FE/Pipe - Template-based FEA for Piping & Pressure Vessel Engineers
|FE/Pipe was authored by Tony Paulin, the original author of CAESAR II.
The same recogintion of stress analysts' needs that lead him to create and develop CAESAR II into the best of its kind, has been extrapolated into FE/Pipe.
Pipe stress programs, and methods such as WRC 107 have many limitations. When we reach these limits, we often guess, do a few hand calculations, and hope we're right.
Wouldn't it be nice to have accurate answers, or even just confirmation of the calculation methods we do use?
We all know that the answers we want come from FEA, but until recently, it has been the domain of the few who can make the enormous investment in expensive software and vast technical training.
This is part of what FE/Pipe changes. It puts FEA technology in the hands of all piping & vessel engineers who need the right answers, but who only have real-world resources available.
FE/Pipe uses simple inputs, like diameters, wall thicknesses, forces and moments - inputs we're familiar with and understand - then creates a complete FE model based on a corresponding library of FE component templates. Once your model, loads and design parameters are set, FE/Pipe performs a true FE analysis, and provides CODE RESULTS!
This means input and output that you can understand!
Anything that may be unclear is quickly available through the on-line help, on-line documentation and technical support.
FE/Pipe provides extremely useful output, not the least of which is graphical confirmation of your model, and stress contours that help you evaluate high stress locations and the quality of your FE model!
- ASME Section VIII Div 1 & 2 stresses
- Load case reports
- Flexibilities - can be used in CAESAR II
- Computed Stress Intensification Factors - SIFs for use in pipe stress programs
- ASME Overstressed Areas
- Highest Primary Stress Ratios - ASME Section VIII Div 2 primary stresses and allowables (sustained)
- Highest Fatigue Stress Ratios - Expansion/peak stresses and allowables
- Highest Shakedown Stress Ratios - Secondary (non-peak) stresses and allowables
Here are just some of the complex models you can create in minutes...
These are just some of the templates FE/Pipe provides. You can string multiple components together, and you also have the ability to import piping input from CAESAR II.
Free, fully time-limited evaluation versions are available. Email, fax or phone your request.
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NozzlePro - FEA, as easy as it gets, for specific, commonly used FE/Pipe templates
In the first step to modularize FE/Pipe's templates, Paulin Research Group has created NozzlePro.
It's a powerful FEA tool that combines the most frequently used FE/Pipe templates with an extremely simple user-interface. (The templates, specifically, are nozzles and structural attachments that intersect with heads, cylinders and cones).
In the words of author Tony Paulin, "FE/Pipe is 10 times easier to use than ANSYS, and NozzlePro is 10 times easier to use than FE/Pipe".
The analysis and output capabilities are the same as FE/Pipe, but the user interface is beautifully simple to use. Radio buttons provide quick option selection, and all input variables are shown graphically, with optional inputs clearly displayed in blue. Abundant help functions graphically describe your input options
A sample input screen is shown below. Note how the diagrams reflect the selected geometries.
Saddle Supports and pipe shoes are now available in NozzlePro. It's not just for nozzles!
Complete vessels with these types of geometry can also analyzed:
Other Geometries Available Include:
- Hemispherical Head
- Elliptical Head
- Dished Head
- Flat Head
- Structural Attachments (except Flat Head)
- Straight Unreinforced Nozzle
- Pad Reinforced Nozzle
- Self Reinforced Nozzle
- Hillside Nozzles
- Offset Nozzles
Output is detailed and easy to follow
Excellent 3D interactive graphics help understand the analysis results:
Functional working demos are available - just let us know and we'll gladly send you one. Email your request to: email@example.com
NozzlePro is a must-have tool for vessel & piping engineers that augments and replaces old methods and rules of thumb with the latest technology. As an FEA tool for piping & vessel engineers, it does more for less money in less time than anything else!
WRC 107 Nozzle Design Comparison
Here we present one of many cases where the WRC 107 is beyond its limitations.
In this particular case, we look at a 10" pad-reinforced nozzle in a large diameter, relatively thin-walled vessel.
Because WRC 107 does not consider pad-reinforced nozzles, the common approach is to examine two cases:
1) the nozzle with vessel thickness = vessel + pad, and then
2) consider the nozzle to be the same diameter as the pad OD, with vessel wall thickness.
Although this geometric assuption for case 2 is a bit of a leap of faith, as engineers, we've been taking this approach since the mid-1960's, and in many cases it provides reasonable results. Until very recently, FEA analysis of a nozzle cost around $10,000, and the alternative to FEA is to build samples and test in a lab. Clearly this 107 shortcut has been the cost-effective, sensible approach.
A 10” nozzle 9.525mm thick is to be designed for a 10 bar pressure in a 2m ID, 10mm thick vessel with an
allowable stress in the hot and cold conditions of 140 MPa. The area replacement calculations show:
Available Area (sq.mm.) = 1138.349
Area Required (sq.mm.) = 1820.430
This tells us that the nozzle requires some reinforcement.
If a pad of 125x10mm is selected, the area calculation improves:
Available Area (sq.mm.) = 3487.349
Area Required (sq.mm.) = 1820.430
A reinforcing pad presumably eliminates the area replacement problem.
Loads on the nozzle are given as follows:
The inplane operating moment is the largest, so it will be checked first.
A comparison of WRC 107 and finite element results is shown below:
Secondary Stress (Pl+Pb+Q)
If the allowable for Pl+Pb+Q is 3Sm, as specified in ASME Section VIII, Div. 2, then the allowable is
(3)(140) = 420 MPa.
The WRC runs of the stresses shows that the nozzle is 177/420 = 42% of the allowable.
The finite element calculation shows that it is 465/420 = 110% of the allowable!
This common error occurs because of the local addition of the repad.
The reinforcing pad changed a problem that represented a reasonable WRC 107 calculation into a problem
that did not. The local thickening of the shell forced the high stress into the nozzle, (as shown above), and
WRC 107 does not evaluate stresses in the nozzle, so it doesn't see it. One might argue that the piping ends at the vessel wall, and any high stress there should be considered in the pipe stress analysis run. When you look at your piping input for this analysis, you've probably run straight pipe into the nozzle, with a 1.0 Stress Intensification Factor (SIF).
Have we ever seen a reduced intersection with a 1.0 SIF? NO! Common practice leads us to overlook two issues here - nozzle stresses and SIFs at boundary conditions! NozzlePro not only gives you the SIFs and stress intensities, it provides allowable loads and flexibilities that can be directly input into your pipe stress program.
There are a variety of conditions where WRC 107 can not be used reliably:
1) Repad geometries
2) Large Openings
5) t/T < 1
7) Close-proximity nozzles
8) Knuckles on dished or elliptical heads
9) Many applications with internal pressure
If you come up against one or more of these, you should look to FEA for an accurate opinion.
System Requirements (both FE/Pipe & NozzlePro)
Hard Drive - Although FE/Pipe's input is easy, it is a true FE program, which means it takes lots of horsepower.
System Memory - Minimum recommended: 2 Meg.; bigger is better.
OS - Windows NT / 2000 / XP Pro / Windows 7
Also required - Microsoft IE 5.0 or higher (free from microsoft.com),
Also recommended - DirectX 7.0a (included in XP, and free to download from microsoft.com)