Hex Flange 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–7/16-14UNC
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Select sizes and quantities — 93 confirmed sizes to ASME B18.2.1
Material
Grade
Finish
| dNominal Diameter (in) | lLength (in) | sWidth Across Flats (max) (in) | kNominal Head Height (in) | dBasic Major Diameter (in) | TPIThreads Per Inch | MOQ | Quantity and inquiry |
|---|---|---|---|---|---|---|---|
| 5/16-18 UNC | 1.25 | 0.5 | 0.32 | 0.3125 | 18 | 1000 | |
| 5/16-18 UNC | 1.375 | 0.5 | 0.32 | 0.3125 | 18 | 1000 | |
| 5/16-18 UNC | 1.5 | 0.5 | 0.32 | 0.3125 | 18 | 1000 | |
| 5/16-18 UNC | 1.75 | 0.5 | 0.32 | 0.3125 | 18 | 1000 | |
| 5/16-18 UNC | 2 | 0.5 | 0.32 | 0.3125 | 18 | 1000 | |
| 5/16-18 UNC | 2.25 | 0.5 | 0.32 | 0.3125 | 18 | 1000 | |
| 5/16-18 UNC | 2.5 | 0.5 | 0.32 | 0.3125 | 18 | 1000 | |
| 3/8-16 UNC | 0.75 | 0.5625 | 0.39 | 0.375 | 16 | 1000 | |
| 3/8-16 UNC | 0.875 | 0.5625 | 0.39 | 0.375 | 16 | 1000 | |
| 3/8-16 UNC | 1 | 0.5625 | 0.39 | 0.375 | 16 | 1000 | |
| 3/8-16 UNC | 1.125 | 0.5625 | 0.39 | 0.375 | 16 | 1000 | |
| 3/8-16 UNC | 1.25 | 0.5625 | 0.39 | 0.375 | 16 | 1000 | |
| 3/8-16 UNC | 1.375 | 0.5625 | 0.39 | 0.375 | 16 | 1000 | |
| 3/8-16 UNC | 1.5 | 0.5625 | 0.39 | 0.375 | 16 | 1000 | |
| 3/8-16 UNC | 1.75 | 0.5625 | 0.39 | 0.375 | 16 | 1000 | |
| 3/8-16 UNC | 2 | 0.5625 | 0.39 | 0.375 | 16 | 1000 |
Showing 16 of 93 sizes
dNominal Diameter (in)5/16-18 UNC
lLength (in)1.25
sWidth Across Flats (max) (in)0.5
kNominal Head Height (in)0.32
dBasic Major Diameter (in)0.3125
TPIThreads Per Inch18
MOQ1000
5/16-18 UNC × 1.375 × 0.5 × 0.32 × 0.3125 × 18 × UNC × 2A × 0.3125 × 0.3065 × 0.489 × 0.548 × 0.577 × 0.875 × 1.125
dNominal Diameter (in)5/16-18 UNC
lLength (in)1.375
sWidth Across Flats (max) (in)0.5
kNominal Head Height (in)0.32
dBasic Major Diameter (in)0.3125
TPIThreads Per Inch18
MOQ1000
5/16-18 UNC × 1.5 × 0.5 × 0.32 × 0.3125 × 18 × UNC × 2A × 0.3125 × 0.3065 × 0.489 × 0.548 × 0.577 × 0.875 × 1.125
dNominal Diameter (in)5/16-18 UNC
lLength (in)1.5
sWidth Across Flats (max) (in)0.5
kNominal Head Height (in)0.32
dBasic Major Diameter (in)0.3125
TPIThreads Per Inch18
MOQ1000
5/16-18 UNC × 1.75 × 0.5 × 0.32 × 0.3125 × 18 × UNC × 2A × 0.3125 × 0.3065 × 0.489 × 0.548 × 0.577 × 0.875 × 1.125
dNominal Diameter (in)5/16-18 UNC
lLength (in)1.75
sWidth Across Flats (max) (in)0.5
kNominal Head Height (in)0.32
dBasic Major Diameter (in)0.3125
TPIThreads Per Inch18
MOQ1000
5/16-18 UNC × 2 × 0.5 × 0.32 × 0.3125 × 18 × UNC × 2A × 0.3125 × 0.3065 × 0.489 × 0.548 × 0.577 × 0.875 × 1.125
dNominal Diameter (in)5/16-18 UNC
lLength (in)2
sWidth Across Flats (max) (in)0.5
kNominal Head Height (in)0.32
dBasic Major Diameter (in)0.3125
TPIThreads Per Inch18
MOQ1000
5/16-18 UNC × 2.25 × 0.5 × 0.32 × 0.3125 × 18 × UNC × 2A × 0.3125 × 0.3065 × 0.489 × 0.548 × 0.577 × 0.875 × 1.125
dNominal Diameter (in)5/16-18 UNC
lLength (in)2.25
sWidth Across Flats (max) (in)0.5
kNominal Head Height (in)0.32
dBasic Major Diameter (in)0.3125
TPIThreads Per Inch18
MOQ1000
5/16-18 UNC × 2.5 × 0.5 × 0.32 × 0.3125 × 18 × UNC × 2A × 0.3125 × 0.3065 × 0.489 × 0.548 × 0.577 × 0.875 × 1.125
dNominal Diameter (in)5/16-18 UNC
lLength (in)2.5
sWidth Across Flats (max) (in)0.5
kNominal Head Height (in)0.32
dBasic Major Diameter (in)0.3125
TPIThreads Per Inch18
MOQ1000
3/8-16 UNC × 0.75 × 0.5625 × 0.39 × 0.375 × 16 × UNC × 2A × 0.375 × 0.369 × 0.551 × 0.618 × 0.65 × 1 × 1.25
