In general, according to common practice, they may be classified as follows: 1. By temperature of the conveyed medium: ambient-temperature PU foam direct-buried insulated pipe, high-temperature PU foam direct-buried insulated pipe, and cryogenic PU foam direct-buried insulated pipe; 2. By outer jacket: FRP-jacketed PU foam direct-buried insulated pipe, HDPE-jacketed PU foam direct-buried insulated pipe, steel-jacketed PU foam direct-buried insulated pipe, and other jacketed direct-buried insulated pipes. 3. By conveyed medium, there are many types, such as PU prefabricated insulated pipe for water supply and high-temperature PU foam direct-buried insulated pipe.
Direct-buried insulated pipe, also known as “pipe-in-pipe,” is produced by a “two-step method” and consists of an HDPE outer jacket, rigid PU foam insulation, and a steel pipe. The insulation material is rigid PU foam with a density of 60 kg/m3 to 80 kg/m3, fully filling the gap between the steel pipe and the casing and providing a certain bonding strength so that the steel pipe, outer casing, and insulation layer form a firm composite. By common practice they are classified as follows. By laying method: direct-buried PU insulated pipe and overhead PU insulated pipe. By temperature of the conveyed medium: ambient-temperature PU insulated pipe, high-temperature PU insulated pipe, and cryogenic PU insulated pipe. By outer jacket: FRP-jacketed PU insulated pipe, HDPE-jacketed PU insulated pipe, steel-jacketed PU insulated pipe, and other jacketed insulated pipes. By conveyed medium there are many types, such as prefabricated PU insulated pipe for water supply, high-temperature-resistant PU insulated pipe, steam direct-buried PU composite prefabricated insulated pipe for steam conveyance, and buried rigid PU foam anti-corrosion insulated pipe for petroleum applications.
Extending the service life of the steel pipe. 2. Outer jacket steel pipe: protects the insulation from groundwater attack, supports the carrier pipe of the buried steel-in-steel insulated pipeline, and can bear a certain external load to ensure normal operation of the carrier pipe. Jiamusi buried steel-in-steel insulated pipe manufacturer contact; quality supplier of buried steel-in-steel insulated pipe; where to find buried steel-in-steel insulated pipe. 3. PU foam layer: maintains the medium temperature and keeps the outer-jacket surface at ambient temperature. 4. Barrier and reflective layer: keeps organic foam from entering the inorganic high-temperature-resistant layer, and reflects part of the heat from the high-temperature-resistant layer.
Composition of direct-buried insulated pipe from Cangzhou Cangkai Pipeline Co., Ltd.: carrier pipe: seamed steel pipe, seamless steel pipe, or Cangkai double-sided submerged-arc spiral-welded pipe may be used according to the conveyed medium. Insulation layer: rigid PU foam. Protective jacket: HDPE or FRP. The use of direct-buried district-heating pipeline technology in prefabricated direct-buried insulated pipe marks a new starting point in the development of China's heating-pipeline technology.
