Filter Housing NDE: Check ASME VIII Requirements First

The panel symptom is a new end-user demand for NDE after a hydrotested, electro-finished filter housing has already shipped. Do not decide from vessel size alone: first compare the construction basis, design documents, and required inspection records with the applicable ASME VIII Division 1 edition and the end-user requirements. Post-delivery examination may be possible, but a test performed now does not automatically satisfy a fabrication-stage code requirement or repair missing construction records.

Check the construction basis before choosing a test

Start with the nameplate, data report, design package, and manufacturing record. Establish whether the vessel was constructed and documented as an ASME VIII Division 1 vessel, whether it carries a Code stamp, and which code edition and inspection basis apply. The fact that the housing was designed by an outsourced vendor does not answer those questions; obtain the vendor's calculations, drawings, weld details, and stated code basis.

For this housing, the stated details are SS316, a 3 mm shell, 1 MPa design pressure, 0.7 MPa maximum operating pressure, ambient temperature, 280 L volume, 8-inch ANSI inlet/outlet, 1-inch BSPT drain, and 1/2-inch BSPT vent. Those values identify the equipment but are not enough to determine the required examination. The code decision depends on the construction details and applicable requirements, including the design documents and weld/examination basis. A small size or mass-produced status does not, by itself, settle whether NDE is required.

• Confirm the governing ASME VIII Division 1 edition and whether the vessel is represented as code-built.
• Read the design documents for specified examination, weld details, and inspection acceptance criteria.
• Check the manufacturer’s data report and fabrication records for examinations already performed and the hydrotest record.
• Compare the end-user’s new guidelines with the code and any applicable Australian requirements; a customer may impose additional requirements.

If the vessel is Code stamped, involve the Authorized Inspection Agency (AIA) before selecting a post-shipment test or changing the records. If it is not stamped, establish the contractual and jurisdictional basis with the customer and responsible design authority rather than treating a later NDE result as proof of ASME conformity.

Read the symptom as a documentation gap first

The immediate issue is not necessarily a failed pressure boundary. It is a mismatch between the original agreement—hydrotest without RT/PT—and a later end-user requirement for an ASME-recognized NDE method. Treat this first as a code-basis and inspection-record question, then as a method-selection problem.

Do not spend time repeating a hydrotest merely to create an NDE record. A pressure test does not examine every weld volume or surface, and it cannot retroactively establish which examination was required during fabrication. Likewise, do not order a generic “UT” without specifying whether the objective is thickness measurement, weld examination, or another defined examination.

Understand what the hydrotest and NDE can prove

A hydrotest applies pressure to the assembled pressure boundary and can reveal leakage or inability to hold the test pressure under the test conditions. It does not map internal weld discontinuities or prove that a specified NDE method was performed. NDE methods have separate capabilities: the method, coverage, examiner qualification, procedure, acceptance criteria, and records must match the question being asked.

RT and UT are commonly used to examine weld volume, while PT detects surface-breaking discontinuities on accessible, clean surfaces. Those descriptions are not a substitute for the construction code’s examination rules. The required method and extent depend on the approved design and applicable code requirements, not simply on the housing being small, stainless steel, or pressure tested.

The phrase “electrolyzed surface” needs clarification. If it means electropolished stainless steel, a smooth finish does not automatically prohibit surface examination, but contamination, residue, surface condition, access, and the examiner’s procedure still matter. PT requires a clean surface and can identify only discontinuities open to the surface. UT does not rely on surface-breaking access in the same way, but the 3 mm wall and weld geometry may make reliable results difficult. The examiner must establish that the selected method can produce interpretable results on this specific construction.

For SS316, do not assume magnetic-particle testing is a suitable substitute: austenitic stainless steel is generally not ferromagnetic. The examiner and design authority should select a method that fits the material, target discontinuity, geometry, surface finish, and governing acceptance requirements. Do not substitute one method for another just because the preferred method is inconvenient after shipment.

Choose a post-shipment examination in a controlled sequence

Use this sequence before authorizing work. It separates the code decision from the practical question of whether the shipped surface and welds can be examined.

