Part VI
Verification
These pages preserve small worked cases and their recorded comparisons. They group the cases by what each comparison shows. Of the 67 cases, 35 compare a solved or recovered result with an independent reference calculation. Another five check prepared loads and boundary conditions. The other 25 check support state changes, repeatability, model reading, or failure reporting. Two remain withdrawn because they checked an incorrect pressure model.
Each page identifies its comparison and execution path. Most cases call solver components directly and use small illustrative values. Their evidence applies only to the stated quantities, inputs, method, and recorded revision. It does not establish that every element, load, support rule, or stress formula is correct. It does not establish a complete real-line analysis or code compliance. See the status of this edition for current product limits.
Each page links to its own exact evidence revision. Archived commands include that
revision and require its source checkout. The current manual uses revision
8212c765ec0bcc812ad4c4f7079bc661b55d70ab. A new execution is identified separately on its case page.
The historical results remain distinct from current product output.
The three pressure comparisons dated 12 October retain revision a72f994d89,
their original model versions and their original section and end-frame conventions.
They have not been rerun for this edition. In particular, their earlier effective-wall basis
does not establish the current nominal/reduced section behavior.
The current source also contains reference checks for section bases, Timoshenko straight members, nonlinear-state confirmation and untied-joint pressure. These source links are further reading, not additional executed case pages in this catalogue.
A. System benchmarks · 4 cases
A piping configuration compared with an independent mechanics calculation.
A pressure-only L line contains a realized quarter-circle bend. Product API results are compared with an independent unit-load reference.
The anchored terminal closure has separate support. The case distinguishes closure force, wall transfer and the pipe anchor reaction.
An L line is anchored at both ends. The case compares signed reactions and bend section actions with a whole-line flexibility reference.
A plane L-bend between two anchors under a 150 K rise, with the elbow made progressively more flexible.
B. Elements and loads · 14 cases
Closed-form solutions for single elements and small frames, plus loads prepared for the solver.
A header and branch meet at one node. The case compares branch-tip displacements and anchor reactions with hand values.
A member fixed at one end carries a lateral tip force. The case compares tip deflection and root reaction with hand values.
A member held at both ends is heated uniformly. The recorded thermal-restraint calculation must return the hand value of the restraint force.
A linear spring has a prescribed displacement. The case tests boundary preparation and the calculated spring reaction.
A member at 45 degrees in plan is transformed to global axes. The case tests direction cosines and stiffness-matrix symmetry.
A straight pipe element calculates weight per meter from mass. It recovers axial end force from a given displacement.
An anchor, spring and imposed rotation enter boundary preparation together. The case tests restrained degrees of freedom and support values.
A hollow pipe uses shear modulus at an exact point or interpolated temperature. The case tests tip rotations and detects an incorrect fallback.
One member passes through load preparation, boundary preparation, solution and force recovery. Two faulty inputs must produce blocking errors.
- From loads to resultantsVI–B10
A cantilever pipe carries a uniform load and a midspan point force. The case tests equivalent end loads, tip movement and midspan resultants.
- Loads on a turned pipeVI–B11
A pipe along global Y carries the same cantilever loads. The case tests coordinate transformations of loads and results.
- Load over part of a spanVI–B12
A cantilever pipe carries a load over its middle half. The case tests equivalent end loads, free-end movement and midspan resultants.
The solver receives four stations in an unsorted order. The case tests the order and the shear and bending moment values.
User factors and pipe mass and size determine seismic and wind loads. The case tests intensities and end forces.
C. Stress recovery · 15 cases
Stresses recovered from known section forces, checked against the formulas of Part III E.
- Axial normal stressVI–C1
An axial force acts on an invented section. The case tests recovery of axial stress as force divided by area.
Moments act about two local axes. The case tests each bending stress as moment divided by the corresponding section modulus.
A straight pipe has an imposed end stretch and twist. The case tests end resultants and their axial and torsional shear stresses.
Pressure acts inside a thin cylindrical wall. The case tests historical recovery of hoop and longitudinal membrane stresses.
Two load states act on the same section. The case tests separate stress-component ranges and refusal of unmatched pressure inputs.
A torque acts on an invented section. The case tests torsional shear stress as torque times radius divided by torsion constant.
A loaded cantilever has known free-end movement. The case tests midspan moment and the stress components recovered from it.
The loaded cantilever runs along global Y. The case compares its midspan moment and bending stress with the pipe along global X.
