Overview

ASTM F1554 grade 55 anchor bolts are manufactured from a modified mild steel that has a higher minimum yield strength (55 ksi) than traditional A36 mild steel (36 ksi). This specification was widely used in the light pole and traffic signal industry long before the ASTM F1554 specification was introduced in 1994 and was commonly referred to as A36M55. Just as with grade 36, grade 55 covers anchor bolts in diameters ranging from 1/2″ through 4″.

Galvanizing

F1554 grade 55 anchor bolts can be provided in either a black or galvanized condition.

Welding

Contrary to popular belief, not all grade 55 material is weldable. If weldability is required, supplementary requirement S1 must be specified. A weldable grade 55 may be substituted at the supplier’s option when grade 36 is specified. All of the grade 55 round bar that Portland Bolt stocks will meet the S1 weldability requirements.

Supplementary Requirements

The following supplemental requirements apply to F1554 Grade 55. Supplementary requirements shall apply only when specified in the purchase order or contract.

S1: The purchaser can specify supplemental requirement S1 which requires weldability through chemical composition restrictions and by a carbon equivalency formula. If S1 is not specified by the purchaser, the Grade 55 material may or may not be weldable.

S2: Instead of the standard color-coding of yellow spray paint to indicate Grade 55, supplemental requirement S2 can be specified by the purchaser to require a permanent manufacturer’s identification on the end of the anchor bolt that projects from the concrete.

S3: Instead of the standard color-coding of yellow spray paint to indicate Grade 55, supplemental requirement S3 can be specified by the purchaser to have a permanent grade identification on the end of the anchor bolt that projects from the concrete.

S4: The purchaser may also specify that Grade 55 be Charpy impact tested at +40⁰F (+5⁰C). The minimum Charpy V-notch energy requirement is an average of 15ft-lbs for three specimens, with no one specimen falling below 12ft-lbs.

Material Substitution

Be skeptical of fastener distributors and manufacturers with limited manufacturing capabilities who attempt to substitute 1045 round bar or even A193 grade B7 material for F1554 grade 55. These materials and other grades of steel may exceed the tensile and yield requirements of the F1554 grade 55 specification, but will usually not meet the elongation and reduction of area requirements. Grade 55 round bar is not commonly available through local warehouses. Portland Bolt buys mill runs of round bar and stocks this material for immediate processing.

Mechanical Requirements

Grade	Size, Inches	Tensile, ksi	Yield, ksi min	Yield, MPa min	Elong. % min	Reduction of Area %, min
55	1/2 – 2	75 – 95	55	380	21	30
	2-1/4 – 2-1/2	75 – 95	55	380	21	30
	2-3/4 – 3	75 – 95	55	380	21	30
	3-1/4 – 4	75 – 95	55	380	21	30
¹Color coding (yellow) is required while permanent stamping with manufacturer’s identification and grade designation are supplementary requirements.

Nuts and Washers

Grade	Size, Inches	Recommended A563 Nut				Washer
		Plain Finish		Hot-Dip or Mechanical Zinc Coated
		Grade	Style	Grade	Style
55	1/2 – 1-1/2	A	Hex	A	Heavy Hex	F436
55	1-5/8 – 4	A	Heavy Hex	A	Heavy Hex	F436
For additional compatible nuts see the Nut Compatibility Chart.