PVC pipe that falls under the SDR (or standard direct ratio) classification are categorized based on the ratio of their average outside diameter to their minimum wall thickness. SDR-35 PVC pipe is often used for gravity sewers.

What is Dr pipe?

1 Answer. It is the ratio of pipe diameter to wall thickness. It is calculated by dividing the specified outside diameter of the pipe by the minimum specified wall thickness. Any size pipe with a common DR is qualified to operate at the same pressure regardless of pipe OD (e.g. 2 IPS DR 11 pipe can have the same operating pressure as 12 DR 11).

What is SDR in HDPE pipes?

In HDPE pipe, “SDR” indicates the ratio of outside diameter to wall thickness. The bigger the thickness of the pipe wall, the smaller the SDR value and the higher the strength of the pipe. For example, if the outer diameter is 315 mm and the wall thickness is 18.7 mm, the SDR ratio is 17, that is SDR 17.

What is SDR pipe?

SDR stands for Standard Dimension Ratio. SDR is the ratio of the outer diameter to the thickness of the PE pipe, which is one of the characteristics of the Polyethylene pipe, and the pipes can be sorted according to the standard tables accordingly.