# Modelling of Vertical Vessels

Read
about START-PROF pipe stress analysis software

There are three options to model the vertical pressure vessels
in START-PROF software:

1. Using nozzle element at the pipe end
node. In this case "global beam flexibility" is not taken into
account (assumed that pressure vessel is absolutely rigid), except the
situation when "FEM" option is used. Thermal expansion of pressure
vessel is taken into account automatically, no need to model the pressure
vessel as rigid elements or set restraint movements.

This method should be used only in the simple cases, when no horizontal
loads acting on the piping and equipment like seismic,
wind, etc.

2. The vessel can be modeled using cylindrical shell
element ("3" on the picture below). The length between nozzle
and intersection point between pipe axis and vessel axis is modeled using
rigid element ("1" on the picture
below). Nozzle element should be inserted
into the point between pipe and rigid element (2). Both "local shell
flexibility" and "global beam flexibility" will be taken
into account using this method. This is a classic method, which is known
by many pipe stress engineers

1 - Rigid Element, 2 - Nozzle Element, 3
- Cylindrical Shell Element

3. This method is faster and easier than method #2 gives the same analysis
result. The vessel is modeled using cylindrical shell
element. Nozzle element is inserted into connection
point between pipe axis and cylindrical shell like a "tee" (node
1 on the picture below). In this case START-PROF will automatically add
the internal hidden rigid element between nozzle and node 1. Using this
method you may skip the step of creating the rigid element manually and
save the time. Both local and global flexibilities will be taken into
account like using method #2.

The methods 2 and 3 can be used
to model the equipment of any complexity and connection of any number
of nozzles into the one vessel.

Also the more realistic model of
the vessel connection to the foundation can be used:

And
vessels of any design can be modeled

### See Also

Modelling Horizontal Vessel

Modelling Column Vessel

Nozzle Element