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Bolts · ASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1

ASME B18.31.3 Inch Fully Threaded Rod, ASTM A193 B7 Specification

Dimensional table, tolerance classes and the DIN / ISO / ASME parts that supersede or match this standard.

ASME B18.31.3 specifies the dimensions and tolerances for inch fully threaded rod, astm a193 b7. The full dimensional table is reproduced below, followed by the DIN, ISO and ASME parts that match or supersede it.

Standard
ASME B18.31.3
Product
Inch Fully Threaded Rod, ASTM A193 B7
Governing standards
ASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1

Equivalence between national standards is dimensional, not always metallurgical. Check the property class separately when substituting.

ASME B18.31.3 Inch Fully Threaded Rod, ASTM A193 B7 Specification reference image

ASME B18.31.3 covers the dimensional requirements for inch fully threaded rod, astm a193 b7. Reproduced below: the complete size table, the tolerance grades, and the companion and equivalent standards referenced when ordering to this document.

ASME B18.31.3 — Scope

ASME B18.31.3 specifies the dimensions and tolerances of inch fully threaded rod, astm a193 b7. Material, property class, surface finish and packaging are governed by separate documents in the same standards family (for example ISO 898-1 for the mechanical property classes of bolts and screws).

Tolerance & Product Grades

ASME B18.31.3, alongside the related ASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1 entries on this site, specifies product grades (typically A or B for fine work and C for general engineering) and tolerance classes for the controlling dimensions. Choose the grade against the precision your application requires.

Dimensions Specified by ASME B18.31.3

Nominal sizeThread seriesStandard lengths (ft)Minimum tensile (ksi)Minimum yield (ksi)Elongation minimum (%)Finish optionsReference standard
1/4-20UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1
3/8-16UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1
1/2-13UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1
3/4-10UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1
1-8UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1
1-1/4-7UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1

Equivalent Standards

Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Inch Fully Threaded Rod, ASTM A193 B7 page. Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.

Companion Standards

ASME B18.31.3 controls only the geometry of inch fully threaded rod, astm a193 b7. The mechanical strength is set by ISO 898-1 (bolts and screws) or ISO 898-2 (nuts); the surface finish is governed by separate finish standards (e.g. ISO 4042 for electroplating). For corrosion testing, the relevant document is ISO 9227 (neutral salt spray).

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Sends the selected values to the quote form below.

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Specification
Business Information

Dimensions & Specifications (ASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1)

Nominal sizeThread seriesStandard lengths (ft)Minimum tensile (ksi)Minimum yield (ksi)Elongation minimum (%)Finish optionsReference standard
1/4-20UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1
3/8-16UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1
1/2-13UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1
3/4-10UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1
1-8UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1
1-1/4-7UNC / optional UNF or 8UN3 / 6 / 1212510516plain / yellow-zinc / black-oxide / hot-dip-galvanizedASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1

Applications & Industries

The sectors that buy Inch Fully Threaded Rod to ASTM A193 Grade B7; ASME B18.31.3 and ASME B1.1, and the duty each one buys them for. Stocked from 1/4-20 to 1-1/4-7 (screw size).

Industries that specify Inch Fully Threaded Rod

  • Refinery maintenance Bolting packages exposed to heat, pressure and hydrocarbon service.
  • Power generation Large flanged joints and equipment supports using inch specifications.
  • Structural plant Tie rods and hold-down assemblies requiring ASTM A193 Grade B7 material.
  • Pressure vessels High-strength threaded rod and studs in flanged pressure equipment.
  • Plant & machine installation Anchoring and levelling machines onto bases and frames.
  • Steel fabrication Hanger rods, tie rods and made-to-length threaded assemblies.

Typical applications

  • assembling flanged joints where a full-length thread is required
  • selecting ASTM A193 Grade B7 strength and a compatible finish
  • cutting standard 3, 6 or 12 ft stock to the required stud length
  • providing a high-strength inch threaded member for nuts at both ends
  • made-to-length assemblies cut and threaded on site
  • clamping a joint from both ends where a headed bolt will not fit

Service conditions to specify against

Marine and coastal
Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
High load
Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
Exterior structural
Hot-dip galvanised options for external steelwork; allow for the thicker coating in the mating thread.

Where to use something else

  • Do not mix coatings and nut materials without checking thread compatibility and service temperature.
  • Not for a joint that must be tightened from one side only — there is no head to hold.

Full application guide: where Inch Fully Threaded Rod are used, how to specify them, and the cases they are wrong for

Inside the plant

Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

  1. Wire rod feeding into a cold heading machine
    01

    Cold heading

    Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.

    Head dimensions and under-head radius checked at set-up and per shift.

  2. Thread rolling machine producing bolt threads
    02

    Thread rolling

    Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.

    Go / no-go ring gauges to ISO 965 tolerance class 6g.

  3. Baskets of bolts staged for heat treatment
    03

    Heat treatment

    Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.

    Core hardness and tensile tested per lot to ISO 898-1.

  4. Zinc plated bolts in a treatment basket
    04

    Surface treatment

    Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.

    Coating thickness and neutral salt spray hours to ISO 9227.

Frequently Asked Questions

Which edition of ASME B18.31.3 does this table follow?

The table reproduces the dimensions we supply inch fully threaded rod, astm a193 b7 to. We do not publish an edition year against it, so where the edition is contractually significant, cite the edition you require on the enquiry and we will confirm it against the table before quoting.

What does ASME B18.31.3 specify for Inch Fully Threaded Rod, ASTM A193 B7?

ASME B18.31.3 specifies the dimensions and tolerances of inch fully threaded rod, astm a193 b7. Material and property class are governed by separate standards in the same family.

What product grades does ASME B18.31.3 define?

ASME B18.31.3 typically distinguishes product grades for precision (A/B) and general engineering (C). The selection for Inch Fully Threaded Rod, ASTM A193 B7 depends on the precision your application requires.

Does ASME B18.31.3 specify the mechanical strength?

No. ASME B18.31.3 controls only the geometry of inch fully threaded rod, astm a193 b7. The mechanical strength is set by ISO 898-1 (bolts / screws) or ISO 898-2 (nuts), and the finish is governed by separate standards.

How do I request a quotation?

Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.