Applies To
	Product:	AutoPIPE
	First Affected Version:
	Found in Version:	12.02.00.14
	Fixed and Released in Version:	12.04.
	Area:	Analysis
	Severity:	Critical
	Backlog Issue Number:	1062015

Behavior

Problem Description

For the negative face at the far end of a reducer, allowable and B2 stress index calculations may incorrectly use Pipe Properties and Pressure/Temperature data from the following pipe. These properties include hot allowable (Sh) and material code. Using these incorrect values may results in higher eq. 10a allowable, higher eq. 11 allowable and lower B2 stress index which is unconservative. This issue will be limited to the cases where the reducer and following point have different pressure, temperature and/or different pipe material properties.

Steps to repeat

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

Step 1: Create a new ASME NC/ND 2015 model with AutoPIPE units selected

Step 2: Define a new pipe identifier with 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

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 of 5ft. in Dx from A00 to A01, using pipe ID “PIP1”

Step 6: Insert a reducer of 2ft. in Dx 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 of 5ft. in Dx using previously defined pipe ID “PIP2”

Step 8: Select pipe properties “PIP2” and change Operating Pressure & Temperature data as below

Pressure: 450 psi
Temperature: 600 Deg F

Step 9: Select pipe properties “PIP2” and change Design Pressure & Temperature data as below

Pressure: 600 psi
Temperature: 700 Deg F

Step 10: Analyze the model and define a new stress summary with default selections except the following changes:

Equation No. 9
Combination 1: Gravity {1}

Equation No. 10a
Combination 1: Zero Moment Case
Combination 2: Thermal 1{1}

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

Notice that equation 10a allowable, equation 11 allowable and B2 stress index for the reducer near end (A01) and reducer far end negative face (A02-) do not match, even though both points have same Pipe Properties and Pressure/Temperature data. Reducer far end negative face (A02-) uses Pipe Properties and Pressure/Temperature data from positive face (A02+). This leads to unconservative allowable and B2 stress index values.

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 NC or ASME ND?
c. Was there a reducer in the model with any of the following conditions true?

i. Reducer and the following pipe have different Pipe identifiers
ii. Reducer and the following pipe have 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.

Otherwise the following mitigation conditions may apply:

1. The following pipe may have more conservative material properties (lower allowable values), in which case the results will be conservative.
2. Modelling a pressure and temperature change at a reducer is not a typical practice.
3. As material changes usually occur at transition welds in straight pipe, a material change at a reducer is unlikely.

Workaround

None

Solution

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 + "_D1062015.TXT"), listing the reducer’s point potentially impacted by this defect. The program shall display the following confirmation message:

“Allowable and B2 stress index calculations for reducers may use incorrect Pipe Properties and Pressure/Temperature data due to a previous program defect #1062015. Would you like to review the evaluation report?”

The contents of the critical error report shall be like the following sample critical error report:

Defect #1062015 Evaluation Report
-----------------------------------

Model Name: TEST1
Model Version: 09.06.02.06
Program Version: 11.01.00.09
Report Filename: TEST1_D1062015.TXT

------------------------------------

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 #1062015. 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 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 point(s) potentially impacted by this defect:
-----------------------------------------------------

A02
B02

Also See:

Critical and High issues released in v.12.04.

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

Bentley AutoPIPE