Method for the manufacture of externally coated tube from steel strip and tube made by the method.

摘要

Externally coated steel tube is made from steel strip by longitudinally folding and welding the strip to form the tube (200), preheating (205) the tube and applying powder (206) to the exterior of the preheated tube. The tube is then baked at a higher temperature before cooling. In order to achieve an even and continuous coating when using thermosetting material as the coating powder, the temperature given to the tube by the preheating (205) is such as to cause the coating powder to melt and spread out immediately on application to form a substantially continuous coating, before substantial curing of the coating material occurs. Suitably, this is provided by passage of the tube through a box (207) which maintains the temperature of the tube.