Skip to main content

Grade 55 All Thread Rod: Specifications & Applications

ASTM F1554 Grade 55 All Thread Rod is a heat-treated, high-strength threaded fastener designed for structural and industrial applications where standard threaded rod does not provide adequate load capacity. Commonly used in anchoring, steel connections, and equipment mounting, Grade 55 offers reliable performance and improved strength for demanding service conditions.

This page serves as a practical resource covering material specifications, mechanical performance, compatible nut grades, coatings and finishes, and common applications of Grade 55 all thread rod.

Order Grade 55 All Thread Rod

Governing Specification: ASTM F1554

ASTM F1554 is the standard specification for steel anchor bolts and threaded anchor rods with minimum yield strengths of 36, 55, and 105 ksi. Grade 55 represents the mid-strength classification within the F1554 specification and is commonly supplied as continuous all-thread rod or as headed anchor rods.

ASTM F1554 Grade 55 Key Characteristics

  • Minimum yield strength: 55 ksi

  • Heat treated to achieve required mechanical properties

  • Weldable when ordered with supplemental chemical requirements (carbon equivalent control)

  • Intended for structural anchoring

  • Available in diameters typically ranging from ½″ through 4″

ASTM F1554 Grade 55 is specifically intended for anchor rods and embedded fasteners used in structural, foundation, and construction applications where higher strength than Grade 36 is required without the reduced ductility of Grade 105.

To further assist with grade selection, the table below compares ASTM F1554 Grades 36, 55, and 105.

ASTM F1554 Grade Comparison: Grade 36 vs Grade 55 vs Grade 105

The ASTM F1554 specification includes three strength grades to accommodate a range of structural anchoring requirements. Selecting the appropriate grade depends on load demand, ductility requirements, and whether welding or field modification is anticipated.

ASTM F1554 Grade Comparison Table

PropertyGrade 36Grade 55Grade 105
Minimum Yield Strength36 ksi55 ksi105 ksi
Typical Tensile Strength58–80 ksi75–95 ksi125–150 ksi
Heat TreatedNoYesYes
WeldableYesYes (with Supplement S1)No
DuctilityHighModerateLow
Common ApplicationsLight anchoring, handrails, small equipmentStructural anchoring, base plates, light polesHeavy structural loads, specialty applications

Key Differences at a Glance

  • Grade 36 offers maximum ductility and ease of fabrication but lower load capacity

  • Grade 55 balances strength and ductility, making it the most versatile structural anchor grade

  • Grade 105 provides very high strength but reduced ductility and is not intended for welded applications

Mechanical Properties

High strength, low alloy, 55 ksi yield steelPer ASTM F1554-15
GradeTensile
Strength		Yield Strength,
0.2% offset		Elongation
in 8 in. (1)		Elongation
in 2 in. (1)		Reduction
in Area
ksiMin ksiMin %Min %Min %
5575-9555182130
  1. 1. Elongation in 8 in. applies to bars. Elongation in 2 in. applies to machined specimens.

Threading and Configuration

ASTM F1554 Grade 55 all thread rod is typically supplied with:

  • UNC (Unified National Coarse) threading

  • Continuous threading over the full length

  • Cut or rolled threads depending on diameter and manufacturer

All thread configurations provide flexibility for field adjustment, leveling, and use with multiple nut and washer assemblies.

Compatible Nut Grades

Proper nut selection is essential to ensure the anchor assembly develops the full strength of the rod. Recommended compatible nut grades for ASTM F1554 Grade 55 include:

  • ASTM A563 Grade DH

  • ASTM A194 Grade 2H

Nuts should meet or exceed the mechanical strength of the anchor rod to prevent thread stripping or premature joint failure.

 

Coatings and Finishes

ASTM F1554 Grade 55 all thread rod is available in a variety of finishes to suit environmental exposure conditions:

  • Plain (Black) – Interior or protected environments

  • Zinc Plated – Mild corrosion resistance

  • Hot-Dip Galvanized (HDG) – Exterior and corrosive environments

  • Mechanical Galvanized – Controlled coating thickness

Note: Galvanized anchor rods require oversized galvanized nuts to account for coating thickness per ASTM standards.

 All Thread Rod Drawing

Chemical Properties

Per ASTM F1554-15
GradePhosphorusSulfurCopper
(when specified)
% by weight% by weight% by weight
550.04 max0.05 max0.20 min

Your Trusted Source for Grade 55 All Thread Rod

STS Industrial supplies Grade 55 all thread rod for structural and industrial applications where higher strength and load capacity are required. Manufactured from heat-treated carbon steel and produced to applicable industry standards, Grade 55 all thread provides reliable performance when used in anchoring, steel connection, and equipment mounting applications. Available in a range of diameters, lengths, and finishes, our team can assist with proper selection and specification support to ensure compliant, dependable performance.