| Applies To | |
| Product(s): | AutoPIPE |
| Version(s): | ALL; |
| Area: | Calculations |
| Date Logged & Current Version | April. 2014 09.06.00.15 |
Problem:
The results for DNV code combinations Collapse and Prop Buck are 0.00 or very small, why?
Solution:
Typical reason for 0.00 or low values:
1. Be sure to check that the node points are actually located below the Water surface. View> Show options> "Water Surface & Sea Level" is checked on, press OK button and confirm node point is with int he blue are of all the waves specified in the model. Only those points below the water surface, will have calculated values > 0.00.
2. The model units may a limiting factor, with the "DNV-OS-F101-INITIALMODEL.DAT" provided in the Example folder (C:\Bentley\AutoPIPE V8i SELECTseries\Examples), change the Tools> Model options> General> units from SI to English and re-run the analysis report:
If the values remain 0.00 there is a problem with one of the settings in the model, see next suggestion for possible reason..
3. Please see the following AutoPIPE help section:
Help > Contents> Contents Tab> Reference Information> Code Compliance Calculations> DNV 2012> Collapse Limit (DNV - 2012)> Equation 5.14,
Code stress value is calculate based on Pext - Pmin,
The external pressure at any point less minimum pressure which is always is assumed to always be 0.00 psi.
Confirm the following dialog settings are correct:
1. Load> Wave>
2. Tools> Model Options> DNV 2012 Result Options
3. Load> Buoyancy>
Note:
1. Check to be sure the water level / ground elevation on the Wave, Wind, and Buoyancy dialog screens all agree. They could have different elevation values that would cause the respective load to be applied to the model incorrectly. To keep things simple, may consider using the Vertical axis location = 0.00 as the water / ground elevation and locate the piping arrangement accordingly. Thus making it easy to understand that anything above the Vertical axis (default Y) = 0.00 will be exposed to wave or wind loads accordingly.
2. On the Buoyancy dialog screen, specific gravity must be greater than 0.00.
3. On the Buoyancy dialog screen, check ON "Apply buoyancy to all segments" otherwise, use segment input grid for selecting segments to which buoyancy will be applied in the analysis.