I ahve a question regarding fatigue analysis of say a piping system with a small bore attachment e.g a 3" cantilever type connection (weldolet, pipe, flange) on a 24" pipe.
I am subjecting the system to a harmonic load in and want to assess the fatigue strength at the junction of the attachment to the pipe.

1.Can this type of analysis be accurately determined by CII using harmonic analysis and how does this compare wrt say a FEA ?

2. I ahve a confusion regarding the stress concentration factor required to calcluate the stress amplitude Sa.(from Pm+Pl+Q+F in Section VIII,Div.2). How does CII calculate this value during a FAT analysis and is this different from the SIF used by CII from App. D for the weldolet

Appreciate a response ASAP

Hi,

Appreciate a response from the gurus.

Don't confuse stress intensification factors (SIF) with stress concentration factors (SCF). Piping codes use SIF in their general stress analysis. The more detailed evaluation you seek using VIII-2 may require this SCF if you seek peak stress (the "F" in Pm+Pl+Q+F).
One way you can simply accommodate the SCF in CAESAR II is to reduce the allowable stress amplitude rather than increase calculated stress. Do this by changing the multiplier in the .FAT file you are using to provide S-N data (or just reduce the allowed fatigue stress amplitude data you type in by hand). Note that the multiplier in the .FAT file is actually a divisor so if you want to reduce your fatigue stress amplitudes by a factor of 2, you double this multiplier. (By default the multiplier is 0.5).