TECHNICAL MANUAL - Sharq.biz

inspection of weldedjointingsEither for the buttfusion jointing or for the electrofusion process, by end of thecooling time the joint quality must be checked according to the standards UNI10520 and UNI 10521, through:non destructive controls: mainly consist on the visual control and on thedimensional control of the ring;destructive controls: consist in the mechanical resistance identification of thejointing through testings carried out according to the reference standards.non destructive testingsbuttfusion welding UNI 10520visual controlThe visual control is relative to the following checks:• the carving by the center of the ring must be above the external diameterof the welded elements, as too deep carvings trace back to temperature orwelding pressure values lower than those foreseen;• on the external surface of the ring there cannot be porosity, dust inclusionsor other contaminations, as these are indicative of unsuitable cleaning of theelements to be welded;• after cooling, the external surface of the ring cannot be excessively bright, asthis is index of overheating of the welded material.dimensional control of the beadThe dimensional control of the bead foresees the following checks:• the width B of the bead must be uniform on the whole area of the welding.At any point of the welding, the width B of the bead cannot vary more than±10% with respect to the average value B m :Inspectionof weldedjointingsB m= ( B min+ B max) / 2where B min e B max respectively are the minimum and maximum measured value;• at any point of the welding, the maximum difference between the two beadswhich form the ring must be lower than 10% of the width B of the bead incase of pipe-pipe joint and 20% in case of pipe-fitting and fitting-fitting joint;• the maximum misalignment of the two welded elements must be lower then10% of their thickness;• at any point of the welding, the width B of the bead must be comprised in thevalue shown in the next table:57