PASS/Nozzle-FEM is a program designed to calculate the stresses and flexibility of nozzle-to-shell junctions using the finite element method (FEM). It also calculates the nozzle’s allowable loads and estimates the strength of the junctions for a wide range of geometric configurations and operating conditions. The program helps engineers to provide higher levels of equipment safety while reducing labor costs at the design stage. It is intended for use by equipment and piping designers and mechanical engineers and can help them to quickly check and satisfy requirements for loads on pressure vessel/equipment nozzles, as well as on non-standard piping fittings. It is recommended for use in design and industrial safety reviews in oil and gas, refineries, petrochemical, chemical, power and other industrial facilities.


No special training required


Unlike other widely available FEM programs (eg. ANSYS, NASTRAN, COSMOS, etc.), PASS/Nozzle-FEM does not require special training and can be used by any mechanical engineer. It automatically creates the FE mesh and estimates the calculation results. The use of FEM calculations as opposed to semi-analytic methods (i.e. WRC 107/297) expands the application range of the program and increases the accuracy of its analyses.

PASS/Nozzle-FEM performs stress analysis for nozzle junctions of different types (including trunnions) connected to cylindrical and conical shells, as well as for elliptic, hemispherical and flat heads. It considers the vessel boundary restraints and loads on the nozzle from the adjacent pipeline. It can calculate nozzle and shell membrane, bending and total stresses. It can also calculate the pipe branch connections to enable a detailed stress analysis of nonstandard tees and stub-ins.

In addition to stress and stability analysis, the program also performs nozzle-shell junction flexibility calculations since this flexibility can considerably influence the vessel and piping stresses. During a stress analysis of pipeline systems, nozzle-vessel junctions are often simulated by anchor supports which leads to an overestimation of stresses and tensions. To address this and automatically create an appropriate non-standard support in the calculation model, the program allows engineers to pass the nozzle-shell junction flexibilities calculated by PASS/Nozzle-FEM into the PASS/START-PROF piping stress analysis program.


New features available in release 3.0


  • Capability to change the orientation of all shell types;
  • Capability to insert a nozzle on the conical reducers and heads;
  • Capability to calculate a shell without a nozzle;
  • Capability to set several load cases in a specific project;
  • Vector type of nozzle placement setting is implemented;
  • New system coordinates (pipe CS) that allows to set shell and nozzle concentrated loads.



    Software graphical interface has been significantly updated, and has become more user friendly.



    Updating of codes (regulatory documents)


    In the development and refinement of each new version of the kernel, a module for strength verification in accordance with various regulatory documents is also reworked, which provides quite flexible and fast processing of updated versions of different codes.

    Stress state can be estimated by different codes: ASME VIII div.1,2; EN 13445-3; GOST 34233.1-2007; JB 4732-1995; PNAE G-7-002-86 (for equipment and pipelines of nuclear power plants) for allowable stresses. Vessel stress and stability analysis (according to GOST 34233.2-2007) is also implemented, as well as reinforcement required of openings under internal pressure (GOST R 52857.3-2007). Nozzle-shell junctions working in corrosive hydrogen sulfide environment are analyzed in accordance with GOST 34233.10-2007.

    Besides finite element method calculation, the program supports CIF and flexibility calculation via semi-analytic methods according to WRC107-79, WRC297-87 (Welding Research Council Bulletins No. 107, No. 297 “Local stresses in spherical and cylindrical casings caused by the external loads”) and BS5500-76 (British standard).

    Calculations as per WRC 537 and per GOST 342233.2,3-2017 have been fixed and updated in the release 3.0


    To get the new version of PASS/Equip, please contact us.


Pin It on Pinterest