Dec 2014, AutoPIPE V8i 09.06.01.10
Can you provide more details on the Nozzle dialog fields, Length and Thickness?
The Nozzle element is used to take credit for the flexibility of surrounding wall where the nozzle piping is attached. Therefore the modeling concept is that the expansion joint is used to represent the wall thickness and flexibility of the vessel / container where the nozzle is mounted. The Nozzle element length should not be equal to the distance from the vessel / container wall to the a mating flange face.
From AutoPIPE online help:
Enter the length of the vessel shell wall. Nozzle length is not used in calculated the nozzle flexibility (which is really the vessel shell flexibility). The length defines a flexible joint to which the nozzle flexibilities (as calculated by AutoPIPE) are assigned.
Enter the outside radius (or half the actual diameter) of the vessel and the thickness of the vessel wall in these two fields.
For new user, there remains a lot of confusion around the Nozzle dialog entries for Thickness and Length. Simply put a nozzle element is modeled as a Flexible joint, as shown in the image below.
The Nozzle Length field specifies how long the flexible joint being modeled will be (distance between A03 - A04) in the program. Aka, the physical length of the Flexible joint in the model. Again, the Length is usually equal to the wall thickness of the vessel / container where the nozzle is attached too.
The Thickness value is used by the program to calculate the respective nozzle stiffness values that will become input into the flexible joint dialog screen (ex, calculated values for: Axial, Shear, torsional, bending stuffinesses).
Again, Length and Thickness are 2 different fields used for 2 different reasons; one modeling and the other calculations.
Under most circumstances Length & Thickness will be the same. However, be careful when entering these values, always look to see what units are being used. In English units, Length is entered in FT (mm), where Thickness is entered in INCH (mm).
Note: for nozzles that have a reinforcing pad, add the thickness of the reinforcing pad to the Length and Thickness values entered on the dialog.
Modeling Vessel / Nozzles