A cantilever carries a load over its middle half. The case tests midspan moment and recovered bending and axial stresses.
Four stations are requested out of order. The case tests shear, moment and stress values and retention of the requested order.
A motionless straight pipe has a directly entered thermal axial force. The case tests end, midspan and swept axial forces and stresses.
An axial effect acts with end bending and a line load. The case tests midspan axial force, moment and separate stress components.
Midspan resultants act on an invented circular pipe section. The case tests transferred section properties and recovered stress components.
Corrosion allowance and mill tolerance reduce pipe-wall thickness. The case tests recovered stresses and the reduction in section modulus.
A fully restrained heated pipe uses hot-point properties. The case tests stress recovery, range to an unloaded state and recorded property labels.
D. Nonlinear supports · 6 cases
Rests, gaps, and friction. The solver finds the active supports; hand calculations compare movements or reactions.
An 8.0 N axial push acts against friction (μ = 0.25, N = 12.0 N). Bounded reaction must be −3.0 N, leaving 0.05 mm displacement.
Friction uses a named transverse reaction of 100.0 N as normal force. Its 30.0 N limit holds a 10.0 N axial push in one iteration.
A 10.0 N axial push exceeds friction limit 6.0 N (μ = 0.30, N = 20.0 N). The support must slide and converge in two iterations.
A sticking support has normal reaction 100.0 N and μ = 0.30. Its 30.0 N limit holds 10.0 N and converges in one iteration.
A closed gap at +0.01 mm needs pulling reaction +3.0 N under load −2.0 N. It must open, leaving displacement −0.02 mm.
Load −10.0 N moves a released end −0.1 mm into its bearing side. The support must re-engage, carrying +10.0 N at displacement 0.0 mm.
E. Algorithm and software checks · 26 cases
Support state changes, repeatability, model reading and recording, and failure reporting. These comparisons assess software behavior, not mechanics.
- Portal frame swayVI–E1
A two-column portal frame carries a lateral force at the top. The case compares assembly and solution with a stored solver result.
The solver prepares nodal forces, uniform weight and imposed displacement. The case tests sums and separate input contributions.
A structured file describes the cantilever without hidden defaults. The case tests file reading, loads, reactions and resultants.
The solved cantilever enters a result record with identified values. The case tests the trace from load values to their sources.
A released one-way support has trial displacement −0.02 mm toward its bearing side. One classification step must re-engage it and count one change.
- Axial gap closesVI–E6
A 10.0 N axial push moves the free trial beyond clearance 0.05 mm. The open gap must close and converge in two iterations.
A lift-off support needs positive contact reaction. A 10.0 N axial push gives the opposite sign, so it must release and converge in two iterations.
Tip rotation releases before a transverse gap of 0.002 mm closes. The solver must follow the sequence over three iterations, one change at a time.
Tip friction in x uses a y reaction of 100.0 N, giving limit 6.0 N. It slides while a 0.0002 mm gap in z closes.
Tip friction in x uses a y restraint reaction and slides. A 2.0 N·mm moment releases the lift-off restraint on rotation about z.
One tip has one-way, gap, friction and rotational lift-off supports. All four must change state on the first iteration and retain state on the second.
Tip friction in x has normal reaction 20.0 N and limit 6.0 N. It slides as a 0.0002 mm gap in y closes.
Tip lift-off in x releases while a transverse 0.0002 mm gap in y closes. Both change state first, then retain state on the second iteration.
At one tip, a one-way support in x releases while a 0.0002 mm gap in y closes. This is the base two-support case.
The same one-way-and-gap problem records convergence in two iterations. This observation applies no convergence tolerance or residual thresholds.
The tip force reverses to −1.0 N, and the transverse gap closes on negative displacement. Both supports change state on the first iteration.
Two tip gaps act in different directions. A 0.0002 mm gap in x closes on positive movement, and the y gap closes on negative movement.
An axial one-way support releases under 10.0 N. A rotational lift-off support about z releases under 2.0 N·mm at the same tip.
One tip has one-way support in x, a 0.0002 mm gap in y and friction in z with limit 3.0 N. All three must change state first.
A two-span chain has supports at two nodes. The middle one-way support releases while a 0.0002 mm tip gap closes.
A two-span chain has a positive-side 0.0002 mm gap at the middle node and a negative-side gap at the tip. Both must close first.
