| Applies To | |||
| Product: | AutoPIPE | ||
| First Affected Version: | 09.01.00 | ||
| Found in Version: | 10.00.00.10 | ||
| Fixed and Released in Version: | 10.01.00.08 | ||
| Area: | Calculations | ||
| Severity: | Critical | ||
| Backlog Issue Number: | 407514 |
Problem Description
Material properties set for valve or flexible joint are used to calculate allowable stress for pipe that follows
Reason
Material properties defined for a valve or a flexible joint are incorrectly used to calculate the allowable stress values for pipe connected to the far end of that valve or flexible joint. The calculated allowable stress values using the material defined for the valve/flexible joint may be higher than the actual allowable stress values for the pipe, leading to un-conservative results. This error impacts all editions of ASME NB, NC and ND piping codes.
To illustrate the defect the following scenario can be considered:
Step 1: Create a new ASME NB model with English units
Step 2: Create a new pipe ID STD12P with the following properties:
Nominal Diameter: 12.00 in
Schedule: STD
Pipe Material: SA106-B
Step 3: Leave the Pressure at 0.0 and Temperature at 70.0
Step 4: Insert an anchor in the model at A00 and connect a pipe run from A00 to A01 using STD12P
Step 5: Connect a valve to the pipe run from A01 to A02
Step 6: Connect a pipe run to the far end of the valve (i.e. from A02 to A03)
Step 7: Select the valve from the Valve tab of Review Component Data dialog and invoke "Modify > Pipe properties over range"
Step 8: On the Pipe Properties dialog enter the name for the Pipe Identifier as STD12V with the following properties:
Nominal Diameter: 12.00 in
Schedule: STD
Pipe Material: SA106-C
Step 9: Analyze the model and take out the Preliminary stress report
Note that the allowable values for the pipe at far end of the valve are based on pipe ID STD12V with pipe material as SA106-C which was selected for the valve. To illustrate similar issue using flexible joint by following the steps above, a flexible joint may be inserted instead a valve.
The following considerations are provided to assist in your evaluation of the potential impact of this defect on the results:
1. Evaluate whether this defect has affected any existing models by considering the criteria below:
a. Was the model created or updated in program version 09.01.00 or later?
b. Was the Piping code for model set to any edition of ASME NB, NC or ND?
c. Was any of the following two conditions true:
i. Was there a valve in the model with different material properties defined for the valve and the pipe connected to the far end of the valve?
ii. Was there a flexible joint in the model with different material properties defined for the flexible joint and the pipe connected to the far end of the flexible joint?
A 'No' to one or more of the above criteria means that this defect does not affect the model’s results. No further consideration for this model is necessary.
Solution:
For a pipe connected to the far end of a valve or flexible joint, program should use material properties defined for the pipe to calculate its allowable stress values.
Additionally, to assist in the screening of the models created in previous program versions for any potential impact by this defect, the program shall automatically examine the model database after opening the model and generate a report (model name + "_D407514.TXT") listing valve / flexible joint far end points where the Pipe ID for the valve/flexible joint is different than the Pipe ID defined for the pipe connected to the far end of the valve/flexible joint. The program shall display the following confirmation message:
“Allowable stress values for a pipe connected to far end of a valve/flexible joint may be incorrectly calculated due to a previous program defect #407514. Would you like to review the evaluation report?”\
The contents of the critical error report shall be similar to the following sample critical error report:
Defect #407514 Evaluation Report
---------------------------------
Model Name: TEST1
Model Version: 09.06.02.06
Program Version: 10.01.00.03
Report Filename: TEST1_D372995.TXT
---------------------------------
Allowable stress values calculated for a pipe connected to far end of a valve/flexible joint with pipe material different than the valve/flexible joint have been revised in this program version to correct defect #407514. Please refer to the published defect report for more details and instructions. To assist in the screening of this model for any potential impact by this defect, program has examined the model’s database and has found that the allowable stress values calculated at the nodes listed below should be re-computed using this program version. After saving this model or running any analysis in this version or later commercial release versions, this screening will no longer be performed.
Piping point(s) potentially impacted by this defect:
----------------------------------------------------
Avoidance:
None
Also See:
Critical and High issues released in AutoPIPE CONNECT v.10.01