US 5,474,227 A · Method of forming seamed metal tube

Abstract

The method of forming a coated seamed metal tube of this invention is particularly, but not exclusively adapted to existing continuous tube forming mills, wherein the tube is formed from a metal strip and welded with the seam located in an upper portion of the tube. In the process of this invention, at least one surface of the strip is coated with a metal coating prior to forming and welding. The tube is then turned to relocate the welded seam in a lower portion of the tube and the lower portion of the tube is then reheated to melt the metal coating and the metal coating then flows downwardly over and coating the welded seam. In the most preferred continuous or in line process of this invention, the tube is continuously spirally twisted following welding to locate the seam in a lower portion of the tube adjacent a heater and the tube is then heated by the heater to the melting temperature of the metal coating, causing the coating to coat the seam.

Claims14

Dependent claims

A method of forming a seamed metal tube having a metal coating from a metal strip, comprising the following steps, performed in sequence:

a) coating at least one surface of said strip with a metal coating having a melting temperature substantially below the melting temperature of said strip;
b) forming said strip into a tube-shaped strip having opposed adjacent spaced lateral edges and said coating on an inner surface of said tube-shaped strip;
c) heating and integrally welding said adjacent edges of said strip to form a tube having a welded seam and locating said welded seam in a lower portion of said tube;
and
d) reheating at least said lower portion of said tube to the melting temperature of said coating, said coating then flowing downwardly over and coating said seam.

2 more elements

Dependencies are inferred from the claim text.

Method of forming seamed metal tube

Life of this patent

Method of forming seamed metal tube

Life of this patent

Abstract

Claims14