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PIPE FEA USING ANSYS

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FEA and ANSYS

Finite Element Analysis (FEA) A numerical technique used for finding

approximate solution of physical problems

Only through the use of modern day computers,FEA becomes effective and practical

ANSYS The FEA software widely used in the industry, one

of Hatch’s main FEA software.

Two interfaces: classical and Workbench share thecore solvers

Workbench is easy to use, best suited for 3Dmodeling

Classical is more powerful, gives the user moreflexibilities

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ANSYS Classical

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ANSYS Workbench

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FEA procedures

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Pipe System To Be Analyzed

Long, large diameter, thin walled steelpipes

Lined with refractory and insulations

There is no other external loads exceptfor self weight

The pipes will see thermal growth atstart up

The roof of the bins may also move dueto thermal expansion at start up

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FEA decisions

3D SOLID elements? – the model is too big!

2D SHELL elements? – possible, but still fairlyexpensive (in term of computing time and model

set up time) 1D BEAM elements – quick and easy, accurate

results for reaction forces and moments, whichmay be used in hand calculations for welds andguidance for support selections.

Detailed 3D / 2D sub models for Y-pipesection and diverters may be analyzed using the1D BEAM model results.

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FEA load cases

The load steps the feed pipes may see: Erect Connect pipes to the bins

Start up, temperature going up (max. 200 C) Production cycles

A good understanding of eachload step is essential for the

success of the analysis!

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FEA load cases

Load cases for the FEA model:0 Run one load case to determine the preload

required from the Spring support and size thespring

1. Room temperature; all support connectedexcept for the expansion joint; gravity loadapplied

2. Room temperature; all support connectedincluding the expansion joint; gravity loadapplied

3. Uniform max. temperature applied on pipes; allsupport connected including the expansion joint;gravity load applied; bin roof thermalmovements applied

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FEA for pipes

“Skeleton” Line Model

Visual representation

of the beam modelBeam Model

Mesh

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FEA for pipes

Element type PIPE16 (pipes and flanges): specialized BEAM element COMBIN14 (expansion joints & spring supports): Spring

elements

LINK 10 (cable support, if applicable): tension only linkelements

Real constants Each element is defined by Element Type and a set of

real constant values For example, “PIPE16 and Real constant set 2” tell

ANSYS these elements behave like a circular hollow

beam, OD=0.4064m, Wall thickness=0.0095m,… Material properties

Mild steel Increase the density for the pipes to match the density

of pipe+refractory+insulation

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FEA Results for Pipes

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FEA Results for Pipes

Displacement in all six degree of freedomsat any node

Reaction forces and moments at any node

Various stress results (bending stress, axialstress, shear stress, von-mises stress,principle stress…) for all elements

Physical properties of the model (volume,mass, moment of inertia…) based on themodel geometry

8/11/2019 pipe-fea 2


pipe-fea 2

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