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Introduction to Iplex Flowtite pipelines

Iplex Pipelines (formerly James Hardie Pipelines) has been a leader in GRP pipeline technology for the water industry in Australia and New Zealand since 1985. Company policy is to keep abreast of the latest developments in pipe manufacturing and has formed a commercial venture with Fibrelogic Pipe Systems of South Australia to market Iplex FLOWTITE pipes produced in a new factory at Lonsdale.

FLOWTITE GRP pipes were first produced in Norway in 1971. The process has been refined over the intervening period to become the leading state " of-the-art" in GRP pipe manufacture. The technology is now being used worldwide on all continents with more than forty winding machines located at seventeen factories.

Manufacturing Process

At Lonsdale pipes are manufactured in sizes of 80 to 3000mm in diameter for both pressure and non-pressure applications using two machines depending on the size of pipe required. Continuous glass filaments and polyester resin are combined with a core of chopped glass and sand for optimal structural effect. There are six distinct layer structures within the pipe wall as illustrated in Figure 1.1.

The process starts with the winding of a de-bonding film of clear Mylar on the rotating mandrel which advances at a uniform speed throughout the process to the first winding station where liner resin reinforced with either 'C' glass (or polyester) veil backed up with a barrier layer is added to the mandrel. This is followed by the inner structural layer comprised of resin and continuous circumferential glass filaments. At the next location the mid wall zone or neutral axis of the pipe wall, is built up using chopped glass, resin and sand supported by a polyester mesh. The outer structural layer comprised of continuous glass and resin is next followed by the outer scuff layer which is resin reinforced with 'C' glass (or polyester) veil.

The increased reinforcing effect of the continuous circumferential glass filaments has resulted in a greater range of pressure ratings than previously available. The reinforced inner and exterior resin surfaces enhance the durability of FLOWTITE pipes.

FLOWTITE pipes in the DN 375 to DN 3000 size range are formed on the "endless" mandrel illustrated in Figure 1.2 where any transportable length up to 21 metres can be produced. However standard pipe lengths are generally 12 metres in these diameters with the option of shorter or longer lengths also available. Pipes in diameters DN 80 to DN 300 are manufactured on a smaller machine, which uses individual mandrels of fixed length. Therefore the maximum pipe length is limited to 6 metres although shorter lengths are also available.

Once formed, the advancing mandrel carries the pipe forward to the curing station. Here induction heating of the steel mandrel internally combined with radiant heat applied externally raises the resin in the pipe wall to a temperature of about 120°C ensuring a rapid and complete cure. The pipe is now self-supporting and the mandrel is withdrawn enabling the pipe cutter to operate.

Pipes continue to move along the production line to the calibrating station where outside diameter and wall thickness tolerances are checked and corrected by machining if necessary. Spigot chamfer and witness marks are added. The pipe is then placed in the hydraulic tester for proof testing to twice the rated operating pressure.

Couplings are cut from specially made "coupling pipes" from the same machine of an appropriate diameter to allow internal boring to create grooves for the rubber seals and central register. They are also proof tested to 2 x PN pressure on a hydrostatic testing machine.

Figure 1.1 Wall cross-section of a FLOWTITE pipe
Figure 1.2 Layout of the winding machine and associated equipment for FLOWTITE manufacture
Figure 1.3 Shows arrangement of "cheeses" or spools of ECR glass used in winding process for supply of both continuous and chopped filaments
Figure 1.4 Configuration of the endless steel srip used to form the endless mandrel used for FLOWTITE pipes
Winding process showing the raw materials combining on the mandrel
Finished pipe emerging from high temperature curing station prior to being cut to length
Coupling blank is machined internally to provide grooves for REKA EPDM seals and centre register

FLOWTITE Applications

With the aging of the world's infrastructure there are millions of kilometres of water and sewer pipelines needing rehabilitation. This is a worldwide problem. What is causing a major dilemma is that that the deterioration is premature and lives predicted at the conceptual stage are not being realised. The prime cause of this problem is corrosion. Typical examples are:

• Internal attack in unprotected concrete gravity flow sewer pipes which deteriorate rapidly in the presence of sulphuric acid as a result of the hydrogen sulphide cycle. In pressure pipes, high levels of carbon dioxide in soft water supplies from underground rapidly degrade cementitious materials.
• External attack can be caused by aggressive soil/ground water conditions or stray electrical currents affecting ferrous and cementitious materials. These pipes are vulnerable when buried in poorly aerated and poorly drained soils of low resistivity. Saline soils, the presence of chlorides or sulphate-reducing bacteria also accelerates corrosion.

Plastic pipes, and specifically a GRP pipes, are not subject to any of these problems and with the improved engineering there has been an increase in their use as a replacement for corrosion prone materials.

The unique properties of Iplex FLOWTITE pipes with high strength combined with flexibility and corrosion resistance make FLOWTITE very attractive for use in most major infrastructure applications, including the following:

• Water Supply Transmission and Distribution Mains
• Irrigation
• Gravity Sewers
• Rising Main Sewers
• Slip Lining
• Submarine Pipelines
• Hydro-electric power station penstocks
• Water & Sewerage Treatment Plants
• Desalination Plants
• Thermal power station cooling systems
• Chemical Effluent Pipelines
• Industrial Process Pipelines
• Storage Tanks

A range of case studies can be found on the international FLOWTITE website www.flowtite.com