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Nov 04, 2004 According to [ATVM143-1:1989], the term maintenance is defined as: Measures for maintaining the nominal condition. The nominal condition is understood to be the determined (required) condition for the respective case of an installation, a structure or individual components (Abschnitt 2.1) (Abschnitt 5.1). Maintenance is closely linked with the other two main groups of measures of rehabilitation and maintenance, i.e. the inspection and the rehabilitation. … |
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The cleaning of sewer systems is an important part of maintenance. It is carried out:
Besides the above-… |
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(Image: Flushing manhole with overflow [Frühl10]) According to EN 752-7 [DINEN752-7] surge flushing is understood to be "the creation of a short-term strongly increased flow for the purpose of removing obstacles or deposits in sewage pipes and sewers." In this process, the sewage or clean water is backed up in manholes (Bild 3.2.2.1), or chambers specially suited for this purpose, and then suddenly released. The shock wave of the backed-up water that … |
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In this process, devices are introduced into the sewer that reduce the cross-section and back-up the sewage. This back-up wash round the devices and moves them which causes the non-hardened deposits to be loosened and conveyed further [Führb80]. With back-up flushing, the following apparatus are used [ATVA140] [NASSCO89a] [Führb80] [Frühl10] [Gürsc21] [ATV95c] [Tchob89] :
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The oldest sewer cleaning processes, which are still partly used today under special circumstances in the sections of the sewer suitable for their use, belong to the group of flushing processes [Frühl10] [Gürsc21] whereby they are divided into:
Both methods can only be used for the removal of loose, non-hardened deposits. They assume a free flow of sewage and a high flow … |
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Feb 16, 2011 In these investigations, the position of the cleaning nozzle lying on the pipe invert remains unaltered. It is positioned in such a manner that any damage that occurs in the pipes and pipe joints can be observed. The investigations are carried out at various pressure levels, whereby the pressure begins at 75 or 100 bar and is raised by steps of 25 bar up to the maximum pressure of the cleaning system. Each level of pressure is maintained for 1 minute … |
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Nov 04, 2004 In order to simulate long-term loading, the respective cleaning nozzle is pulled through the 12 m long test section 40 to 60 times with a constant water pressure of 150 bar measured at the HP pump and a constant speed of approximately 4 m/min. This pull-through speed was determined on the basis of evaluation of several applications in practice as well as calculation documentation. In the course of the investigations, 30 l of sand, gravel and stones … |
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Nov 04, 2004 Rehabilitation and Maintenance of Drains and Sewers High pressure Water Jetting Process (HP Water Jetting Process)
Unprofessional application of the high pressure water jetting process can cause pipe damage in the form of grooves, chipping, cracks or holes in pipe walling and linings (Abschnitt 2.1) (Bild 3.2.3.1) (Bild 3.2.3.1). Especially dangerous moments occur … |
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The high pressure water jetting process (HP water jetting process) [Lenz96] is the almost universal process, used in about 90 % of all sewer cleaning processes for removing deposits within the scope of regular maintenance as well as for cleaning as a preparatory measure for sewer inspection or rehabilitation. It can usually not be used when hardened deposits are present or for removal of flow obstacles, e.g. internally projecting laterals, artificial … |
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Nov 04, 2004 In accessible sewers manual cleaning can be carried out, on the one hand, for the removal of extended, hardened or crystalline deposits and, on the other hand, for careful preparation for rehabilitation measures. In the first case, pickaxes, compressed air hammers, careful blasting, small motor graders, loaders and others are used. In the second case, and depending on the piping material and the selected method of rehabilitation, special tools such … |
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Feb 16, 2011 Mechanical cleaning apparatus are primarily used for removing and loosening hardened deposits and then for the removal of solids. They are introduced into the sewer through the manholes and pulled (hoist pull), pushed (spiral) or pressed (transport medium of a pressure pipe) through the section of the sewer to be cleaned.
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Nov 04, 2004 A member of this group is the pipe ring chisel, which is utilised in straight sections from DN 400 or ovoid cross sections from 200/300 for removing hard deposits also on all sides (Bild 3.2.4.3.1) (Bild 3.2.4.3.1) [Schop81].
