Under Pressure® Design Software

Under Pressure is a downloadable PC program that enables quick, accurate designs of pressure housings and pressure vessels. Under Pressure contains a database of commonly used pressure vessel materials that can be easily edited and supplemented for the user’s specific needs. Designed to be used by the working engineer or scientist, this menu-driven software is interactive and user-friendly.

Our latest release, Under Pressure 4.60, no longer requires a security dongle and is offered as a free download to the community. UPWin 4.60 uses the legacy project files so you can begin using Under Pressure with your current projects. UPWin 4.60 does ship with a new database so be sure to apply any customizations you may have performed on previous Under Pressure versions before opening your project files.

The software requires the Windows Operating System (XP, Vista, Windows 7, 10).

During installation, if a run-time error 339 occurs, please see the troubleshooting document under “Downloads” to resolve the error.

Screen shot of our downloadable PC software.

Screen shot of our downloadable PC software.

Key Features

  • Design Loop allows variation of single parameter
  • Calculates both thin wall and thick wall collapse pressures
  • Equations from Roark & Young’s formulas for stress and strain
  • Large materials database is provided that can be expanded by the user

  • Graphic representation of the pressure vessel
  • On-line graphic display of radial and tangential stress distribution
  • The manual contains a color comparison of numerical stress results with graphically displayed stress distribution results generated by a computer-aided structural analysis using the finite element method
  • Complete hard-copy manual with step-by-step walk-through of Under Pressure’s features
  • Soft copies of the manual are included in the original Microsoft Word format and in an Adobe Acrobat PDF format so that you can re-print the manual as needed

Under Pressure evaluates structural capabilities, deflections, and weights of common pressure vessel geometries such as cylindrical tubes, spheres, as well as hemispherical, conical, flat circular, and flat annular end enclosures.

The user can choose from a housing shape of tube, sphere, or end cap. Within the end cap category are several subcategories, such as hemispherical and flat annular. The flat annular end cap can be further delineated by choosing among several options, such as fixed, simply supported, guided, and free. The user also selects the material, housing component geometry, and pressure analysis range; the stress analysis is then rapidly calculated. A design loop can be selected and the analysis can be repeated while a single parameter (e.g. wall thickness) is varied. Stresses and deflections are given for internal or external pressures, over a user-selectable pressure range. English or metric units can be specified. The program uses equations from Formulas for Stress and Strain, sixth edition, by Raymond J. Roark and Warren C. Young.

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