Structural Bolt Head Markings

The ASTM requires structural bolts to be distinctively marked. These bolt head markings include the manufacturer’s mark, the grade of bolt (ex. A325, A490), and markings to classify the type of bolt (Type 1 or Type 3).

In addition to the mandatory markings, certain manufacturers may include additional markings to distinguish them from others. Below are the mandatory bolt head markings using our manufacturer’s mark. To learn more about our structural bolting products, visit our main structural bolting page.

Bolt Head Markings Table