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Hex Cap Screw ASME B18.2.1

ASME B18.2.1 (Current)

Material
Carbon Steel
Property Class
Grade 5, Grade 8
Finish
Zinc Plated, Blackened, Plain
Size range
1/4-20UNC–7/8-9UNC
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Select sizes and quantities — 147 confirmed sizes to ASME B18.2.1

Material
Grade
Finish
dNominal Diameter (in)lLength (in)sWidth Across Flats (max) (in)eWidth Across Corners (min) (in)kNominal Head Height (in)dBasic Major Diameter (in)MOQQuantity and inquiry
1/4-20 UNC0.50.4380.4880.1630.251000
1/4-20 UNC0.6250.4380.4880.1630.251000
1/4-20 UNC0.750.4380.4880.1630.251000
1/4-20 UNC0.8750.4380.4880.1630.251000
1/4-20 UNC10.4380.4880.1630.251000
1/4-20 UNC1.1250.4380.4880.1630.251000
1/4-20 UNC1.250.4380.4880.1630.251000
1/4-20 UNC1.3750.4380.4880.1630.251000
1/4-20 UNC1.50.4380.4880.1630.251000
1/4-20 UNC1.750.4380.4880.1630.251000
1/4-20 UNC20.4380.4880.1630.251000
1/4-20 UNC2.250.4380.4880.1630.251000
1/4-20 UNC2.50.4380.4880.1630.251000
1/4-20 UNC2.750.4380.4880.1630.251000
1/4-20 UNC30.4380.4880.1630.251000
1/4-20 UNC3.250.4380.4880.1630.251000

Showing 16 of 147 sizes

1/4-20 UNC × 0.5 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)0.5
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 0.625 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)0.625
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 0.75 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)0.75
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 0.875 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)0.875
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)1
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1.125 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)1.125
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1.25 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)1.25
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1.375 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)1.375
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1.5 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)1.5
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1.75 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)1.75
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 2 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)2
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 2.25 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)2.25
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 2.5 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)2.5
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 2.75 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)2.75
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 3 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)3
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 3.25 × 0.438 × 0.488 × 0.163 × 0.25 × 20 × UNC × 2A × 0.25 × 0.245 × 0.428 × 0.505 × 0.15 × 0.106 × 0.75 × 1

dNominal Diameter (in)1/4-20 UNC
lLength (in)3.25
sWidth Across Flats (max) (in)0.438
eWidth Across Corners (min) (in)0.488
kNominal Head Height (in)0.163
dBasic Major Diameter (in)0.25
MOQ1000

Product details

Description
Hex cap screw manufactured to ASME B18.2.1 with a hexagon head and partially threaded shank. The thread is UNC class 2A, and the unthreaded body length depends on the nominal diameter. Available in carbon steel, Grade 5 or Grade 8, with zinc plated, blackened, or plain finish. Diameters from 1/4-20 UNC to 1-8 UNC are listed. For quotation, specify diameter, thread series, length, grade, and finish.
Features
Hexagon head for standard spanners and sockets · Partially threaded shank with plain bearing section under the head · UNC thread class 2A · Available in diameters 1/4-20 UNC through 1-8 UNC
Applications
Shear-loaded joints where a plain shank is required, Steel structure connections, Machinery and equipment assembly, Maintenance and repair work

Order assurance

Confirmed for the quoted product and order.

Reports & inspection

Agreed in the quotation.

  • EN 10204 3.1 material certificate
  • Dimensional inspection report
  • Certificate of conformity
  • Mechanical test report
  • Chemical analysis report
  • Coating inspection report
  • Batch and lot traceability

Packaging & delivery

Options we supply.

  • Bulk carton packing
  • Small boxes with outer cartons
  • Palletized shipment
  • Fumigation-free pallets
  • Inner poly bags
  • Buyer branding and labels

Product questions

What sizes of Hex Cap Screw ASME B18.2.1 do you supply?

Execution standard: ASME B18.2.1. The confirmed specification table covers 1–7 diameters and 0.5–5.5 lengths. Use the specification table to select the exact variant required for quotation.

Which materials, grades and finishes can I order?

Material: Carbon Steel; Property class: Grade 5, Grade 8; Finish: Zinc Plated, Blackened, Plain. Availability should be confirmed against the selected specification and order quantity.

Where are these hex bolts typically used?

Typical applications include Shear-loaded joints where a plain shank is required, Steel structure connections, Machinery and equipment assembly, Maintenance and repair work. Final suitability depends on the selected material, grade, finish and operating conditions.

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