Hi all,
Can anybody explain me how the hot allowables in the material database are calculated for the EN-13480 materials?
If I do a calculation for Sh according to chapter 5 I get different (higher) values, so I want to double-check both me and CII.
Thanks in advance for your answers.

This is a non-trivial, complex computation. These material properties took months of work and involved collaboration between a number of individuals.

Specifically what material are you interested in, and what temperature?

I was double-checking for the simple S235 material (1.0345) at 300 degr. Celsius.

I've got the fcold where Rm/3 is the minimal value of (Rm/3 OR f). f being the minimum value of (ReH/1.5 OR Rp0.2/1.5 OR Rm/2.4).

For the fh I get a value of 102 N/mm2 though where CII gets a value of 88 N/mm2.

When I calculate the allowable stress range for expansion stress using CII fh of 88 I get the same result for fa as CII. So the difference is in the calculation of fh.

All calculations are done according to chapter 5 and 12 of EN-13480 and material properties from EN-10028-3.

Hello Corne

Firstly, I think the material to which you refer is P235GH 1.0345 not S235. I hope I am correct in this assumption. P235GH is a non austenitic steel (in other words, a carbon steel) so we have to proceed along these lines. We consider a 16 mm thick section:

From paragraph 5.2.1.1 we have the following equation at 300C:

f = min(Rp0,2t/1,5: Rm / 2.4) Note: Reh does not control here
= min(132/1,5; 360/2,4) = 88 MPa

For the flexibility analysis, we go to paragraph 12.1.3.2:

fc = min(Rm/3; f) = min(360/3; 88) = 88 MPa

fCR = SRTt / SFCR, but we are not in the creep range, so this equation is ignored.

Finally:

fh = min(fc; f) = 88 MPa.

In the equation from paragraph 5.2.1.1 it is our opinion that you cannot use Reh, especially as you are you are considering a temperature of 300C.

I do not profess to be an expert in these matters, but I consider the consverative approach is the correct one. However, others may have a differetnt view.

Ray, thanks for your answer.
Which EN do you use to get the Rp0,2t value? I think that can be the difference.

Hello Corne

We purchase our EN material specifications from the British Standards Institution. We have found the odd typo. Do you have a different value for Rp0,2/t at 300C for example? For P235GH 16 mm thick, our specification gives the value as 132 MPa

What odd typo have you found?

I'm at home atm and don't have the code here, but by head I thought Rp0,2 at 300C was 153 N/mm2. The value of 132 is at 400C.

Hi Ray,
I think i've found the mistake. The plate and strip EN-10028-2 and the seamless pipe 10216-2 code give way different allowables for P235.

Hello Corne

I am not saying you are wrong, because I do not know what documentation you are looking at. I have in my hand the following specification:

BS EN 10216-2: 2002(E) - Seamless Steel tubes for pressure purposes.

I look at P235GH 1.0345 (16 mm) and I find that Rp0,2/t at 300C is 132 MPa. If you would like a scan of that page, you can email me at techsupport@coade.com. Simpy mention my name in the subject line, and I shall do the necessary.

The problem may arise because each European Community country re-writes the specification in their own language, thus possibly introducing errors - I but I simply do not know.

We have had numerous queries centred around these European materals.

About the typos: The only problem we have encountered is when the Yield and UTS have been transposed, and one or two yield values at elevated temperatures have been transposed.

Hi Ray,

in this situation it was my mistake (or maybe the code makers one).
I checked EN-10028 for plate and strip cause that was the code I had around. For some reason there is a big difference in between EN-10028, which gives 153 N/mm2, and EN-10216 (seamless pipe) which has 132 N/mm2.

Ray and corne,

Appreciate for the good work and bringing out the rare and important topic.

I read the fc and fh calculation,very nice and interesting. However, I found a correction and the process is re-written below:

The ruLing equation is
Fa = U (1.25 fc + 0.25 fh) [Eh/Ec] [Chapter 12]

And we need to find out “ fc “ and “ fh “.

fc = min [ Rm/3 ; f ] Note: “f” is calculated with equation 5.2 at room temp

&
fh = min [ fc ; f; fcr ] “f” is calculated with 5.2 at calculation temp.


NOW LETS CALCULATE

1. “fc”

According to 5.2,
- f = min( Reh/1.5 or Rp0.2t ; Rm/2.4)

As per the table-4, EN 10216-2, Rm = 360 Mpa and Rp0.2 = 235 Mpa [room temp]

Thus “f = min( 235/1.5 ; 360/2.4)
f = 150 Mpa
Therefore,from fc = min [ Rm/3 ; f ]
fc = min [360/3 ; 150 ]
fc = 120 Mpa.

2. “fh”

According to 5.2,
f = min( Reh/1.5 or Rp0.2t ; Rm/2.4)

As per the table-4, EN 10216-2, Rm = 360 Mpa and Rp0.2 = 132 Mpa [calculation temp 300 deg C]

Thus “f = min( 132/1.5 ; 360/2.4) = min [ 88 ; 150 ] = 88 Mpa
[ Fcr= can be skipped ]

Therefore,from fh = min [Fc; f ; Fcr ] = min [120 ; 88 ; fcr ]
fh = 88 Mpa

So, the final value for the material P235GH at temp 300 degree C
Fc = 120 Mpa
Fh = 88 Mpa

There is a correction in Fc value with reference to Ray`s calculation.

Your clarification will be entertained.

The issue here is not the values of Fc or Fh, which if you look in the CAESAR II material database are the same values as you list above.

The difference here is that by default CAESAR II will use 12.3.4-2 instead of 12.1.3-1 for the expansion load case. If you want to use 12.1.3-1 then go back to the input and on the "Special Execution Options" dialog, turn off (uncheck) the option for "Liberal Stress Allowable".