Hi,

I tried to get the Tank Nozzle Stiffness using CII input data for nozzle - API 650. I got the output values for the stiffness, forces and moments in the error check data (start run). Where can I get the calculations, formulae and basis of these results, to verify as per API hand calculations for these values (axial translational stiffness, longitudinal bending stiffness,..radial forces,longitudinal moments...).

Thanks and regards,
Nisar Ahmed
Feb. 17, 2010

You can't, that information is not output anywhere.

Thanks Richard for your prompt response.
You mean, Caesar II program evaluates these results and displays them in the start-run error check, but not in any output report. Hope CII should have the nozzle stiffness calculations shown somewhere in Caesar reference guide or training manuals.

Regards
Nisar Ahmed
Feb. 18, 2010

The "Error Check" process evaluates the "API-650 Nozzle Input" and determines the stiffnesses. These computed stiffness values are then inserted into the model at the nozzle node, for subsequent use in the FEA solution. These computed stiffnesses are available for review at the output level, in the "Miscellaneous Report". However, CAESAR II does not generate or display any "formulas" used to arrive at these values.

Thanks Richard.

We are checking flange leakage calculation for storage tank settlement. Appreciate for your expert advice to questions A, B and C below.

A) Can we input the computed stiffness value (N/cm referred in my previous query Feb 18, 2010) at the shell-nozzle junction in the CII input with anchor at the nozzle node + stiffness + displacement (c-node for foundation settlement). No nozzles or flanges near tank nozzle are rigid, there need to be some flexibility, hence, can we add these realistic stiffness data on the shell-nozzle junction and nozzle flange end.

B) We are using stiffness value of 1E+6 for rigid flange node (using anchor + stiffness with c-node) at tank nozzle flanged end. This helps in reducing bending moments and axial forces for flange leakage calculation using CII equivalent pressure method per ANSI B16.5. Is this permissible or do you suggest any better way. What is the appropriate stiffness value can we input for nozzle flanges. CII help message for stiffness provides following information.

Stif
Translation: (UNITS: N./cm. )

Rotation: (UNITS: N.m./deg )

Stiffness associated with any support, guide, limit stop, rod or spring that can be defined as a restraint. If left blank then the defined restraint will be considered rigid. The default |rigid restraint stiffness is 1.0E12.

K1 is the initial stiffness of a bilinear restraint (i.e. X2). Any positive stiffness may be entered if the restraint is not rigid.

Stiffnesses greatly in excess of 1.0E15 should be avoided. If a stiffness value is specified for an anchor, the entered stiffness will apply for all (6) degrees of freedom at the anchored node.

C) Why is the Pressure equivalent (Peq) calculation not working in CaesarII 5.20.2 build 100122 with the flange input spread sheet. I get the output report as follows:

Table of Contents

LISTING OF STATIC LOAD CASES FOR THIS ANALYSIS 2
Flange Peq : 4 (OPE) W+D1+T1+P1+H 3

Output disabled for field "Axial Force"
Output disabled for field "Bending Moment"
Output disabled for field "G/C"
Output disabled for field "P Equivalent"
Output disabled for field "Rating Temperature"
Output disabled for field "Allowable Pressure /Stress"
Output disabled for field "Ratio"

Report Contains No Data to Display

A) You don't need to do anything here, CAESAR II will automatically include the computed nozzle stiffness.

B)See (A) above.

C) I have no idea. Send your "flange file" in to techsupport@coade.com and we'll take a look at it.

Regarding question C above, I have encountered the same, i.e. "Output disabled... Report Contains No Data to Display". In my case, it was solved by going to the Load Case Options tab in the Static Analysis window and setting the Flange Analysis Temperature (the column to the far right). This was defaulted to None. Chosing T1 etc., the report came out fine.