Aluminum casting helium leak testing uses a tracer gas to detect leakage. Pressure-decay testing measures pressure change over a defined interval. A report marked "PASS" is meaningful only when the tested part, test conditions and acceptance requirement are identified.
For a pump housing or valve body, start with the pressure boundary on the drawing. Then check whether the report covers that boundary at the required manufacturing stage. This guide explains how to select the information to request, read a sample record and compare supplier reports.
Download the editable leak-test report review worksheet (CSV). Use it to record the buyer's requirement, each supplier's evidence and any questions that remain open.
Helium, pressure decay or bubble testing?
| Method | What the test observes | Conditions to identify in the report |
|---|---|---|
| Helium tracer gas | Helium reaching a detector through a leak path | Test arrangement, gas concentration, pressure conditions, background, reference leak, result and units |
| Pressure decay | Pressure change during a timed measurement | Test volume, pressure basis, stabilization, temperature conditions, measurement interval and permitted drop |
| Bubble test | Visible bubbles at an accessible leak location | Medium, pressure, observation time, inspected surfaces and agreed visual acceptance |
An instrument's advertised sensitivity does not establish the performance of the complete part-and-fixture test. The selected method must be validated for the required acceptance limit and the actual sealing arrangement.
INFICON's aluminum-casting application describes transmission-housing tests with fixtures that seal individual passages. It includes different tracer-gas arrangements at different production stages. The useful lesson for a buyer is to identify the test direction and sealed boundary, rather than treat "helium tested" as a complete specification. Its application-specific limits are not universal aluminum-casting requirements.
Define the part and the pressure boundary first
A casting wall, a machined sealing face and an assembled joint are different potential leak paths. Mark which cavities are pressurized or evacuated, which ports are connected or blanked, and whether leakage to the outside or between internal passages is being evaluated.
For a pump housing, identify the cover face, shaft or seal interface, threaded ports and any separate cavities. For a valve body, identify the passage pairs that must remain isolated. A test of the body alone does not automatically establish the leak performance of the complete valve or pump assembly.
Record the manufacturing state: as-cast, heat-treated, final-machined, coated or assembled. If impregnation or another approved treatment is allowed, identify when it occurred and the agreed retest requirement. A result before a later machining operation cannot, by itself, document the condition after that operation.
How to read an aluminum casting leak-test report
Read the record from identification to disposition. Start with the drawing revision and specimen identity; finish by checking that the recorded result was judged against the correct requirement. A missing field is a request for clarification, not proof that the physical part leaks.
An annotated pressure-decay record
Illustrative training example only. All identifiers, readings and limits below are fictional. They are not Bohua test results, customer records or recommended settings. The actual procedure and acceptance criteria must be agreed for the part.
| Report field | Illustrative entry | What the buyer should check |
|---|---|---|
| Part and revision | EX-PH-01, drawing Rev C, specimen EX-0042 | The record identifies the ordered design and the tested specimen |
| Lot and process state | EX-LOT-07; T6; final-machined; cleaned and dry; no impregnation | The result covers the required production stage and treatment history |
| Boundary and fixture | Cavity A to outside; ports P1-P3 sealed; fixture EX-F02 Rev B | The fixture drawing identifies every temporary seal and the boundary evaluated |
| Procedure and medium | EX-LT-04 Rev C; pressure decay with dry air | The procedure and test medium match the approved requirement |
| Pressure basis | 300 kPa gauge | Gauge pressure is explicitly identified; the operating tolerance belongs in the procedure |
| Timing and conditions | Fill sequence per procedure; 30 s stabilization; 10 s measurement; recorded part temperature 23 C | Timing stages are distinct; temperature and conditioning are documented |
| Acceptance requirement | Maximum pressure drop 25 Pa during the 10 s measurement | The limit has a unit, interval and traceable requirement reference |
| Actual result | 18 Pa during 10 s; PASS under EX-LT-04 Rev C | The result is judged against this example's criterion, not a different leak-rate specification |
| Equipment and verification | Station EX-01; calibration and fixture-check references attached | The referenced records identify validity dates and the checks applicable to this setup |
| Release record | Report EX-R07; specimen ID, test time and reviewer recorded | The disposition remains traceable to the raw result and any subsequent action |
The example shows how to read a pressure-drop result. It does not establish an equivalent helium leak rate. If an instrument reports a flow value calculated from pressure decay, ask for the method and calibration basis used for that conversion.
CTS's pressure-decay calibration explanation describes a repeatable fill, stabilization and measurement sequence, together with a non-leaking master part and a calibrated leak standard. Ask for the relevant setup-validation reference instead of accepting an instrument model number as the entire evidence package.
