Nozzle FleX plugin for SAP2000

Meshed nozzle with pad

Quickly get flexibilities of equipment nozzles or piping branches

Built for pipe stress engineers, this plugin helps in your day to day work by calculating the stiffness of vessel nozzles and piping branches. This lets you calculate accurate loads on these connections while avoiding the uncertainty of old methods like WRC 297, or generalised formulae like B31J.
  • Calculates nozzle stiffness and branch flexibility factors
  • Calculates SIF’s or SCF’s
  • Can be used for cylindrical vessel nozzles and piping branches
  • US or SI units
  • 90 degree branches or Angled branches
  • Hillside nozzles
  • With or without reinforcing pad
  • With or without header cut-out
  • Can use the FEA model for further modelling in SAP2000 if desired
  • Adjustable mesh density
  • Nozzles on heads
Vessel nozzle models

Nozzles on pressure vessel heads

The plugin lets you calculate flexibilities and stress concentration factors of nozzles on hemispherical, semi-elliptical or torispherical heads.

Nozzle on hemispherical head
SE head circumf bending deformation (SAP 2000)

Plug-in useage demonstration:

How to use the calculated stiffnesses in CSiPlant pipe stress software:


SAP2000 is the leading structural analysis and FEA package by Computers and Structures, Inc (CSi). It integrates seamlessly with CSiPlant pipe stress software to transfer structural models and pipe support loads.

The Nozzle FleX plugin is created and supported by Xtrados Pty Ltd. We have a history of writing software and add-ons for piping engineers. Xtrados is not affiliated with CSi.


Download the manual here to learn more about the plugin and how you can use the results in your pipe stress models. Examples are provided for CSiPlant and CAESAR II by Hexagon.


Download the self-extracting executable. You don’t need admin privileges to install, but you may need to unblock the file or ignore Windows Defender warnings. 

Please contact us to obtain a trial key and pricing. See the above manual for full details and to help you with installation.

You can also trial SAP2000 if you don’t have it currently.


We have compared outputs against other software and found generally consistent results. Please see the Verification page.