Tube cleaning

Wiki Loves Earth in focus during May 2015Discover nature, make it visible, take photos, help

Wikipedia!

From Wikipedia, the free encyclopedia

For the article about the tube cleaning of steam locomotive boilers see: Tubecleaning (locomotive).Tube cleaning describes the activity of, or device for, the cleaning andmaintenance of fouled tubes.The need for cleaning arises because the medium that is transported throughthe tubes may cause deposits and finally even obstructions. In systemengineering and in industry, particular demands are placed upon surfaceroughness or heat transfer. In the food and pharmaceutical industries as well asin medical technology, the requirements are germproofness, and that the tubesare free from foreign matter, for example after the installation of the tube orafter a change of product. Another trouble source may be corrosion due todeposits which may also cause tube failure.Depending on application, conveying medium and tube material, the followingmethods of tube cleaning are available:

Contents [hide] 1 Lost tubes2 Chemical process3 Mechanical process

3.1 Off-line process3.2 On-line process

4 Thermal process5 Special types6 See also7 References

Lost tubes [edit]In medical field, "lost" tubes are tubes which have to be replaced after singleuse. This is not genuine tube cleaning in the proper sense and is very oftenapplied in the medical sector, for instance with cannulas of syringes, infusionneedles or medical appliances, such as kidney machines at dialysis. Thereasons for the single use are primarily the elimination of infection risks but also

Article Talk Read Edit More Search

Edit links

Main pageContentsFeatured contentCurrent eventsRandom articleDonate to WikipediaWikipedia store

InteractionHelpAbout WikipediaCommunity portalRecent changesContact page

ToolsWhat links hereRelated changesUpload fileSpecial pagesPermanent linkPage informationWikidata itemCite this page

Print/exportCreate a bookDownload as PDFPrintable version

LanguagesDeutsch

Create account Log in

the fact that cleaning would be very expensive and, particularly with cheap massproducts, out of all proportion in terms of cost. Single use is therefore commonpractice with tubes of up to 20 mm diameter. For the same reasons as in themedical sector, single use may also be applicable in the food andpharmaceutical process technology, however in these sectors the tubediameters may exceed 20 mm.In other fields (e.g., in heat exchangers), tubing may also sometimes need to bereplaced (or removed, plugged, etc.), but this typically occurs only after aprolonged use, when the tube develops serious flaws (e.g., due to corrosion).

Chemical process [edit]Chemical tube cleaning is understood to be the use of cleaning liquids orchemicals for removing layers and deposits. A typical example is the deliming ofa coffee maker where scale is removed by means of acetic acid or citric acid.Depending on the field of application and tube material, special cleaning liquidsmay be used which also require a multi-stage treatment:

chemical activationcleaningrinsing

This method of cleaning calls for a shutdown of the relevant system whichcauses undesired standstill periods. To safeguard a continuous productionoperation it may be necessary to install several systems. Another disadvantage:in the field of large-scale technology (reactor, heat exchanger, condenser, etc.),huge quantities of cleaning liquids would be required which would cause majordisposal problems. A further problem occurs in the food industry through thepossible toxicity of the cleaning liquid. Only the strict observance of rinsinginstructions and an exact control of the admissible residue tolerances canremedy things here. This in turn requires expensive detection methods.Generally the process of chemical tube cleaning is applicable for any diameter,however practical limits of use ensue from the volume of a pipeline.

Mechanical process [edit]A mechanical tube cleaning system is a cleaning body that is moved through thetube in order to remove deposits from the tube wall. In the most simple case it isa matter of a brush that is moved in the tube by means of a rod or a flexiblespring (device). In large-scale technology and industrial sector, however,several processes have developed which necessitate a more detailed definition.

