Standards in piping: DIN, EN, ISO – and what became of the old DIN numbers

Three levels, one system: DIN, CEN/EN and ISO

Technical standardisation today takes place on three levels: national (in Germany DIN, founded in 1917, since the standards agreement of 1975 the recognised German standards body), European (CEN, the European Committee for Standardization) and international (ISO). Electrical engineering has parallel organisations (DKE, CENELEC, IEC) – for piping material the line ISO – CEN – DIN is what counts.

The decisive mechanism is the obligation to adopt: an adopted European Standard (EN) must be taken over unchanged into the national body of standards by all CEN members – in Germany as DIN EN. Conflicting national standards have to be withdrawn. That is exactly how the old DIN standards of piping have been replaced by EN standards since the 1990s: not by prohibition, but by orderly replacement. For many common series the essential connection dimensions were carried forward – interchangeability is therefore often given, but has to be checked for the specific part by type, DN, PN, sealing face, bolt pattern, material and service conditions.

So that the same standard is not developed twice, the Vienna Agreement (1991) governs the cooperation between ISO and CEN: a standards project is led on one level and voted on in parallel – the result then applies on all three levels and is called, for example, DIN EN ISO 1127.

What the prefixes mean

The number itself is a plain serial number without any system. What matters in practice: when a standard is adopted, the EN/ISO number stays the same everywhere – only the country prefix changes (DIN EN, BS EN, NF EN …). And the date of issue is part of the standard: EN 1092-1:2018 can differ in detail from the 2008 edition.

Old DIN number → what applies today

The assignments come from the “replacement for” notes in the national forewords of the respective DIN EN standards and were checked against the standard texts. The selection follows our supply and stock programme – it does not replace the standard text.

Pipes

Butt-welding fittings

Flanges and gaskets

Threaded fittings, threads, valves, inspection documents, materials

National DIN standards without a direct EN replacement

Not every DIN standard was replaced at European level. Where no EN counterpart exists, the national standard remains in force and is maintained nationally where necessary – in our range above all:

And internationally? ASME, JIS, GOST

Outside Europe, other standards worlds apply. In the USA, ANSI accredits the standards work of the professional bodies – for piping components above all ASME (the B16 series for flanges and fittings, B31 for piping) and ASTM (materials). When people speak of an “ANSI flange”, they almost always mean ASME B16.5 – our page EN 1092-1 vs ASME B16.5 shows the direct comparison of the two systems. In Japan the JIS standards assign each field a letter (JIS B 2220: flanges). The Russian-influenced GOST world can matter above all in projects related to the states of the Eurasian Economic Union. The most important rule of practice for all systems: similar numbers or nominal sizes never mean identical dimensions – NPT is not Rp, Class is not PN.

The most important replacements in detail

For the most frequently asked old numbers there are short pages of their own with material re-keying, practical notes and FAQ – DIN 2440/2441 → EN 10255 (threaded pipes), DIN 2448/2458 → EN 10220 (pipe dimensions), DIN 17175 → EN 10216-2 (boiler tubes), DIN 1629/1630 → EN 10216-1, DIN 2605/2615/2616 → EN 10253 (butt-welding fittings), DIN 17457/17458 → EN 10217-7/10216-5 (stainless steel tubes), DIN 2391 ff. → EN 10305 (precision tubes) and hollow sections → EN 10210/10219 – plus, in the other direction, a guide through the body of rules in force today and the edition-by-edition comparison of the standards. These pages are so far published in German only.