Electropolish Removal & Passivation Acceptance Calculator — Sample Report

1 · Design inputs

An EP and passivation certification coupon: 0.5 g mass loss over 100 cm² of treated area, austenitic stainless. Surface analysis by AES gives Cr/Fe of 1.2 and an oxide layer of 20 Å.

2 · Method

t = m / (ρ · A) removed thickness from coupon mass loss

accept when t ≥ t_min AND Cr/Fe ≥ (Cr/Fe)_min AND oxide ≥ depth_min

The removal calculation is pure geometry: a coupon of known treated area loses a measured mass, and dividing that mass by the material density and the area gives the mean depth of metal removed. The result is reported in both micrometres and inches, since App. H states the minimum in imperial and most coupon work is weighed in metric. Area is entered in cm² or in², converted internally, and density defaults to the value conventional for austenitic stainless while remaining an input for anything else. Note what the arithmetic assumes: it is a mean over the whole treated area, so it credits uniform removal and cannot see a surface that polished heavily in the accessible regions and barely at all inside a fitting bore. The passivation side is a pair of independent threshold comparisons. The Cr/Fe minimum depends on the analytical method, because AES and XPS sample different depths and return systematically different ratios for the same surface — selecting the method sets the appropriate minimum automatically, and an explicit override is available where a specification imposes its own. Oxide depth is compared against its own minimum in ångströms. Both passivation checks are optional: omit the measurement and that check is skipped rather than failed, so an EP-only coupon can be evaluated without inventing passivation data. The overall status passes only when every check that was actually run passes, and each failure raises its own named warning rather than a bare verdict. All four thresholds — minimum removal, Cr/Fe minimum, the method default, and minimum oxide depth — are defaulted inputs so they can be aligned with your licensed App. E and App. H criteria.

3 · Calculation

1. Removed thickness: t = 0.5 / (8.0 × 100) = 6.25 × 10⁻⁴ cm.
2. In micrometres: 6.25 × 10⁻⁴ × 10 000 = 6.25 µm; in inches, 0.000246 in.
3. Removal clears the App. H minimum → removal PASS.
4. Cr/Fe 1.2 against the AES minimum of 1.0 → PASS; oxide 20 Å clears its minimum → PASS.
5. All three checks pass → overall PASS.

4 · Results PASS

5 · Verification statement

The result values above are locked as fixture ep-passivation.json, case “removal + Cr/Fe + oxide all 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 — App. H (electropolishing, material removal acceptance) and App. E (passivation, Cr/Fe and oxide-layer criteria). Acceptance thresholds are defaulted inputs.