WSD Polyethylene Outside Diameter (OD) conversion to Nominal Diameter (DN)
The Hong Kong Water Supplies Department (WSD) publishes a conversion table (Table 22.09-2) in their Particular Specification, Appendix 22.09, to ensure internal diameter alignment when connecting Polyethylene pipes to other pipe materials like steel and Ductile Iron.
PE is defined by its outside diameter (DN/OD for pipes and dn for fittings), whereas Ductile Iron is defined by its nominal internal diameter (DN). A PE pipes thickness (SDR Rating) determines the pipes actual internal dimension. The table below provides the official WSD conversions given in Table 22.09 for pipes and fittings, regardless of the PN / SDR rating being used.
All dimensions are given in mm.
|
PE Nominal Size (DN/OD) / Nominal Outside Diameter (dn) (outside diameter of PE pipes and fittings) |
Equivalent Size in DN (WSD nominated matching size) |
|
20 |
15 |
|
25 |
20 |
|
32 |
25 |
|
50 |
40 |
|
63 |
50 |
|
90 |
80 |
|
125 |
100 |
|
180 |
150 |
|
250 |
200 |
|
315 |
250 |
|
355 |
300 |
|
450 |
350 |
|
500 |
400 |
|
560 |
450 |
|
630 |
500 |
|
710 |
600 |
|
800 |
700 |
Note: Larger sizes are not stipulated in Appendix 22.09 but are available up to DN/OD 1000 in PN16 SDR11 and DN/OD 2000 in PN10 SDR17
Page from WSD PS Appendix 22.09 for reference.
