pipe made of E235+N (1.0308) strength at elevated temperature for EN 13445 (and PED)

[Vikko]

I need to use a seamless hot rolled pipe of material E235+N (1.0308) because that is what I found at the shop with the required dimensions. Here is a reference:

http://www.steelnumber.com/en/steel_composition_eu.php?name_id=566

It is in the list of material of the standard EN 10305-4:2016 (Steel tubes for precision applications - Technical delivery conditions - Part 4: Seamless cold drawn tubes for hydraulic and pneumatic power systems) which referes to PED (there is annex ZA Annex ZA: Relationship between this European Standard and the Essential Requirements of Directive 2014/68/EU aimed to be covered). In this standard it is delivered only in the normalized heat treatment condition (+N) which is what I have also.

Also EN 10305-4 is in the PED list at:

https://ec.europa.eu/growth/single-...ds/harmonised-standards/pressure-equipment_nl

E235 is also in other standards like EN 10297, but that is not even in the PED list. (any reason why the same material under a standard is in the PED list while not under another standard?)

The problem is that in these standards there is no table with the proof or yield strength at elevated temperature, so it seems useless for a PED application... (I do not see any logic for including such material and then not giving these values, so what is the purpose of this issue is beyond me). Can I use P235GH values instead ? They seem to be quite similar I suppose.

 

[XL83NL]

No. You can’t, unless a PMA support these values at elevated temperatures. That would require of yield and may be tensile properties at elevated temperatures. There’s no single reason to assume it’s equal.

Do you have a copy of the MTR to determine if the material maybe meets other specs?

As a customer or client, I wouldn’t accept this approach.

I think the reason it’s in there is that it can be used for e.g. attachment parts on vessels, e.g. load bearing lugs.

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

 

[Vikko]

I rechecked the material certificate: I said it wrong in the first post. The material is double classified as both:
- EN 10210-1 S355J2H +N ( 1.0576 )
- EN 10297-1 E355 +N ( 1.0580 )

Here the reference:

http://www.steelnumber.com/en/steel_composition_eu.php?name_id=649

http://www.steelnumber.com/en/steel_composition_eu.php?name_id=570

At this point I think I found the values I need in AD 2000 Merkblatt W4 for EN 10304-4. I really do not understand why they did not add these values in EN 10305-4 if this standard is for the PED. But considering the general mess in the EN standards for PED it does not surprise me a lot

For what it matters "attachment parts on vessels, e.g. load bearing lugs" do not need to be classified for PED as far as I understand: only pressure parts requires EN 10204 certificate (see in annex I of EU/2014/68 at point 4.3 they say that only the principal pressurized parts for category II III and IV need the EN 10204 certificate of type 3.1).

https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32014L0068&from=EN#d1e32-202-1

 

[XL83NL]

For what it matters "attachment parts on vessels, e.g. load bearing lugs" do not need to be classified for PED as far as I understand: only pressure parts requires EN 10204 certificate (see in annex I of EU/2014/68 at point 4.3 they say that only the principal pressurized parts for category II III and IV need the EN 10204 certificate of type 3.1).

Refer to guideline G-05. However, there are other requirements than MTR's (material certificates). For example, certain chemical (for e.g. weldability) and mechanical properties need to be known for welded on attachment parts, when these are e.g. welded to main pressure bearing parts.

Where do you intend to use this part (I believe you mentioned its a tube) for?

PS: this argument isnt really a good argument to use such a 'doubtful' material for pressure bearing purposes:

I need to use a seamless hot rolled pipe of material E235+N (1.0308) because that is what I found at the shop with the required dimensions

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

 

[Vikko]

I need it for a pressure part. I know that mine is not a great argument, but there is no otherwise. The steel manufacturer does not care to make pipes in every sizes, dimensions and materials possible, for someone who only buys a short piece of pipe. (The pipe manufacturer do not even know that we exist, we only deal with pipe shops). Why don't you give me a good argument for the EN standard writers not to include the elevated temperature strength of this E355 +N ... they should have copied better from DIN standars: that is the only possible conclusion (because I found the values in AD 2000 Merkblatt W4).

 

[XL83NL]

Ive been in the same situation but there's an otherwise, usually. Why not machine it from bar? What dimensions do you require?
We need materials every now and then that aren't available on the market. Settling for anything else that is available would praise us out of the market, eventually. You have to be creative. (PS: we dont exist for them also, so we work our way around them!)

Why don't you give me a good argument for the EN standard writers not to include the elevated temperature strength of this E355 +N ... they should have copied better from DIN standars: that is the only possible conclusion (because I found the values in AD 2000 Merkblatt W4).

Well, Im not the committee for those materials, so I cant argument for that sake, but the reason I see it, is the E-steels are engineering purposes (hence the E); applications that for most instances dont require hot tensile and yield properties. Otherwise, one would buy P-steels, wouldnt they?

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

 

[Vikko]

It is a 6" 25mm and around 100mm length; it is too costly to machine it from a plate or bar (like 10 times more or less). (In any case I closed the case, I will use a lower thickness of 22mm of A106 and then adjust the calculation just lowering the tolerances on thickness (1/8 of tolerance (corresponds to around 3mm) in this case is really large, 2% is more reliable in this case)).

S, E, P, etc (in the EN steel name) refers to the final application, but the name is unique with the chemical composition only. Numbers are much more neutral in regard to the application: it is the final user who choose the final application, not the steel manufacturer. (in AD 2000 Merkblatt they can use also S235 for pressure vessel for example (not only E355); who cares if someone chose to call that steel "structural" or for "engineering"). E355 tubes in EN 10305 are all cold drawn as required by standard, so they have much lower tolerance, which is printed in the standard (but they are produced with a preferred diameter which is small, like no more than 80mm for EN 10305-4 to 3/400mm for EN 10305-1 and others of the serie). But the same material is also in EN 10297-1, where there are no restrictions on the manufacturing process and bigger sizes are made. The fact that EN 10305-4 is in the PED list would mean that there should be no problem using it, but without the strength at higher temperature does not make a lot of sense to me...