Method for manufacturing high-strength X80 steel spiral welded pipe

The invention discloses a method for manufacturing a high-strength (X 80) steel spiral weld pipe. The weld pipe adopts a parent metal of X 80 rolled steel plate, and the chemical compositions of weld pipe are: 0.02 to 0.09 percent of C, 0.10 to 0.42 percent of Si, 1.50 to 1.85 percent of Mn, less than or equal to 0.022 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.45 percent of Cr, less than or equal to 0.50 percent of Ni, less than or equal to 0.30 percent of Cu, less than or equal to 0.35 percent of Mo, less than or equal to 0.025 percent of Ti, less than or equal to 0.11 percent of Nb, less than or equal to 0.06 percent of V, less than or equal to 0.06 percent of Al, less than or equal to 0.008 percent of N, less than or equal to 0.0005 percent of B, and less than or equal to 0.23 percent of Pcm. The manufacturing procedures includes: decoiling, leveling, edge milling, prebending, molding, internal welding, external welding, pipe end expending, hierarchical ultrasonic exam