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Step Bolt ASME B18.5

ASME B18.5 (Current)

Material
Carbon Steel
Property Class
Grade A
Finish
Zinc Plated, Plain
Size range
1/4-20UNC–7/16-14UNC
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Select sizes and quantities — 74 confirmed sizes to ASME B18.5

Material
Grade
Finish
dNominal Diameter (in)lLength (in)TPIThreads Per InchThread SeriesThread ClassdBasic Major Diameter (in)MOQQuantity and inquiry
1/4-20 UNC0.7520UNC2A0.251000
1/4-20 UNC0.87520UNC2A0.251000
1/4-20 UNC120UNC2A0.251000
1/4-20 UNC1.12520UNC2A0.251000
1/4-20 UNC1.2520UNC2A0.251000
1/4-20 UNC1.37520UNC2A0.251000
1/4-20 UNC1.520UNC2A0.251000
1/4-20 UNC1.7520UNC2A0.251000
1/4-20 UNC220UNC2A0.251000
1/4-20 UNC2.2520UNC2A0.251000
1/4-20 UNC2.520UNC2A0.251000
1/4-20 UNC2.7520UNC2A0.251000
1/4-20 UNC320UNC2A0.251000
1/4-20 UNC3.2520UNC2A0.251000
5/16-18 UNC118UNC2A0.31251000
5/16-18 UNC1.12518UNC2A0.31251000

Showing 16 of 74 sizes

1/4-20 UNC × 0.75 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)0.75
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 0.875 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)0.875
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)1
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1.125 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)1.125
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1.25 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)1.25
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1.375 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)1.375
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1.5 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)1.5
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 1.75 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)1.75
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 2 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)2
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 2.25 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)2.25
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 2.5 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)2.5
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 2.75 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)2.75
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 3 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)3
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

1/4-20 UNC × 3.25 × 20 × UNC × 2A × 0.25 × 0.26 × 0.237 × 0.844 × 0.813 × 0.145 × 0.125 × 0.26 × 0.245 × 0.156 × 0.125 × 0.031

dNominal Diameter (in)1/4-20 UNC
lLength (in)3.25
TPIThreads Per Inch20
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.25
MOQ1000

5/16-18 UNC × 1 × 18 × UNC × 2A × 0.3125 × 0.324 × 0.298 × 1.031 × 1 × 0.176 × 0.156 × 0.324 × 0.307 × 0.187 × 0.156 × 0.031

dNominal Diameter (in)5/16-18 UNC
lLength (in)1
TPIThreads Per Inch18
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.3125
MOQ1000

5/16-18 UNC × 1.125 × 18 × UNC × 2A × 0.3125 × 0.324 × 0.298 × 1.031 × 1 × 0.176 × 0.156 × 0.324 × 0.307 × 0.187 × 0.156 × 0.031

dNominal Diameter (in)5/16-18 UNC
lLength (in)1.125
TPIThreads Per Inch18
Thread SeriesUNC
Thread Class2A
dBasic Major Diameter (in)0.3125
MOQ1000

Product details

Description
Step bolt with round head and square neck, manufactured to ASME B18.5. The square neck engages the workpiece to resist rotation during assembly. Threads are UNC series, class 2A, with a reduced body diameter under the head. Available in carbon steel Grade A with zinc plated or plain finish. Diameters from 1/4-20 to 1/2-13 UNC. Specify diameter, length, finish, and quantity for quotation.
Features
Round head with square neck under the head · UNC threads, class 2A, full thread length to head · Carbon steel Grade A, zinc plated or plain finish · Diameters from 1/4-20 to 1/2-13 UNC
Applications
Climbing steps on utility and transmission poles, Guardrail and highway barrier assembly, Steel tower and lattice structure connections, Joints where a wide bearing head spreads load over soft or thin material

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 Step Bolt ASME B18.5 do you supply?

Execution standard: ASME B18.5. The confirmed specification table covers 1–7 diameters and 0.75–5.5 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 A; Finish: Zinc Plated, Plain. Availability should be confirmed against the selected specification and order quantity.

Where are these carriage bolts typically used?

Typical applications include Climbing steps on utility and transmission poles, Guardrail and highway barrier assembly, Steel tower and lattice structure connections, Joints where a wide bearing head spreads load over soft or thin material. Final suitability depends on the selected material, grade, finish and operating conditions.

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