Design codes

There is a still a great lack of clarity in Europe concerning the regulations regarding the design of atmospheric storage tanks. Transparent rules have been drawn up for specific applications such as underground fuel tanks. However, this is not the case with leg-mounted sanitary storage tanks, for example for dairy applications. This is emphasised more by the fact that each municipal implements a different policy and the required knowledge is often lacking. At European level, the initiative has been taken by introducing the following design codes:

EN 14015

Design code applicable to the somewhat bigger atmospheric storage tanks with a flat bottom. Formerly known as the BS 2654. The EN 13445 therefore replaces the BS 2654. (In some cases, the BS 2654 is still applied in Belgium because the Flemish Environmental Agency makes reference to this document).

EN 13445

Design code applicable to tanks with an internal pressure of >0.5 bar (g). The EN 13445 replaces the RToD (Regels Toestellen Onder Druk [rules for pressure vessels]); also known in the Netherlands as the “Steam Equipment rules”. However, the RToD may in still be applied and is in fact only "frozen” (no more updates will be made). The EN 13445 can also be applied for atmospheric applications. Since this is originally intended as a design code for pressure tanks, the wall thickness is consequently relatively large due to the circumstances during hydrostatic testing.

SEP (Standard Evaluation Protocol)

In the Netherlands, this translates as ‘good engineering practise’. For a reputable tank construction company like De Gouwe, we can relate to this definition. For calculating the wall thickness, the wall thickness calculation specified in the EN 13445 or the RToD is often applied. By applying this method, we can build a sanitary tank for foodstuffs (or other applications). The tank is high-grade quality, sufficiently solid and price-wise interesting. There are, however, suppliers that translate ‘good engineering practice’ differently. This can often be recognised by conical bottoms that are welded directly (without bevelled edging) to the body and have a thin wall thickness (<3 mm). These tanks are of an entirely different quality and the companies manufacturing them generally do not have a machine park that is equipped for tank construction.

KIWA

Design code originating from the steel construction industry. Since a corrosion surcharge is applicable to steel tanks and the roots of the KIWA come from the steel construction industry, this results in relatively thick-walled (read: expensive) stainless steel storage tanks. When a KIWA declaration is applied for under the environmental permit, a tank can be designed in accordance with the EN 13445 with a quality check by the KIWA. In a number of cases, it is possible to obtain a KIWA certificate to cover the entire installation if the tank is manufactured in accordance with design code EN 13345, provided the installation activities for the pipe work have been realized by a KIWA certified agency. If a tank is only being placed and the environmental permit makes reference to a KIWA certificate, then the tank has to be built entirely by a KIWA certified company in accordance with the KIWA design code.

PED

The PED (Pressure Equipment Directive) is not a design code but a European regulation for tanks and pipe work whereby the design pressure is greater than 0.5 bar (g). The consequences of this for the design and use of an installation strongly depend on factors such as the pressure, volume, medium, etc. The Gouwe is up-to-date on the PED regulation and takes this into account in its recommendations and products.