Yes. Both ANSI/AWWA C150/A21.50 and ANSI/AWWA C151/A21.51 state that Ductile Iron pipe is available for water working pressure greater than 350 psi. These standards also list Pressure Class and Special Thickness Class Ductile Iron pipe. The Pressure Class designations (150 psi to 350 psi) in the standards are based on a 2.0 safety factor times the sum of working pressure and 100 psi allowance of surge. This establishes a net thickness to which a service allowance of 0.08-inch and a casting tolerance (which is dependent on the diameter of the pipe) is added. Based on the same design criteria, 6-inch Special Thickness Class 56 Ductile Iron pipe would be rated at 1,726 psi internal working pressure. Special Thickness Classes of Ductile Iron pipe are normally specified only because of high external loads due to deep bury, high dynamic loading, etc.; however, Special Thickness Class Ductile Iron pipe has also been specified and installed in systems with working pressures greater than 1,000 psi. For information and limitations, contact the manufacturers of Ductile Iron pipe.