Category Archives: Technical

What is the required thread pitch for ASTM F1554 anchor bolts?

The specification states that if no thread pitch is specified, the anchor bolt should have Unified National Coarse (UNC) threads, which is the standard construction grade thread pitch, with a standard Class 2A thread dimensional tolerance.  ASTM F1554 mentions both Class 1A and Class 2A dimensional tolerances, but defaults to the standard Class 2A tolerance, if nothing is specified. ASTM F1554 does not at any point mention Unified National Fine (UNF) threads or the tight tolerance Class 3A thread dimensional requirement and thus Portland Bolt will always assume that UNC coarse threads are required unless our customer or a drawing specifies another thread pitch.

Virtually all F1554 anchor bolts are manufactured with UNC coarse threads, but on the rare occasion when 8 UN threads are required they will be specified on the plans by an engineer.  The F1554 specification does mention 8 UN threads as a potential option in diameters above 1” diameter, but in Portland Bolt’s collective experience it is exceedingly rare to see 8 UN threads on a F1554 anchor bolt being specified or required on drawings.  ASTM F1554 also does not mention metric diameters in the most recent version of the specification, but also does not prohibit metric diameters.  However, the availability of metric round bar in North America is very limited and most anchor bolt manufacturing companies in the United States are not tooled up to produce metric F1554 anchor bolts cost-efficiently.  If a metric diameter F1554 anchor bolt is specified or shows up on a drawing, the contractor should work with the Engineer of Record to determine if it is feasible to use a soft conversion to the closest Imperial size.

11. Thread Dimensions
11.1 Uncoated Anchor Bolts:
11.1.1 Unless otherwise specified, threads on Class 1A and 2A anchor bolts shall conform to Class 1A and 2A, Unified Coarse Thread Series of ASME B 1.1, respectively. When an anchor bolt class is not specified, Class 2A shall be furnished. 
11.1.2 For diameters above 1.0 in, a purchaser may specify threads conforming to Class 2A, 8 UN Thread Series of ASME B1.1.

Does F1554 cover epoxy anchor bolts?

ASTM F1554 is frequently specified and supplied as all thread rod that is embedded into an existing concrete foundation and used with epoxy. The F1554 specification does not mention epoxy or specify a type of epoxy in any way, but it is a very common application for F1554 all thread rod to be used as an epoxy anchor bolt.

Does F1554 cover wedge anchors?

No.  ASTM F1554 does not cover wedge anchor bolts or mechanical anchor bolts of any kind.  Section 1.6 of ASTM F1554 reads as follows: “This specification does not cover the requirements for mechanical expansion anchors, powder-activated nails or studs, or anchor bolts fabricated from deformed bar.”

Should I specify or use a bent anchor bolt or a headed anchor bolt/threaded rod with a nut?

Right angle bend F1554 anchor bolts are a very common configuration for a generic anchor bolt that is commonly used for light poles, substations, and other common construction applications. However, Portland Bolt has seen a shift from the predominate use of bent bolts to a very large increase in specifying headed anchor bolts or a threaded rod with a welded nut.  In fact, AISC Design Guide 1 specifically mentions that bent anchor bolts have limited pullout strength when compared to headed anchor bolts or a rod with a welded nut. Design Guide 1 goes as far as to recommend headed anchor bolts and threaded rods with a welded nut as the recommended practice for anchorage moving forward. This being said, bent anchor bolts are still very common and Portland Bolt has an extensive inventory of both bent anchor bolts and headed anchor bolts to fulfill the requests of our customers.

Does F1554 have a torque requirement?

No. There is no specified torque requirement for ASTM F1554.  In fact, there are no torque requirements for anchor bolts in general.  Per AISC Steel Construction Manual 13th Edition, the normal effort of an ironworker with a regular spud wretch is adequate to install nuts on anchor bolts.  If an anchor bolt is to be torqued to a specific torque requirement, this requirement must be specified by the engineer and the contractor must be given specific instructions.

Does F1554 allow for square head bolts or head styles other than hex or heavy hex?

The specification only mentions heavy hex or hex head bolts conforming to the dimensional requirements of B18.2.1, which is the ASME dimensional specification for hex bolts and heavy hex bolts. Portland Bolt manufactures F1554 square head anchor bolts on a regular basis, but any other head style would be unusual, but possible, and would need to be discussed before manufacturing.

What is the pullout strength for F1554 anchor bolts?

F1554 anchor bolts have clear tensile and yield strength requirements, but calculating the final pullout strength of an anchor bolt in a concrete foundation involves a very complex amount of variables including concrete type/strength, the structure, embedment depth, anchor bolt configuration, and many other forces and issues.  Due to the complexity and liability of calculating actual pullout strength of an anchor bolt, only an engineer can make this determination on a case by case basis.

Can I weld to F1554 anchor bolts?

It depends on the grade. F1554 grade 36 is mild steel and is weldable. Grade 55 is a modified mild steel and is weldable, provided it meets the weldability requirements as described in Supplementary Requirement S1 of the F1554 specification. Grade 55 material that does not meet the S1 carbon equivalency parameters is not weldable. Grade 105 is not weldable since the heat generated during welding could alter the mechanical properties of the medium carbon alloy quenched and tempered material.

Can I galvanize F1554 anchor bolts?

All three grades of F1554 (grade 36, 55, and 105) can be galvanized. Both hot-dip galvanizing per ASTM F2329 and mechanical galvanizing per ASTM B695, class 50 are acceptable. Portland Bolt operates an in-house, state-of-the-art hot dip galvanizing line designed specifically for threaded fasteners.