UT Quality/Technology & insights/Digital vs conventional radiography
Digital and conventional radiography read a similar image, but they reach a usable result on very different clocks. Conventional film carries darkroom development on top of every exposure — and on a construction spread, that time is the whole story.
Representative time to a readable result on a 24-inch girth weld — the exposure, plus the 45 minutes of film development that digital simply does not have.
Time to an accept/repair decision — 24" weld
Film's clock does not stop at exposure — every exposure adds 45 minutes of development before the image is usable. Digital has no development step, so its exposure time is its total time. Add development in, and digital wins at every pipe size.
| Pipe diameter | Digital (total) | Film exposure | Film development | Film total | Digital advantage |
|---|---|---|---|---|---|
| 10"–12" | 1 min | 3 min | 45 min | 48 min | 48× faster |
| 16" | 5 min | 3–5 min | 45 min | 48–50 min | ~9.6–10× faster |
| 20" | 8 min | 5–10 min | 45 min | 50–55 min | ~6.2–6.9× faster |
| 24" | 10 min | 8–12 min | 45 min | 53–57 min | ~5.3–5.7× faster |
| 30" | 12 min | 12–16 min | 45 min | 57–61 min | ~4.8–5.1× faster |
Film total = exposure + 45 minutes of development. Digital advantage = film total ÷ digital time, computed directly from the columns to its left.
Yes. On a representative 24-inch girth weld, conventional film takes about 57 minutes to a usable image, roughly 12 minutes of exposure plus 45 minutes of darkroom development, versus about 10 minutes read on screen for digital. That is over 5 times faster to an accept/repair decision.
Conventional film carries about 45 minutes of darkroom development on top of every exposure, and the image is not usable until it is out of the darkroom. Digital radiography is read on screen with no development step, so the crew never stops for a darkroom.
Typical exposure time, digital versus conventional film: 10 to 12 inch about 1 minute vs 3 minutes; 16 inch about 5 minutes vs 3 to 5 minutes; 20 inch about 8 minutes vs 5 to 10 minutes; 24 inch about 10 minutes vs 8 to 12 minutes; 30 inch about 12 minutes vs 12 to 16 minutes. Every conventional exposure then adds 45 minutes of film development, for a film total of about 48 minutes at 10 to 12 inch, 48 to 50 minutes at 16 inch, 50 to 55 minutes at 20 inch, 53 to 57 minutes at 24 inch, and 57 to 61 minutes at 30 inch. Digital has no development step, so it is faster than film's total time at every size, from about 5 times at 30 inch up to about 48 times at 10 to 12 inch.
UT Quality runs digital and film RT alongside automated ultrasonics — and will tell you which fits your weld.
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