- One-way support lets goVI–E22
A 10.0 N axial push gives an active one-way support an inadmissible reaction sign. The support must release and converge in two iterations.
Two friction supports have coefficient 0.30 and normal reaction 10.0 N. Tangential reactions 2.0 N and 3.5 N must retain sticking and sliding, respectively.
A closed gap has displacement equal to clearance 0.25 mm and bearing reaction −2.0 N. One classification step must retain contact without a change.
A lift-off support in contact has trial reaction 0.0 N at displacement 0.04 mm. One classification step must release it and count one change.
A released rotational one-way support must re-engage at iteration 4 of 4. The solver must report non-convergence failure rather than a converged result.
W. Withdrawn · 2 cases
Historical cases for an incorrect pressure model. Their records remain withdrawn.
The historical helper combines thermal restraint and pressure thrust for a fixed-fixed pipe. The case tests equivalent loads and axial recovery.
The historical helper assembles thermal and pressure effects with a partial-span transverse load. The case tests displacements and resultants.
Still to come
The practitioner’s cases the suite does not yet contain.
- A line on several rests under weight, with every support load worked by hand.
- A three-dimensional line with out-of-plane bends at real pipe sizes, solved through the program’s own model-to-solve path.
- A tee, with the branch stress intensified on the branch section.
- A variable spring hanger designed by the standard procedure and analyzed with its preload.
- A rest near a pump nozzle that lifts off under thermal load.
- A guide with clearance on the short leg of an L-bend, closing under thermal load.
- A line sliding on several shoes with friction, and the anchor load it produces.
- An expansion range formed as operating minus sustained, and the stress computed from it.
- A full piping example with imposed nozzle movement and cold spring, beyond the bounded rigid-motion and fit-state checks.
- Worked examples from the Kellogg manual.
The planned program
Original September 2026 plan, with current scope distinguished below.
The cases above were written during solver development. The original plan called for a fuller program to compare release capabilities with independent references under declared tolerances. That goal remains broader than the current development evidence. A resulting scope statement would identify one release.
The statement would not be a certificate or a finding of compliance with any code. It would not establish that SWBPIPE matches another program in every respect.
The original plan identifies three kinds of reference:
- Closed-form cases for axial load, bending, torsion, thermal expansion, springs, gaps and friction, with expected values computed by a separate reference program that shares no code with the solver.
- Published benchmarks: the open verification cases of EDF’s Code_Aster for a straight pipe (SSLL106), the three-dimensional Hovgaard piping system (SSLL101) and a bent pipe in bending (SSLX102). If the program gains dynamic analysis, the plan also includes the NRC piping benchmark problems of NUREG/CR-1677.
- Equivalent models run in established commercial programs where a license is available, with each program’s version and native input kept with the result.
The plan assesses each capability group separately as passed or not passed. This table records the planned scope; it does not report completed qualification.
| Group | What it covers |
|---|---|
| Straight pipe, static | Axial load, bending, torsion, thermal expansion, imposed movements, reactions and stresses, in several orientations and units. |
| Piping systems, static | Assembled three-dimensional lines with bends, under weight, thermal and applied loads. |
| Nonlinear supports | Gaps, rests that lift off, friction, and the order in which loads are applied. |
| Each export format | Whether the model that reaches the receiving program is the model intended (Part V B). |
| Agents and screens | Whether a model built by an agent and the same model built by a person reach the solver identical, with the same warnings. |
| Dynamics | Modal and response-spectrum analysis, if the program gains them. |
The rules are written before the tests run. Expected values never come from the program under test. Each quantity has a tolerance set in advance. That tolerance does not increase after a failure. A test without a required reference or license counts as not passed. Failures remain in the record.
Each report lists every required test, including failures and tests that could not run. Each record identifies who or what produced it. Work by an agent is labeled as an agent’s work. A record cannot claim a review that did not occur.
The planned evidence will follow the structure of NASA’s public standard for models and simulations, NASA-STD-7009B. This plan does not claim compliance with that standard.
The original sequence starts with test machinery and closed-form cases, including deliberate failure checks. It then places Code_Aster straight-pipe and Hovgaard cases, export checks, and nonlinear supports before dynamic analysis.
Development gate machinery now exists. Its ordinary transport covers two selected static cases through the headless CLI in sparse_interactive or dense_scrutiny mode. It does not establish completion of the planned groups or authorize engineering use. Browser fixtures also remain separate from native Rust solver evidence.