Applies To
Product(s):	AutoPIPE
Version(s):	ALL;
Area:	Calculation
Date Logged & Current Version	March 2025 24.00.02.243

Problem:

How to calculate the Stress Indice SIF values for a socket weld joint per ASME NCD 2021 given the following information?

Solution:

 Follow these steps:

1. Open AutoPIPE help section: 
Help ribbon> Contents button> Contents Tab> Reference Information> Code Compliance Calculations> ASME BPV-III-1-NCD (2021 - 2023)> Stress Indices (2021 - 2023) NCD - Stress Indices (2021)>

2. Find reference to Table NCD-3673.2(b)-1, since this is a socket joint on a pipe run node point, the weld type = Circumferential Fillet weld / Socket weld. Locate the correct part of this table.

3. Make sure to reference any notes (ex. Note #11)

4. As seen from the image above, this run node point has 2 different pipe sizes. Therefore, calculate the SIF for both pipe sizes. 

5. Evaluate conditions of SIF calculations

Accordingly at node point C25: CX = 0 from reported information provided, which is less than both of the calculated conditions for SIF equations (ex. 0.20 & 0.78). 

Therefore, the SIF value should be i = 1.33. Reference the output report above, at node C35 the SIF is 1.3, however at node point C25 the SIF = 2.8.

Q. Why is the SIF calculated to 2.8?

hint: look at the notes referenced for this type of connection.

6. Per note 11, sketches c-1, c-2, and c-3 have a minimum CX value. Although the AutoPIPE joint input has Weld size (Cx) = 0.00 (imaged above), there is a minimum value for Cx. At this time, Mach 2025, AutoPIPE does not have a setting for which sketch should be used to calculate the minimum CX value, AutoPIPE will take the conservative approach and use the smallest weld size, Cx = 0.75tn. 

7. Calculate SIF values 

In summary, AutoPIPE's results are correct per the code while using a conservative approach.