A Thin Walled Double Pipe. It is a pipe within a pipe, or encased in an outer covering, with an annulus (interstitial space) between the two diameters. They're carefully and dependably built by today's most respected manufacturers, and priced to bring you incredible value.
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Packaged with an outer pipe of carbon steel are used. Its inner material is made of stainless steel and the outer material is made of black steel wall. The diameter of the tube is 13 cm and its length is 60 m. It is proposed to insulate this section of the furnace wall with glass wool insulation (k = 0.038 w/m·k) in order to reduce the heat loss by 90 percent, assuming the outer surface temperature of the metal section still remains at about 110°c, determine the thickness of the insulation that needs to be used.