PASS/NOZZLE-FEM 3.5. Program Manual

1. General

1.1. Program designation

PASS/NOZZLE-FEM program is designed for stress and flexibility analysis of pressure vessel and piping components, including branch junctions of steel tanks for oil storage by finite element method (FEM).

At strength and stiffness calculation FEM got a wide spread occurrence. The program designed, unlike the universal finite element analysis programs (ANSYS, NASTRAN, COSMOS, etc.,) does not require special training of users and considerable time consumption. Creation of finite element model and estimation of the achieved results regarding the deflected mode of branch connection are performed automatically.

Deflected mode calculation is performed both for radial and tilting branch connections in cylindrical and conical shells, and also in elliptic, spherical and flat bottoms, as well as laterals in piping. Calculation with FEM allows expanding considerably a range of application and solution accuracy of the task.

Accuracy of strength calculation of vessels and pipelines in junction is determined considerably by estimation of branch connection stiffness (flexibility). Usually, at strength calculations of pipeline systems a junction of pipeline and vessel is substituted by dead support, which leads to getting of overstated stresses and tensions in the connection.

At calculations of vertical vessels (including column type) a fixation of shell is performed in the attaching point of supports. At that upper part of the shell is not fixed, which leads to additional flexibility of branch connection.

For the calculation of nozzle junction with ends of horizontal vessel is recommended to use a model of head with a cylindrical shell which are usually modeled to the nearest secure or strengthen the shell.

In addition to the calculation with FEM, the program have an opportunity of stiffness and tension calculation of nozzle's junction with use of stress intensification coefficients on the basis of [8-18] (WRC107/297/537, BS5500). Allowable stress level is stipulated by normative documents [12, 17, 3-7].

A possibility of strength and stability estimation is provided both for the element, into which a nozzle is to be cut-in, and a calculation of hole reinforcement under pressure influence only, in accordance with normative [13] and [14] correspondingly.

The program has an opportunity of strength calculation of branch connection working in corrosive hydrogen sulphide environment, in accordance with normative document [16], as low-cyclic loads action as per [15].

Program operation is resulted in conclusion to strength of branch connection at specified loads, as well as tables of stiffness and allowable loads active on the nozzle.

This program is recommended for designing purposes and checking calculations regarding facilities of oil-refining, petrochemical, natural gas, petroleum and other branches of industry.