HH type finned tubes are also called rectangular finned tubes. HH type finned tubes is special H type finned tube, which have double tubes. The HH-shaped finned tube is to weld two steel sheets with a circular arc in the middle symmetrically with the light tube to form fins. The front of the fin is shaped like double "H", so it is called HH-type finned tube. HH-type finned tubes have great effects to recover the waste heat of exhaust gas from power station boilers, industrial boilers, industrial kilns, ship power plants, etc.