Name: Structural Nuts
A194 Grade 2H & A563 Grade DH; For Use with Structural Bolts & Washers.
Descriptions: A six-sided internally threaded fastener which is both thicker and wider across the flats than a same-sized finished hex nut. Nuts in sizes 7/16 and smaller shall be double chamfered. Larger sizes are either double chamfered or chamfered on top with a washer faced bearing surface.
Applications: This is the strongest of all comparably-graded nuts because of its greater length of thread engagement and greater resistance to dilation (widening or stretching). Grade-A nuts are used with low-carbon heavy hex bolts. Grade-C nuts are recommended for use with A-325 structural bolts. Grade-2H nuts are recommended for use with bolts in high-pressure and high-temperature service. Grade-DH nuts are recommended for use with A-490, Type-1 structural bolts and Grade-DH3 nuts for use with A-490, Type-3 structural bolts.
Material: Nuts shall be made from a steel which conforms to the following chemical composition requirements (heat analysis)--Grades-A & C-- Carbon: 0.55% maximum; Phosphorus: 0.12% maximum; Sulfur: 0.023% maximum.
A 194 Grade-2H-- Carbon: 0.40% minimum; Manganese: 1.00% maximum; Phosphorus: 0.04% maximum; Sulfur: 0.05% maximum; Silicon: 0.40% maximum.
A 563 Grade-DH-- Carbon: 0.20-0.55%; Manganese: 0.60% minimum; Phosphorus: 0.04% maximum; Sulfur: 0.05% maximum. Grade-DH3-- Carbon: 0.20-0.53%; Manganese: 0.40% minimum; Phosphorus: 0.046% maximum; Sulfur: 0.050% maximum;
Copper: 0.20% minimum; Chromium: 0.45% minimum; (Either Nickel: 0.20% minimum or Molybdenum: 0.15% minimum, may be used)