Neumayer, Knauder, Pilz, Lang, Major
Posters - Additional Information # 2001 Munich
The importance of plastics piping systems based on glass fibre reinforced unsaturated polyester resins (GRP-UP) for water supply, industrial or sewer pipe works has continuously increased worldwide. Centrifugal casting (CC) is one of the most important technologies to manufacture CC-GRP-UP pipes. UP-resins, mineral fillers and glass fibres (Figure 1) are injected according to specific laminate designs into a rotating steel cylinder (mould) by a so-called feeder (6 m – shaft, Figure 2). Due to centrifugal forces equal approx. 75 times gravity the constituents are compacted to a dense laminate (Figure 3), followed by an exothermal polymerization process resulting in cured and stable pipe wall laminates with excellent mechanical and chemical properties (Figure 4).
Considering the characterization of the pipe wall material properties several aspects has to be taken into account deducted from the above described production process.
1. The material to be characterized is created during the centrifugal casting process by centrifugal forces. Due to centrifugal acceleration – equal 75 times gravity – the injected constituents are highly compacted forming a dense laminate.
2. The number of various constituents and the manufacturing process result in a rather complex mechanical performance profile of the pipe wall material.
3. The orientation of fibres as a result of mould rotation leads to anisotropic material behaviour.
4. Depending on the application (pressure, gravity, jacking) the pipe wall is designed as a sandwich construction with different functional layers (Figure 5).
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