1. Get the requirement in writing. Ask the end user to identify the required code or standard basis, examination method, weld or area coverage, acceptance criteria, and required report format. “ASME-recognized NDE” is not a complete inspection instruction.
2. Reconcile the requirement with the design file. Have the responsible vessel designer review the drawings, calculations, weld details, and original inspection plan. Identify whether the requested examination is a code requirement, an added end-user condition, or a correction to missing documentation.
3. Consult the AIA when the vessel is Code stamped. Ask the AIA how the proposed examination affects the construction records, data report, and any required revision. Do this before testing; a favorable NDE result does not automatically resolve a code-stamp or documentation issue.
4. Inspect the actual finish and geometry. Confirm what “electrolyzed” means, whether the examined surface is clean and accessible, and whether welds can be reached. Record the shell thickness, weld configuration, curvature, and any obstructing fittings for the examiner.
5. Have the NDE examiner select and qualify the procedure for the target. Define whether the target is a surface flaw, weld-volume flaw, or wall-thickness measurement. For UT on a 3 mm shell, require a demonstrated setup and explain how geometry, near-surface response, and calibration will be addressed; do not presume a generic UT scan is adequate.
6. Agree on reporting and disposition before examination. Set the extent of coverage, calibration basis, indication recording, acceptance criteria, and who decides disposition. Use the acceptance criteria tied to the applicable construction basis or written end-user requirement, not an improvised pass/fail rule.
7. Perform only the agreed examination and preserve traceability. Identify the vessel and weld locations in the report, retain the procedure and examiner records, and return results to the design authority and AIA when applicable.

RT may remain an option if the required access, geometry, radiation controls, and written examination requirements can be met. PT may be practical for accessible weld surfaces when surface-breaking examination is the objective and preparation is compatible with the finish. UT may be proposed, but on this thin shell the examiner must show that the method and equipment can provide reliable, interpretable coverage. No single method can be selected from the provided vessel dimensions alone.

Verify that the report closes the requirement

Before accepting the work, compare the NDE report against the written requirement and the agreed scope. Confirm the report identifies the vessel, the method used, the examined locations and extent, the procedure, the examiner, the results, and the acceptance criteria. Verify that any recorded indication has a disposition approved by the responsible design authority, not merely a verbal statement that the test passed.

For UT, review the examiner’s demonstration and the recorded technique for this 3 mm wall and weld shape. Check that calibration and coverage support the stated conclusion. If the setup could not resolve or inspect the target region, classify that region as not examined rather than assuming a clean result.

For PT, verify surface preparation and coverage of the accessible examination area, and confirm that the report addresses any relevant indications. PT results say nothing about subsurface weld volume. For RT, verify the radiographic coverage and interpretation against the required extent and acceptance basis.

Finally, reconcile the new report with the hydrotest record, design documents, data report, and customer requirements. If the vessel is Code stamped, obtain AIA direction on any revision to the Manufacturer’s Data Report (MDR) or other code documentation. Keep the distinction clear: a later examination may provide useful condition information, but the AIA or responsible code authority determines whether it closes the applicable documentation and compliance issue.

Avoid the shortcuts that waste inspection time

• Do not argue from vessel size. “Small housing” is not a documented code exemption. Check the applicable code basis and construction details.
• Do not treat the customer’s original agreement as a code waiver. Contract language cannot override applicable code requirements; a customer can also add requirements beyond the code.
• Do not treat hydrotest as a substitute for NDE. It tests pressure-boundary performance at test conditions, not the same attributes as RT, UT, or PT.
• Do not accept a method name without scope. Specify target, areas, extent, procedure, acceptance criteria, and reporting before the examiner arrives.
• Do not assume surface finish decides the method by itself. Clarify the actual electrolytic process and let the examiner assess cleanliness, access, and procedure suitability.
• Do not assume UT is automatically effective on a 3 mm shell. Require a demonstrated setup for the actual wall and weld configuration.
• Do not revise stamped documentation unilaterally. Coordinate with the AIA and design authority before changing the data report or declaring compliance.

Escalate the code decision when records do not agree

Stop the inspection plan and obtain a written disposition if the design basis, data report, end-user requirement, and proposed method conflict. For a Code-stamped vessel, escalate to the AIA and responsible design authority before representing the housing as compliant or revising the MDR. If the jurisdictional or contractual basis remains unclear, ask the customer’s code authority or the relevant official standards body to identify the governing requirement.

Frequently asked questions