| 摘要 |
Pipes used for carrying hot fluids such as steam and process liquids and gases, often above 212 DEG F., and pipes for carrying cold fluids such as for refrigeration and air conditioning systems, are usually insulated where they extend for any appreciable distance in areas of different temperatures, for reducing heat transfers. Such pipes are used in central heating and cooling distribution systems for cities, schools, universities, prisons, military bases, in industrial processing plants, and the like, whether installed above ground or underground. Polyisocyanurate and similar foamed insulation materials including polyurethane are better insulators than those now commonly used, such as foamglass, fiberglass, mineral wool, and calcium silicate; polyisocyanurate has a very low K factor and is stable at up to 400 DEG F. for sustained temperatures and up to 450 DEG F. peak temperatures. Foaming the polyisocyanurate about the pipe and within a thin, waterproof sleeve provides a well insulated pipe that is protected from water. Support members are applied to the thin waterproof sleeve and are spaced apart in an outer conduit to provide an air space so the pipe and sleeve can expand and contract within that conduit. This system provides a long-lived, highly efficient, insulated pipe wherein the chances of the insulation breaking down in the presence of water within the conduit or under thermal movement stresses is reduced to virtually nil. Vents and drains in the outer conduit as assembled allow for testing the integrity of the system and for purging the conduit of ground water and water vapor that may enter the conduit, as upon floods, high water tables, cooling and condensation, and the like.
|
