Tube cleaning

Tube cleaning describes the activity of, or device for, the cleaning and maintenance of fouled tubes.

The need for cleaning arises because the medium that is transported through the tubes may cause deposits and finally even obstructions. In system engineering and in industry, particular demands are placed upon surface roughness or heat transfer. In the food and pharmaceutical industries as well as in medical technology, the requirements are germproofness, and that the tubes are free from foreign matter, for example after the installation of the tube or after a change of product. Another trouble source may be corrosion due to deposits which may also cause tube failure.^{[citation needed]}

Depending on application, conveying medium and tube material, the following methods of tube cleaning are available:

In the medical field, "lost" tubes are tubes which have to be replaced after single use. This is not genuine tube cleaning in the proper sense and is very often applied in the medical sector, for instance with cannulas of syringes, infusion needles or medical appliances, such as kidney machines at dialysis. The reasons for the single use are primarily the elimination of infection risks but also the fact that cleaning would be very expensive and, particularly with cheap mass products, out of all proportion in terms of cost. Single use is therefore common practice with tubes of up to 20 mm diameter. For the same reasons as in the medical sector, single use may also be applicable in the food and pharmaceutical process technology, however in these sectors the tube diameters may exceed 20 mm.^{[citation needed]}

In other fields (e.g., in heat exchangers), tubing may also sometimes need to be replaced (or removed, plugged, etc.), but this typically occurs only after a prolonged use, when the tube develops serious flaws (e.g., due to corrosion).^{[citation needed]}

Chemical tube cleaning is understood to be the use of cleaning liquids or chemicals for removing layers and deposits. A typical example is the deliming of a 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 liquids may be used which also require a multi-stage treatment:

This method of cleaning calls for a shutdown of the relevant system which causes undesired standstill periods. To safeguard a continuous production operation 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 major disposal problems. A further problem occurs in the food industry through the possible toxicity of the cleaning liquid. Only the strict observance of rinsing instructions and an exact control of the admissible residue tolerances can remedy 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.^{[citation needed]}

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