This U.S. industry comprises establishments primarily engaged in manufacturing clay sewer pipe, drain tile, flue lining tile, architectural terra-cotta, and other structural clay products. Cross-References. Establishments primarily engaged in-- ? Manufacturing bricks and structural clay tiles--are classified in U.S. Industry 327121, Brick and Structural Clay Tile Manufacturing; ? Manufacturing ceramic floor and wall tiles--are classified in U.S. Industry 327122, Ceramic Wall and Floor Tile Manufacturing; ? Manufacturing clay refractories--are classified in U.S. Industry 327124, Clay Refractory Manufacturing; and ? Manufacturing nonclay refractories--are classified in U.S. Industry 327125, Nonclay Refractory Manufacturing.