Standard dimension ratio (SDR) is a method of rating a pipe's durability against
pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country a ...
. The standard dimension ratio describes the correlation between the pipe dimension and the thickness of the pipe wall.
Common nominations are SDR11, SDR17 and SDR35. Pipes with a lower SDR can withstand higher pressures.
Pipe
outside diameter
Pipe wall thickness
References
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Piping