| Applies To | |
| Product(s): | AutoPIPE Vessel |
| Version(s): | ALL |
| Area: | Error Message |
| Date Logged & Current Version |
Jan 2025 45.00.03.001 |
Problem:
The following message appears in AutoPIPE Vessel, how to avoid it?
271 MAXIMUM ALLOWABLE WORKING PRESSURE : maximum pressure < design pressure (xx MPa compartment No.xx).
Solution:
As mentioned by the error text, the reported MAXIMUM ALLOWABLE WORKING PRESSURE is less than the design pressure. Open the complete report to "MAXIMUM ALLOWABLE WORKING PRESSURE" sub report, and review to find the issue.
Keep in mind that the MAWP represents the maximum pressure for the weakest part of a design. As a result, all components of an assembly (ex. Shell, Head, Neck, Flange, Cap, etc..) should be considered a potential issue until it is eliminated from suspicion.
Note:
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- If out-of-scope heads allow for a lower pressure than a within-scope head, then MAWP value as calculated by the software is going to be incorrect. User shall calculate the maximal allowable pressure for those out-of-scope heads in a valid way before stating that MAWP as per ASME/APV is correct. Reported MAWP cannot cover an element that is not within the norm's scope of application.
- MAWP is Maximum allowable working pressure is taken from the Design conditions Required MAWP setting, or is calculated at design conditions (design Pressure and temperature) at corroded condition.
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Scenario #1:
Given the error:
Solution:
After reviewing the complete MAXIMUM ALLOWABLE WORKING PRESSURE report, found:
item 02 / 31.05 is not sufficient to support the external pressure, the maximum external pressure is therefore set to zero.
Modify item 02 / 31.05 as needed until the message is no longer shown (consider increasing the item size, etc..).
Note: Recommend to review all Errors and Warnings to see if any others may help to find a cause for this Error message 271. In a particular model with the above mentioned Error, the following additional Error was also found:
- 20 EXTERNAL PRESSURE: stiffener (No. 001) INSUFFICIENT or NOT CONSIDERED
Therefore Error 271 is a consequence of Error 20 on the stiffener. Fixing Error 20 would resolve Error 271.
Suggest to increase the stiffener size.
Scenario #2:
User's design was constructed with the third chamber having the capability to withstand operating and design condition higher pressures than 1.134 Mpa. Therefore, why is the error appearing
Solution:
After reviewing the complete MAXIMUM ALLOWABLE WORKING PRESSURE report, find:
From the Summary of forged items find:
A flange rating of 150# is the reason why the MAWP of chamber #3 is limited to 1.134 MPA.
In order to increase the MAWP of chamber 3, suggest to increase the flange rating from 150# to 300#.
Note: Recommend to review all errors and Warnings to see if any others may help find a cause for this given Error. In a particular model with the above mentioned Error, the following warning was also found:
- 589 FLANGE (nozzle F): the rating class is less than required rating class (300)
This would be a clear indicator to the user to perform a through review of the model input. In conclusion, the program was able to help the user locate an input mistake.