Transitions and Adapters
Polyethylene 'Transition' or 'Adapter' fittings are used to connect PE gravity drainage pipe to another pipe material, such as: Ductile or Cast Iron, PVC, VCP (Clay), RCP (Reinforced concrete pipe). Transitions are typically a PE socket end with a rubber ring joint slides over the other pipes spigot end.
Manufacture - Transitions are machined from a single piece of PE100 PE hollow bar and include an integrated puddle flange. The puddle (when encased in Concrete) anchors the transition joint to the existing pipe material. This prevents changes in temperature and ground movement pulling the PE and transition RRJ socket off the existing pipe end. (Understand why PE pipes must be anchored here.)
Concentric vs. Eccentric Transitions - The difference in Inside diameters between the existing pipe and the PE pipe determines if the transition design must be Concentric or Eccentric. DSD states that Eccentric designs must be used where the internal diameters between the PE and joining pipe differ by ≥ 5%. This maintains a free draining level invert inside the pipe, avoiding an internal steps that cause septic pooling. Refer DSD PS Appendix 5A, Clause 5.8.9.
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![Transition Concentric Ill]()
Concentric Design - Example: DN300 PE is 355 OD SDR 17 which has 311mm ID, this is connecting to a DN 300 CI fitting with an 316mm ID. So 316/311 = 1.6%, which is < 5%, so Concentric design is OK. -
![Transition Eccentric Ill]()
Eccentric Design - Example: DN150 PE is 160 OD SDR17 which has a 140mm ID, this is connecting to a DN150 CI fitting with an ID of 152mm ID. So 152/140 = 8.5%, which is >5% so the transition must be Eccentric.
Non Pressure use only - Transition fittings must not be used in pressure applications, they are designed for an operating pressure of up to 0.5Bar (5m of head), For applications with a greater pressure requirement contact us for a special socket design.
PE Spigot end transitions - are also available by special order. These can be inserted into the sockets of existing DI, CI, Clay, PVC or Concrete pipes, contact us for lead-time.
