Existing vessel acc. AD-Merkblatt, modificate using other code?

[Haralt]

Hello!

An industrial pressure vessel (heat exchanger tube and shell type, stainless steel W 1.4301) was in 2000 designed and installed according to the German pressure vessel code AD-Merkblatt. It is installed in Germany.
It has design temp. 0 to 180 oC, and design pressure -1 to +4 bar(e). where "e" stand for effective pressure related to the normal atmospheric pressure.

Now it is interesting to make the stationary chamber on tube side longer by prolonging the stationary chamber shell.

The stationary chamber shell(large diameter, about 3 m) is welded to the tube sheet. It has not any 3 meter dia. flange connection, only a DN 600 manway for access the tube plate on that side.
Flange connection is very expensive in this size (3 meter dia.), therefore the easiest and cheapest would be to just cut the existing stationary chamber shell and prolonge it by inserting an additional piece of stationary chamber shell and welding it.

Can this prolonging of the stationary chamber be calculated and design according to EN 13445-3,
thus using another pressure vessel code than the originally used for this vessel?

Best regard
Haralt

 

[mechanical2014]

Hi!

Yes, it shall be done as per EN13445 (In EU at least), in the same fashion as the original design requirements.
Although, i understand you want to do modification on existing heat exchanger. But, i am not getting exactly what you want to achieve.

 

[Haralt]

Hello!

Thank you mecanicals2014 for your answer.

Some more info:
The design temp. and design pressure are maintained the same, and are not going to be changed.
The reason for the modification is to get more space above the tube plate for performing mechanical cleaning of the inside of the tubes, that get scaled.
The heat exchanger is in vertical position.
The code EN 13445-3 was not used for the original design, but as I already mentioned, the German pressure vessel code AD 2000 Merkblatt was used.

The AD 2000 Merkblatt is still valid in Germany, as I understand, and can be used for new pressure vessels installed in Germany.
But, what I understand, AD 2000 Merkblatt is not harmonised in the other countries in Europe, that are member in Union Européen.

Perhaps, the North American pressure vessel code ASME 8 division 1 could alternatively be used for the proposed modification?
(I think the ASME pressure vessel code are accepted by pressure vessel authorities in many countries outside North America)

Must the whole existing pressure vessel be recalculated acc. to the used code or only the part(prolonged chamber shell) that are going to be modified?

I think these questions are interesting not only for me, but also for other mechanical design engineers.

Best regards
Haralt

 

[GHartmann]

You are going to be better off staying within the EC design codes. Going to ASME would require a review of the whole design and could result in some reratings. In the US, your modification would be covered under an "R" stamp (repair). Certainly there should be a EC equivalent.

There is a so called unified EN standard, but each country still has there own version. (Only the country has the authority to impose these rules as a part of law)

My understanding is there is a German version of the EN standard that has supplemented AD Merkblatt

 

[mechanical2014]

In my opinion, please involve EU appointed "NOTIFIED BODY". We are not discussing a important factor, which is over and above the design codes i,.e PED. Now PED is a law in EU and it accepts only harmonized standards. EN13445 is a harmonized standard but i doubt about AD-Merkblatt. Moreover in PED there is very thin line between modification and new built and it shall be evaluated on case by case basis for any modification. Combining all,only notified body can give you a clear way forward.

 

[Haralt]

Thank you Mr. GHartmann and Mr. mechanical2014 for your answers!

Mr. GHartmann, yes there exists a German version of the pressure vessel code EN 13445, namely DIN EN 13445. But, I assume it is the same as EN 13445, it is only that it is written in German.

There also exist a British version, namely BS EN 13445, and it is written in English.
And a french, namly NF EN 13445 written in french. I the same way, for every country that is member in the Union Européen there seems to exist a own language version. For example for Sweden, SS EN 13445 which is writtem in Swedish language. Even Norway, that is a free country, that is not member in Union Européen, has a version namely NS EN 13445.

Best Regards
Haralt

 

[DBreyer]

THE AD2000 code clearly states that it is not allowed to be mixed with other codes, since it follows a closed concept.

So it would not be acceptable to use EN 13445 for calculation and execution.
Some of the requirements may be different.
For example: AD 2000 might require a 3.2 test certificate for the material you want to use, whereas EN 13445 only requires 3.1 test certificates.
Also NDT requirements might be different.

PED is not relevant here since the vessel is already in service and you don't place it on the market.

If you want a definitive answer get in contact with your "ZÜS" e.g. TÜV or DNV and ask if it is acceptable for them if you mix standards.
Since what you want to do is a change of the pressure vessel you will also need a new "Prüfung vor Inbetriebnahme". Your "ZÜS" will most likely want to review your calculations in this process.

AD2000 meets all requirements of the PED and is therefore still valid (in the whole European Union) for fabrication of pressure vessels. This is described in AD2000-Z1.

The easiest way would most likely be for you to do the work according to the AD2000 standard.

Best Regards

Daniel Breyer
Inspection Engineer

http://lnkd.in/dFcQA-w