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Applicable to screw types as indicated by code symbols.
  • Type A thread forming, except for short lengths.
Unit of Measure

Manufacturer

Manufacturer

N/A Industrial Fasteners Institute

Specifications

Product

N/A Tapping Screws

Unit of Measure

N/A English

Nominal Size or Basic Screw Dia.

N/A No. 20

Nominal Size or Basic Screw Dia. (Decimal)

N/A 0.3200 in
Applicable to Screw Types1 N/A 2

Max. Width Across Flats (A)

N/A 0.500 in

Min. Width Across Flats (A)

N/A 0.489 in

Min. Width Across Corners (W)

N/A 0.545 in

Max. Head Height (H)

N/A 0.230 in

Min. Head Height (H)

N/A 0.208 in

Max. Washer Dia. (B)

N/A 0.676 in

Min. Washer Dia. (B)

N/A 0.624 in

Max. Washer Thickness (U)

N/A 0.055 in

Min. Washer Thickness (U)

N/A 0.035 in

Min. Protrusion Beyond Gaging Ring (F)

N/A 0.125 in

Codes and Standards

Codes and Standards

N/A Abstract of ASME B18.6.4 1998
  • 1 1 = Circle, 2 = Diamond, 3 = Triangle, 4 = Square