WET SEAL FOR BUTT JOINTS Russian patent published in 2002 - IPC

FIELD: water-proofing of butt joints in process of construction of various objects, for instance, metal columns, protection against corrosion, reduction of heat loss, protection against corrosive agents in point of protected joint. SUBSTANCE: wet seal for butt joints comes in the form of jacket of closed cross-section made of thermally shrinked polymer material. On ends of its perimeter there are positioned electric heating elements. Jacket includes two layers as minimum and is produced by method of joint extrusion of layers. Outer layer is chemically cross-linked high-density polyethylene, electrodes are manufactured in the form of embedded zigzag elements and are located on internal surface of inner layer in zone of ends of jacket. They are subjected to preliminary mechanical enlargement of 10-100% of size of their internal section. Inner layer of jacket is produced from high-density polyethylene. If wet seal is put on butt joint carrying coat of polymer material then inner layer of jacket should be made of material of coat of butt joint. Electrode can be made of wire. Electrode located in zone of end of jacket is fabricated in the form of pair of open rings. Electrode can be placed in zone of end of jacket along helical line. Amplitude of zigzag electrode exceeds thickness of inner layer of jacket in zone of its end and spacing of zigzag electrode amounts to 0.5-2.5 thickness of inner layer of jacket in zone of its end. Thickness of inner layer in zone of location of zigzag electrode diminishes towards nearest butt of jacket. EFFECT: raised reliability of wet seal on butt joint, reduced labor input into its positioning. 9 cl, 2 dwg