Reinforcing Bar Identification

Each individual reinforcing bar is manufactured with a series of individual markings:

• The top letter or symbol identifies the producing mill and deformation pattern.
• The next marking is the bar size.*
• The third marking symbol designates the manufacturing material — usually either "S" for carbon-steel (ASTM A615) or "W" for low-alloy steel (ASTM A706).
• Finally, there will be a grade marking (4 or 5, for 420 or 520) or by the addition of one line (420) or two lines (520) that must be at least five deformations long.

*CRSI Board of Directors, through the Engineering Practice Committee, is encouraging producer Members to revert to an inch-pound bar marking system for all sizes and grades of deformed reinforcing steel products. The intention of this resolution is to reduce confusion and the chance of errors/delays from the construction supply chain. Click here to view the full resolution.