METHOD FOR PRODUCING ZINC PLATED WATER AND GAS PIPELINES Russian patent published in 2008 - IPC B21C37/09 

FIELD: rolled tube production.

SUBSTANCE: method comprises steps of producing tubes of carbon steels by shaping and high-frequency welding of coiled sheet strips whose width depends upon diameter of welded tubes at coating metal surface with zinc layer. Strips surfaces before shaping and welding are coated with zinc layer, then edges of strips are trimmed according to their thickness by width value determined with use of expression: hj = hm in(Smax + Sj)/Smax where hmin =3.0 -minimum width of trimmed edge of zinc plated coiled sheet strips with wall thickness 1.8 mm, mm; hj - real value of width of trimmed edge of zinc plated coiled sheet strips, mm; Smax = 5.5 - maximum thickness of coiled sheet strips, mm. Zinc plating on outer and inner seams of tubes after removing fins is not performed. In order to make tubes, coiled sheet strips with thickness of zinc coating in range 30 -60 micrometers are used. Absence of swelling, flowing zones, of non-uniform coating along length provides lowered zinc consumption.

EFFECT: improved quality of outer and inner surfaces of tubes, increased efficiency of plants for continuous zinc plating of sheet strips, lowered cost of process and ready products.

5 cl, 1 tbl