Abstract: Described in the article are the design and development of passes for the typical Φ475 mm× 45 mm tube size of the piercing mill, the mandrel pipe mill and the sizing (reducing) mill of the Φ460 mm PQF plant. Detailed are the design method as used for the Φ488 mm pass of the PQF mill proper, and the trial manufacture of pipes with the said pass. The actual operation result demonstrates that the design of the pass is reasonable, and pipes rolled with the pass are of good quality. Thanks to the successful development of the said pass, the maximum tube size of the Φ460 mm PQF plant has extended from the original Φ457 mm×57 mm to the Φ475 mm×57 mm.