EN 13445-3 - 10.5.2

[Newport2]

Hello,

I have to design for the first time with EN 13445, until now I have always used the ASME code.

I want to design a bolted flat end (internal seal) with cut-outs according to EN 13445-3. To do this, I first need to determine the thickness of the unweakened flat end according to section 10.5.2.

The design formulae contains the correction factor CF. According to formula (10.5-4), this is the maximum of 1 or a root term. To calculate the root term, the minimum thickness of the flange area e1,a is required. However, the formula for calculating e1,a (section 10.5.2.2) already contain the correction factor CF.

However, EN 13445 does not contain any specification on how to proceed now. Is an iterative solution permissible? Or is it necessary to proceed differently? I would be grateful for any answer, I have not been able to answer the problem satisfactorily so far despite long research.

Best regards
JK1991

 

[XL83NL]

Welcome to the painful wonderful world of EN 13445. The code with so many 0 mistakes.

Analysis thickness, in general, is defined as

To determine the required thickness e, which is the thickness of the flange that's within the gasket perimeter, one needs to know e[sub]A[/sub] and e[sub]P[/sub]. e[sub]A[/sub] takes into account C[sub]F[/sub], which on its turn depends on e[sub]1,A[/sub]. The latter is the thickness of the part outside the gasket perimeter. Therefore, its iterative, but explicit.

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

 

[Vikko]

it is ITERATIVE.

Consider that for a bolter flat cover you have 2 kind of thickness (fig 10.5-1):
- thickness (e)
- flanged extension thickness (e1) which could be lower (see 10.5.1.2 and fig 10.5-1, 2 to 4) for a raised face or a grooved face.

The word "analysis" (referred to the thickness (e) with the lowercase letter subfix 'a') just means it is an ITERATIVE method and that the design has to be presumed first and then analyzed and confirmed by claculation after. (Be carefull with the subfixes in capital letters and lowercase letters).

So you insert these 2 parameters (e[sub]a[/sub] and e[sub]1,a[/sub]) and do all the calculation of:
- e[sub]A[/sub] thickness (A for Assemly or seating or bolting up condition)
- CF is a correction factor above 1
- e[sub]P[/sub] thickness (P for the operating Pressure condition)
- e[sub]P1[/sub] flanged extension thickness (P for the operating Pressure condition)

the verification is:
- e[sub]a[/sub] >= max (e[sub]A[/sub], e[sub]P[/sub])
- e[sub]1,a[/sub] >= max (e[sub]A[/sub], e[sub]P1)[/sub]

If both are verified, the design is correct.

Even if it is not well specified in this section, it is always presumed that you shall also verify the design in the testing condtion (with test pressure at ambient temperature), so repeat just the same as above.

 

[Newport2]

Sorry, I was busy and forgot to thank you. Your post has helped me!