Effective reconstruction of high-capacity tanks, reconstructing of single-shell high-capacity tanks.

Corrosion problem solution

The protection of living environment and nature is the most important requirement nowadays. Elimination of existing damages to environment and prevention of future pollution – this is our target.

The ETK company, whose name is the abbreviation of Czech words ‘Ecology, Technology, Quality’, always brings on the market timeless technologies that fully meet even the most severe ecological standards.

Dangerous substances must be stored so that they might not constitute a threat to underground waters, soil and air. The existing regulations (the Act on Water Management No. 254/2001 coll. in later wording, ČSN EN 13 160, ČSN 75 34 15, ČSN 65 02 02) require special efficient insulation, protection and check of tightness, providing for long-time protection of environment from pollution impacts.

In 1990, the ETK company was the first to come with the technology of modernisation of single-shell tanks by means of plastic liners, in pumping stations, high-capacity storage depots of fuels and lubricants, airports and varied other localities, where there are stored not fuels and lubricants only, but also other substances dangerous to the environment. At present, more than 1.000 tanks are operated in this manner in Czech Republic only. Our attention is now directed on high-capacity single-shell tanks with flat bottom, where our company has got something to offer even nowadays, because these large tanks are built-in in the terrain already in their majority and their complete replacement would be both time-demanding and very costly. The usual method of reconstruction of high-capacity tanks consists in welding the double bottom with steel plates, thus creating an intermediate space monitored by detecting instruments. The ETK company has at its disposal a quality team of specialists and workers trained both in the home market and abroad, with an ample experience in the area of detection of untightness. Naturally, ETK responds to these technologies, too, and it supplies the monitoring system Gardner Den¬ver Thomas V80Ex H, intended for monitoring of the intermediate space of these high-capacity tanks directly, and ranging with the first category in the indication of untightness according to the latest standard ČSN EN 13 160. This system is utilised in all European refineries. The last installed instruments are in the refinery of Slovnaft Bratislava for the monitoring of new double-shell steel tanks with flat bottom. The instrument Gardner Denver Tho¬mas V80Ex H is designed so as to suit the installation both inside, but primarily outside. There are also other instruments in the market, presented by their manufacturers as suitable for these technologies, however, their workmanship, equipment and quality cannot compete with the instruments of Gardner Denver Thomas. Needless to say, the ETK company did not content itself with mere monitoring of double steel bottoms of these tanks. The fact that steel is used for the modernisation primarily was not lost on ETK workers, and therefore, the company brings upon the market a singular method of its own. Our long-time and well-tried experience with lining smaller tanks has inspired us in development of technologies for reconstruction of high-capacity storage tanks, built in the refineries and large fuel storage facilities.

The ETK technology for single-shell tanks with flat bottom consists in additional sealing by means of elastic, welded plastic strips (sheets). These sealing strips show a high elasticity and lasting endurance to the effects of the stored medium. After corrosion treatment of the tank bottom and possible repairs of eroded places, a special intermediate layer is laid on the bottom; it is resistant to pressure of the medium stored in the tank, it provides for lasting permeability of air in the intermediate layer and forms a continually monitored intermediate space. The permeability of air in the intermediate layer of the tank bottom is important from the standpoint of trouble-free functioning of the whole indicating system. Next, the sealing plastic strips intended for the stored medium in question are welded together as a second bottom and clamped to tank walls. The joint is impermeable both for the medium and air. By means of the vacuum in this intermediate space, the whole bottom is checked continually by a vacuum instrument made by the Gardner DenverThomas company.

The flat bottoms of large tanks are exposed to enormous loading and tension. When stocking the medium in and out, the welded plates of the tank bottom get deformed, with damage to welds as possible consequence. Namely the deformations of the bottom can bring about possible leaks; therefore, a great emphasis must be laid upon the choice of technologies and materials.

At present, the bottoms of these high-capacity tanks can be repaired with steel plates, laminate, or by above-mentioned laying of elastic plastic sheets. In this technology, the steel plates are welded from one side only; with such a high load, the tank bottom can suffer damage. In case that such a defect occurs, the stored medium penetrates the intermediate space of tank bottom, and the resultant repair is time-demanding, it requires considerable financial costs and is also dangerous as far as work safety is concerned. The method of reconstruction of the tank bottom with lami¬nate has its pitfalls as well. The laminate is laid in the tank in two layers. The first one is laid upon the existing tank bottom directly, and upon it, there is laid a permeable intermediate layer, forming the indicating intermediate space. The last layer of laminate is glued to the tank wall, thus sealing the whole space. As the intermediate space between two layers of laminate is monitored only, the indicator of untightness does not detect defects of the steel tank bottom. As mentioned already, during stocking the medium in and out, the tank bottom is moving incessantly and is exposed to tension. The iron and the laminate are in essence materials of different elasticity; therefore, the laminate breaks off the iron, with resulting impairment of integrity of the system, which can lead even to spontaneous escape of the medium into soil or penetration of underground water into the space of the tank. This defect can incur in the joints of laminate layer with steel shell, where – as mentioned already – the tension or differences in heat dilatation of used materials can produce undesirable leaks.
With the technology of laying plastic strips, such problems do not occur, due to high elasticity and conformability of the material. Other not negligible advantages of the plastic system include an immediate stop to inside corrosion and condensation of water in intermediate space. The inner lining has a thermo-insulating effect, too, and it eliminates stray currents; as one and only method, it allows for an easy and fast repair of possible damage to outer steel tank bottom.

One of the most important factors of using the plastic system is a considerable reduction of costs related with the reconstruction and an important shortening of time of modernisation, while complying with all the most severe Czech and European standards and regulations. For these activities, ETK has implemented a new environmental system of quality according to ISO 9001:2001 and the related management systems according to European standards 14 001:2005 a OHSAS 18001:1999. The staff of the ETK company trusts that with this technology they will be going ahead both in foreign and home markets and will be able to generate new possibilities of modernisation of high-capacity tanks with flat bottom, and not only of them.

Leaflet to download (*.PDF)

The exhibition Uniti-Expo in Stuttgart

About our participation PETROLmagazín reports.

ETK foam
Restaurant Hotel Nový York
Animation: principle of vacuum leak detection system
Animation: principle of overpressure leak detection system

Lining of tanks, tank cleaning, service
and construction of pumping stations

ETK s.r.o.
Skřivánčí 9a
466 01 Jablonec nad Nisou

Phone.: 737 227 660, 483 360 077
Fax: 483 360 099


ID: 00554812
VAT reg. n.: CZ00554812

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