Home › Calculation Changelog — Versioned Record of Calculation Behavior

Calculation Changelog — Versioned Record of Calculation Behavior

Versioned record of every change to calculation behavior. Scope: packages/calc-core

(equations, limits, verdict logic, fixtures). UI-only changes are excluded — if a

number a calculator produces could change, it is recorded here.

Policy:

Every entry names the affected module ids and the fixture files that lock the change.
No calculation ships without a green fixture; "Verified" notes the derivation basis

(hand calculation, PVP Suite validation set, or published source-sheet example).

generated from this file at build time.

2026-07-21 — PiperFEA nozzle/shell FEA goes live

Scope note: this entry covers services/fea, outside this file's usual

packages/calc-core scope, because it is a calculation surface users can now run.

fea.nozzle-shell — nozzle-to-shell finite element analysis (gmsh shell meshing + CalculiX), run on an isolated server-side worker rather than in the browser. Reports, per load case: Pl vs 1.5(k)Smh, Qb vs 3(Smh), Pl+Pb+Q vs 3(Smavg), and Pl+Pb+Q+F vs Sa — plus a job report in the legacy FE/Pipe tabular layout with a 3D junction-stress plot.
Fatigue allowable Sa implemented as the ASME VIII-2 Appendix 5 design fatigue curve selected by material class, with the E-ratio correction and the NB-3228.5-form Ke strain-concentration factor. The "B31" bound f·1.25(Sc+Sh) (f = 6N^-0.2, capped at 1.0) and the Markl bound 245000/N^0.2 are reported alongside it.

Sa and the B31 bound reproduce the legacy NozzlePro / FE-Pipe reference reports **to the psi on all 35 golden fixtures** carrying a fatigue result — including the three cases where Ke > 1 drives the allowable well below the bare curve value.
Secondary stress (Pl+Pb+Q) ratio agreement against the reference set: **19 of 24 runnable fixtures gated**, 15 within ±20% and 4 within ±35%. Fixtures outside those bands are tracked in the sweep, not gated, and geometry outside the validated envelope is refused at submission rather than answered with a number.

v1 reports the surface-maximum von Mises within a junction-local window in place of a through-thickness linearized Pl / Pl+Pb+Q — conservative, and with no membrane/bending split yet the same value appears on both sustained rows.

flexibility.expansion-loop — guided-cantilever expansion loop / Z / L leg sizing, metallic (k=1) and plastic (k=2) families. Fixtures: expansion-loop.json, 5 cases (published flow-sheet L/Z/U trio, CPVC arm, cold-contraction case).

L/U/Z results reproduce the published coefficient rules 6.225·√(ΔL·D) and 4·√(ΔL·D) within 0.03%.

supports.variable-spring-select — PT&P variable-spring catalog selection (mode: derived data). Fixtures: variable-spring-select.json.
supports.compact-spring-select — compact-spring selection. Fixtures: compact-spring-select.json.

Selection logic checked against published catalog load tables; catalog data remains mode-derived with attribution.

BPE: bpe.cip-velocity (SD-6.3.5.2.1), bpe.tube-weld-acceptance (MJ-8.4-1), bpe.pre-pren (App. F-3), bpe.ferrite-number (WRC-1992), bpe.ra-finish (SF-2.4.1-1), bpe.ep-passivation (App. H/E), bpe.polymer-thermal-expansion (PM-4.2.3). Fixtures: one file per module.
Equipment: equipment.shell-nozzle-loads (WRC-107 / VIII-2 5.5 screen), ASME VIII-1 vessel.ug27-shell, vessel.ug32-head, vessel.ug28-external (+UG-99), vessel.ug37-nozzle-area; aux.wrc-terms.
Non-Metallic: nonmetallic.hdpe-n755, nonmetallic.frp-grp (NM-2 / ISO 14692 / BS 7159).
Auxiliary: aux.app2-flange (Sec VIII App 2 loose-type), aux.asce-occasional.

ASME authorization (2026-07-04) recorded: B31.1, B31.3, BPVC, and BPE may run licensed_embedded in the Code Data Service; BPE Part DT-4.1 fitting dimensions embedded, SD-3.1.2.2 dead-leg limit populated. All other standards stay user_supplied.

Seventeen calculators fixture-anchored to the PVP Suite validation set (112 checks); the exact inputs behind each PVP expected value were reverse-derived and locked as fixtures.

bpe.unit-converter (App. U incl. Ra & slope units), bpe.dead-leg (SD-3.1.2.2 with small-branch advisory), bpe.slope-check + bpe.slope-report (SD-2.4.3 GSD + drainability classification), bpe.spray-flow (SD-3.9.2 device-type bands). Fixtures: bpe-unit-converter.json, dead-leg.json, slope-check.json, slope-report.json, spray-flow.json.

Full-parity port of the standalone BPE toolset — case-for-case against the legacy @bpe/calc-core results.

Piping: piping.b313-wall-thickness, piping.b311-wall-thickness, pipeline.b31-wall-thickness, piping.b31-allowable-pressure, pipeline.b31-allowable-pressure, piping.leak-test-pressure, piping.bend-thickness, piping.miter-allowable-pressure, piping.branch-reinforcement.
Flexibility/stress: piping.b31-sif (App. D closed forms), piping.displacement-stress, piping.sustained-stress, piping.fatigue-factor, pipeline.b31g.
Supports: supports.spring-variability, supports.max-spring-rate; non-code noncode.pipe-weight, noncode.pipe-section, noncode.thermal-growth, noncode.collapse-pressure, noncode.rolling-offset, noncode.interpolate.
Connections/Auxiliary: connections.nozzle-load-check, connections.nema-sm23, connections.flange-equivalent-pressure, aux.wind-asce, aux.b31e-seismic, aux.pressure-thrust, aux.column-buckling.
Non-Metallic: nonmetallic.hdpe-pressure-rating, nonmetallic.support-span.

Hand-derived fixture per module (derivation recorded in each fixture's description); stress-range and SIF modules cross-checked against the PVP Suite selftest values (e.g. SE = 11,770.588, SA = 29,325, elbow ii = 2.26557).