Materials & preparation
SDR, PN and pipe classes: what do the markings on the pipe mean?
PE100 SDR17 PN10: three numbers that determine pressure, wall thickness and welding parameters. How to read the pipe marking.
MRS, SDR and PN belong together
MRS (Minimum Required Strength) states the material's long-term strength: PE100 has MRS 10 MPa, hence the name. SDR (Standard Dimension Ratio) is the ratio between the pipe's outer diameter and its wall thickness: a lower SDR means a thicker wall and a higher pressure rating.
PN (nominal pressure) is the pressure class the pipe is designed for, e.g. PN10 (10 bar) for SDR17 and PN16 for SDR11 at 20 degrees Celsius. The numbers only apply at the reference temperature stated by the manufacturer.
Why the numbers matter when welding
The welding parameters in DVS 2207-1 and the manufacturer's tables are read from the pipe's outer diameter AND its wall thickness (SDR/wall series). Two pipes with the same diameter but different SDR are not welded with the same pressure and times.
For butt fusion the two pipe ends must have the same diameter, SDR and wall series. For electrofusion, different SDRs can often be combined, provided the coupler is approved for exactly that combination.
Read the marking on the pipe
The marking on the pipe typically states the material (e.g. PE100), diameter, SDR, PN class, standard (e.g. EN 12201 for water supply), manufacturer and production date. Always photograph the marking before the work - it is good documentation later.