Comments, Questions, and Answers
Item #1:
The thermal expansion for a model is based off the temperature difference between the Load Case temp and the ambient temp. Therefore, if ambient was 70F and the Load Case temp was 100F, the thermal expansion (and thus thermal load) would be based of 30F difference.
The thermal expansion in code compliance is based on the moment calculations of the corresponding load case (e.g. Amb to T1). These moment values are provided in the Forces and Moments report and represent the difference between operating and ambient temperature. If a separate combination exists that compares two operating load cases (e.g. T1 to T2), the temperature difference shall be between T1 and T2.
Item #2:
The axial force in code compliance is taken from the axial force evaluated during analysis of the model.
AutoPIPE thermal expansion is calculated using the equation found in the link here.
Item #3:
Question: are the pressures in gauge or absolute value?
Answer: Open AutoPIPE model, select a pipe run, open Operating Pressure & Temperature dialog,
The pressure entered in AutoPIPE are in gauge pressure (not atmospheric).
Item #4:
Question: How does these programs deal with the Thermal stratification (Thermal Bowing) in the piping system? Provide the details on modeling?
Answer: Thermal stratification or banana effect occurs mainly in fluids whose density varies as a function of temperature. This is a multitude of processes, including the petrochemical industry and solar thermal plants.
Although it occurs mainly in horizontal pipes, it can occur in vertical lines as a result of the wind or the sun.
Thermal stratification occurs when heating is neither slow nor uniform, and as a consequence flow channels of different temperatures are generated. The warmer and less dense currents travel through the top of the tube, which expands considerably more than the bottom.
This is how the pipe bends on itself (like a banana, hence its name) generating stresses that must be considered in the calculation, and also high forces and moments that can misalign a rotating equipment.
AutoPIPE allows you to select the lines to which the thermal stratification will be applied, which allows modeling the heating or cooling in stages of a plant.
Quickly analyze the thermal stratification scenario. Decide on which lines you want to apply them or apply them on the entire set with one click.
See Also
Loads and Load Sets - AutoPIPE