Radiographic testing and industrial X-ray inspection

Radiography today runs on four capture technologies. Each records the same physics, but they differ in speed, image handling and how codes treat them.

• Film radiography: the long established reference. High image quality, wet processing, physical film archives. Still widely specified for code welds.
• Computed radiography (CR): reusable phosphor imaging plates read by a scanner. No chemicals, digital files, flexible like film for field work.
• Digital radiography (DR): flat panel detectors give images in seconds. Common in fixed labs, production casting lines and increasingly in the field.
• Real time radioscopy: live X-ray imaging while the part moves, used for high volume castings, electronics and assemblies, often with automated defect recognition.

Codes such as ASME Section V include requirements for film and digital techniques, so confirm the technique your code edition and customer accept before you order.

X-ray tubes are switched on and off and offer adjustable energy, which suits labs and thinner sections. Gamma sources such as Ir-192, Se-75 and Co-60 need no power and travel well, so field crews use them for pipelines, vessels and thick sections. Gamma sources cannot be turned off, which means strict licensing, source handling, exclusion zones and a radiation safety officer. For any on site work, ask how the crew sets up and controls the exclusion zone and how that affects other trades nearby.

For welds, the governing code sets technique and acceptance. ASME Section V describes how to perform radiography (Article 2), while the construction code, for example ASME Section VIII for pressure vessels or ASME B31.3 for process piping, sets how much to radiograph and what is acceptable. Structural steel under AWS D1.1 has its own RT requirements and acceptance criteria, and pipelines often follow API 1104. For castings, acceptance is usually set by comparing images with ASTM reference radiographs for the alloy and thickness range, such as ASTM E155 for aluminum and magnesium castings or E446 and E186 for steel castings, with the severity level set on the drawing or purchase order. Ask the provider which reference set they hold and how they grade.

1. You share the part or weld details: material, thickness, joint type or casting geometry, quantity and the governing code or specification.
2. The provider writes or selects a technique: source, energy, film or detector, image quality indicators, number of exposures and coverage.
3. Lab work: parts are shot in a shielded bay. Field work: a crew mobilizes, sets an exclusion zone and often works off shift to keep other trades clear.
4. A qualified Level II, or Level III where required, interprets the images against the acceptance criteria.
5. You receive a report with weld or part identification, technique details, findings and accept or reject, plus film or digital images.

Field work is usually scheduled by day or shift. Lab work on castings commonly turns in 2 to 7 business days, with rush options.

Field radiography is mostly priced as a crew day rate plus mobilization, travel and per diem, and productivity depends on access, pipe size and how many shots each weld needs. Lab radiography is priced per part, per view or per hour. Thick sections need longer exposures or a different source, which slows throughput. Code work requiring Level III review or formal technique sheets adds time.

Ask for RT certifications at Level II for interpreters (ASNT SNT-TC-1A or CP-189 based employer programs, or a central scheme), NAS 410 personnel and NADCAP accreditation for aerospace castings and welds, ISO/IEC 17025 scope covering radiography for lab testing and, for field gamma work, the radioactive materials license and the name of the radiation safety officer. State or Nuclear Regulatory Commission rules govern radiography personnel, so ask that the crew members hold any radiographer certification the jurisdiction requires.