Table below provides dimensions of HDPE pipes for PE100 material of rating PN25, SDR 7.4 or S3.2. The following section provides a brief background of the various definitions used and the applicable calculations while referring to PE pipes.
As per EN 12201 SDR (Standard Dimension Ratio) = \(\frac{Outside Diameter}{Wall Thickness}\)..........(1)
PN is the pressure rating of pipe at 20°C.
PN Rating of SDR pipe is calculated using the formula PN = \(\frac{20σ}{(SDR-1)}\)..........(2)
where the maximum allowable structural stress or hydrostatic design stress σ is determined from the MRS (Minimum Required Strength).
ISO 4427 covers three material grades: PE63, PE80 and PE100. The MRS for PE63, PE80 and PE100 pipe are 6.3Mpa, 8.0MPa and 10.0MPa respectively. As per ISO 4427, the minimum design safety factor or overall service (design) coefficient is considered as 1.25.
Allowable structural stress or design stress for PE100 pipe is σ = \(\frac{MRS}{Factor of Safety}\) = \(\frac{10}{1.25}\) = 8 MPa.
Hence using equation (2) SDR of 7.4 corresponds to PN = \(\frac{20*8}{(7.4-1)}\) = 25 bar.
The polyethene pipe series is expressed as S = \(\frac{(SDR-1)}{2}\)..........(3)
Using equation (3) SDR of 7.4 corresponds to S series = \(\frac{(7.4-1)}{2}\) = S 3.2.
Based on the above formulas, a higher wall thickness translates into lower SDR values, lower S values and higher pressure rating PN of the pipe.
Maximum pipe wall thickness = Nominal size - Average ID - Minimum wall thickness.
| Nominal Size DN (mm) |
Size (inches) |
Minimum Wall (mm) |
Average ID (mm) |
Weight (kg/m) |
|---|---|---|---|---|
| 20 | 0.79 | 3.0 | 13.6 | 0.17 |
| 25 | 0.98 | 3.5 | 17.60 | 0.25 |
| 32 | 1.26 | 4.4 | 22.70 | 0.40 |
| 40 | 1.57 | 5.5 | 28.30 | 0.63 |
| 50 | 1.97 | 6.9 | 35.40 | 0.99 |
| 63 | 2.48 | 8.6 | 44.80 | 1.56 |
| 75 | 2.95 | 10.3 | 53.20 | 2.22 |
| 90 | 3.54 | 12.3 | 63.90 | 3.18 |
| 110 | 4.33 | 15.1 | 78.00 | 4.76 |
| 125 | 4.92 | 17.1 | 88.70 | 6.14 |
| 140 | 5.51 | 19.2 | 99.30 | 7.71 |
| 160 | 6.30 | 21.9 | 113.60 | 10.06 |
| 180 | 7.09 | 24.6 | 127.80 | 12.71 |
| 200 | 7.87 | 27.4 | 14.90 | 15.72 |
| 225 | 8.86 | 30.8 | 159.70 | 19.89 |
| 250 | 9.84 | 34.2 | 177.50 | 24.54 |
| 280 | 11.02 | 38.3 | 198.80 | 30.78 |
| 315 | 12.40 | 43.1 | 223.60 | 38.97 |
| 355 | 13.98 | 48.5 | 252.20 | 49.43 |
| 400 | 15.75 | 54.7 | 284.00 | 62.80 |
| 450 | 17.72 | 61.5 | 319.60 | 79.44 |
| 500 | 19.69 | 67.6 | 356.70 | 97.19 |
| 560 | 22.05 | 75.7 | 399.50 | 121.90 |
| 630 | 24.80 | 85.1 | 449.60 | 154.19 |
| 710 | 27.95 | 95.9 | 506.70 | 195.82 |
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