Coiled HPPE vs HPPE lengths with Weld Connections
Coiled HPPE vs HPPE lengths with Weld Connections
(OP)
Have been investigating the pros and cons of using coiled HPPE pipe, it seems only valid for long sections due to high transport, and handaling costs.. can anyone shed some more light on the pros and cons of Coiled HPPE? and for that matter why HPPE is better than Ductile iron - Setting up a Foul Sewerage Rising main with a DWF of around 5l/s.





RE: Coiled HPPE vs HPPE lengths with Weld Connections
HPPE is more corrosion resistant that ductile iron (generally), but not as strong under external loading.
HPPE should have lower friction for the flows, and can be obtained in pressures up to around 16 bar.
This is quite a big subject and would need either specific questions or refer to a manufacturer's website such as Pipelife for HPPE / HDPE uses and specifications.
Hope this helps
RE: Coiled HPPE vs HPPE lengths with Weld Connections
http://www.dipra.org/ (see the Publications link on the left)
Also, the "devil-is-in-the-details". For example, as StephenA says, polyethylene pipe has better flow characteristics than ductile iron which is true for the materials ...but for any given NOMINAL pipe size, the ID of ductile iron is much larger than the ID of polyethylene. You may have to use a larger nominal PE pipe to get the same performance as a smaller DI pipe.
www.SlideRuleEra.net
RE: Coiled HPPE vs HPPE lengths with Weld Connections
I would suggest for anything under 4" use a coil. Anything over (and including 4") I would fuse it in straight sections using a skilled person. It's fast enough anyways and the cost is about the same once you factor in handling the roll so it uncoils properly. + usually you have to buy it in a standard amount like 300' so you may need 450' and have to buy 600.
Reasons to think about.
Flow characteristics
Flexibility
Shock / hammer abilities
Freeze / thaw properties / insulating
non conductivity? - course this makes it harder to locate.
Corrosion - rock impingement
Cost of installation (depending)
rehabilitation later using sliplining etc dependng if you are using mitered joints
cost of excavation and required fill. I think its a little more forgiving.
RE: Coiled HPPE vs HPPE lengths with Weld Connections
For the coiled lengths we used electrofusion couplers, these are more expensive than butt fusion but the machine is cheap and at coiled lengths of 50 and 100m the overall process is fast and cost effective.
For diameters over 125mm the pipes come in 6 or 12m lengths. Butt fusion is used which is a cheap process. The problem is that the length of time per weld (including cooling) is long so to get good production you need several machines. What we did is to preassemble the pipes into 24m lengths and then connect these lengths together as required (for this reason think twice before ordering 6m lengths)