DIN 2673 versus EN 1092-1 type 04-34

Hi there, and welcome fellow Dutchman! Good to see you joined ET.

Although I’ve never looked at these EN flanges before, I’ve used several EN 1092-1 flanges for the pipe specs I’ve made over the years. I’d say the answer to your question is yes, it’s a bad design. There are some crazy sections in EN 1092-1 if you start digging, which is what you’ve done too, for good reason.
Have you looked at the appendix in EN that, if I’m not mistaken, covers some history? Also, you could try to contact the CEN/TC committee responsible for EN flanges and ask for their opinion.

PS: translating is quite easy nowadays with the built in translator in recent MSWord versions, it does the job quite well.

Huub
- You never get what you expect, you only get what you inspect.

Thanks for your response XL83NL,

Flanges are the most important part in a piping system, therefore I will take a closer look on some types and in response of your reply.

Flange data in historical perspective.
Carl Sagam once said “you have to know the past to understand the present”. In other words, if you can link facts, then the answer is already there.

Taken from the introduction alinea in BS-EN 1092-1 (2007),
Major changes against edition 2001:
-flanges PN160, PN250, PN320 and PN400 have been introduced;
-further collar types have been introduced;
-materials have been updated.
Re-calculation acc EN 1591-1 for,
-type 11, 05, 01, 02-32, 02-33;
-type 35, 36, 37;
-type 21, 04-34 have not been re-calculated acc EN 1591-1;
-type 12, 13 have been adjusted to the results for type 11.

Before year 2001 all the type numbers where DIN codes.


Just more original data,

Some time ago I did a little research of the weights of ASME flanges in comparison with DIN flanges. In most cases the ASME flanges are heavier. There was an article (can't find it anymore) on internet about the 2nd war period in Germany about shortage of raw materials. They needed it for the war industry. In the period 1936 – 1943 there were some changes in the DIN codes. I can not verify the decrease in weights in that period, mine oldest source is the “Deutscher flanschenkatalog” from 1967. It could be a minor explanation for the differences in weights. On the other hand, I know that the CODES are normative.

CEN/TC 74
A standard or norm is established when there is a need from the business community for a new product standard, in this case a flange. If three quarters of the ISO member countries agree, it becomes official.


But the business community must take the initiative with an adjustment and/or new product. I am a private citizen, not a business, so I have mine doubts whether my proposal will be considered.
An other point is, if this type is not used in business, it will never come to light. I have searched in ± 120 CS pipe specs and nowhere is this type 04-34 used. Therefore I sent my report to Hertecant Flanges in Belgium because they have, as only European manufacturer?, type 04-34 in their program. I have asked them how they deal with this, because they should make this disclosure at the CEN/TC 74. This moment of writing I did not receive an answer from Hertecant.


How to reduce the number of flanges in the EN 1092-1?

ASME B16.9 9 types of flange components
EN1092-1 16 types of flange components

I have split the types by material and pressure range,

Proposal;
Type 33 to combine with type 37
Type 35M to combine with type 35 ISO
Type 02M to combine with type 04
Type 04-34 to re-design

The committee CEN/TC 74 could have reduced the number of types with a little more imagination, this benefits the right choice and stock management in the business community. Because there is a tendency in process technology to work with increasingly higher temperatures so that chemical processes run better, the welding neck is now the only candidate for this. It is possible that a better flange concept will be developed in the near future that offers more advantages compared to the welding neck flange. Maybe this will be the new type 15 or type 22? A more balanced EN 1092-1 standard improves choice (like the ASME B16.9).
Is this delusion, fantasy or possible?

I tried to find an European site where I can discuss these issues but nothing there, so I went to Eng-Tips where the ASME dominates, witch is also familiar in Europe.

Thanks for getting this far.