Smooth connection between flange and pipes The interior of the flange is welded in a circle and polished,NO welding slag. Sensor position not protrude inside surface of flange Flange thickness we used is 10mm,12mm and 15mm,the deformation coefficient of the flange surface within 0.5mm TWICE weld make sure the firmness and gilding surface,weld joint size less than 6mm Inside of pipe head polish 5cm,achieve better air flow and sound Exhaust bellows use crochet net transverse,reducing vibrate frequency Beautiful surface finish,polish or brush