Coiled HPPE vs HPPE lengths with Weld Connections 3

[wunderjah]

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.

 

[StephenA]

Coiled HPPE is used for smaller sizes to save on butt welding or electro-fusion coupling 12m (or 18m) lengths.

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

 

[SlideRuleEra]

There is another side of the story, presented by the Ductile Iron Pipe Research Association - you may want to read some of their comparative publications:

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.

http://www.SlideRuleEra.net

 

[Pulpboy]

I tried heavy wall coiled 6" pipe... about the biggest you could get to save on fusion machines and operators during a directional drill. I would go with straight sections next time. It was a pain in the ass.

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.

 

[Zambo]

I don't know what can be supplied by special arrangement but last time I worked with HDPE we received all pipes up to 110mm as coils. 125mm was available coiled but is larger than a standard truck load. The other problem with 125mm coils (and to a certain extent 110mm) is crimping of the pipe during coiling. Some sections have to be cut out and rejoined.

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)