Trenchless pipe rehabilitation
The grave pipe rehabilitation includes a variety of methods for obtaining the underground infrastructure of supply and disposal lines. These are necessary to repair age damage to pipes and sewers . In contrast to the open construction method, no roads or sidewalks have to be broken up with closed measures . This eliminates repair costs for wear at the separation points. Another advantage is that no new route and only limited installation space below the surface is necessary. With trenchless renovation, residents are less annoyed by noise, dust and exhaust gases, and disruptions to road and delivery traffic are also limited. Another ecological plus point is that no large amounts of soil have to be excavated. This protects the tree roots .
Historical development
The trenchless renewal of pipelines in the drinking water and gas sectors began in Germany as early as the mid-1950s. In this way, the drinking water pipeline from Wilhelmsburg, which is still in operation today, was renovated in 1956.
In the 1960s, British engineers experimented with methods that could be used while preserving substance to rehabilitate the over 165-year-old London sewer network. 1971 succeeded Eric Wood with the CIPP a basic innovation. The idea was to line a canal with a hose soaked in synthetic resin , which can be hardened "in situ" (lat. On site ) to form a self-supporting pipe. A few years later, Wood's process, which produced many successors, was granted a patent.
At the beginning of the 1980s, a British energy company (British Gas / today: BG Group ) suggested a method by which pipes that were no longer functional could be replaced with new ones without trenches: burst lining. In the 1990s, the area of gravity pipelines was increasingly added through new technologies .
Over the past 30 years, trenchless process and material variants have been successively developed. The best-known and most frequently used processes include pipe lining, partial liners, pipe string lining , burst lining, close-fit processes and pipe-eating (microtunnelling).
Procedure
Partial liners
The partial liner, also known as a short liner, is a fiberglass or felt tube impregnated with reaction resin. It is cut exactly to the inside diameter of the sewer section to be rehabilitated. The material is corrosion-resistant and can be used in multiple layers. This allows different wall thicknesses to be achieved.
The decisive factor for the static load-bearing capacity of the liner is the amount of reaction resin with which the carrier material is impregnated. Be used epoxy - polyurethane - or Organomineralharze. The partial liner is drawn in through existing openings. Thanks to the supplied compressed air, the hose is firmly attached to the pipeline. The material has hardened within a short time and is therefore firmly attached to the old pipe.
Partial liners can be used to repair cracks, leaky sleeves and corrosion damage, among other things .
Pipeline lining / relining
With pipe string lining, a flexible pipe string is inserted into the old pipeline via excavation pits . The strand often consists of polyethylene or polypropylene and is connected in one piece or lengthways with a force fit. Its length corresponds at least to the length of the pipe section to be rehabilitated. The remaining annulus, a cavity between the new and old pipe, is at least partially dammed.
Depending on which bending radius is permissible for the new pipes used, the pipe string liner can be installed in smaller dimensions without a construction pit via existing sewage shafts. The pipe string lining is primarily used for renovation purposes.
For the last part of supply lines, the area of house connection and house entry, this process is often used in the area of gas and water supply. This is where the renovation capsule is used.
Pipe lining
Pipe lining is a common method for trenchless pipe rehabilitation. Here a hose is inserted into the pipe to be rehabilitated. The hose can then be cured in various ways, glued to the old pipe or left free in the old pipe.
Pipe lining hardening on site
Here, a plastic hose ( hose liner or inliner ) soaked with synthetic resin is inserted into the sewer and then cured thermally or with UV light to form the new "pipe in the pipe". The area of application extends from free gradient pipes to pressure pipes (drinking water, gas and waste water) and a pipe dimension range of DN 100 - 2,500 mm.
Inner coating
The interior coating is mainly used for pipes in buildings (downpipes, toilet pipes and kitchen drains, etc.). In this process, the liquid resin is sprayed or spun onto the inside of the old pipe wall. The process can be used with almost all materials (PVC, stoneware, concrete, cast iron, GRP, PE, PP, etc.), but there must not be any larger holes or sleeve offsets (gaps) in the lines.
Renovation of sewage pipe nominal widths from 50 mm - 150 mm from the inside in inhabited apartments and buildings is possible.
