Non Destructive Testing: Radiography

Industrial radiography is a volumetric inspection that utilizes two types of ionizing radiation: X-ray and gamma ray. These types are selected based upon their degree of penetration, which depends on their energy and the density of matter through which they are traveling. DBI, Inc. supplies a complete line of radiographic testing services for both shop and field applications. These applications include testing and grading of welds on pressurized piping, pressure vessels, high-capacity storage containers, pipelines, and some structural welds. Other tested materials include concrete (locating rebar or conduit), welder’s test coupons, machined parts, plate metal, or pipe wall (locating anomalies due to corrosion or mechanical damage).

Conventional Radiography Testing (RT): Conventional radiography testing uses a sensitive film that reacts to the emitted radiation to capture an image of the part being tested. This image then can be examined for evidence of damage or flaws. The biggest limitation to this technique is that films can only be used once and they take a long time to process and interpret.

Computed Radiography Testing (CRT): Nearly everything that is done with conventional film-based radiography testing can be completed faster and more accurately using an advanced computed radiography system. CRT produces digital images on reusable phosphorous plates with lower exposure requirements. This process translates to smaller exclusionary zones and decreased exposure times in your facilities. The original archived image cannot be altered, thus maintaining the integrity of the raw data. Without altering the archived image, the electronic image-viewing software can be sharpened, filtered, and zoomed for analysis by the technician or customer to enhance evaluation.

Digital images can be e-mailed or posted on the web, allowing others to aid in analysis or report results. Viewing software also allows for digital annotation and measurement using a mouse and/or keyboard instead of overlays. CRT uses the same radiation producing devices as conventional radiography. CRT requires no film, which means there is no need to buy or dispose of chemicals.

Advantages of Radiographic Testing

  • Provides an extremely accurate permanent record.
  • Very versatile and can be used to examine many shapes and sizes.
  • Quite sensitive, assuming the discontinuity causes a reasonable reduction of cross section thickness.
  • Permits discontinuity characterization.
  • Widely used and time-proven.
  • Volumetric NDT method.

Limitations of Radiographic Testing

  • There are safety hazards with the use of radiation devices.
  • Thickness limitations, based on material density and energy used.
  • Can be time consuming.
  • Dependent on discontinuity orientation.
  • Requires extensive experience and training on personal taking the radiographs and during the interpretation.
Contact DBI for Radiographic Testing