METHOD AND DEVICE FOR INNER CORROSION PROTECTION OF WELDED JOINT ZONE OF PIPES Russian patent published in 2002 - IPC

FIELD: construction at laying of pipelines and provision of corrosion protection of the inner surfaces of pipe welded joints having a manufacturer's inner coating over the entire length, except the pipe ends. SUBSTANCE: the device has a bush in the form of metal coiled band representing a spring provided with a flexible locking member fixing it against uncoiling for defixing. The flexible locking member represents a section of string-type wire. The peripheral band coils are spatially separated from the band axial coils, have a lesser length and are provided with heat-insulating material. The wider band axial coils are provided with a coiled gasket impregnated with polymeric binder. The device is preliminarily placed in the cavity of one of the pipes, the joint for welding is assembled with provision of a gap between the pipe ends with bringing out the ends of the flexible locking member through this gap outside. The device is displaced by part of its length to the cavity of the other pipe using the end of the flexible locking member. By tension of the ends of the flexible locking member the latter is extracted from the device, using the gap. The spring band gets defixed, the spatial separation between its peripheral and axial coils is eliminated and the band gets self-uncoiled due to mechanical energy accumulated in it. The remaining part of mechanical energy accumulated in the band provided for the rated force of band pressing of the gasket impregnated with polymeric binder to the protected inner surface of the joint zone with a partial covering of the inner coating of the pipes. The pipes are joined by welding. The heat-insulating material prevents and intolerable action of welding heat of the thermosensitive polymeric binder. EFFECT: expanded range of hardware components. 14 cl, 7 dwg