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

Property Class 12.9 Steel Inch Fully Threaded Rod, ASTM A193 B7

Mechanical properties, corrosion behaviour and the full dimensional range for this grade.

Property Class 12.9 Steel Inch Fully Threaded Rod, ASTM A193 B7 are supplied to ISO 898-1 property class 12.9. Corrosion behaviour is requires plating or black-oxide protection, the material is magnetic, and the usable service range is commonly limited to approx. +300 °C; confirm against the coating and the load. In practice this grade is the highest common strength class, for high-load machine assembly.

Grade
ISO 898-1 property class 12.9
Corrosion resistance
Requires plating or black-oxide protection
Magnetic response
Magnetic
Service temperature
commonly limited to approx. +300 °C; confirm against the coating and the load

Property values are typical for the grade. Certified mechanical test data is available on request for production orders.

Property Class 12.9 Steel Inch Fully Threaded Rod, ASTM A193 B7 reference image

For inch fully threaded rod, astm a193 b7 in Property Class 12.9 Steel, the controlling selection factors are corrosion exposure, strength requirement and service temperature. The grade data for Property Class 12.9 Steel (ISO 898-1 property class 12.9) is summarized below together with every size supplied.

Why Choose Property Class 12.9 Steel for Inch Fully Threaded Rod, ASTM A193 B7

The highest common strength class, for high-load machine assembly. For inch fully threaded rod, astm a193 b7, this matters when requires plating or black-oxide protection is the primary requirement.

Mechanical & Physical Properties

Grade designationISO 898-1 property class 12.9
Magnetic responseMagnetic
Service temperaturecommonly limited to approx. +300 °C; confirm against the coating and the load
Corrosion characteristicRequires plating or black-oxide protection

Corrosion Behavior in Service

Carbon and alloy steel inch fully threaded rod, astm a193 b7 require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.

Galvanic & Galling Considerations

For inch fully threaded rod, astm a193 b7 in steel, the dominant compatibility issue is hydrogen embrittlement at high property classes (10.9 and above) when electroplated. Plating must be followed by an appropriate baking treatment, or a non-electroplated finish (mechanical zinc, zinc flake) should be substituted.

Sizes of Inch Fully Threaded Rod, ASTM A193 B7 Available in Property Class 12.9 Steel

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

Technical Drawing

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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

What corrosion resistance do Property Class 12.9 Steel Inch Fully Threaded Rod, ASTM A193 B7 offer?

Property Class 12.9 Steel Inch Fully Threaded Rod, ASTM A193 B7 provide requires plating or black-oxide protection with a service range of commonly limited to approx. +300 °C; confirm against the coating and the load.

When should I move from ISO 898-1 property class 12.9 to class 8.8 for Inch Fully Threaded Rod, ASTM A193 B7?

Step up to class 8.8 when the joint preload approaches the proof load of the current class. The higher class adds preload at the same diameter, often saving size and weight.

Is Property Class 12.9 Steel prone to hydrogen embrittlement?

Class 10.9 and above can be susceptible to hydrogen embrittlement when electroplated. Specify post-plating baking, or use mechanical-zinc / zinc-flake finishes which avoid the cathodic plating step.

Which finish is best for outdoor Inch Fully Threaded Rod, ASTM A193 B7?

For outdoor service in steel, hot-dip galvanizing gives the longest life; zinc-flake (Geomet/Delta-Tone family) gives a thinner film with excellent salt-spray performance; standard zinc plating is the lowest-cost option for general indoor / shielded outdoor use.

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.