# UT, ET and Hydrostatic Testing: How to Specify the Inspection Question

Canonical: https://jundapipe.com/en-CA/blog/ut-et-hydrostatic-pipe-testing

Compare the questions addressed by UT, ET and hydrostatic testing, then define method, coverage and acceptance without assuming interchangeability.

Specify inspection by the question that must be answered, then define the method, coverage and acceptance criteria. Ultrasonic testing, eddy current testing and hydrostatic testing are not interchangeable labels. Whether one may replace another depends on the governing product standard, project specification and agreed procedure.

Junda’s [published capability list](https://jundapipe.com/production-environment) separates a UT/ET flaw-detection system from hydraulic pressure testing. It describes different inspection purposes, but it does not establish an examination package for every product order.

## Which question does the inspection need to answer?

| Inspection question                                                  | Method to evaluate                                  | Evidence that remains necessary                               |
| -------------------------------------------------------------------- | --------------------------------------------------- | ------------------------------------------------------------- |
| Are specified discontinuities detectable under the agreed procedure? | UT or ET as applicable to the material and geometry | Procedure, reference checks, coverage and acceptance criteria |
| Does the product meet the specified pressure-tightness test?         | Hydrostatic testing under the required procedure    | Test basis, conditions, material identity and result          |
| Does the material meet chemistry and mechanical requirements?        | The specified material analyses and tests           | Traceable results under the applicable product requirements   |
| Does duplex material need an additional metallurgical check?         | Applicable project-selected examination             | Method, sampling and acceptance requirements                  |

This table helps define the inspection scope; it does not prescribe which test is sufficient for a particular pressure system.

## Why can a test name be insufficient?

“ET passed” does not identify the procedure or criterion. [ASTM E426-16(2021)](https://store.astm.org/e0426-16r21.html) has a defined scope for certain tubular materials and techniques. Confirm that the offered examination matches the actual alloy, geometry and condition.

Likewise, “hydrotested” leaves the test pressure, duration, medium, acceptance criterion and material identity unresolved unless the governing specification and records supply them. A successful product test is not a universal operating pressure rating for the assembled system.

For UT, ask the supplier to identify the applicable standard, procedure, technique, coverage and acceptance level. Do not assume a generic capability statement proves coverage of every orientation or region of a pipe.

## How can a vague statement be made reviewable?

Replace “all pipes tested” with a defined record containing five elements: identified material; specified method and procedure; coverage and exclusions; acceptance criteria; and documented result with disposition of any nonconformance.

For example, an inspection schedule can require the supplier to fill those fields for each order line. The buyer then checks whether the response satisfies the project requirement, rather than comparing unsupported percentages across quotations.

## Which document governs substitutions?

Read the complete product standard and purchase specification. [ASTM A312/A312M-25](https://store.astm.org/a0312_a0312m-25.html) provides for supplementary pipe requirements. For tube standards within its scope, [ASTM A1016/A1016M-24a](https://store.astm.org/a1016_a1016m-24a.html) explains the precedence of product requirements and more stringent order requirements.

If a supplier proposes a different examination, document the basis and obtain the required project approval. Do not infer permission from a capability page or from a test being cheaper or easier to arrange.

Send the product specification and inspection schedule through the [Junda contact page](https://jundapipe.com/contact). The [ET guide](https://jundapipe.com/blog/eddy-current-testing-stainless-steel-tubes) provides method-specific questions, while the [document review guide](https://jundapipe.com/blog/stainless-pipe-material-certificate-traceability) addresses the connection between reports and delivered material.