Nut, Size: 3/4" UNRC, Heavy hex nuts shall be constructed of either Monel 400 (Class A) or Monel 405 (Class B), per ASTM F467, with a minimum proof strength of 70,000 psi (483 N/mm2), Nuts shall have machined threads (UNC) per ANSI B1.1, with Class 2B fit, and shall receive a Mechanical Property Marking of “F 467U” or “F 467V” in accordance with ASTM F468, along with a symbol identifying the manufacturer.