CEN/TC 265/WG 9 - Site built tanks for liquids at ambient temperatures

This document specifies the requirements for the materials, design, fabrication, erection, testing and inspection of site built, vertical, cylindrical, flat bottomed, above ground, welded, steel tanks for the storage of liquids at ambient temperatures and above, and the technical agreements that need to be reached (see Annex A).
This document does not apply to tanks where the product is refrigerated to maintain it as a liquid at atmospheric pressure (see EN 14620 part 1 to 5).
This document is concerned with the structural integrity of the basic tank structure and does not provide requirements for considering process design, operational issues, safety and firefighting facilities, in-service inspection, maintenance or repair. These aspects are covered in detail in other Codes of Practice (see Annex B).
This document applies to closed-top tanks, with and without internal floating roofs (see Annex C) and open-top tanks, with and without floating roofs (see Annexes D and E). It does not apply to 'lift-type' gas holders.
This document applies to storage tanks with the following characteristics:
a)   design pressure less than 60 mbar  and design internal negative pressure not lower than 6,0 mbar (see 5.1 for pressure limitations);
b)   design metal temperature not lower than -40 °C and not higher than +300 °C (see 5.2.2);
c)   maximum design liquid level not higher than the top of the cylindrical shell.
The limits of application of this document terminate at the following locations:
-   face of the first flange in a bolted flange connection;
-   first threaded joint on the pipe or coupling outside of the tank shell, roof or bottom; and
-   first circumferential joint in a pipe not having a flange connection.
This document is applicable to storage tanks where, irrespective of the material strength used, the  maximum allowable stress does not exceed  260 N/mm2.
In addition to the definitive requirements, this document also states that the items detailed in Annex A have to be documented. For compliance with this document, both the definitive requirements and those required in Clause 4 are meant to be satisfied.