Step 1: Cutting Round Bar to Length
All thread rod is mass produced and commonly available off the shelf in 3’, 6’, 10′ and 12’ lengths. The first labor operation in the mass-production of all thread rod is cutting the material to its desired length. With smaller diameters (3/4” and below) the material is typically bought in a large coil which is then straightened, drawn down to a pitch diameter, descaled, and cut to length. With larger diameters, the material is typically cut from steel round bar, instead of coil, which requires no straightening.
Step 2: Threading
Once the round bar is cut, the rod is fed directly through cylindrical roll threading dies. This roll threading process takes reduced diameter rod (pitch diameter) and forces it between rotating dies. The displacement of the rod forms a full-sized thread. It is a quick and efficient method for manufacturing which results in significant cost savings over cutting the threads. Rods that are readily available off the shelf are mass produced using this method of threading.
Most mass-producers supply these long lengths of all thread rod to bolt manufacturers and fastener distributors who buy and sell these long lengths of all thread rod to contractors who cut the rods to length in the field. However, most often bolt suppliers will cut the threaded rods to specific lengths required for the project.
The short answer is no. The reasons behind the answer are a little more complicated. The F3125 Grades A325 and A490 specification is designed for headed fasteners intended for structural applications only. These two grades cannot be manufactured in any configuration of fastener. Because these two specifications are used for headed fasteners only, both are not available in an all thread rod configuration. For all thread rod with similar strength characteristics to A325, you can look at substituting A449 or A354 Grade BC depending on the diameter of the material; for an A490 all thread rod equivalent, the F3125 specification states to move to A354 Grade BD. Any grade substitution should be approved by the Engineer of Record.
It is very common to see A36 all thread rod specified on a project. A36 is an ASTM specification covering common mild steel round bar which all thread rod is commonly manufactured from. However, it is a steel grade, not a fastener specification. Why is it a problem to call out A36 as the all thread rod grade? The biggest problem with ordering bolts to an ASTM steel standard is that these specifications, like A36, do not have the necessary fastener information like type or class of threads, coating possibilities, and nut/washer compatibilities. These are all relevant things that a manufacturer needs to ensure you end up with the correct product. The best option is to find the relevant ASTM standard that covers all thread rod, such as A307 Grade A, A307 Grade B, or F1554 Grade 36.
Typically, the answer is no. It is rare for distributors or manufacturers to keep traceability on their all thread rod because more often than not it is sold without certifications. If they do have mill test reports, there is rarely a Reduction of Area value which is required to determine whether or not the material meets F1554 Grade 36. Other issues include the maximum tensile strength requirement is often exceed and the Elongation requirement is rarely met.
If your project requires F1554 Grade 36 all thread rod, make sure you check with the manufacturer and require full certification documents to confirm that the material meets this specification prior to ordering.