| Applies To | |
| Product(s): | AutoPIPE |
| Version(s): | ALL; |
| Area: | Code calculation |
| Date Logged & Current Version | April. 2021 12.05.00.16 |
Problem:
In a particular model, the cold and hot allowable stress have been changed for the following pipe identifier to 18800 psi. The rest of the materials in the model have 15700 psi for the cold and hot allowable stress.
However, software doesn't recognize this new hot and cold allowable stress for gravity and occasional cases ( R1) and lists the allowable as 15700 psi for gravity and 18840 for occasional cases but in Thermal expansion case the right amount of allowable stress is listed as 0.5x(1.25x18800+0.25x18800)=14100 psi.
Pipe Identifiers with 18800 as cold and hot allowable stress: "4-" and "5-" . Find the allowable stresses are different for Equation 8, and 11 at some node points in the model
Solution:
Equation 8 calculates the allowable stresses using the allowable stress at design temperature (Design Sh) and Equation 11 uses the material hot and cold allowable for calculating the allowable stress at the point.
This allowable stress can be modified or updated from the Design Pressure and Temperature dialog as shown below.
For the given model, the hot and cold allowable stresses for Pipe IDs “4-“ and “5-“ have been changed to 18800 psi but the Design Sh is the same as 15700 psi and is used in equation 8 for calculating the allowable.
Hence the allowable stress for equation 8 (Sustained Loads) will be:
1.0×S_h=1.0×15700 =15700 psi
The allowable stress for equation 9 (Occasional Loads) will be:
1.2×S_h=1.2×15700=18840 psi
These are the same allowable stresses as reported by AutoPIPE.
See Also
ASME BPV-III-1-NB, AutoPIPE Nuclear Piping Code FAQ