Spiral seamed corrugated laminated pipe with uncorrugated interior

Claim 1

A LAMINATED PIPE COMPRISING A HELICALLY WOUND WEB FORMED THROUGHOUT OF A PLURALITY OF LAYERS OF FORMABLE SHEET MATERIAL, INCLUDING AN INNER LAYER EXTENDING CONTINUOUSLY IN A PLURALITY OF HELICAL TURNS TO FORM THE INTERIOR SURFACE OF THE PIPE, THE INNER LAYER HAVING SMOOTH, UNCORRUGATED INNER AND OUTER SURFACES BETWEEN ITS SIDE EDGES; AND A CORRUGATED OUTER LAYER EXTENDING IN A PLURALITY OF HELICAL TURNS AROUND THE INNER LAYER TO FORM THE EXTERIOR SURFACE OF THE PIPE, THE OUTER LAYER HAVING ALTERNATING HILLS AND VALLEYS EXTENDING HELICALLY OF THE PIPE; EACH TURN OF THE INNER AND OUTER LAYERS BEING SECURED TOGETHER ALONG THEIR EDGES IN A SINGLE HELICALLY EXTENDING SEAM, SAID SEAM SECURING ONE EDGE OF EACH TURN OF WEB TO THE OPPOSITE EDGE OF THE ADJACENT TURN OF WEB, THE JUNCTION OF SUCCESSIVE TURNS OF THE INNER LAYER IN THE SEAM EXTENDING ALONG A VALLEY OF THE OUTER LAYER, A PLURALITY OF VALLEYS OF THE OUTER LAYER SUPPORTING THE INNER LAYER AROUND THE PIPE BETWEEN SUCCESSIVE TURNS OF THE SEAM, WHEREBY THE JOINED SMOOTH INNER LAYER TURNS EXTEND CONTINUOUSLY CIRCULARLY AND LONGITUDINALLY OF THE PIPE AND ARE SUPPORTED AND STRENGTHENED BY THE OUTER LAYER TURNS.