Horizontal Vessels - CAESAR II - Reference Data

CAESAR II Applications Guide

Reference Data

Horizontal vessel models are built using combinations of straight pipe and nozzle flexibility simulations (WRC 297). The following example illustrates the most accurate way to define horizontal vessel flexibility.


  • OD = 12.750.

  • Wall= 0.687.

  • Flange length = 5.0 inches.

  • Flange weight = 250 lb.

  • Elements 5 to 6, 6 to 10, 15 to 16, 16 to 20, and 20 to 22 are rigid and the associated diameter and wall thickness is that of the vessel. These rigid elements are stiff relative to the vessel.

  • The rigid element from 26 to 30 models the flange at the end of the nozzle and are rigid relative to the nozzle diameter.

  • Local shell flexibilities are defined between the nodes 22 and 24.

  • The above model considers the flexibility of the horizontal vessel section, the free translation horizontal restraint at 15, and the local flexibility of the vessel shell in the vicinity of the nozzle.

The following partial dialog boxes illustrate the modeling techniques used to define the horizontal vessel.

Vessel Legs Not in Contact with Vessel

Vessel Legs - portion not in contact with vessel T=100Fº, P=0.0psi

Element 15-16 is identical except for the restraints as shown above.

Vessel Legs in Contact with Vessel

DY = Vessel Radius

Element 16-20 is identical.