Grade on a 6" pipe?

Grade on a 6" pipe?

• A. 1:80 or 1/10 in
• B. 1:100 or 1/8 in
• C. 1:50 or 1/2 in
• D. 1:200 or 1/20 in

Answer: (B)

Grade here means the slope of the pipe—the vertical drop per horizontal length for gravity flow. For a 6" drainage pipe, the standard slope is about 1:100, which is a 1% grade. That translates to a drop of 0.01 ft per 1 ft, or roughly 0.12 inches per foot. In practice this is commonly rounded to 1/8 inch per foot. So the best match is 1:100, or about 1/8 inch per foot. Slopes like 1:80, 1:50, or 1:200 would be noticeably steeper or shallower and not the typical grade used for a 6" line.

Grade here means the slope of the pipe—the vertical drop per horizontal length for gravity flow. For a 6" drainage pipe, the standard slope is about 1:100, which is a 1% grade. That translates to a drop of 0.01 ft per 1 ft, or roughly 0.12 inches per foot. In practice this is commonly rounded to 1/8 inch per foot. So the best match is 1:100, or about 1/8 inch per foot. Slopes like 1:80, 1:50, or 1:200 would be noticeably steeper or shallower and not the typical grade used for a 6" line.