Applies To
Product(s):	AutoPIPE Vessel
Version(s):	ALL
Area:	Calculations
Date Logged & Current Version	Oct 2024 45.00.03.001

Problem:

For the combined loading calculation, how is the general stress intensity calculated?

Solution:

EN standard never call that f as hoop:

For the primary membrane stress we are based on PD5500:

See below calculation for sigma omega as per PD5500, clause B3.2, equation B-3.

Sigma eq-/+ (general stress intensity) is being calculated using sigma omega and Sigma P.

Example:

s_eq = max [ ( s_q / E_c- s_z / E_lt ) ; ( s_q / E_c + 0.5|P| / E_c ) ; ( s_z / E_lt+ 0.5|P| / E_c) ].

s_eq = max [ ( 293.35 / 1- 142.18 / 1 ) ; ( 293.35 / 1 + 0.5|12.01| / 1 ) ; ( 142.18 / 1+ 0.5|12.01| / 1) ] = 299.35 MPa

As shown in detailed output report:

Note:

1. Make sure that the "Summerized Report " option is unchecked, rerun strength calculations, and regenerate the output report.

2. As per EN 13445-3 9.3.2 (Symbol Description) eb is the "mean thickness within the external length lbo" (l'b is not mentioned here) and lbo is the "Maximum length of nozzle outside the shell for reinforcement". lbo is not limited to the thicker part length of the neck. The coincidence of lbo with the height of the S.R. in the figure 9.4-9 is fortuitous, the figure 9.6-2 shows a more general interpretation of this case (see lbo2)

3. The possibility of imposing the reinforcement length in APV only applies to l'b (the effective length of nozzle outside the shell for reinforcement ) which is only used to calculate the surface area, as per EN 13445. Taking only the lbo length into account in the calculation of eb thickness may be conservative in some cases for S.R., but this is the strict application of the code.

Q. For the combined loading calculation, how is the general stress intensity calculated?

Problem:

Solution:

See Also