As a distributor supporting NADCAP approved and SpaceX approved supply chains, we understand that UT testing isn’t a box to check.

When a part is going into a flight-critical structure, “close enough” isn’t a spec. Stainless Shapes supplies ultrasonically tested (UT) stainless steel bar and plate to aerospace manufacturers who need documented, 100% volumetric inspection before the material ever reaches machining. Every heat we ship with UT certification comes with full traceability back to the melt source.

As a distributor supporting NADCAP approved and SpaceX approved supply chains, we understand that UT testing isn’t a box to check. It’s the difference between a part that clears first-article inspection and one that gets kicked back. Whether you’re sourcing 15-5PH round bar for a fracture-critical bracket or plate stock for a pressure vessel, we can match your UT class, coverage requirements, and heat-treat condition to the print.

Ultrasonic testing uses high-frequency sound waves to inspect a piece of stainless steel without cutting it. A transducer sends sound through the material, and any internal flaw (a crack, void, inclusion, or area of porosity) reflects that sound back differently than solid, sound metal does. The result is a map of the material’s internal condition, generated before a single chip is cut.

For aerospace bar and plate, this typically means one of two testing methods:

• Immersion UT submerges the part or bar in a water tank so sound couples evenly into the material from every angle. This method, performed per ASTM E 2375, is the standard approach for detecting small subsurface defects like porosity and micro-cracking, and it works across a wide range of diameters and wall thicknesses.
• Contact UT, performed per AMS-STD-2154, uses a transducer placed directly on the material surface. It’s common in field and shop-floor settings and doesn’t require submersion, though it typically demands more operator skill to interpret results consistently.

Aerospace specs go a step further than “was it tested”: they specify how much of the part must be inspected. A callout for 100% coverage means every square inch of usable material is scanned, not a sample. That’s the standard we work to on UT-tested SST bar per AMS 5648, and it’s non-negotiable on flight hardware, landing gear components, and other fracture-critical parts where a missed flaw isn’t an acceptable risk.

Not every testing lab can sign off on aerospace-grade UT inspection, and not every distributor can get material tested to the standard your prime contractor requires. NADCAP accreditation exists precisely because aerospace OEMs need a consistent, audited benchmark for nondestructive testing quality. It’s the same reason Boeing, Lockheed, and other primes require NADCAP-approved sources before they’ll accept a part onto their supplier list.

Stainless Shapes supplies material tested to NADCAP- and SpaceX-approved standards, meaning the UT process, equipment calibration, operator certification, and documentation all meet the scrutiny those programs demand. In practice, that shows up in two spec callouts you’ll see on aerospace-grade stainless bar:

• AMS-STD-2154 Class A and Class AA define acceptance criteria based on flaw size and location. Class AA is the more stringent of the two, typically reserved for the most critical rotating or fracture-sensitive components, while Class A covers a broader range of structural applications. Knowing which class your print calls out (and confirming the supplying lab can actually certify to it) is one of the first things we check before quoting material.
• 100% coverage requirements mean the entire part geometry gets scanned, with no gaps in the inspection area. This is standard on programs where a missed subsurface flaw could mean structural failure, and it’s the level of scrutiny SpaceX-approved and NADCAP-approved supply chains are built around.

Aerospace and defense programs rarely call out UT testing in isolation. It comes bundled with material chemistry, heat treatment, and processing specs that all have to align before a heat of material is acceptable. Here’s a look at the spec stack we regularly supply against, pulled from a recent customer order for UT-tested 17-4PH bar:

• AMS5648: the base material specification for precipitation-hardening stainless steel bar and forgings, ultrasonically inspected per ASTM E2375 (immersion method) or AMS-STD-2154 Type I, with 100% coverage required.
• AMS-STD-2154: the governing UT standard itself, called out here to Class A and Class AA acceptance criteria.
• AMS-H-6875: heat treatment of steel raw material, establishing the baseline process controls for hardening and tempering.
• AMS2759/3: the specific heat treatment specification for precipitation-hardening corrosion-resistant steel parts, covering the H-condition tempering process.
• PS2024: a customer/prime-specific process specification governing supplemental requirements beyond the base AMS callouts.
• BAC5619: a Boeing process specification, commonly referenced on programs supplying into Boeing’s aerospace supply chain.
• RPS12.01: a customer-specific raw material or process specification used to define additional acceptance criteria on a given program.

We can source and certify material against this full spec stack, or against whatever combination your engineering team calls out on the print. If your PO references a spec you don’t see listed here, ask. Between our mill relationships and NADCAP-approved testing partners, we can typically get it covered.

UT testing tells you a piece of material is free of internal defects. Heat treatment is what gives that material the mechanical properties your part actually needs: strength, hardness, and corrosion resistance in the right balance for the application. For precipitation-hardening grades like 17-4PH, that means selecting the right H-condition per AMS2759/3.

We supply UT-tested stainless bar and plate heat treated to:

• H900: the highest-strength condition, used where maximum tensile and yield strength matter more than ductility.
• H925: a slightly lower strength than H900 with modestly improved toughness.
• H1025: a common aerospace structural condition, balancing strength and ductility.
• H1050: similar balance to H1025, often specified where a customer’s process spec calls for a specific tempering window.
• H1075: moderate strength with improved corrosion resistance and toughness over the higher-strength conditions.
• H1100: lower strength, higher ductility and impact resistance.
• H1150: the lowest-strength, highest-ductility and toughness condition in the standard H-condition range.

Each condition changes the mechanical property tradeoff, and the right choice depends entirely on what your part needs to do in service. If your print specifies a condition outside this range, or you’re not sure which H-condition matches your application, our team can help you cross-reference the spec before you commit to an order.

• UT is 100% volumetric inspection, not a sample check. Ultrasonic testing uses high-frequency sound waves to detect internal flaws (cracks, voids, inclusions, porosity) before machining, and aerospace specs like AMS5648 require full coverage, not spot-checking.
• Two testing methods serve different needs. Immersion UT (ASTM E2375) is the lab standard for catching small subsurface defects; contact UT (AMS-STD-2154) is more portable for field and shop-floor use but requires more operator skill.
• NADCAP and SpaceX approval signal audited, trustworthy testing quality. These accreditations confirm that the UT process, equipment calibration, operator certification, and documentation meet the standards that primes like Boeing and Lockheed require before accepting parts.
• Coverage class (Class A vs. Class AA) matters as much as passing the test. Confirming which AMS-STD-2154 class a print calls out, and that the testing lab can actually certify to it, is a critical upfront step before quoting material.
• UT testing and heat treatment work together, not separately. UT confirms material is defect-free; heat treatment (per AMS2759/3, conditions H900 through H1150) determines the strength-to-ductility tradeoff the part actually needs in service.

If your next order requires ultrasonic tested material to AMS5648, AMS-STD-2154, or a customer-specific spec like BAC5619 or RPS12.01, Stainless Shapes can source, test, and certify it end-to-end. Request a quote with your print and spec callouts, and we’ll confirm coverage class, heat treat condition, and lead time before the material ships. Call 1-800-748-9811 today.