A critical piece of information when specifying a bolt for a project is the grade. Often times the actual ASTM grade is not known, so a “structural grade” is requested. This is usually the result of the grade being left off of a drawing, so the company responsible for procuring the required fasteners are either making an assumption or know that the application involves structural steel. Unfortunately “structural grade” is not enough information to know what the exact grade of bolt required is. The most common grades of fasteners when talking about a structural application are, ASTM A325 or A490, however these two bolts are for structural steel connections, so if the application is different, then a different grade is needed.
ASTM F3125 is also a structural grade, however there are six different grades that fall under it and would also need to be known before the appropriate grade of bolt can be supplied. Basically, asking for a “structural grade” is not enough information to know which grade of fasteners would work best. As with any situation where the grade of bolt comes into question, it is best to contact the Engineer of Record to figure out what the appropriate grade would be for a given application.