The apparatus is driven by compressed … |
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Feb 16, 2011 This type of apparatus is remote controlled and used with TV monitoring in the nominal size region DN 200 to DN 600 for removing hardened deposits (Bild 3.2.4.3.2) (Bild 3.2.4.3.2) (Bild 3.2.4.3.2) (Bild 3.2.4.3.2), internally projecting laterals (Bild 3.2.4.3.2) (Bild 3.2.4.3.2) and other flow obstacles such as roots (Bild 3.2.4.3.2). The motive force is hydro-dynamic or hydraulic oil. In order to ensure that the process will protect the pipe, … |
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Nov 04, 2004
The "automatic hammer-bore nozzles" (Bild 3.2.4.3.3) (Bild 3.2.4.3.3) belong to this category. They were developed for the removal of hardened deposits, blockages and root ingress in the nominal size region of DN 100 to 1000. The motive power is provided by the … |
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Feb 16, 2011 (Image: Pipe saw robot [FI-KMG]) Cutting apparatus are used in the nominal size range from DN 100 to DN 600 for the removal of internally projecting laterals and other localised obstacles as well as roots. They are usually used with the aid of TV observation [NASSCO89a] [WPCF85]. As regards the method of operation, this can be divided into the mechanically operated apparatus and those that work with high pressure water jets. The mechanically operated … |
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Feb 16, 2011 Sand blasting apparatus can be used in order to obtain a particularly high degree of cleaning, especially for creating a metallic white surface on steel and cast piping. The apparatus is pulled into the pipe to be cleaned by means of a tension ring and slowly pulled back with the hose during the sandblasting process, during which the used sand is blown forward to the pipe. This apparatus is supplied for nominal size range DN 60 to DN 1600 (Bild 3.2.4.3.5) |
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Nov 04, 2004 Special apparatus have been developed in the past few years, especially in the non-man-accessible regions, for removal of hardened deposits, internally projecting laterals or artificial obstacles and roots, as well as for achieving a specially high degree of cleanliness. They can be divided according to their method of operation into:
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The process for increasing the flow velocity by the introduction of air is used, for example, in Hamburg in pressure piping. Two or four times a day, or at irregular periods of long-term flushing, air is blown into the pressure pipe system and in this way the flow cross section is reduced. The increased velocity of the flow causes any gathered deposits to be whirled up and conveyed further. In pressure piping that is adapted to the lie of the land, … |
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A further possibility for removing deposits in piping systems is offered by the Ultrasonic process. This process, developed and patented in France, can be used in the nominal size range from DN 20 to DN 600 for drains and sewers as well as for hot water systems [FI-Alben] [Loese98a] [Loese98b]. The manufacturer claims that with a working pressure of 700 to 1050 bar and a water flow of 12 to 17 l/min, pipes of PVC, PE, fibre cement, cast iron, steel … |
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(Image: Vibration nozzle Rümax [FI-IBG]) The cleaning effect of the vibration nozzle is based on the creation of a frequency field, which separates the structure of the deposits to be removed from the pipe or sewer wall and conveyes it away with the wastewater (Bild 3.2.4.4.3). According to the manufacturer, the process can be used for the removal of mineral deposits, concrete, slag, filler masses or similar substances from sewers in the nominal size … |
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These processes are utilised for the removal of
The former case is limited mostly to industrial pipes and pipelines for oil and gas. In the sewage sector it is reserved for exceptional cases. An example of an application of the removal of incrustations in dam wall drainpipes is dealt with in detail in [Siebe81]. Conditions for these applications are especially:
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(Image: Removal of roots by the use of foamed herbicides) The mechanical root removal methods mostly used today, e.g. by cutting or boring (Abschnitt 3.2.4.3) usually leads to strengthened new root formation requiring treatment again at relatively short intervals [Schmi81]. An alternative to this is seen as the treatment with various herbicides, about whose suitability comprehensive experiments have been carried out [Sulli77] [Ahren70] [Townl73]. The … |
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Biological cleaning processes are utilised for the degradation of fats and fibrous materials in the sewer wall slime, as well as phenols, proteins and mineral oils and, furthermore, for removal or reduction of odour nuisances [Baig76] [Jense77]. Fundamentally, there are two possible paths to biological support of the degradation processes of organic oils and fats [ATVAG3116] :
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Nov 04, 2004 In particular cases, special processes are used for cleaning, such as:
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Mechanical cleaning can be carried out
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