RU2002108867A - The method of heat and waterproofing shaped products - Google Patents

Claims (1)

Method of heat and waterproofing a shaped article, for example, bends, tees, transitions, including installing it in a waterproofing shell, sealing the shell and applying a heat-insulating composition to the pipe, foaming and curing it, characterized in that the polyethylene sheath is preliminarily made by extruding the dried polyethylene granules low pressure pipe grades, and when extruding the inner surface of the polyethylene sheath is treated with an electric spark discharge with a capacity of 28000 V, and the outer surface of the shaped steel pipe - with a shot blasting machine to obtain the necessary roughness, after cooling, the polyethylene pipe formed in the extruder is cut into billets, a heat-insulating composition is prepared - polyurethane foam by mixing in the tank of the filling machine liquid components - polyol and polyisocyanate in a ratio of 1: 1.57 ÷ 1.63 at a temperature of 16-24 ° C, calculate the mass of the composition according to the formula:

where P is the estimated mass of the composition of the polyurethane foam; V is the annular volume; j is the estimated apparent density of the polyurethane foam in the structure; K is the coefficient of excess foam, determined experimentally and depending on the thickness of the insulating layer deviated from the set heating temperature of steel pipes and shells, is taken equal to 1.02 to 1.2 at the level of development of production, the calculated weight of the composition determines the duration of pouring into the insulated volume

where τ is the casting time, s; P is the estimated mass of the composition, kg; Q - installed capacity of the filling machine, kg / min, shaped shells are cut from polyethylene pipes, fragments of which are fed to the finished steel shaped piece, under the polyethylene shell of the shaped piece is installed a three-conductor indicator of the system for operational remote monitoring of the insulation state, which are parallel to the pipe axis in the plane of the same diameter and corresponding to the 3, 9, and 12 o’clock position of the dial, fragments of the shell are welded using butt mirrors or using manual extras Udera, the joints are filled with molten polyethylene, after welding, the entire pipe structure is heated in the furnace to 28 ° C, end caps are installed, the polyurethane composition is poured into the annulus through the hole, after foaming the composition is cured for 10-15 minutes, the plugs are removed, and the ends of the heat-insulating compositions are coated with waterproofing material.