Flow coat galvanizing
AssigneeAllied Tube & Conduit Corporation
InventorsCarl H. Unger, Kalyan K. Maitra
Life of this patent
Estimating the term…
Abstract
This continuous galvanizing method and apparatus passes a linear element to be galvanized, e.g., wire, rod, or tube, through a surrounding, relatively short length of conduit which is attached as a cross-tee to the end of a delivery pipe rising from a centrifugal pump submerged in a vat of molten zinc, and continuously flooded with liquid zinc to coat the linear element. The zinc flowing from the open ends of the conduit, and falling as excess from the element being coated, drops back into the vat for recirculation. The vat is covered to provide a substantially closed operating space above the pool of molten zinc to enable the coating to take place in an inert atmosphere.
Claims20
In a continuous process for galvanizing linear elements, an improved method of applying molten zinc to a cleansed and preheated linear element to be galvanized comprising:
- passing the linear element axially through a horizontal open-ended tube having ends of interior cross-sectional area at least as great as any other interior cross-section of said tube and interior cross-sectional dimensions greater than the exterior cross-sectional dimensions of said linear element so as to provide a clearance space between said linear element and the interior walls of said tube;
- coating the linear element with molten zinc by pumping molten zinc in a continuous stream directly into the underside of said open-ended tube intermediate its ends from a pool of molten zinc beneath said open-ended tube at a rate sufficient to immerse the linear element in flowing molten zinc as it passes through said open-ended tube and to overflow from the ends of the tube and at a rate sufficient to flood the space between said linear element and the interior walls of said tube for at least a portion of the length of said tube;
- and
- collecting by gravity the zinc flowing from the ends of said open-ended tube and dripping from the coated linear element.
In a continuous process for galvanizing metal conduit having an outer surface, a method of applying molten zinc to a cleansed and preheated metal conduit to be galvanized comprising:
- rolling a band of metal into tubular form with abutting edges;
- welding the abutting edges to form said conduit;
- cleaning said conduit with acid;
- rinsing said conduit;
- preheating said conduit in an inert atmosphere;
- providing a source of molten zinc;
- providing an inert gaseous environment over said source;
- passing said conduit through an application zone in an inert atmosphere;
- and
- pumping a stream of molten zinc from said source around said conduit so that each point on said conduit's outer surface makes contact with said stream for 0.167 second or less, whereby said conduit is coated with molten zinc and is galvanized.
A method of galvanizing a linear element composed of a ferrous metal by means of a pump, said method comprising:
- providing an upwardly open reservoir of molten zinc;
- maintaining an atmosphere of inert gas within an enclosed space above the surface of the molten zinc in said reservoir;
- heating the linear element to be galvanized to a temperature at least as great as that of the molten zinc;
- driving said heated linear element axially through an application zone located above said surface in said enclosed space;
- pumping under pressure a stream of said molten zinc from said reservoir to a position at one side of said linear element adjacent said application zone, said stream having a delivery rate determined at least in part by the speed of said pump;
- projecting said stream under pressure from said pump from said position through said application zone around the entire circumference of said linear element in quantity exceeding that which will adhere to said linear element, said stream requiring no heating to remain molten from the time of departure from said reservoir to the time of return to said reservoir;
- adjusting said delivery rate of said stream projected under pressure from said pump through said application zone:
- and
- allowing the excess and unadhered molten zinc to fall from said linear element onto the surface of the molten zinc in said reservoir, whereby said linear element is coated with zinc without requiring heating of said stream in said inert atmosphere and said excess and said unadhered molten zinc is returned to said reservoir.
A method, as claimed in 15, wherein the flow rate of the zinc pumped into said open-ended tube is adjustable to flooding requirements of linear elements of different cross-sectional size.
Dependencies are inferred from the claim text.