Defined Wearing Course Ensures Long Service Life
Waste water sewers are permanently exposed to high chemical (chemical substances such as acids, lyes, etc.) and mechanical stress loads (wear from suspended solids such as sand and gravel or stress loads from high-pressure flushing).
As we all know, increased abrasive wear results in a shorter service life. Internationally, the individual hose liner systems are tested for this during their approval processes and need to prove that they are suitable for a service life of 50 years or more.
Compared to all other hose liners on the market, Alphaliners possess a particularly high level of surface quality. This is achieved by using a vylene-bonded high-grade resin layer of approx. 0.5mm (at least 0.4mm acc. to DIBt approval Z-42.3-447). Currently, Alphaliners are the only hose liners worldwide where the minimum wearing course thickness is defined on the pipe inside. This specially smooth and resistant wearing course provides the Alphaliner with excellent abrasion resistance.
During the production process, a special resin-impregnated polyester vylene fabric is applied to the Alphaliner surface where the wearing course fulfils its function, ensuring exact adjustment of the resin content. 85% of this vylene is resin-impregnated so it merges permanently with the structurally supporting glass fibre complex, providing a specially smooth and highly wear-resistant surface.
According to DWA worksheet M 143-3, the wear of the wearing course must not impact the functionality and service life of the liner; the manufacturer needs to describe and present this in detail in a certificate of suitability acc. to DIN EN 295-3 (Darmstadt tipping trough) and DIN 19523 (high-pressure flushing trial). The standard stipulates that the wearing course is always thicker than the abrasion resistance established in the Darmstadt tipping trough trial (EN 295-3) for the liner, and that the wearing course forms no part of the liner's structurally relevant composite thickness. Without proof of abrasion resistance acc. to EN 295-3 you need to allow for a 1mm increase in wall thickness across the entire liner as an additional wearing course.
In its current DWA worksheet M 143-3 (2012 white paper), Germany is now the first country bindingly instructing on-site curing hose liners to always be equipped with a wearing course.
- Integrated coating (thermoplastic material),
- high-grade resin layer (pure resin coating)
- glass-, felt-, or vylene-bonded resin-rich layer
on the inner surface of the hose liner. Compared to the integrated coating, the resin-rich wearing courses excel in very high mechanical resistance. Hose liners' wearing courses as high-grade resin layer are based on excess resin from the supporting laminate and not consistently reproducible. Depending on resin viscosity, pressurisation of the liner, etc., the resin layer's thickness varies considerably and can exhibit increased wear in case of particularly high mechanical stress loads, or the pipe bottom may become damaged due to regular high-pressure flushing in the sewer. Applying a glass-, felt-, or vylene-bonded resin-rich layer onto the base course makes it possible to realise a consistently reproducible thickness in every liner.
Vylene materials such as polyester vylene ensure a very high resin content in this layer of at least 80 - 90%. Polyester vylene with its special properties has proven itself in the hose liner application for over 15 years.
For the Alphaliner system, the Darmstadt tipping trough trial established an abrasion resistance of 0.23mm. With an end-to-end overlapping high-grade resin layer of approx. 0.5mm, this hose liner has proven its great safety margins. No other hose liner system specifies the thickness of its wearing course. Therefore, these liners do not allow any statements about their safety margins. From experience, safety margins are necessary in particular for high-pressure flushing as in real-life situations, higher pressure stress loads than indicated in the approval test acc. to DIN 19523 occur due to ignorance when cleaning the sewer.
Approx. 2,000,000m of Alphaliner installed since early 2010 show no surface damage.
The Alphaliner system is a safe and economical investment for long-term communal and industrial sewage system rehabilitation.