Pressure Pipe

PVC

PVC pressure pipes are manufactured from PVC resin compounded with stabilisers, lubricants and pigments. They do not contain any plasticisers and hence are known as unplasticised PVC or PVC-U.

PVC-U pipes have been used for pressure applications in Australia since the 1960’s, but have a much longer service history elsewhere in the world. Over this time, industry has recognised the many benefits of PVC for pressure pipes: material stability, immunity from corrosion, high strength to weight ratio, ease of handling and installation and excellent flow characteristics.

Further developments in PVC pressure pipe technology has led to the introduction of Oriented PVC (PVC-O) and Modified PVC pressure pipes (PVC-M).

PVC is the most commonly used pipe for water reticulation by Australian water agencies. It is used extensively in irrigation and industrial applications.

The size range for PVC pressure pipe in Australia typically extends to 600mm (DN600)

PE

Polyethylene (PE) pipe manufacture commenced in Australia in the 1950′s with small diameter pipes used for rural, irrigation and industrial applications. Since then, PE use and the number of applications for PE pipes has grown enormously particularly in the areas of gas reticulation, coal seam gas, mining and trenchless applications.

The flexibility of PE pipe allows cost savings in installation. Trenchless technology can avoid the need for open trenches and reduce the disturbance to the public and environment by pulling long welded strings of PE pipes through holes below ground, bored by horizontal directional drilling machines. PE is often used in renovation of old pipelines as it can be readily inserted as a structural lining into an old pipeline. PE’s resistance to ground instability means that PE gas and water systems were the only systems to survive the major earthquakes in Kobe, Japan in 1995.

PE pipe can be supplied in straight lengths or in coils, reducing the need for joints and fittings. PE pipes can be jointed using butt and electrofusion techniques or using compression fittings.

Low density PE has high flexibility and retention of properties at low temperatures. The main applications of LDPE are in micro irrigation, low pressure drip irrigation and crop irrigation applications.

PE 100 is the most recently developed polyethylene grade and has higher strength, toughness and resistance to slow-crack growth than earlier generation materials.

PE pressure pipes are designated by their outside diameter or DN. For water and other general pressure applications, the maximum allowable operating pressure with a minimum service coefficient is designated by the pressure rating or PN. The SDR of a PE pipe refers to its ‘Standard Dimension Ratio’ which describes the geometry of the pipe and is the ratio of the outside diameter and the minimum wall thickness. Pipes with a higher SDR have a thinner wall than pipes with a low SDR.

PE pipes are used in a wide range of applications including:

  • Water supply
  • Sewerage
  • Gas reticulation
  • Compressed air
  • Mine and slurry pipelines
  • Coal seam gas collection
  • Irrigation
  • Drainage

PE is manufactured in Australia in sizes up to 2,000mm diameter (DN2000).

PEX

Crosslinked polyethylene (PEX) has several advantages over metallic pipes (copper, iron, lead) in hot and cold water plumbing applications. It is flexible, resistant to scale, will never corrode or develop pinholes, is faster to install than metal or rigid plastics and has fewer connections and fittings.

PEX pipe is made from crosslinked HDPE (high density polyethylene) polymer. The polymer is melted and continuously extruded into a pipe before the crosslinking process, which provides PEX with its high temperature performance. Crosslinking may be accomplished by several different methods.

Sizes of PEX pipe typically available in Australia range from 16mm (DN16) up to 50mm (DN50).