Thermocouple devices, widely employed in industries like oil refineries, nuclear power plants, and chemical facilities, are critical for accurate temperature measurement and control. Their precise readings ensure safety, efficiency, and product quality. Regular testing of these devices is essential to verify their accuracy, linearity, and response time under diverse operating conditions. This rigorous testing prevents costly downtime, safety hazards, and quality issues by ensuring optimal performance. By maintaining reliable thermocouple devices, industries can optimize processes, minimize risks, and contribute to overall plant safety and productivity.

The Challenge

Our client encountered a quality control challenge in assessing the concentricity of drilled holes in stainless steel Thermowells. One of the components in ThermoCouple devices is a ThermoWell. Thermowells are used to guard temperature sensors such as thermocouples, thermistors, and bimetal thermometers against damage from excessive pressure, material velocity and corrosion. These thermowells are made of stainless steel and have a diameter ranging from 14mm. Accurate concentricity is crucial for the performance of ThermoCouple devices, as misaligned holes can lead to inaccurate sensor readings, reduced sensor lifespan, and potential safety hazards.  Our client needed a solution to assess the concentricity of drilled holes.

The Solution

Blue Star’s solution involved using the Olympus 45MG machine with a V260 probe for ultrasonic thickness measurements on the stainless-steel thermowell. The V260 probe was chosen due to its small diameter, suitable for the narrow space inside the thermowell. To ensure reliable readings, the surfaces at the measurement point were prepared to be concentric or parallel and cleaned free of debris. The V260 probe was coupled to the surface at a normal angle for optimal signal transmission. Following these principles, the ultrasonic thickness gauge displayed repeatable measurements ranging from 4mm to 8mm along the thermowell, providing valuable data for assessing the material’s integrity.




  • Reliable Consistency: The 45MG Ultrasonic machine delivers consistent and precise measurements.
  • Visual Verification: Clear back wall echoes validate measurement accuracy.
  • Minimal Variation: Readings consistently stay within a tight range (+/- 0.2mm to +/- 0.3mm), ensuring precise data.


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