Curved step wedge calibration blocks for small bore pipework inspection 

An oil and gas customer in the Middle East required custom Curved Step Wedge (CSW) calibration blocks to support the calibration and validation of ultrasonic testing (UT) equipment used to inspect small bore carbon steel pipework.

Designed to match the outer diameter (OD) of the customer’s pipework, the blocks provide representative calibration standards for accurate equipment setup before inspection.

The inspection challenge

Small bore pipework presents a challenge for ultrasonic testing, as calibration blocks must accurately replicate the geometry of the component being inspected.

Flat reference blocks cannot reproduce the curvature of smaller diameter pipe, making stable probe positioning during calibration more difficult. The customer required curved calibration blocks to match different pipe diameters and support routine inspection.

Our solution

Working to the customer’s specification, Sonaspection manufactured two custom Curved Step Wedge (CSW) calibration blocks from carbon steel using precision machining.

Each block was machined with 2 – 10 mm calibration steps and manufactured to match the customer’s pipework:

• • 1.5″ OD Curved Step Wedge calibration block

• • 2″ OD Curved Step Wedge calibration block

The processes used enable tight dimensional tolerances, supporting consistent and repeatable ultrasonic equipment calibration.