EN-13445 Questions 1

[CobusvanJ]

Hi,

My questions are w.r.t. EN 13445-2 and 4.

Design - HP Heater
Shell Side - Steam - Design Pressure 2 550kPa - Design Temp 350deg C

Tube Side - Water - Design Pressure 30 700kPa - Design Temp 230deg C

Design Code is EN 13445.

Channel Material 15NiCuMoNb5
Shell Material - 16Mo3

We have a very experienced designer specifying some of the details, and due to weight restrictions and ease of welding he specified 15NiCuMoNb5 forging for the tubesheet. The issue is that in neither EN 13445-2 or EN 10222 or anywhere else for that matter can I find such a forging material. Therefore I have to specify another material.

According to Annex E Table E.2-1 of En 13445-2 15NiCuMoNb5 is material group 3.1. The only forging material in the same table falling under material group 3.1 is P420QH. Is this the only forging material available to me considering the design conditions? We need a strong material for pressure and as we will be using explosive welding on the tubes. Is there a problem welding P420QH to 15NiCuMoNb5 and P420QH to 16Mo3?

Further to this issue is that we are confused whether 15NiCuMoNb5 is actually group 3.1 (as stated in Annex E of En 13445-2), and not 4.2... Can anyone please confirm the correct material group as the Stahlschlussel we have also states material group to be 4b, and according to the chemical composition of 15NiCuMoNb5 it also complies with the criteria of material group 4.2.

Another issue is that I cannot determine the PWHT requirements as Table 10-1.1 of EN 13445-4 states in Note 1 "Heat treatment conditions of materials groups 2.1 and 3.1 will be covered later.". What do I do in this case? There is also no PWHT for material group 4.2, should it turn out that 15NiCuMoNb5 is mat group 4.2, what then?

Thank you for your help.

 

[vpl]

I'd go back to the designer and ask him to find another material.

Patricia Lougheed

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[ulyssess]

You can use 15NiCuMoNb5 within EN 13445. As the material is not within an harmonized standard, you need a particular material appraisal, see EN 13445-2:2009 par. 4.3.3. For more details see also

http://ec.europa.eu/enterprise/sect...ing-principles-for-the-content-of-pma_en.pdf.

As this material is defined in VDTÜV 377/3, one of the TÜV could be the first choice as notified body.

Which thickness is needed for the tubesheet? Could plate material be an alternative? 15 NiCuMoNb5-6-4 is in the harmonized standard 10028-2, no PMA required.

For which reason do you need a material from group 3.1 ore 4.2? Even if Q420QH is classified in group 3.1, the yield strength at 350°C is much lower compared to 15NiCuMoNb5.

15NiCuMoNb5 was shifted from group 4.2 to 3.1 as this material does not comply with the definition of group 4 "Low vanadium alloyed Cr-Mo-(Ni) steels with Mo ? 0,7 % and V ? 0,1 %". 15NiCuMoNb5 does not contain vanadium, the content of Cr is rather low.

Table 10.1.1 is under revision (edition 2009/FprA1:2011), and currently submitted to the Formal Vote. The question concerning group 3.1 and specifically 15NiCuMoNb5-6-4 is solved. Group 4.2 is no longer considered. The question of PWHT should be clarified with the material manufacturer and the notified body within the PMA.