	Applies To
	Product:	AutoPIPE
	First Affected Version:	9.1.0
	Found in Version:	11.01
	Fixed and Released in Version:	11.01
	Area:	All
	Severity:	Critical
	Backlog Issue Number:	656782

Problem Description

For the negative face at the far end of a reducer, stress, allowable and SIF calculations may incorrectly use Pipe properties and P/T data from the following pipe. These properties include hot yield (Sy), allowable stress intensity (Sm), material code, thermal wall gradients (deltaT1, deltaT2) and pressure. Using these incorrect values may results in lower eq. 11 stresses, higher ratchet allowable, higher eq. 10 allowable, and lower B2 stress index. This defect impacts all editions of ASME NB piping code.

Steps to Repeat

To illustrate this defect, the following scenario can be considered:

Step 1: Create a new ASME NB model with AutoPIPE units selected

Step 2: Define a new pipe identifier with the following data

Pipe identifier: PIP1
Nominal Diameter: 12.00
Schedule: STD
Pipe Material: SA312-TP316H

Step 3: Insert following data on Operating Pressure & Temperature dialog for point A00 as below

Pressure: 200 psi
Temperature: 300 Deg F
Delta T1 350 Deg F
Delta T2 200 Deg F

Step 4: Insert following data on Design Pres & Temp dialog for point A00 as below

Design pressure: 400 psi
Design temperature: 600 Deg F

Step 5: Insert an anchor at A00 and a run from A00 to A01, using pipe ID “PIP1”

Step 6: Insert a reducer at A01 and define pipe ID “PIP2” for the far end A02 of the reducer, with following definitions

Pipe identifier: PIP2
Nominal Diameter: 20.00
Schedule: STD
Pipe Material: SA387-11-2

Step 7: Insert another run from A02 to A03 using previously defined pipe ID “PIP2”

Step 8: Modify pressure/temperature data from point A02 to A03 as below

Pressure: 450 psi
Temperature: 600 Deg F
Delta T1 200 Deg F
Delta T2 100 Deg F

Step 9: Modify design pressure & Temperature data from point A02 to A03 as below

Design pressure: 600 psi
Design temperature: 700 Deg F

Step 10: Analyze the model and define a new stress summary with default selections except the following for Equation No. 10 transient:

Combination 1: Zero Moment Case
Combination 2: Thermal 1{1}

Step 11: Generate stress summary and stress indices sub-reports

Notice that eq. 11 stress, ratchet allowable, equation 10 allowable, and B2 stress index for the reducer near end positive face (A01+) and reducer far end negative face (A02-) does not match, even though both faces exhibit same Pipe properties and Pressure/Temperature data.

Evaluation Criteria

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 9.1.0 or later?
b. Was the Piping code for the model set to any edition of ASME NB?
c. Was there a reducer in the model with any or both of the following conditions true:

i. Reducer and the following pipe has different Pipe identifiers
ii. Reducer and the following pipe has different Pressure/Temperature data

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.

Workaround

None

Solution

Stress, allowable and B2 stress index calculations for negative face at far end of a reducer should use Pipe properties and Pressure/Temperature data defined for the reducer.
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 + "_D673865.TXT"), listing the reducer faces potentially impacted by this defect. The program shall display the following confirmation message:
“Stress, allowable and B2 stress index calculations for reducers may use incorrect Pipe properties and Pressure/Temperature data due to a previous program defect #673865. Would you like to review the evaluation report?”

The contents of the critical error report shall border on the following sample critical error report:

Defect #673865 Evaluation Report
---------------------------------
Model Name: TEST1
Model Version: 09.06.02.06

Program Version: 11.01.00.09
Report Filename: TEST1_D673865.TXT
---------------------------------
Stress, allowable and B2 stress index calculations for reducers may use incorrect Pipe properties and Pressure/Temperature data from the following pipe due to a previous program defect #673865. Please refer to the published defect report for more details, mitigation conditions and instructions. To assist in the screening of this model for any potential impact by this defect, program has examined the model database and has found that stress, allowable and B2 stress index results at the following reducer faces 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.
Reducer face(s) potentially impacted by this defect:
----------------------------------------------------
A02-
B02-

Also See:

Critical and High issues released in v.11.01.00

Known Issues in AutoPIPE (Enhancements, defects, etc..)