Radiographic Inspection (RI) FAQs
Radiographic inspection is one of the few non-destructive testing methods that can inspect the inside of a metal component rather than just across its surface. Use the FAQ below for answers to the questions we hear most often from manufacturers and industrial professionals across Indiana, Michigan, and Illinois.
To request radiographic testing services for your application, contact our team or request a quote.
Radiographic Inspection NDT Basics
What is radiographic inspection (RI)?
Radiographic inspection, also called radiographic testing (RT) or metal x-ray testing, is a non-destructive testing method used to identify internal defects within a metal component. Radiation passes through the part to produce an image of its internal structure. An inspector reviews that image for cracks, porosity, inclusions, and other flaws that surface-level methods can't see. If you're searching for "NDT x-ray inspection" or "metal x-ray testing," this is the same method.
For a deeper walkthrough of the entire radiographic inspection process, see our RI 101 guide.
What is the RI process, step by step?
Radiographic inspection involves passing radiation through a part and having a qualified inspector interpret the resulting image. Because the process involves radiation safety controls and produces a permanent image record, it follows a controlled sequence. For a full breakdown of how AMT carries out each stage, visit our radiographic inspection services page.
Does radiographic inspection use X-rays or gamma rays?
Both are used in industrial radiography, and the principle is the same: radiation passes through the part and exposes film or a detector on the other side. X-ray sources are more common for shop-floor testing, since they can be switched on and off and don't require the same handling and storage precautions as a radioactive isotope. Gamma ray sources are sometimes used for field inspection or larger components.
What kinds of parts and materials can be tested with RI?
Radiographic inspection works across a wide range of metals and material thicknesses, which is part of why it's commonly used for castings and complex components. AMT tests parts up to 20 lbs. Beyond weight, the main constraints are part thickness and density, since denser or thicker sections require more radiation energy or longer exposure time to produce a readable image.
Choosing the Right NDT Process: Radiographic Inspection Vs. Other NDT Methods
RI, MPI, or FPI: which method do I need?
The deciding factor is where the flaw is likely to be. Magnetic Particle Inspection (MPI) and Fluorescent Penetrant Inspection (FPI) are surface methods. MPI works only on ferromagnetic metals, and FPI covers a broader range of materials but still only catches flaws that break the surface.
RI finds defects sitting inside a part, like porosity in a casting or a void in a weld, that neither surface method can detect. If a defect could be below the surface, or if your application requires the kind of permanent record RI produces, radiographic inspection is the right method.
Compare surface methods in more detail on our MPI and FPI resources.
Which testing standard or specification should I use for RI?
That decision belongs to the design engineer, not the testing lab. The engineer knows the part's intended use and service environment, and NDT requirements are typically already documented on the drawing or purchase order by the time testing begins.
At AMT, we test to whatever your documentation specifies, working within the frameworks outlined on our testing standards page.
Capabilities of Radiographic Inspection
What kinds of defects does RI detect?
Radiographic inspection is built to find internal discontinuities, including:
- Porosity and gas pockets trapped during casting or welding
- Shrinkage and voids from uneven cooling
- Inclusions of foreign material within the part
- Internal cracks that never reach the surface
For surface flaws, MPI or FPI are typically the faster and more cost-effective NDT inspection option.
What are the advantages and limitations of RI?
RI's key advantage is depth. It's the only one of AMT's three NDT methods that can confirm what's happening inside a part, rather than the surface. It also produces a permanent film or digital record for applications where documented traceability is part of the requirement.
The tradeoff is time and access. RI generally takes longer than MPI or FPI, since it involves radiation safety controls and image interpretation rather than a visual check for indications. It also typically requires access to both sides of the part, which isn't always possible depending on geometry.
Working with American Metal Testing for Metal Component X-Ray Services
Which industries rely on radiographic inspection?
Radiographic metal testing is common for aerospace, military and defense, transportation, wind turbine components, and safety and rescue equipment. Learn more on the industries served page.
Much of AMT's radiographic inspection work supports our sister company, Aero Metals, and we also test for outside manufacturers across numerous sectors.
Does American Metal Testing serve my area?
AMT is based in La Porte, Indiana, and serves customers throughout Indiana, Michigan, and Illinois. Our lab is NADCAP-accredited and staffed by NAS-410-certified inspectors. Whether you're a large manufacturer or a first-time customer, your parts are evaluated to the same standard.
How do I get a part tested with RI, or how can I request a quote?
Contact our team with your part specifications and any documentation outlining your NDT requirements, and we'll walk you through next steps. You can also request a quote directly.
