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: concavity 0.004 in, convexity 0.005 in, misalignment 0.010 in. Limits as entered from the project's licensed Table MJ-8.4-1 for this size.

2 · Method

concavity limit = fraction × T_w · convexity limit = fraction × T_w

misalignment limit = absolute value (size-dependent)

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

The calculator scales two of the three limits and leaves the third absolute, which mirrors how the table is written and is worth understanding rather than accepting. Concavity and convexity are limited as a fraction of the nominal wall thickness because both are, in effect, a statement about how much of the wall the weld has lost or gained — a tenth of a wall means the same thing structurally on thin-wall and heavy-wall tube, so the criterion scales with T_w. Misalignment does not scale that way: it is a fit-up and tube-tolerance quantity, driven by ovality, end preparation squareness and clamping, and its limit in the table is an absolute dimension that varies with tube size rather than wall. Each measurement is divided by its own limit, producing three dimensionless ratios on a common scale, and the largest is reported as the governing discontinuity with the overall verdict taken from it — a weld passes only if all three pass. Where the governing ratio exceeds 1 the calculator raises the reweld-eligibility warning pointing at MJ-8.4.2, since a rejected hygienic weld is not simply re-run without limit. Every limit is a user-supplied input: the numeric acceptance values in Table MJ-8.4-1 are copyrighted table content and are not embedded here. The defaults offered are the widely-published engineering fractions as a starting point only, and each must be confirmed against your licensed copy for the governing tube size before the verdict means anything.

3 · Calculation

1. Concavity and convexity allowables: 0.10 × 0.065 = 0.0065 in each.
2. Concavity ratio = 0.004 / 0.0065 = 0.6154.
3. Convexity ratio = 0.005 / 0.0065 = 0.7692.
4. Misalignment ratio = 0.010 / 0.015 = 0.6667.
5. Largest ratio is convexity → 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 “within limits -> pass”, tolerance 0.001, 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 — Table MJ-8.4-1 and Fig. MJ-8.4-1 acceptance criteria for concavity, convexity and misalignment; limits are user-supplied, not embedded. · ASME BPE — MJ-8.4.2, reweld eligibility for a rejected joint.