SDR-9 SDR-11 What Does It Mean?

There is basically to different types of HDPE mortars available on the market for consumers that I have come across, SDR-9 and SDR-11 mortars. The price different between mortar made from these to different grades of HDPE made me wonder what the numbers meant. So I emailed a company that manufactures HDPE pipe and asked them what the SDR numbers mean.

This is what they told me, "All HDPE pipe is measured by SDR .  SDR is a formula, which represents the pipe diameter, divided by the wall thickness, equals the SDR. As examples, 22" DR 11 pipe has a 2" wall thickness (22/11=2), while 22" DR 9 has a 2.45" wall thickness (22/9=2.45)."

So doing some basic algebra and filling the equation.

Diameter/DR = Wall Thickness
 		  

 

2" SDR-9 :

Diameter/DR = Wall Thickness
2/9=.22"

 

2" SDR-11 :

Diameter/DR = Wall Thickness
2/11=.18"
 

So the difference between the two types of HDPE mortars is that the wall thickness in the 2" SDR-9 mortars are .04" thicker than in the 2" SDR-11 mortars.

 

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