METHOD FOR PREPARING TUBE ENDS FOR WELDING AT CHANGING DEFECT PORTION OF MANIFOLD PIPELINE Russian patent published in 1998 - IPC

FIELD: pipeline transportation systems, possibly restoration of pipelines of steel tubes. SUBSTANCE: method comprises steps of comparing dimensions and shapes of tube ends joined by welding; realizing comparison with reference circle whose diameter is equal to nominal diameter of repaired pipeline; providing coincidence of dimensions and shapes of tube ends; in order to realize it before mounting shot tube carrying out plastic deformation of tube metal at acting upon tube wall along its whole perimeter by distributed effort until achieving tube end cross sections equal to reference circle by shape and diameter. Action of distributed effort in zones with dimensions inside nominal tube diameter is directed from tube center and in zones with dimension outside nominal tube diameter - to tube center. Intensity of distributed effort in each cross section of pipeline is set in dependence upon fluctuation of dimensions of real cross section from nominal diameter, wall thickness and tube diameter. Technique provides strict coincidence of edges of welded tubes, lowers local deformations. EFFECT: enhanced efficiency and accuracy of method. 2 cl, 4 dwg