Some commonly used copper pipe sizes are 1/4 inch to 8 inch tubes that come in 20 foot lengths, 10 inch pipes that come in 18 foot lengths and 12 inch pipes that come in 12 foot lengths. These are straight pipes.
These pipes are used for household water service, solar heating, fuel, natural gas and other uses. They can also be bought as coils.
Other pipes are used for DWV (or drain, waste, vent), HVAC and solar heating. These come in 1 1/4 inch to 8-inch lengths in straight, 20-foot long pipes. Other copper pipes are 3/8 inch to 4 1/8 inch bought in 20-foot lengths. These pipes are used for air conditioning, refrigeration and natural gas.