Lining with retracted hoses
A flexible hose, usually consisting of an outer layer made of PE, a fabric core made of reinforcing fibers (e.g. Kevlar) and a media-specific inner layer, is pulled into the old pipe. The hose then remains in the old pipe without being glued to it. The fabric core absorbs the internal pressure, the external pressure continues to be carried by the old pipe. An annulus remains between the old pipe and the liner.
Burst lining
This process breaks up the old pipeline and displaces it into the surrounding subsoil . At the same time, a new pipe of the same or larger nominal size is pulled in. Depending on the application of force, a distinction is made between dynamic and static burst lining.
With dynamic burst lining , a cable winch supports the bursting and pulling in process. A compressed air-powered bursting hammer serves as the displacement body. The ramming energy is transferred to the old pipeline so that it is broken open.
With static burst lining, the force is introduced hydraulically via a linkage . The ladder-like connected rod pulls a bursting body through the old pipe, destroys it and at the same time introduces the new pipe.
Burst lining is used for the trenchless renewal of gas, water and sewage pipelines. It is suitable for the renewal of old pipes made of stoneware, asbestos cement, gray cast iron, plastic or unreinforced concrete as well as for steel pipelines .
Close-fit procedure
The term close-fit stands for close-fitting, which means that there is minimal or no annular space left. Used z. B. a compact pipe made of high density polyethylene (PE-HD) that can be deformed. When it is warm, the PE-HD pipe is folded into a C-shape. Once cooled, it is wound onto pipe drums and transported to the construction site. The deformation reduces the pipe cross-section by up to 30 percent, which makes it easier to pull it into the pipe to be rehabilitated.
After being pulled into the old pipe, the new inliner pipe is heated with hot steam. The heat triggers the memory effect, which brings the PE-HD pipe back to its original round shape. The inliner fits snugly against the old pipe from the inside (close-fit) and remains permanently in this shape. The close-fit process can be used to renovate pipes and ducts.
Pipe eating (microtunnelling)
With pipe-eating, the old lines are first run over with micro-tunnel machines. Then the defective pipes are "eaten up" with special removal tools, i. H. milled off. With jacking pipes, a new sewer is laid in the same route, which enables the installation of larger pipe cross-sections. The microtunnel machines consist of steel articulated shields that are steered with integrated hydraulic cylinders . They can be controlled very precisely so that an exact pipe position can be guaranteed.
In trenchless pipe rehabilitation, pipe eating is one of the renewal processes.
quality control
For quality control and assurance, there are a large number of regulations and leaflets in Germany with different legal binding force. The DIN-EN standards are a benchmark for impeccable technical behavior. Other important sources of information are the worksheets and information sheets of the ATV-DVWK (Abwassertechnische Vereinigung - German Association for Water Management, Sewage and Waste) and the quality and test regulations of the German Institute for Quality Assurance and Labeling eV The information sheets of the Pipeline Rehabilitation Association (RSV ), which was founded in 1992 by the leading German pipe rehabilitation companies as an association for quality assurance.
Individual evidence
- ↑ Zu Eulenburg, Artur: Stable at the top ( page can no longer be accessed , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. . In: bi Umwelt Bau 4/2009, p. 74. Retrieved on December 21, 2009.
- ^ Zech, Horst: Overview of techniques and experiences in sewer rehabilitation. In: 3R International 10/2009, p. 562.
- ^ Institute for Underground Infrastructure: Rehabilitation of house connection lines. Experience report (PDF; 1.7 MB). Retrieved December 21, 2009.
- ↑ GSTT: GSTT Information 20-1. Retrieved January 23, 2020 .
- ↑ Diringer & Scheidel pipe renovation: Berstlining . Retrieved December 21, 2009.
- ↑ Lipskoch, Frederik: Perfect fit in the pipe. In: Der Gemeinderat 4/2009, p. 55.
- ↑ Hölterhoff, Jens: Trenchless laying of sewers and sewers (PDF; 230 kB). In: German Society for Trenchless Technology eV. Accessed December 21, 2009.
- ↑ Dilg, Rainer: Quality standards for pipe lining processes ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. . In: tis 6/2003, pp. 40-46. Retrieved December 21, 2009.
