Can Portland Bolt manufacture a 1" x 6" fully threaded A325 heavy hex structural bolt?
Bolts manufactured to the ASTM A325 specification have a fixed thread length for a given diameter, which is often shorter than other grades of bolts. For example, a 3/4″ diameter A325 has 1-3/8″ of thread and a 1″ A325 has 1-3/4″ of thread, regardless of the overall length of the bolt. Our structural bolts product page contains a table of thread lengths for each available diameter.
The A325 specification contains specific language limiting these bolts to these thread lengths. Section 1.5 of the specification reads as follows:
1.5 This specification is applicable to heavy hex structural bolts only. For bolts of other configurations and thread lengths with similar mechanical properties, see Specification A449.
However, the A325 specification also has a supplemental requirement (S1) that allows A325 heavy hex bolts to be fully threaded. The (S1) supplement states that A325 “bolts with nominal lengths equal to or shorter than four times the nominal bolt diameter shall be threaded full length.” In other words, if the bolt is longer than four times the diameter it cannot be fully threaded. Fully threaded A325 heavy hex structural bolts are stamped with “A325T” on the head of the bolt instead of “A325”.
So, does this mean that Portland Bolt will not manufacture with an A325 with extra thread that exceeds four times the diameter in length? No. We see A325 bolts with extended thread lengths specified by engineers all the time. ASTM specifications are guidelines that provide a buyer of a product with expectations as to the chemistry, strength, and configuration of a product they are purchasing. It is our responsibility to bring the issue of thread length to our customer’s attention and to let them know that technically, the correct bolt with extended thread should be ordered to the A449 specification. However, if the customer understands and still wants to proceed with an order of A325 bolts with extended threads, we will manufacture them.