Catalogue specifications for 225 mm polyethylene pipe.
225 mm HDPE pipe means pipe with a 225 mm outside diameter. That figure alone does not define an order — at this diameter the factory produces 11 different pressure classes, which differ in wall thickness and therefore in bore, weight and price. What completes an order is the diameter plus the SDR and the material grade.
At 225 mm, wall thickness ranges from 4.4 to 37.4 mm and nominal pressure from 2.5 to 25 bar, depending on the SDR and on whether the material is PE80 or PE100.
| SDR 51 | Wall thickness 4.4 mm — nominal pressure 2.5 bar in PE80, 3.2 bar in PE100 |
|---|---|
| SDR 41 | Wall thickness 5.5 mm — nominal pressure 3.2 bar in PE80, 4 bar in PE100 |
| SDR 33 | Wall thickness 6.9 mm — nominal pressure 4 bar in PE80, 5 bar in PE100 |
| SDR 26 | Wall thickness 8.6 mm — nominal pressure 5 bar in PE80, 6 bar in PE100 |
| SDR 21 | Wall thickness 10.8 mm — nominal pressure 6 bar in PE80, 8 bar in PE100 |
| SDR 17 | Wall thickness 13.4 mm — nominal pressure 8 bar in PE80, 10 bar in PE100 |
| SDR 13.6 | Wall thickness 16.6 mm — nominal pressure 10 bar in PE80, 12.5 bar in PE100 |
| SDR 11 | Wall thickness 20.5 mm — nominal pressure 12.5 bar in PE80, 16 bar in PE100 |
| SDR 9 | Wall thickness 25.2 mm — nominal pressure 16 bar in PE80, 20 bar in PE100 |
| SDR 7.4 | Wall thickness 30.8 mm — nominal pressure 20 bar in PE80, 25 bar in PE100 |
| SDR 6 | Wall thickness 37.4 mm — nominal pressure 25 bar in PE80 (the catalogue states no PE100 figure) |
Figures from the factory catalogue (DIN 8074 / ISO 4427-2). A lower SDR means a thicker wall, a higher pressure rating and a smaller bore.
The nominal pressure figure applies at 20 °C. If the line runs warmer, the real allowable pressure is lower and has to be calculated with the temperature derating factor.
225 mm also appears in the catalogue's gas table: SDR 11 at a minimum wall of 20.5 mm and SDR 13.6 at a minimum wall of 16.6 mm, supplied in 12 m. Note that gas pipe is a separate product — produced to INSO 11233-2, with its own marking and approval and electrofusion jointing. Water supply pipe of the same diameter cannot be used in a gas network.
