Modeling Piping Connection to Pressure Vessels

Read about START-PROF pipe stress analysis software

For Nozzles START-PROF automatically consider following:

Analysis results can be found in Loads on Nozzles and Equipment Table. See also "How to Reduce the Nozzle Loads in START-PROF"

The flexibility of junction point between vessel and pipe consists of two parts: local flexibility and global flexibility. Local flexibility consider local deformation of the shell near the nozzle. The global flexibility consider bending of the whole vessel like pipe bending.

Nozzle element is used for modelling of pipe connection to the pressure vessels and columns. There can be three options:

1. Nozzle element at the end node. In this case global flexibility is not taken into account, except the situation when flexibilities was calculated using Nozzle-FEM software. The thermal expansion of the vessel are automatically modeled, nozzle movements are taken into account.

2. The vessel is modeled using cylindrical shell element (3). The length between nozzle and intersection point between pipe axis and vessel axis is modeled using rigid element (1). Nozzle element should be inserted into the point between pipe and rigid element (2). This method can be used to model the equipment of any complexity and connection of any number of pipes to it. Both local and global flexibility can be considered using this method. The thermal expansions of the vessel are taken into account usinf thermal expansion of the cylindrical shell and rigid element.

   

3. The vessel is modeled using cylindrical shell element. Nozzle element inserted into connection point between pipe axis and cylindrical shell like a ordinary tee (node 1). In this case START-PROF will automatically create the rigid element, no need to add it manually. Both local and global flexibility can be considered using this method.

Properties

 

Property

Description

Name

Text field. Element can be sorted by name and selected in the project tree

Auto calculation of nozzle temperature movements

Automatically calculate the nozzle movements as DX*Alpha*(T-Ta), DX*Alpha*(T-Ta), DX*Alpha*(T-Ta), where Alpha is thermal expansion factor (taken from selected material properties), T is equipment temperature, Ta is ambient temperature, DX, DY, DZ are distances from anchor point to the nozzle specified by user. If checkbox is not checked, then nozzle movements can be specified manually

Material of Vessel

Material from materials database

Manufacturing technology of Vessel

For ASME B31.1, ASME B31.3, DL/T 5366-2014 seamless pipe will always use Wl=1.0. For electric-welded pipe Wl will be specified from database. More...

When using  GOST 32388-2013, pipe physical properties are taken from different materials databases depending on pipe type (seamless/welded).

Temperature of Vessel, Тop

Design temperature in operating mode. More...

This property can be changed in different operation modes. To see the value of this property in all operating modes push the button

Remove restraints for hanger selection

If this option is activated, then some restraints are removed from nozzle element during weight run of variable and constant spring selection. During main analysis restraints are working. This trick allows to remove the weight part of loading from the nozzle element. Springs will take the exact load, at which displacements from pure weight load is zero. Options:

  • Remove vertical restraint. Only vertical restraint will be released during hanger selection

  • Remove custom restraints. You should manually choose which restraints should be released during hanger selection

  • Remove all restraints. During hanger selection all direction restraints will be released

Internal diameter of vessel

Internal diameter of vessel

Length from anchor to nozzle X,Y,Z

Distance between anchor of the pressure vessel and nozzle.

These values are used when modelling nozzle movements due to temperature expansion of the vessel. Used only when nozzle added into the end node. Movement along each axis is calculated using equation ΔX=α(Tope-Tambient)LX.

Thermal expansion factor is taken from material database for selected material.

Nozzle flexibility

There are a several options:

  • Rigid. Flexibilities are zero. Nozzle considered as rigid
  • Manually. Six flexibilities should be specified manually
  • By WRC 297
  • By PD 5500
  • By FEM. Flexibilities are automatically calculated using finite element method (PASS/Nozzle-FEM software). This option is unavailable at this moment. It is under development and become available soon.

Lrad - Linear flexibility along nozzle axis

Lcir - Linear flexibility perpendicular to nozzle axis and perpendicular to the vessel axis

Llong - Linear flexibility perpendicular to nozzle axis and along the vessel axis

Rrad - Angular torsion flexibility of nozzle (around nozzle axis)

Rcir - Angular flexibility in plane of nozzle and vessel axes

Rlong - Angular flexibility out-of-plane of nozzle and vessel axes

Allowable loads / stresses

There are a several options:

  • No check. Loads on the nozzle are not checked
  • Manually. User should specify six allowable loads manually
  • Stress check by WRC 107/537/297. START-PROF will check the local stresses in the shell element (or head element) and local stresses in the junction point between vessel and nozzle using WRC 107/537/297
  • Stress check by FEM. This option is unavailable at this moment. It is under development and become available soon.
  • Allowable loads by FEM. This option is unavailable at this moment. It is under development and become available soon.

 

Menu and Toolbar Access

To insert a nozzle, select the desired node and use the menu option: Insert > Equipment > Vessel Nozzle