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

FIELD: sealing of butt joints welded in process of construction of various objects, for example, metal columns, structures made of pipes, protection of butt joints against corrosion, reduced heat loss in point of joint, protection against corrosive agents. SUBSTANCE: elements of electric heater in the form of metal wire with high ohmic resistance, predominantly, nickel-chromium-iron alloy are given periodic form on at least part of its length, mainly sinusoidal or zigzag, are laid on thermally softening plastic shell above point of joint and given shape of bent joined members. Electric heater is formed by two sections of wire connected in parallel and has taps for connection to source of electric current so connected to parallel sections that difference in ohmic resistance of these sections does not exceed 5.0% of ohmic resistance of single section. Parallel sections of wire in configuration given to them are fixed with the use of thermosoftening plastic material. Thermosoftening plastic material comes in the form of tape which thickness amounts to 0.5-5.0 diameter of wire. Each section of wire can embrace corresponding joined member over half of its perimeter, as minimum, following configuration of joined members at point of butt joint. Wet seal for butt joints can include additional parallel sections of wire which have ohmic resistance equal to or different from ohmic resistance of corresponding main section. Additional sections of wire can be located along sides of main sections or above main sections and can be insulated from them by means of thermosoftening plastic material. Thermosoftening plastic material has one hole, as minimum, to feed heat insulating, preferably, foaming material into space limited by thermosoftening plastic material. EFFECT: increased reliability of hydraulic insulation of butt joint and diminished amount of labor input. 7 cl, 2 dwg _