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Plastics are macromolecular organic compounds formed by the chemical clustering of low molecular weight chemical building blocks (so-called monomers) [Bos00]. Due to the large number of possible clusters (linear, branched, crosslinked) polymers can be synthesized into thermoplastics and thermosetting plastics (thermosets) based on the desired properties. (Image: Schematic view of the arrangement of the chain molecules in plastics and their properties … |
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Thermoplastics also apply for plastic pipes. Thermoplastics deform under a certain temperature range (thermo-plastic). They do not undergo chemical change in their composition when heated and can be remoulded again and again. This unique property enables the welding of thermoplastic pipes and fittings. (Image: Heating and cooling cycle of thermoplastic) (Image: Structure of thermoplastics) This process is not reversible if a thermal decomposition of … |
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Thermosets can melt and take shape once; after they have solidified, they stay solid. The thermosetting process may be induced by heat, generally above 200 °C (392 °F), a chemical reaction occurs that is irreversible. (Image: Heating and cooling cycle of thermosetting plastic) (Image: Structure of thermosets) |
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Thermoplastics are constructed from small or non-branched (i.e. linear) hydrocarbon chains, which are connected to one another by a weak physical bonds.These binding forces are more effective when the chains are aligned in parallel. Such regions are called crystalline (red circle), and are in contrast to amorphous (disordered) regions in which the macromolecules are entangled [WikiThermoplast]. (Image: Thermoplastic chains) |
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Important thermoplastics are:
For plastic sewer pipes, the following thermoplastics are used :
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Pipes of plastic materials have been utilised in sewage technology since the 1930s. Today, they are not only applied when sewers have to be newly laid, but particularly also when drains and sewers have to be renovated. Besides the type of plastics, the following principles of construction are also differentiated:
(Image: Fabekun® HS pipes - blue = … |
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Solid wall systems are categorised into:
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Scope of application The extruded single-layer systems of uPVC are manufactured in the nominal size range DN/OD 110 up to about 630 (normatively up to 1,000) and with lengths of 500, 1,000, 2,000 and 5,000 mm. The pipes are connected by means of a spigot-and-socket joint with a gasket inserted at the factory. DIN EN 1401 is valid for all uPVC pipes. [EN1401-1:2009] (Image: Pipe joint of a solid wall uPVC pipe with a sealing ring inserted at the factory … |
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Scope of application Extruded single-layer systems of HD-PE according to DIN EN 12666 are manufactured in the nominal size range DN/OD 110 up to about 1,200 (exceptionally up to 1,600) with lengths of 5,000, 6,000 and 12,000 mm. The pipes are joined using sleeves and flanges as well as butt welding using a heating element and electrofusion welding. Connecting sleeves with sealing elements inserted at the factory are also used
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Scope of application According to DIN EN 12666, pipes made of extruded two-layer systems of HD-PE are manufactured in the nominal size range DN/OD 100 up to about 1,200 with lengths of 5,000, 6,000 and 12,000 mm. The pipe joints are identical with those of the extruded single-layer systems of HD-PE. [EN12666-1:2011] (Image: Two-layer system made of HD-PE with an inspection friendly light inner layer) (Image: Two-layer system made of HDPE with outer … |
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Scope of application The extruded multi-layer systems with mechanical protective properties of PE (PE 100) according to DIN EN 12201 are principally applied for pressure- and vacuum sewerage systems. However, they are also used as gravity pipelines. The pipes are predominantly joined by means of electrofusion welding. [EN12201:2013] (Image: Solid wall pipes with an outer protective layer (protective casing) and an inspection friendly light inner layer) (… |
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Scope of application The multi-layer systems include the co-extruded core-foamed three-layer systems of uPVC. They are subject to the approval document of the German Institute for Construction Engineering in Berlin and are manufactured in the nominal size range DN 100 to 600 with lengths of 500, 1,000, 2,000, 5,000 and 12,000 mm. The pipes are joined by means of connecting sleeves with a sealing medium inserted at the factory. DIN EN 13476 Part 2 is … |
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According to DIN 16961, pipes with profiled wall and smooth pipe inside are “pipes with an outside profile, pipes with a dissolved section, profiled or solid wall wound pipes as well as core-foamed pipes”.