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Send the drawing, target alloy, finishing scope, MOQ, and delivery timing. Bohua will review it like a real sourcing project, not a generic contact request.
Identify the units before comparing numbers
Pressure drop, pressure change per unit time and leak flow are different reported quantities. Preserve the original unit and measurement interval. For a reported standard volumetric flow, identify the reference conditions and test gas. For a tracer-gas result, identify the concentration and whether the reported value has been corrected by the instrument or procedure.
A unit conversion alone does not show that tests using different gases, pressure differences or fixtures are equivalent. Any correlation used for acceptance must be documented and approved for the application.
Two suppliers both report PASS: are the results comparable?
Consider these two fictional report summaries. Both suppliers have recorded a pass under their own stated procedures, but the summaries do not yet establish compliance with one common buyer requirement.
| Review item | Supplier A summary | Supplier B summary |
|---|---|---|
| Specimen state | Final-machined housing | As-cast housing |
| Test method | Air pressure decay | Helium tracer-gas test |
| Reported result | Pressure drop over a stated interval | Leak-rate reading |
| Acceptance basis | Procedure revision and pressure-drop limit attached | Instrument printout says PASS; buyer requirement reference missing |
| Boundary evidence | Cavity and fixture drawing attached | Tested passage list not supplied |
| Buyer's next action | Check the attached method against the purchase requirement | Request the requirement reference, process stage and passage map |
Use the buyer's approved drawing and test procedure as the comparison baseline. Do not rank the suppliers by the smaller-looking number or by the method name alone. A more sensitive detector does not resolve a mismatch in specimen state, sealed passages or acceptance criteria.
When the buyer permits alternative methods, agree on the validation and correlation evidence before using either result for release. Until then, label the comparison "information incomplete" and assign the missing items to an owner. Keep that document-review status separate from the test result itself.
Check the setup before assigning a casting defect
An unexpected result should trigger a review of the part and test system together. Check temporary plugs, seals, the fixture revision and the applicable verification records. For pressure-decay measurements, examine the recorded temperature and stabilization conditions before comparing results collected under different conditions.
INFICON's pressure-decay discussion explains how temperature changes can influence a pressure measurement. Its example concerns plate heat exchangers; it provides method background, not a casting-specific acceptance rule.
For vacuum housings, trapped gas around blind tapped holes may also need investigation. Record the evidence before describing an indication as through-wall leakage.
Once the leak location is established, use the aluminum casting defect diagnosis guide to organize the investigation. Keep radiographic or CT findings linked to the specimen, but evaluate leak-test acceptance against its own requirement. The porosity inspection guide explains the different questions these inspection methods address.
Preserve the original failed or invalid record. Record the reason for a repeat test and any approved rework, treatment or fixture correction. A later passing result needs a traceable disposition; it should not silently replace the earlier history.
Agree on sampling, records and release before the quote
State whether the requirement applies to every part, selected samples or a qualification batch. A lot summary and a serial-number record answer different traceability questions. Agree on the record granularity, sampling plan and response to a failure rather than inferring them from the word "tested."
The quotation should identify the test provider, fixture scope, method validation, production testing, requested reports and any approved retesting. Ask whether these items are included in the price. A supplier can then identify an unresolved requirement before it becomes a delivery disagreement.
Use the RFQ preparation checklist for drawings, quantities and project inputs. Use the quotation scope page to review the commercial stages. The report worksheet below is for reviewing leak-test evidence; it does not replace the drawing or the approved test procedure.
Download the supplier comparison worksheet
Download the leak-test report review worksheet (CSV).
Enter the buyer requirement and the corresponding report reference for each supplier. Mark each item "Matches requirement," "Clarification needed," "Does not match requirement" or "Not applicable with reason." Record an owner and next action for every unresolved item. These are document-review findings; part acceptance follows the agreed release procedure.
The worksheet covers part identity, process stage, pressure boundary, method, gas, conditions, fixture, calibration, limits, actual results, sampling and disposition. It contains no preset acceptance limits. Keep completed customer reports and proprietary drawings within the agreed project-sharing process.
Discuss the test scope with Bohua
Bohua supply boundary: this guide does not claim an in-house helium leak-test system. A helium requirement needs explicit confirmation of the test provider, equipment, fixture, validation and quoted scope. Review the confirmed quality-control scope and obtain written agreement for the project.
For a useful review, identify the part and drawing revision, the cavity or passage map, required process stage, test method and acceptance specification. Include the requested quantities and report format. If a requirement is still open, identify it as a question for engineering review rather than inserting a generic limit.
Start an RFQ review. Submit the project details, then email the drawing and test specification as directed on the inquiry page.
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