Polyethylene and poly vinyl chloride
(PVC) pipes have replaced traditional galvanized iron, steel and
ductile iron pipes due to their resistance to corrosion, ease and
speed of installation and cost.
Polyethylene is particularly popular
in the pastoral industry as it is:
- available in long lengths (typically 50 to 300m coils for
diameters up to 110mm),
- flexible and easily transported,
- easily laid and joined, and
- suitable for most flows and pressures required on
properties.
The main joining techniques
available for polyethylene pipe include:
- compression couplings,
- butt welding;
- electrofusion; and
- Stub flanges and backing plates.
Polyethylene pipe should be laid
below ground to avoid the effects of extreme temperature changes
(both hot day time and cold night time temperatures), damage from
stock and farm equipment. Below ground installation will also
protect against damage form rodents and from fires. Generally
pipes installed below the ground will have a longer working
life. Ripping and trenching are the two main techniques used
for installing pipe underground.
- For a given flow rate, a LARGER diameter pipe will have lower
pipe friction loss.
- For a given flow rate, a SMALLER diameter pipe will have a
higher velocity and higher pipe friction loss.
- Higher velocity in a larger diameter pipe produces less pipe
friction loss when compared to the same velocity in a smaller
pipe.
- Higher pipe friction losses require larger pumps or can reduce
flows at outlets, they can also result in higher power costs to run
pumps.
- Pipe velocities should not exceed 5 m/s and preferably be less
than 1.5 m/s.
Manufacturer of butt welding
machines for poly pipe:
http://www.dixonind.com.au/
Training courses for poly butt welding with the Plastics
Industry Pipe Association of Australia Ltd:
http://www.pipa.com.au/Training.html
Hydraulic pipe design guide
http://www.iplex.com.au/iplex/html/hydraulic.shtm
Further information on pipes available in Review of Water Reticulation Equipment for
Rangelands pastoral Applications Review compiled by Ralph
William UniSA (information on this page extracted from review)
