Full channel expansion joint, no welding defects and dirt. All use internal polishing tube, according to the special requirements, electric polishing tube can be provided. The suitable bending process being put to use for all elbow, to ensure that the surface of the elbow crack, peeling, lamination and other defects. All straight sections are subject to an endoscopic inspection to ensure internal surface finish. According to the customized process Austar finish the acid cleaning and passivation work, according to customer requirements can also provide steam cleaning services, can be more in-depth removal of dirt. The structure design and installation Angle of heat exchanger have considered the necessity of complete exhaust.