SWBPIPE

Free, open-source pipe stress analysis.

SWBPIPE · in development

SWBPIPE is a program for piping flexibility and stress analysis. It computes the movements of a piping system, the forces and moments in it, the loads on its supports, and the stresses recovered from them by open formulas. The mechanics, the evidence for them and the source are public. Use it to learn the method, work a design out and try the alternatives, then validate the design in the program your industry accepts. Agents are being built into it that take the same actions you can in the model, at your direction.

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Chapter I

An agent that works in the model with you.

Here is the kind of job it is being built for, on an illustrative model. The vessel nozzle load at 130 is over its allowable in the operating case, and you ask why. The agent reads the model and the last run, and finds the cause: as the riser grows, the pipe lifts off the rod hanger at 80, and the nozzle picks up the weight the rod was carrying.

It proposes a variable spring in place of the rod, with its reasoning and the questions it still has to settle: the travel, the rate and the variability at 80. You apply the change a row at a time, or not at all, and run again.

Whatever the agent proposes enters the model only when you apply it.

The SWB Piping Design Agent is being developed to research engineering context before proposing a model change. Its public Piping Engineering Knowledge Reader is available now; live research integration is still in development.

Isometric sketch of the Loop 4 header, from pump P-401 to vessel V-402 with a branch to the header tie-in. A proposed variable spring at node 80 replaces a rod hanger that goes slack as the riser grows, and the resultant nozzle load at node 130 in the operating case falls from 7.4 to 3.9 kilonewtons. 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 PUMP P-401 DISCHARGE VESSEL V-402 NOZZLE HEADER TIE-IN SPRING H1 REST, GAP 3 GUIDE PROPOSED SPRING AT 80 REPLACES ROD HANGER NOZZLE 130, OPE1: RESULTANT 7.4 → 3.9 kN LOOP 4 HEADER NOZZLE LOAD AT 130 IS OVER ITS ALLOWABLE IN OPE1: (1) AS THE RISER GROWS ABOUT 6 MM AT T1, THE PIPE LIFTS OFF THE ROD HANGER AT 80 AND THE NOZZLE PICKS UP ITS WEIGHT. (2) A VARIABLE SPRING AT 80, SIZED TO THE RESTRAINED-WEIGHT LOAD, KEEPS CARRYING IT AS THE HEADER RISES. (3) TO SETTLE: TRAVEL, RATE AND VARIABILITY AT 80.
Fig. 1.—Loop 4 header. The agent’s reasoning for its proposal, set as the note on the figure. An illustrative model; the values are not engine output.
The SWBPIPE window. A table of hangers on the left; on the right the agent's proposal to replace the rod hanger at node 80 with a variable spring, with its rationale, the constraints it considered, and two open questions.
Plate I. A proposal as the program is designed to show it: each changed row, the reasoning and the questions still open. Interface in development.

Chapter II

You can read every part of it.

The model, the mechanics and the evidence for them are all open to read and check.

2.1The model is a table.

One row per node. The drawing is made from the rows, so it shows what you entered.

2.2The mechanics are open.

A 3D beam solver with supports that can lift off, close a gap or slide, and load-case combinations. Every line of it is public. Each verification case is published with its reference, the test that checks it and the command to run it, and each current limit with what to do meanwhile.

2.3The agent works as you do.

It is being built to read the same model and results you do, and to change the model only through the actions you take yourself. Each change it proposes waits for you to apply it.

The SWBPIPE window in its Both view: the layout table with one row per node on the left, the drawing made from it in the middle, and the inspector for node 20 on the right.
Plate II. The layout table and the drawing made from it. Interface in development.

Chapter III

Your code, your data.

The code data comes from you.

Flexibility factors, stress intensification factors and component data come from the codes and catalogues you already have the right to use, and you enter them with the model, with a note of where each came from. The program computes movements, loads and stress components; the code check (sustained, expansion range and occasional) is made in the program you validate in. The modelling guide sets it out.

We plan for the agent to help you turn your own spreadsheets and data sheets into libraries, and keep them current as your sources change. They are your files, kept on your machine.

Chapter IV

Where it fits in your work.

What SWBPIPE is for

SWBPIPE is for learning the method, working a design out and trying the alternatives. The design is validated, and judged against the code, in the program your industry accepts. Until then its results are not a basis for professional work.

A model can be exported as a model batch file (.mbf). Today the file carries the geometry, anchors and guides, and a list of what it leaves out comes with every export.

In SWBPIPE

Route, support, run and learn, as many people as need it, at no cost.

In your accepted solver

One seat validates the design your team settled on, under your engineer’s judgement. That model is the design basis.

Current limits

The program is young, and today some of its results are wrong. Pressure is applied incorrectly. Bends drawn in the program are analysed as straight chords. Springs carry no preload, and valve and flange weights are left out. Supports act along global axes only, and their loads are reported without components. A model that can still move as a mechanism can be reported as solved. The status of this edition lists every limit, and what to do meanwhile.

The name

Named for Shipman, Watts and Burrows.

In 1941 the M. W. Kellogg Company published Design of Piping Systems, the first general method for the stresses, reactions and movements of a piping system in space.

Its acknowledgment pays tribute to W. H. Shipman, whose systematic solution of the single-plane problem paved the way, and credits G. W. Watts and W. R. Burrows of the Standard Oil Company (Indiana), who extended his method to three planes, with

“the most significant step towards the general solution.” Design of Piping Systems: Expansion Stresses and Reactions in Piping Systems, 1941

For decades the method was worked by hand, one coefficient at a time. SWBPIPE solves the same problem by the stiffness method, and keeps the mechanics, the evidence and the source open for anyone to read.

Read the open manual →