Brazing spiral finned tube processing in two steps.
First, strip the plane perpendicular to the axis of the tube by spiral wound around the outer surface of the tube, and the ends of the strip welded on the pipe is fixed, then to eliminate the gap at the contact strip and pipe with brazing method The steel and steel pipe welded together. Because this method is expensive, it is commonly used another method soon wrapped around steel tube into the tank within an overall zinc galvanizing instead. Although the use of hot-dip galvanizing bath is not necessarily the overall well infiltrated small gap between fins and pipes, but on the outer surface of the fin and the outer surface of the pipe has formed a complete galvanized layer. Holistic galvanized spiral finned tube, because they were restricted galvanizing layer thickness (thickness galvanized zinc layer is firmly poor, easy to fall off), plus zinc solution can not penetrate inside the entire gap, therefore, the fins and a combination of steel was still not high. In addition, the heat transfer coefficient than steel zinc is small (about 78% of steel), and therefore low heat transfer capability. Zinc in acid and alkali, sulfide vulnerable to corrosion, and therefore unsuitable for galvanized spiral finned tube air preheater production (waste heat recovery boiler flue gas).