Method of preparing a surface for welding

Claim 1

A MECHANICAL PROCESS FOR MAKING A TUBULAR ARTICLE FROM A BLANK OF TIN PLATED STEEL HAVING OPPOSITE MARGINAL SIDE SEAM FORMING EDGES COMPRISING: MOVING THE BLANK ALONG A PATH THROUGH GRINDING STATIONS AT A PREDETERMINED SPEED; ROTATING A PLURALITY OF FLAP WHEELS AT THE GRINDING STATIONS AT A ROTATIONAL SPEED THAT GIVES THE FLAP WHEELS A PERIPHERAL GRINDING SURFACE SPEED IN LINEAL FEET PER MINUTE IN THE NEIGHBORHOOD OF 8.8 TIMES THE SPEED OF THE BLANK IN LINEAL INCHES PER MINUTE; PROGRESSIVELY LIGHTLY CONTACTING THE SHEET ON OPPOSITE SIDES THEREOF ADJACENT THE OPPOSITE MARGINAL EDGES WITH A FLAP WHEEL GRINDING SURFACE TO SUBSTANTIALLY REMOVE ALL OF THE TIN PLATING AND ANY UNDERLYING OXIDES AND SMOOTH THE UNDERLYING STEEL TO PROVIDE SMOOTH STEEL WELDING SURFACES ADJACENT THE SIDE SEAM FORMING MARGINAL EDGES; FORMING THE BLANK INTO A TUBE SO THAT OPPOSED WELDING SURFACES ARE IN CLOSE OVERLAPPED RELATIONSHIP AND WELDING THE OVERLAPPED SURFACES TOGETHER.