What happened to ASTM A307 Grade C?
One change with regard to specifications that will have a significant impact on the construction fastener industry is the August 2007 elimination of the grade C designation within the ASTM A307 specification. ASTM A307 is the standard specification for low carbon steel construction fasteners. Until recently, A307 had three grades A, B, and C. Grade A covers bolts for general applications, grade B covers heavy hex bolts and studs for cast iron flanges, while grade C covered unheaded anchor bolts, either bent or straight, intended for structural anchorage purposes. Last year’s elimination of A307 grade C is the result of a virtually identical specification, F1554 grade 36 developed in 1994, replacing it.
Although A307 grade C and F1554 grade 36 are virtually identical, there are some subtle yet very important differences. The ASTM F1554 specification was introduced in 1994 and covers anchor bolts designed to anchor structural supports to concrete foundations. F1554 grade 36 is manufactured from low carbon steel just like ASTM A307 grade C was but in addition to being a bent or straight anchor bolt, can also be a headed bolt that is embedded in concrete and used for anchoring purposes. Most commercially available all thread rod that meets ASTM A307 and is used for anchor bolts will not meet ASTM F1554 grade 36. Additionally, imported A307 hex bolts that are commonly embedded in concrete and used as anchor bolts will not meet F1554 grade 36. However, many fastener distributors and even some manufacturers who do not have a thorough understanding of the differences between ASTM A307 grade C and F1554 grade 36 continue to provide A307 bolts believing they will cross-certify to ASTM F1554 grade 36 which is simply not the case in most instances. It is important to be aware of the differences between these two specifications to limit exposure to unnecessary liability.