| Applies To | |
| Product(s): | AutoPIPE Vessel |
| Version(s): | ALL |
| Area: | Error message |
| Date Logged & Current Version | April 2018 40.06.00.07 |
Problem:
The following message appears:
604 Unit Distortions on Nozzles (L001): PD 5500 Figure G.2.2-19 deflections of cyl. shells due to radial loads, values beyond curve boundaries (r/t=311.432430,5 , L/r=3", i would like to know, what does it mean "PD 5500 Figure G.2.2-18
Why is it appearing and how to avoid it?
Solution:
All of the design codes have some dimensional parameters based on vessel geometry which needs to be within boundaries to use the aforementioned method (ex. PD5500).
As the error message above indicates:
Unit Distortions - type of calculation being performed.
Nozzles (L001): - the issue is related to Nozzle with item number = L001
Designation = Cylindrical SHELL
tag = TB1:
PD5500 Figure G.2.2-19 Maximum radial deflection of a cylindrical shell ubjected to radial load W for r/t between 100 and 300 (see figure below)
(r/t=30,5 , L/r=1,573771) - AutoPIPE Vessel calculated dimensionless ratios:
- r/t=311.4 however graph range = 100 to 300
- L/r=3 however graph range = 3 to 40 (Value is outside of range, Error)
Because values are beyond curves, AutoPIPE Vessel does not extrapolate, there are results but this is for the user to decide if it acceptable or not. results are out of the predictions curves. Therefore you have the following options:
Option #1: Accept the warning and continue working,
Option #2: Modify the parameters of the model in order for the dimesionless ratios to be within the graph ranges
Option #3: Change the designing method to a different method in AutoPIPE Vessel
Option #4: Use a different application to perform a full Finite Element Analysis. and import data back into AutoPIPE Vessel for completely analysis.
Note, There is a specific calculation performed per PD5500 to determine the Nozzle Flexibility / Nozzle Loads. This is not mandatory by Design Codes, this is just an extra check in AutoPIPE Vessel which can be useful for users. The implantation was based on rules provided by BS PD 5500 Annex G, because it was the only code that allowed this type of calculation. However, newer codes may now have provisions for that determine the Nozzle Flexibility / Nozzle Loads. Again, the calculation in AutoPIPE Vessel would be performed in addition to other nozzle loads checks, that’s why the warning message refers to PD5500 even if the user may have selected a different setting for Code and Standards (ex. EN 13445).
There is no option to remove this calculation (performed for vertical vessels only).