SAMPLE
Piping Toolset — Calculation Report
generated by calc-core · 2026-07-30

Welding Tee Stress Intensification Factor Calculator (B31.3 App. D / B31J) — Sample Report

ProjectSample Project — Demonstration Only Job No.SAMPLE-001 Client—
CalculationWelding Tee Stress Intensification Factor Calculator (B31.3 App. D / B31J) Calc byPiping Toolset (calc-core) Checked byUNCHECKED — sample
Date2026-07-30 Rev0 BasisASME B31.3 Appendix D Table D300 closed forms (elbow: ii=0.9/h^⅔, io=0.75/h^⅔; welding tee: io=0.9/h^⅔, ii=0.75·io+0.25)

1 · Design inputs

NPS 6 Sch 40 welding tee (6.625 in OD × 0.28 in nominal wall) per ASME B16.9 — the same pipe size the App D closed form is validated against in the PVP-parity test suite.

Componentwelding tee—
Pipe OD D6.625in
Nominal wall T0.28in

2 · Method

Closed-form welding-tee relations, evaluated in sequence from the pipe geometry:

r2 = (D − T) / 2

h = 4.4·T / r2

io = max( 0.9 / h2/3 , 1 ) ii = max( 0.75·io + 0.25 , 1 ) k = 1

where D is the pipe outside diameter, T the nominal (mean) wall thickness, and r2 the mean pipe radius. The bend-radius input that the elbow closed form needs is not used here — a welding tee has no bend radius. io is computed first from h; ii is then derived from io by Table D300's fixed linear relation rather than from its own independent formula, and k is taken as 1 outright because a tee's branch does not gain the flexibility credit a curved bend does. Both SIFs are floored at 1 — a computed value below 1 (heavy wall relative to radius) is reported as 1, matching the Code's floor. The calculator also flags h < 0.05 as outside the closed form's validated range, where B31J tabular data should be used instead of the formula.

3 · Calculation

  1. Mean radius: r2 = (D − T)/2 = (6.625 − 0.28)/2 = 6.345/2 = 3.1725 in.
  2. Flexibility characteristic: h = 4.4·T/r2 = 4.4·0.28/3.1725 = 1.232/3.1725 = 0.38834.
  3. Out-of-plane SIF: io = 0.9/h2/3 = 0.9/0.388342/3 = 1.69084 (above the 1.0 floor, so no clamping applied).
  4. In-plane SIF: ii = 0.75·io + 0.25 = 0.75·1.69084 + 0.25 = 1.26813 + 0.25 = 1.51813.
  5. Flexibility factor: k = 1 — fixed for a welding tee, unlike an elbow's 1.65/h.

4 · Results COMPUTED

h — flexibility characteristic0.38834—
io — out-of-plane SIF1.69084—
ii — in-plane SIF1.51813—
k — flexibility factor1—

5 · Verification statement

The result values above are locked as fixture b31-sif.json, case “PVP: 6in sch40 welding tee”, tolerance 0.00001, in the calc-core continuous verification gate (see https://pipingtoolset.com/trust/validation.html). Allowable-stress and factor data are user-supplied inputs; citations: ASME B31.3, Process Piping — Appendix D, Table D300, stress intensification and flexibility factors for welding tees. · ASME B31J, Standard Test Method for Determining Stress Intensification Factors (i-Factors) for Metallic Piping Components — the tabular dataset these closed forms approximate absent Code Data Service tables. · ASME B16.9, Factory-Made Wrought Buttwelding Fittings — the welding-tee dimensional standard the closed form's geometry assumes.

SAMPLE REPORT — auto-generated from a verification fixture to show the report format. Not a project calculation. ⚠ Engineering-aid tool. Public code equations; allowable-stress and factor data are user-supplied. Results MUST be independently verified and reviewed by a qualified/licensed engineer before any design, fabrication, or operation decision.