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The following distinctions are made according to DIN EN 13476 Part 2 and Part 3: Type A (1): Multilayer construction or hollow-wall construction with axial hollow sections Type A (2): Hollow-wall construction with spirally or radial formed hollow sections Type B: Ripped or corrugated wall construction [EN13476-2:2007] [EN13476-3:2009] (Image: Plastic pipes with profiled wall and smooth pipe inside - Types A) (Image: Plastic pipes with profiled wall and … |
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Type A (1): Multilayer construction or hollow-wall construction with axial hollow sections A pipe or fitting with a smooth internal and external surface and in which the outer and inner walls are connected by internal axial ribs or a foamed or non-foamed intermediate layer of thermoplastics, shall be designated Type A1 (Image: Hollow-wall construction with axial hollow sections) |
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Type A (2): Hollow-wall construction with spirally or radial formed hollow sections A pipe or fitting with a smooth inside and external surface and in which the outer and inner walls are connected by internal spiral or radial formed ribs, shall be designated Type A2 (Image: Hollow-wall construction with spirally formed hollow, rectangular sections) (Image: Hollow-wall construction with radial formed hollow, circular sections) |
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Type B: Ripped or corrugated wall construction: A pipe or a fitting with plain internal surface and a solid or hollow spiral or annular profiled external surface shall be designated Type B: (Image: View of an extruded solid wall pipe with ribbed outer surface) (Image: View of an extruded solid wall pipe with ribbed outer surface) |
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Scope of application Pipes that are composed of an extruded solid wall system with ripped or corrugated outer surface are joined by means of sockets. Their manufactured lengths are 2,000, 3,000 and 5,000 mm. The pipes have a plain inner surface and a concentrically ribbed outer surface. (Image: View of an extruded solid wall pipe with ribbed outer surface) (Image: Elevation and section of an Ultra-Rib sewage pipe with pipe joint [FI-Upono]) |
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Spiral-wound pipes are made of PVC-U, PE or PP by means of a winding process and are provided with a screw-shaped circumferential profile reinforcement or as a double-wall profile; whereby the inner surfaces of the pipes are always smooth. Spiral-wound pipes of PE are defined and described in DIN 16961 and also in PAS 1065. [DIN16961-1:2011] [PAS1065] (Image: Longitudinal section through spiral pipes (Bauku GmbH) [FI-Bauku]) |
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Glass fibre reinforced plastics (GRP) are among the thermosetting plastics, which are no longer fusible by temperature influence. Basic raw materials for GRP are thermosetting resins (epoxy, vinyl ester or unsaturated polyester resin) which are used as binders and, glass and quartz sand and calcium carbonate powders which are used as aggregates The latter two components are referred to as fillers, additives for increasing the volume of the mixture … |
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Glass fibre reinforced plastics usually consist of two components, resin and glass fibres. The addition of fillers is possible. The resin used is primarily polyester resin and epoxy resin is also used in small quantities. In the given case of application, the glass fibre reinforcing is primarily used in the form of
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The following methods are used in the manufacture of pipes and fittings made of GRP [Grüne72] [Himml81]: Hand lamination In this process, used mainly for the production of fittings but also for pipe joints, glass fibre mats or weaves are placed on a mould or the component and the resin is applied and spread by hand. Fibre spray method Simultaneous spraying of resin, glass fibre cut from roving and filler materials onto a mould. The work is carried out … |
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Two different variations can be distinguished for this method: Option 1: Inserting a glass fibre mat by hand into a wooden cylinder (mould). This is then put into rotation and the resin is then added at the same time by means of a pipe. Option 2: The resin, the cut glass fibre, as well as the filler material are inserted into the rotating mould by means of a special insertion arm. This is done either all together or in the desired sequence, so that … |
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(Image: Structure of a pipe wall of a GRP pipe cast by the centrifugal spray method (option 2)) |
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What defines the mechanical properties of GRP pipes? The mechanical properties of GRP pipes are determined by Schlehöfer and Grünwald [Schle73] [Grüne72]: The adhesion between resin and fibres, The type, content and position of glass fibres and The percentage of fillers. (Image: GRP jacking pipe) The pipe stiffness, which is relatively low when resin and fibres are used exclusively, can be adjusted to the respective requirements by integrating layers with … |
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