45 degree cut on PSV Discharge Piping 1

[UKCats]

Does anybody have a scientific reference (or test data) to why end of an open pipe is cut at a 45 degree angle. My recollection is a straight cut could build up harmomics (standing waves) and reduce capacity. If you notice, organ pipes, and many automobile exhaust pipes are cut at an angle.

Trying to get this in API 520/521 but need scientific reference or test data.

 

[pleckner]

Perform the calcuation for velocity. The 45 deg cut provides a larger cross sectional exit area and thus lowers the exit velocity. This translates into less noise and pipe vibration.