331511  Iron Foundries

This U.S. industry comprises establishments primarily engaged in
pouring molten pig iron or iron alloys into molds to manufacture
castings, (e.g., cast iron man-hole covers, cast iron pipe, cast iron
skillets). Establishments in this industry purchase iron made in other
establishments.

The data published with NAICS code 331511 include the following
SIC industries:

3321 Gray iron foundries 
3322 Malleable iron foundries