Questions & Answers
What is the Standard Dimension Ratio (SDR)?
The SDR or the ‘Standard Dimension Ratio’ and refers to the geometry of the pipe. SDR is defined as the ratio of the nominal outside diameter to the nominal wall thickness. It is common to use the SDR as a method of pressure rating pipes.
Therefore a higher SDR indicates a thinner-walled pipe at any given diameter.
Common SDR’s are : 7.4, 9, 11, 13.6, and 17
Stefan Dreckötter