Our Plastic Materials
For the production of pipeline components, Praher uses mainly following thermoplastics:
Polyvinyl chloride (PVC-U)
PVC is, after polyethylene, one of the most widely produced and used polymer for pipe installations. PVC is produced by means of polymerization of vinyl chloride. It has good all-round properties and is easily cemented, welded and heat formed.
Two classes of PVC exists: soft PVC, produced by adding plasticizers and hard PVC also called unplasticized PVC (PVC-U) which is the most used polymer for pipeline systems.
PVC-U is an amorphous thermoplastic with versatility of use due to a good chemical, corrosion and weathering resistance. Proven as physiological harmless, PVC-U parts are suitable for contact with drinking water and food.
Chlorinated polyvinyl chloride (CPVC)
A post-chlorination of PVC-U generates CPVC (chlorinated polyvinyl chloride) characterized mainly by a higher temperature resistance but also higher tensile strength, toughness and chemical resistance than PVC-U.
Corzan® CPVC industrial systems from Praher are able to withstand harsh chemicals at higher temperatures (up to 80°C) and are utilized in different industries like the chemical process industry, metal working, the chlorine-alkali-industry and the palp and paper industry, etc.
Polypropylen is a thermoplastic belonging to the polyolefin formed by the polymerization of propylene.
PP is a semi-crystalline material with a density lower then of other common used thermoplastics. It has very good mechanical properties, resists chemically against a broad range of media and has a high heat deflection temperature.
Mainly three types of PP are used for industrial applications: the isotactic homopolymer (PP-H), the block copolymer (PP-B) and the randomized copolymer (PP-R).
Due to its homogeneity PP-H is preferred by Praher for the production of industrial valves.
Polyvinyliden fluoride (PVDF)
PVDF is a semi-crystalline thermoplastic synthesized from vinylidene fluoride by polymerization in emulsion or in suspension.
Polyvinylidene fluoride is belonging to the class of fluoropolymers having an unique combination of properties: excellent chemical resistance, high thermal stability, very good mechanical properties.
PVDF has an extremely good pressure-temperature range and an outstanding resistance against UV and -radiation, which allows it to be used for many unique applications when compared to other thermoplastics.
Advantages in the use of plastics
Right choice of material
1. Chemical resistance
The chemical resistance list gives an informative overview of our thermoplastics and elastomers. We distinguish three types of resistance:
Resistant materials: The material is unaffected.
Conditionally resistant materials: The medium can attack the material or causes swelling, service life is shortened. Reduced operating time and operating pressure.
Non resistant materials: The material is greatly impaired.
The pressure rating (PN marking) of an industrial part made of thermoplastic is determined for water as medium at a temperature of 20°C and a constant pressure. The pressure-temperature load capacity is of great importance for an optimal operation for a long service life of a thermoplastic industrial piping system. This results in a temperature reduction factor:
3. Safety or Design Factor
It should be also taken into consideration that the transported medium and the environment around the piping system respectively has an influence on the pressure resistance. In conclusion, the pressure reducing factors (as safety or design factors) can be determined by means of the diagrams above with reference to changing temperature conditions. Finally, the Safety or Design factor has to take into consideration all characteristics of a specific pipe line, like for example:
• pressure peaks – water hammer
• chemical resistance
• temperature fluctuation
• operating states (cavitation, abrasion, …)