUT Russian patent published in 2015 - IPC B23K31/02 B23K33/00 B23K9/235 B23K101/10 

FIELD: process engineering.

SUBSTANCE: invention relates to welding of pipelines from high-strength pipes. Pipe end edges are grooved for welding at the ratio between total grooving width and depth of welding elements making 1.3 to 2.0. Elements are assembled. Preheating is executed at 170-200°C. Said elements are arc welded to make a circular butt joint over the pipe perimeter. Note here that thermal cycle parameters are controlled in welding whereat heat input to metal varies from 0.8 to 1.2 kJ/mm. Weld beads are applied to make the butt weld with the ratio between depths of previous and next beads makes 1.0-2.0. Note also that every pass is performed by parallel application of two beads, temperature between applied weld beads varying from 170 to 220°C. Weld is cooled at the rate of 150-200°C by covering with heat-insulation belts to be removed after butt temperature of 50°C.

EFFECT: higher load-carrying capacity of pipelines.

3 dwg, 1 tbl