| Applies To | |||
| Product: | AutoPIPE | ||
| First Affected Version: | 06.03.00 | ||
| Found in Version: | 09.06.02.06 | ||
| Fixed and Released in Version: | 10.01.00.08 | ||
| Area: | Library | ||
| Severity: | Critical | ||
| Backlog Issue Number: | 339236 |
Problem Description
Allowable values at points using material specifications with more than one thickness range may be calculated incorrectly
Reason
Stress allowable values for points having a pipe ID which uses a material specification that has more than one thickness range may be calculated incorrectly. The piping standard may provide multiple values for minimum yield strength or ultimate strength based on the thickness of selected pipe, however AutoPIPE only uses a single value for the minimum yield and ultimate strength values. For some material specifications with more than one thickness range, AutoPIPE may use a higher value of these allowable values regardless of selected thickness value of the pipe, leading to un-conservative results. This error impacts the following material libraries and materials:
ASME2000 through ASME 2013 - SA312-TP321, SA312-TP321H, SA376-TP321, and SA376-TP321H
B313-04 through B313-14 - A312-TP321, A312-TP321-C, A312-TP321H, A376-TP321, and A376-TP321H
JSME-08 - SM400A, SM400B, SM400C, SM490A, SM490B, SM490C, SM490YA, SM490YB, SM520B, SM520C, and SM570
To illustrate the defect the following scenario can be considered:
Step 1: Create a new ASME NC model with Edition set as 2007
Step 2: Create a pipe ID STD12, with 12” nominal diameter, Schedule set as 40 and select the Pipe Material as “SA312-TP321”
Note that the Cold allowable field will be updated to 16,700 and Minimum yield will be set to 30,000. ASME IID requires the yield value to be 25,000 for thickness values greater than 0.375”.
Step 3: Insert an anchor in the model at A00 and connect a pipe to the anchor
Step 4: Analyze the model and then open up the Stress summary dialog
Step 5: Create a new stress summary with “Service Level” set as D, “Allowable case for Sh, Sy in Eqn. 9” set as “Ambient”, and Combination 1 set as “Gravity{1}” for both equation 8 and 9
Step 6: Take out the stress summary report
Note that the allowable value of 50,100 is reported for Eq. 9a, which is 3*Sh = 3*16,700. If the correct yield value of 25,000 was used, the allowable value would be capped at 2*Sy = 2*25,000, = 50,000.
Note that other allowable stress values dependent on the cold yield or ultimate strength may also be impacted by this defect.
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 6.0.0 or later?
b. Was the material library selected for the piping code any one of the following:
i. ASME2000 or later
ii. B313-04 or later
iii. JSME-08
c. Was any of the following conditions true:
i. ASME2000 or later: Was there a pipe ID in the model with material specification set to SA312-TP321, SA312-TP321H, SA376-TP321, or SA376-TP321H?
ii. B313-04 or later: Was there a pipe ID in the model with material specification set to A312-TP321, A312-TP321-C, A312-TP321H, A376-TP321, or A376-TP321H?
iii. JSME-08: Was there a pipe ID in the model with material specification set to SS400, SM400A, SM400B, SM400C, SM490A, SM490B, SM490C, SM490YA, SM490YB, SM520B, SM520C, or SM570?
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. Otherwise, the following mitigation conditions can be considered:
1. Allowable stress values which are not dependent on minimum yield strength Sy at ambient temperature or ultimate strength at ambient temperature are not impacted by this error.
2. Pipe IDs for which the yield or ultimate strength values corresponds to the pipe thickness value set for that pipe ID are not impacted. For example: minimum yield value of 30,000 psi is provided by ASME IID for material specification SA312-TP321 for thickness values up to 0.375”. Pipe IDs with thickness values equal or lower than 0.375” with material specification set to SA312-TP321 will not be impacted by this defect.
Solution:
Program shall store all the values for thickness dependent material properties in the material library and should select the correct value based on the selected thickness of the Pipe ID.
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 + "_D339236.TXT") listing the Pipe IDs in the model with the impacted materials selected. The program shall display the following confirmation message:
“Allowable stress values materials with different thickness ranges may be incorrectly calculated due to a previous program defect #339236. Would you like to review the evaluation report?”
Avoidance:
Set the affected pipe IDs material to NS and manually enter the correct minimum yield and/or ultimate strength value on the pipe properties dialog.
For defining new pipe IDs with affected material specifications – select the affected material specification and press OK on pipe properties dialog. This will update all properties including temperature dependent properties. Modify the pipe ID and set the material to NS and enter the correct minimum yield and/or ultimate strength values.
Also See:
Critical and High issues released in AutoPIPE CONNECT v.10.01