Hello all,

Recently we've passed along some nozzle loads from a CAESAR II flexibility to a consultant office that's using Codecalc to perform vessel calculations.

Vessel's diameter: 20 in - 28,5 mm.
Vessel's Pressure: 125 bar.
Nozzle's diameter: 2 in - SCH 160.

From the Codecalc report we`ve received (WRC107 Analysis):

Include Pressure Stress Indices per Div. 2 No
Compute Pressure Stress per WRC-368 No

I`m not familiar with WRC107's calculations, but i'm very concerned that the above options indicates that pressure effects are not been taken into account.

Can anyone give some basic background over this matter?

P.S.: I've already contacted the consultant's office, but untill now all I've received weer some criptic responses.

Thank you.

Refer to the 2 COADE newsletters on these topics, from July 2001 and June 2000. These are available from www.coade.com -> Support -> Newsletters.

Here is some information from the help for this input.

Pressure Stress Indices are described in ASME Sec. VIII Div. 2 Table AD-560.7.

This value should only be used if user intends to perform a fatigue analysis. ASME VIII Div.2 paragraph AD-160 should be checked to see if the fatigue effect needs to be considered. These factors are used for estimating the peak stress intensity due to internal pressure. While, the peak stress intensity due to external loads is accounted by including the WRC 107 SIF (Kn and Kb factors).

Please note that the program currently DOES NOT perform the complete fatigue analysis per Section VIII Div.2 Appendix 4 & 5 rules. Instead the value of peak stress intensity is reported which can be used by the user to perform fatigue effect comparisons.

Compute Pressure Stress per WRC-368
Check here to compute pressure Stresses (in Shell and Nozzle) per WRC-368. WRC-368 provides a method for calculating the stresses in cylinder to cylinder intersection (such as cylinder-nozzle), due to internal pressure and the pressure thrust loading.

Utilizing WRC 368 along with WRC 107/297 is not very accurate for calculating the combined stress from pressure and external loads. This is because the WRC-368 only provides the maximum load and not the location. While, WRC-107 provides the stress at various locations.