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Using S275 JR for pipework on EN 13480 code

Using S275 JR for pipework on EN 13480 code

Using S275 JR for pipework on EN 13480 code

Hi All,

We're having a part for some pipework made which will be sandwiched between 2 flanges, it falls into PED cat 2. It is 320mm thick and has an OD 1240mm. Ideally it could be machined from plate or round. Looking at EN 13480 - 2 it looks like permissible plate materials are:


the round materials look similar in that they require a P variant.

We are running at 5 Bar and fluid temp is up to 350ºC but very short run times <10 Secs. We anticipate a Delta on Temperature of around 1ºC from ambient at the skin only.

Getting the above materials as stock in the required thickness or large enough round is extremely difficult (certainly in the UK). We can prove that S275JR is acceptable and is readily available in the sizes we require, however is it still permissible to use this material to conform to code and PED?


RE: Using S275 JR for pipework on EN 13480 code

This is something you should deald with your NoBo.

Technically, this sandwiched spool has a design temperature of 350 °C, and thus requires listed mechanical properties at 350 °C (thus temperatures greater than ambient). This is why you need P instead of S, as the structural guys dont need to go to 50 °C or higher.

Since it's cat II, you need to back the calcs up and have them present. NoBo will typically only deal with hydro, provided he will show up. Cat II nevertheless demands a technical file with a calculation. Simply using S material and saying it's desgin is 350 °C will leave you nowehere, regardsless if your right in a practical sense (i.e. it doesnt get hot). You need to back this up somehow; the calc showing a max delta T of 1 K could be sufficient already. Can the sandwiched spool also see negative temperatures?

How did you classify this item btw? As piping, or a pressure accessory? Which table did you use?

RE: Using S275 JR for pipework on EN 13480 code

Hi XL,

The part will not see negative temperatures. This section will 'make up' part of the pipework, so therefore it's pipework as opposed to pressure accessory. I suppose you could almost say in theory that it is a short section of pipe itself. i.e. a 320mm length of pipe with a 1240 OD and an 800 ID.

Can I take from your comment above then that as long as we show and document are calcs that S275JR is acceptable? (in your opinion?)

RE: Using S275 JR for pipework on EN 13480 code

Do you have a sketch? Upon further review it indeed may not be a pressure accessory, but a piece of piping component. Still, since it's cat II, you need some paperwork.
I would take this up with my NoBo and suggest him the approach (for apporval) to provide calculations showing that S275 suffices since no mechanical properties at elevated temperatures are required.

RE: Using S275 JR for pipework on EN 13480 code

Thanks for the advice, we'll run it past our NoBo and explain that we do not require mechanical properties of P265 etc Due to low delta T.

RE: Using S275 JR for pipework on EN 13480 code

I think you can have a problem with the NoBo to demonstrate the properties of S275JR at 350 C. IYou have some provisions in AD Merkblatt and EN 13445 but only up to 300 C for materials without guarantee properties at high temperature.

You could try with EN 1993-1-2 eurocode for fire design. See https://www.fomento.gob.es/recursos_mfom/04_0.pdf page 94 (it's the spanish transposition translated to english).

Best regards

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