Calibration Blocks 101

13 Nov Calibration Blocks 101

Calibration blocks come in many guises, but they all have one core similarity: they’re used to assess precision of equipment and refine their correctness to ensure accuracy.

When it comes to ultrasonic testing kit, there are many different types of blocks used to measure this. The following discusses these and looks at which are suitable for calibrating various UT equipment.

Calibration blocks: the 12 types

1. ASME ultrasonic calibration block: An angle-beamed block with 4 EDM, axial and circumferential notches for both outer dimension and inner dimension measurements.
2. DC Calibration block: An AWS-type block that uses metal track interspace and beam exit point calibration standard. Measures distance, sensitivity, refracted beam and beam index calibration.
3. DSC calibration block: Similar to the above, it also calibrates alternate and longitudinal wave span and sets alignment for the sound beam spot of incidence, spread angle and sensitivity. Fully compliant with AWS and ASHTO conditions.
4. IIW (International Institute of Welding) type 1 calibration block: Comes in a fabricated design according to application requirements, such as circular groves and notches.
5. IIW type 2 calibration block: A revised version of the above, with distance calibration marks to the 2.0: hole. Complies to IIW ASTM E164.
6. RC calibration block: Assesses the resolution capacities of an angle beam transducer.
7. SC calibration block: Inspects for shear wave sensitivity and complies with ASTM E164 and BRRA/AWS requirements
8. TOFD calibration block: Measures time of flight diffraction for the volumetric testing of welds.
9. UT V1 block calibration: An ultrasonic flaw detector for the quality of welded joints.
10. UT V2 block calibration: Similar to the above, it checks the probe points of sound waves in steel.
11. 5 step calibration block: As the name suggests, this uses 5 steps to verify ultrasonic thickness gauges.
12. 10 step calibration block: A more intense version of the above that measures greater levels of density and dimension.

What block for which job? Popular Industries

Some of the most common industries that use UT testing are automotive casting, railway systems, aircraft parts and piping. The type of calibration block to use for testing equipment might require a single type or choosing multiple examples, depending on the task at hand and kit used.

The following defines these four generalised classifications.

Automotive Casting: Calibration blocks that use step and tapered wedges in both imperial and metric measurements are appropriate here. 5 step blocks are the most often used but can come in any geometry if created for specific tasks. They detect defects in density and dimension.

Railway system casting: The most widely used is the UT V1 calibration block, closely followed by the V2. Both support the resolution capability of ultrasonic straight beam probes and the non-testing area (for steel).

Aircraft parts: A wide variety of calibration blocks are necessary, thanks to the multiple parts involved in this sector. Both types of IIW blocks are in general use, but others might be more suitable depending on the different parts to be tested.

Piping: The AME calibration block is ideal in most situations – indeed, it’s been manufactured specifically to address piping UT needs. Of course, the exact diameter and thickness of the block will need to be appropriate, meaning care must be taken to identify exactly what’s required.

We’ve only mentioned the most common calibration blocks here, along with the types used most often for testing. The key to the right type is guided by the UT application. Shape, form, size and use will determine the right equipment and, thus, the right calibration block/s to select.

The aim of the inspection and the material to be measured will drive the kit needed and the calibration block required. Such blocks will need to be engineered to be fit for purpose. Working with a talented design and production precision engineering team is key for accuracy and cost efficiency.

SixDe’s calibration block experience makes us the perfect production partner, working with your company’s needs from the drawing board to delivery of the physical blocks. And, being a homebred Aussie company, we’re wholly committed to the government’s drive to accelerate Australia’s manufacturing industry back to the global player it used to be. Get in touch today to discuss this and other manufacturing needs.