NDT calculators
18 free calculators for radiography, ultrasonic, magnetic particle and penetrant testing, each showing its formula, its assumptions and the standard or regulation it comes from. Metric or imperial.
Radiography
Source decay, exposure time, unsharpness, shielding and boundaries.
Radioactive source decay
Current activity from the assay activity and the time since the assay, or how long until the source falls to a given activity.
Exposure time for a new distance or activity
Start from an exposure that worked, change the source-to-film distance or the source strength, and get the new time.
Geometric unsharpness (Ug)
Ug from the source size and the exposure geometry, or the shortest source-to-object distance that keeps Ug under a limit.
Shielding: half-value and tenth-value layers
Transmission through a given thickness, or the thickness needed for a given reduction, from a half-value or tenth-value layer.
Radiation boundary distance
From the source activity and gamma constant, or a rate you measured, estimate the distance to the 2 mR/h and 100 mR/h lines.
Dose from rate and time
How much dose a given rate and time add up to, or how long you can stay before reaching a dose.
Ultrasonic
Refraction, angle-beam geometry, thickness, near field and decibels.
Snell's law: refracted angle
The refracted angle in the part from the wedge angle and the two velocities, the wedge angle for a refracted angle you want, and the critical angles.
Angle-beam skip distance and sound path
Skip and sound-path distances for a plate and a refracted angle, and where a reflector sits from its sound path.
Thickness from time of flight
Thickness from the round-trip transit time and the velocity, or the transit time a thickness should give.
Wavelength and near-field length
Wavelength from velocity and frequency, and the near-field length of a circular or square element.
Decibel and amplitude ratio
Decibels from an amplitude ratio and back, and the gain change that moves a signal from one screen height to another.
Sound velocity in common materials
Typical longitudinal and shear velocities for common materials, in metric and inch units.
UT thickness, velocity and gauge error
Thickness from transit time, a material's velocity from a known thickness, how far off a reading is when the gauge is set to the wrong velocity, and the hot-steel correction.
Magnetic particle
Coil ampere-turns, circular magnetization and prod current.
Coil magnetization (ampere-turns)
Ampere-turns and coil current for longitudinal magnetization from the part's L/D ratio and the coil's fill factor.
Circular magnetization and prod current
The current range for a head shot or central conductor from the part diameter, and for prods from the spacing and thickness.
Yoke lift test and ASME coil shot
How much a yoke has to lift under each document, and the ampere-turns and current ASME Section V asks for on a coil shot.
Penetrant
Dwell and developing times by specification and part temperature.
Units
Activity, dose, length, pressure and velocity conversions.
For reference only — verify against your procedure and the governing code.
Standards and documents are cited by their publishers' names to identify them. ndt.support is not affiliated with, endorsed by or sponsored by ASTM International, ASME, ABS (the American Bureau of Shipping), the U.S. Nuclear Regulatory Commission, NIST or the Laboratoire National Henri Becquerel. Formulas are paraphrased and cited by clause; get the documents themselves from their publishers.
Fifteen of these are also on tracendt.com: NDT calculators
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