Tube Weld Acceptance Calculator (ASME BPE MJ-8.4-1) — Sample Report

1 · Design inputs

A production coupon on 3/4 in OD × 0.065 in wall tube, measured on the outside surface: concavity 0.004 in, convexity 0.005 in, misalignment 0.007 in. Limits as entered from the project's copy of Table MJ-8.4-1 for this size and surface.

2 · Method

concavity limit = fraction × T_w

convexity limit = absolute height (in) — or fraction × T_w if you set that basis

misalignment limit = fraction × T_w — absolute (in) for the largest tube sizes

ratio = measurement / its own limit · governing = largest ratio · PASS when ≤ 1

Each of the three limits carries its own basis, because Table MJ-8.4-1 does not state them alike, and the calculator takes the basis as an input rather than assuming one. On the outside (non-process-contact) surface, where these three measurements are taken, concavity is limited as a fraction of the nominal wall of the thinner member — in effect a statement about how much section the weld removed, the same proportion on thin-wall and heavy-wall tube. Misalignment is also a fraction of T_w for most tube sizes; for the largest sizes the table switches to an absolute outside-diameter limit, and the card's misalignment basis switches with it. Convexity on the outside surface is an absolute height. The product-contact column reads differently — both concavity and convexity there scale with T_w, and there is no numeric inside-diameter misalignment criterion at all — which is the other reason the basis is an input: enter the column that applies to the surface you measured. Each measurement is divided by its own resolved limit, the largest of the three ratios is reported as the governing discontinuity, and the weld passes only if all three pass. Where a ratio exceeds 1 the calculator reports the disposition MJ-8.4.2 draws: concavity and convexity may be rewelded once by reflow, while misalignment is not on that list, because a reflow cannot move the tube ends. The card opens with the three limit fields blank and computes nothing until you fill them: read each limit and its basis from your own copy of the table for the surface and tube size — the examples below show values as a user would enter them, not defaults.

3 · Calculation

1. Allowables: concavity 0.10 × 0.065 = 0.0065 in; convexity 0.015 in as entered; misalignment 0.15 × 0.065 = 0.00975 in.
2. Concavity ratio = 0.004 / 0.0065 = 0.6154.
3. Convexity ratio = 0.005 / 0.015 = 0.3333.
4. Misalignment ratio = 0.007 / 0.00975 = 0.7179.
5. Largest ratio is misalignment → governing, and it is at or below 1: PASS.

4 · Results PASS

5 · Verification statement

The result values above are locked as fixture tube-weld-acceptance.json, case “3/4 in x 0.065 in, within limits -> pass”, tolerance 0.0001, 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 BPE-2026 — Table MJ-8.4-1 and Fig. MJ-8.4-1: O.D. and I.D. acceptance criteria for concavity, convexity and misalignment, with Notes (2) and (7)–(9); limits and their basis are user-supplied inputs. · ASME BPE-2026 — MJ-8.4.2, rewelding: one reflow attempt, and only for the listed defects.