Off-line process [edit]An off-line process is characterized by the fact that the system to be cleanedhas to be taken out of operation in order to inject the cleaning body(ies) and toexecute the cleaning procedure. An additional distinction must be madebetween active and passive cleaning bodies.Passive cleaning bodies may be a matter of brushes or special constructions

Schematic representation of the cleaning process and of the filtrationtechnology

like scrapers or so-called "pigs", for instance, which are conveyed through thetubes by means of pressurized air, water, or other media. In most cases,cleaning is implemented through the oversize of the cleaning bodies comparedto the tube inner diameter. The types range from brushes with bristles of plasticor steel to scrapers (with smaller tube diameters) and more expensive designswith spraying nozzles for pipelines. This method is applied for tube and pipediameters from around 5 mm to several metres. Also belonging to this field isthe cleaning of obstructed soil pipes of domestic sewage systems that is doneby means of a rotating, flexible shaft.The active cleaning bodies are more or less remote controlled robots that movethrough the tubes and fulfill their cleaning task, pulling along with them not onlycables for power supply and communication but also hoses for the cleaningliquid. Also measuring devices or cameras are carried along to monitor thefunction. To date, such devices have still required minimum diameters of around300 mm, however a further diminution is being worked on. The reasonablemaximum diameter of this kind of devices is 2 m because above this diameteran inspection of the pipe would certainly be less expensive. For such largediameters a robot application is imaginable only if health-hazardous chemicalsare in use.

On-line process [edit]In the on-lineprocess, thecleaningbody movesthrough thetubes withtheconveyingmediumand cleansthem bymeans of itsoversizecomparedto the tubediameter. Inthe range ofdiametersof up to 50 mm these cleaning bodies consist of sponge rubber, in largerdiameters up to the size of oil pipelines it is a matter of scrapers or so-calledpigs. Sponge rubber balls are applied mainly for cooling water, like sea, river, orcooling tower water. For the chemical or pharmaceutical industry, speciallyadapted cleaning bodies are imaginable but the conveying media flows are soweak that off-line processes are employed in most cases. Given the fact that the

cleaning bodies are not allowed to remain in the conveying medium they haveto be collected after passing through the tubes. In the case of sponge rubberballs this is done through special strainer sections; for scrapers or pigs anoutward transfer station is provided. According to the Taprogge process, thesponge rubber balls are re-injected upstream of the system to be cleaned by acorresponding ball recirculating unit whereas the scraper or pig is mostly takenout by hand and re-injected into another collector. Sponge rubber ballstherefore safeguard a continuous cleaning while the scraper or pig system isdiscontinuous.

Thermal process [edit]In thermal tube cleaning the layer or deposit is dried through a heating wherebyit flakes off due to its embrittlement and is then discharged, either by theconveying medium or a rinsing liquid. Depending on the required temperature,the heating can be either a parallel tube heating or an induction heating. Thisprocess is an off-line process. Occasionally it is also used for the sterilization oftubes in the pharmaceutical or food industry. A diameter range cannot beindicated here because this method can be applied for certain processes only; atechnical limitation of the heating is given only by the materials and the requiredamount of heat.

Special types [edit]Special types of tube cleaning are all such types which are partly inexperimental stage only and do not come under the process types mentionedbefore, such as, for example:

induction of water hammers, so that the layer or deposit comes off throughshort-term material elongationuse of vibration generators, partly at the tubes through vibration exciters,partly by means of piezoelectric crystals in the conveying medium, in orderto transform the conveying medium into a cleaning medium throughreduction of the surface tensionmagnetic fields to avoid tube calcificationnanotechnical treatment of tube surfaces to avoid layers and deposits

See also [edit]FoulingFouling MitigationBiofouling

References [edit]

Privacy policy About Wikipedia Disclaimers Contact Wikipedia Developers Mobile view

This page was last modified on 6 March 2015, at 03:06.Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply.By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia is a registered trademarkof the Wikimedia Foundation, Inc., a non-profit organization.

This article does not cite any references orsources. Please help improve this article byadding citations to reliable sources. Unsourcedmaterial may be challenged and removed.(January 2008)

Categories: Fouling Piping Tubing (material)

MoreTube cleaningInteractionToolsContentsPrint/exportLanguages

Lost tubes[edit]Chemical process[edit]Mechanical process[edit]Off-line process[edit]On-line process[edit]

Thermal process[edit]Special types[edit]See also[edit]References[edit]