Threaded pipe air preheater is one of the boiler heating surface at the rear, its function has three: to a certain way of boiler burning or fuel to air temperature to a certain extent, to meet the combustion air temperature, air preheater; 2 some boiler heating medium temperature is higher, not reduce heating medium by the surface outlet smoke temperature, to improve the efficiency of the boiler or to make, it is not blocking the advantages of gray, afraid of wear, corrosion on boiler applications, after optimization of heat transfer and flow resistance, a thread of smoke tube heat transfer is equivalent to 1.7-1.8 - the root of the same size of ordinary smoke tube. This not only make the pipe number decreased significantly, but also can reduce the diameter of the pot shell, therefore, pressure parts of steel consumption significantly reduced, saving steel, reduce the cost. Threaded ? seamless tube in air conditioning system