dNominal Diameter (in)3/8-16 UNC
lLength (in)0.75
sWidth Across Flats (max) (in)0.5625
kNominal Head Height (in)0.39
dBasic Major Diameter (in)0.375
TPIThreads Per Inch16
MOQ1000
3/8-16 UNC × 0.875 × 0.5625 × 0.39 × 0.375 × 16 × UNC × 2A × 0.375 × 0.369 × 0.551 × 0.618 × 0.65 × 1 × 1.25
dNominal Diameter (in)3/8-16 UNC
lLength (in)0.875
sWidth Across Flats (max) (in)0.5625
kNominal Head Height (in)0.39
dBasic Major Diameter (in)0.375
TPIThreads Per Inch16
MOQ1000
3/8-16 UNC × 1 × 0.5625 × 0.39 × 0.375 × 16 × UNC × 2A × 0.375 × 0.369 × 0.551 × 0.618 × 0.65 × 1 × 1.25
dNominal Diameter (in)3/8-16 UNC
lLength (in)1
sWidth Across Flats (max) (in)0.5625
kNominal Head Height (in)0.39
dBasic Major Diameter (in)0.375
TPIThreads Per Inch16
MOQ1000
3/8-16 UNC × 1.125 × 0.5625 × 0.39 × 0.375 × 16 × UNC × 2A × 0.375 × 0.369 × 0.551 × 0.618 × 0.65 × 1 × 1.25
dNominal Diameter (in)3/8-16 UNC
lLength (in)1.125
sWidth Across Flats (max) (in)0.5625
kNominal Head Height (in)0.39
dBasic Major Diameter (in)0.375
TPIThreads Per Inch16
MOQ1000
3/8-16 UNC × 1.25 × 0.5625 × 0.39 × 0.375 × 16 × UNC × 2A × 0.375 × 0.369 × 0.551 × 0.618 × 0.65 × 1 × 1.25
dNominal Diameter (in)3/8-16 UNC
lLength (in)1.25
sWidth Across Flats (max) (in)0.5625
kNominal Head Height (in)0.39
dBasic Major Diameter (in)0.375
TPIThreads Per Inch16
MOQ1000
3/8-16 UNC × 1.375 × 0.5625 × 0.39 × 0.375 × 16 × UNC × 2A × 0.375 × 0.369 × 0.551 × 0.618 × 0.65 × 1 × 1.25
dNominal Diameter (in)3/8-16 UNC
lLength (in)1.375
sWidth Across Flats (max) (in)0.5625
kNominal Head Height (in)0.39
dBasic Major Diameter (in)0.375
TPIThreads Per Inch16
MOQ1000
3/8-16 UNC × 1.5 × 0.5625 × 0.39 × 0.375 × 16 × UNC × 2A × 0.375 × 0.369 × 0.551 × 0.618 × 0.65 × 1 × 1.25
dNominal Diameter (in)3/8-16 UNC
lLength (in)1.5
sWidth Across Flats (max) (in)0.5625
kNominal Head Height (in)0.39
dBasic Major Diameter (in)0.375
TPIThreads Per Inch16
MOQ1000
3/8-16 UNC × 1.75 × 0.5625 × 0.39 × 0.375 × 16 × UNC × 2A × 0.375 × 0.369 × 0.551 × 0.618 × 0.65 × 1 × 1.25
dNominal Diameter (in)3/8-16 UNC
lLength (in)1.75
sWidth Across Flats (max) (in)0.5625
kNominal Head Height (in)0.39
dBasic Major Diameter (in)0.375
TPIThreads Per Inch16
MOQ1000
3/8-16 UNC × 2 × 0.5625 × 0.39 × 0.375 × 16 × UNC × 2A × 0.375 × 0.369 × 0.551 × 0.618 × 0.65 × 1 × 1.25
dNominal Diameter (in)3/8-16 UNC
lLength (in)2
sWidth Across Flats (max) (in)0.5625
kNominal Head Height (in)0.39
dBasic Major Diameter (in)0.375
TPIThreads Per Inch16
MOQ1000
Product details
- Description
- Hexagon head bolt with a flange face, manufactured to ASME B18.2.1. The thread is partial, leaving a plain shank under the head. Available in UNC diameters from 1/4-20 to 3/4-10, thread class 2A. Supply material is carbon steel in Grade 5 or Grade 8, with zinc plated, blackened, or plain finish. For quotation, specify diameter, length, grade, and finish.
- Features
- Integral flange under hex head provides wide bearing surface · Part-thread body with plain shank for shear applications · UNC thread series, class 2A · Available in diameters 1/4-20 UNC to 3/4-10 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 Flange Screw ASME B18.2.1 do you supply?
Execution standard: ASME B18.2.1. The confirmed specification table covers 1–7 diameters and 0.5–4.5 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 flange 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.







