Newest FAQs
According to section 9 of the ASME B18.2.6 specification, which covers dimensional tolerances for hex bolts, A325 and A490 structural bolts can actually be produced between .12 to .25 of inch less than the published length and still meet the specification. This small difference isn’t much, but mass bolt producers save a significant amount of... Read more
What many people do not realize is that the head of a bolt is formed by heating the end of a piece of steel round bar and then forging (reshaping) the heated end into a head. The head is not welded on or otherwise “attached” to the end of the round bar. For example, the... Read more
“My plant uses hex head cap screws, ASTM A193-B7 as standard. We typically stock the constant thread series 8 TPI fasteners above 1 inch diameter. However, many tapped items like expansion joints come with UNC thread counts, like 7 threads per inch (TPI) for 1-1/4″ diameter bolts. This causes a problem sometimes when fasteners don’t... Read more
ASTM A36 is a steel (raw material) specification, while ASTM A307 is a fastener specification. In other words, once you take A36 round bar and cut it, thread it, bend it, forge a head on it, or otherwise process it and turn it into a fastener, it becomes an A307 bolt. Often times, ASTM A307... Read more
RA% is a term that stands for “reduction of area percentage.” It is an important requirement of the ASTM F1554 specification, in addition to other specifications. This value is reported as a percentage of the original test piece. When fasteners undergo mechanical testing, they are pulled to failure and the diameter of the point at which... Read more
The lines on the head of a bolt indicate its grade. SAE J429 (Society of Automotive Engineers) bolts have radial lines, whereas ASTM (American Society for Testing and Materials) uses a combination of letters and numbers to indicate the grade. Three radial lines will indicate an SAE grade 5 fastener, while six radial lines will... Read more
No. As a matter of fact, nobody does. The ASTM F3125 grade A325 specification clearly denotes the diameter range of this grade of fastener to be ½” through 1-1/2” inclusive. Therefore, an A325 bolt larger than 1-1/2” diameter simply does not exist. It cannot be manufactured because there are no dimensional or strength requirements for... Read more
We’ll try our best. The relationship between tension and torque should be looked at cautiously, since it is very difficult to indicate the range of conditions expected to be experienced by a fastener. Torque is simply a measure of the twisting force required to spin the nut up along the threads of a bolt, whereas... Read more
Engineers occasionally specify the use of F3125 Grade A325 heavy hex structural bolts as anchor bolts, but technically they are supposed to be used for structural steel connections only. Part of the problem is that the A325 specification is very specific as to the application and thread length. Because A325 bolts are typically used in... Read more
Frequently, imported mild steel all thread rod will not meet ASTM A307 grade C. The three different grades of the A307 specification identify their intended application where grade C is embedded in concrete and used for anchoring purposes, grade B is used in cast iron flange connections, and grade A covers general applications. Normally, imported... Read more