Cisterne: differenza di realizzazione e qualità


To find out if a specific industrial product has been manufactured according to predefined construction standards, and if it complies with the regulatory obligations in force at the time, usually it comes with a declaration. By this one, the manufacturer certifies that he has followed technical indications on how to do it and that, if there are laws and regulations on the subject, he has respected them.

For thermoplastic tanks, the situation is intricate. There is no product standardization valid for the set of typologies. Of course, there are process standardization, that ensure manufacturing quality and respect for the environment, but on how a tank is generally built, the unified standards do not concern all but only certain types. The regulated ones are essentially two, divided by construction method: by extrusion and by molding.

In case of tanks in rotational extrusion (Helix), and also formed from sheet, there is more than one reference standard. One is harmonized in Europe, EN 12573. There is other one much more detailed from DVS (German Association for Welding and related processes). That is DVS 2205-2. This one, and its annexes, provides for the various construction forms (conformation of walls, bottoms and roofs, presence of leak containment devices), the thicknesses to be made in relation to the geometric dimensions and the products contained, the thermal loads, from snow and wind, the methods of assembly and fixing to the ground etc.

For rotomolded tanks, there is a harmonized standard in Europe. This is EN13575, which sets characteristics and test methods for above ground, blown or rotational molded thermoplastic tanks dedicated to chemicals. However, it has several limits: it contemplates volumes only from 400 to 10.000lt, products that have densities up to 1.4kg / dm3, atmospheric pressurization and temperatures normally not higher than 25°C.

Outside these cases, each manufacturer adopts construction criteria that came from his own experience and from tests he has performed over time. The of product quality guarantee for the customer is therefore found in the reliability of the manufacturer, in certification of quality standards in manufacturing, in certification of the raw materials used.

Special case is using tanks in construction field. In fact, the current European Construction Products Regulation (CPR) provides for a specific quality certification procedure for those products that do not fall within the scope of harmonized standards.

This is the Declaration of Performance (DoP). The manufacturer can issue it on the basis of a technical verification (ETA) performed by an authorized certification body (TAB), which refers to a European Technical Assessment Document (EAD) issued for the specific category of products. Although thermoplastic tanks are not currently included among these (only the issue of tanks with containment for fuels is underway), it is nevertheless a possible way to provide the market with detailed product certification. Valid outside construction field as well.

Cisterne in Plastica

Maurizio Giulimondi, Via del Paleotto 9/4, 40141 Bologna (BO) C.F. GLMMRZ55R27H501Y