F.A.Q.


How do I decide between a Corrosion Thickness Gauge and a Precision Thickness Gauge?

  • Select an Ultrasonic Corrosion Thickness Gauge if your primary goal is detecting internal rust, pitting, scale, or wall thinning in pipes, tanks, boiler tubes, or structural steel (0.025" to 36.0" range, 0.001" / 0.01 mm resolution). Dual-element probes excel at reflecting sound off rough, uneven interior surfaces.

  • Select an Ultrasonic Precision Thickness Gauge if you are measuring smooth, manufactured components—such as thin sheet metal (down to 0.006"), plastic bottles and medical tubing (down to 0.005"), machined aerospace parts, or glass—where you require 0.0001" (0.001 mm / 1 µm) resolution.

Can an ultrasonic thickness gauge measure through paint and protective coatings without removing them?

Yes. Models equipped with Echo-Echo (E-E / Thru-Paint) mode—such as the Checkline TI-25MXT, Dakota ZX-6, Dakota ZX-6DL, and ElektroPhysik MiniTest 440—measure the transit time between two consecutive back-wall echoes inside the steel substrate, automatically ignoring external paint or epoxy coatings up to 0.040"–0.075" thick. Furthermore, combination models like the Checkline TI-CMX and Dakota CMX1-DL / CMX2-DL can display both the coating thickness and the metal wall thickness simultaneously on screen.

Why is ultrasonic couplant gel required for measurement?

High-frequency ultrasonic sound waves (1 MHz to 20 MHz) are rapidly attenuated by air—even a microscopic air gap between the transducer wear face and the test surface will block sound transmission. Applying a drop of ultrasonic couplant gel (or glycerin/high-temperature couplant for hot pipes) displaces the air barrier and allows acoustic energy to couple cleanly into the test specimen.

How do I calibrate an ultrasonic thickness gauge for different materials?

Because every material transmits sound at a distinct acoustic velocity (e.g., 0.2330 in/µs in carbon steel vs. 0.2510 in/µs in aluminum), ultrasonic gauges are calibrated in one of three ways:
  1. Built-In Material Presets / Direct Velocity Entry: Select the material from the onboard library or dial in its published sound velocity.

  2. 1-Point Calibration (Velocity Mode): Place the probe on an uncoated sample of the exact material with a known thickness and adjust the velocity until the display matches the known thickness.

  3. 2-Point Calibration: Calibrate across both a thin and a thick reference step on a NIST-Traceable Step Calibration Block to simultaneously set zero offset and sound velocity across your entire working range.


Checkline TI-45NHD Ultrasonic Wall Thickness Gauge

Discontinued Product
About this item
  • General Purpose Wall Thickness Gauge for measuring on a variety of materials with protective rubber shell
  • Range:
    0.040 - 8.00 inches
    1.00 - 200.00 mm

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Checkline TI-UMX2 Underwater Ultrasonic Thickness Gauge

Discontinued Product
About this item
  • Checkline TI-UMX2 Underwater Ultrasonic Thickness Gauge with datalogging
  • Resolution: .001" (0.01 mm)
  • Rated for dive depths up to 1000 ft (300 meters)

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