Insulation Weight on Rigid Elements - CAESAR II - Help

CAESAR II Users Guide

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CAESAR II
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CAESAR II Version
12

The insulation weight for the rigid is assumed to be equal to 1.75 times the insulation for an equivalent length of straight pipe of the entered outside diameter.

Total Weight on Rigid Elements

The total weight for rigid elements where the entered weight is zero will be zero.

The total weight for rigid elements where the entered weight is not zero is calculated as follows:

Weight = Wu + Wf + Wr +1.75(Wi+Wc)

Where:

Wu = User-defined rigid weight (the Thermal Expansion/Pipe Weight report will show user-defined weight divided by entered length)

Wf = Calculated fluid weight for equivalent straight pipe (this is reduced by refractory lining)

Wr = Calculated refractory weight for equivalent straight pipe

Wi = Calculated insulation cladding weight for equivalent straight pipe

Wc = Calculated cladding weight for equivalent straight pipe

CAESAR II does not calculate stress on rigid elements. Forces and moments are not normally printed for rigid elements however, you can select the appropriate check box found in Environment>Special Execution Parameters from the Piping Input spreadsheet to print these loads.

Modeling using Rigids

Zero-weight rigid elements are useful where modeling non-pipe components where thermal growth or load transfer is important.

Use zero-weight rigids to model piping hardware such as expansion joint tie rods, base plates, and trunnions.

You can also use these dummy rigids to provide connectivity between the centerline of an element and the outside edge of the element. The most common example of this is when you need to add a dummy rigid that runs from the node at the centerline of the vessel to the outside wall where you want to connect the nozzle.

You can also model equipment using a series of rigid elements, joining nozzles to a body and perhaps to a support point. This approach will properly distribute thermal strain through the component based on this geometry and the entered element temperatures. For more information on the use of these construction rigids, see the CAESAR II Applications Guide in various sections as appropriate to a particular modeling technique.