Standard SDR PVC Pipe Sizes

• Polyvinyl chloride (PVC) pipe is broken up into classes. Class 125 SDR pipe has a standard dimension ratio of 32.5. Class 160 SDR pipe has a standard dimension ratio of 26. Class 200 SDR pipe has a standard dimension ratio of 21. Class 315 SDR pipe has a standard dimension ratio of 13.5. According to "Mechanical and Corrosion-Resistant Properties of Plastics and Elastomers," there are six SDR standards for poly-vinyl chloride (PVC) pipe: SDR 13.5, SDR 18, SDR 21, SDR 25, SDR 26 and SDR 32.5.
  
  

PVC Pipe Pressure Ratings

• Pressure ratings are constant for PVC SDR pipe regardless of its nominal size. SDR 26 pipe is rated to 200 psig. SDR 21 pipe is rated to 200 psig. SDR 13.5 can handle pressure up to 315 psig. Chlorinated polyvinyl chloride pipe (CPVC) shares the same ratings. The American Society of Testing and Materials (ASTM) International standard D679 defines the acceptable specifications for PVC sewer pipe. ASTM standard D2665 applies to PVC plastic drain, waste and vent pipe.
  
  

PE Pipe Pressure Ratings

• Polyethylene (PE) pipe is also rated by SDR. "Gravity-Driven Water Flow in Networks" states "for PE pipe, the pressure ratings are considerably smaller than PVC for the same schedule and pipe size." Performance class PE 80 pipe with an SDR of 11 carrying gas is allowed to operate at a pressure of 4 bars. Performance class PE 80 pipe with an SDR of 11 carrying water has an admissible operating pressure of 12.5 bars. PE 100 performance class pipe with an SDR of 11 can carry gas at 10 bars and drinking water at 16 bars.
  
  

SDR-PR Pipe

• SDR-PR stands for Standard Dimension Ratio -- Pressure Rated. PVC pipe can be identified as either SDR or SDR-PR pipe. Both SDR and SDR-PR pipe sizes are designed to handle specific pressures regardless of its size. ASTM standard D2241 defines the standard specifications for PVC SDR-PR pipe.
  
  

Effects of Temperature

• Higher temperatures weaken plastic pipe.Hemera Technologies/AbleStock.com/Getty Images
  
  As the temperature of a pipe's contents rises, its pressure rating drops. "Residential Construction Academy: Plumbing" says "the maximum pressure of 400 psi for SDR 11 CPVC pipe is based on its being used to distribute water at 73 degrees Fahrenheit." An SDR 11 PVC pipe rated for 400 psi at room temperature is only rated for 100 psi when the water temperature rises to 180 degrees.