I created a semplified autopipe model (completely above ground, without soil) to try to verify formulas that it use to calculate the equivalent stress according to ASME B 31.4.
In correspondence of a node in a fully unrestrained pipe, the calculated equivalent stress is exact the same value of hoop stress;(see below values)
Category
Stress
Allowable
Hoop
229.1
322.68
Sustain
114.69
242.01
Expansion
0
Eq Tensile
403.34
in correspondence of a node in a fully restrained pipe, the calculated stress values are listed below
72.38
207.24
296
I’m not able to understand which equations it has been used.
Can someone help me?
Another question: in the result grid, is reported a column named “pressure”, what means?
Thanks in advanced.
Regards
Hi Franco,
For fully unrestrained pipe above ground, it is sensible that you may see equivalent tensile stress equal to Hoop stress provided there is no torsional stress. Please check the topic "Reference Information > Code Compliance Calculations > ASME B31.4 (2006) > Equivalent Tensile Stress" for details. Also see attached zip file containing a PDF having more details on Equivalent Tensile Stress calculations.
For the second question, the pressure column represents the longitudinal pressure stress. Please see the following from the online help. Hope this helps.
B314_Eq_Tens.zip
Regards,
Bilal Shah
Answer Verified By: Luke Andrew