Inspection of Conventional Welds
AIT performs automated, semi-automated and manual ultrasonic inspection of conventional welds.
An example of Phased Array Automated Ultrasonic Testing (PA-AUT) of conventional welds would be the inspection of tendons.
Tendons anchor a floating offshore platform to the sea floor by attaching the tendon to a connector on the suction pile at the sea floor and to the pontoons of the platform just below the surface. Tendons range in length from 1800' to almost 4000' and are considered to be high fatigue components due to the movement of the platform and the Vortex Induced Vibrations (VIV) from sub surface currents.
AIT performed a combination inspection using PA-AUT and Time of Flight Diffraction (TOFD) to ensure that the weld quality met the rigid acceptance criteria established through full scale fatigue testing, mechanical testing and fracture mechanics which resulted in the determination of the critical flaw size. Based on the critical flaw size, the weld could contain a flaw of this given size and the flaw would not propagate to failure during the 200 year fatigue life of a tendon weld. The critical flaw size was provided to AIT in a project specific Engineering Criticality Assessment (ECA).
An example of Automated Ultrasonic Testing (AUT) of conventional welds would be the inspection of offshore drilling riser components.
Drilling risers are composed of a main tube and the “auxiliary lines” chock & kill, mud boost and at least one hydraulic line. All of the components are carbon steel with the exception of the hydraulic line which is normally duplex stainless steel.
A typical raster scan approach is used to inspect the welds. During a raster scan, the probes are moved back and forth to ensure that ultrasound passes through the entire examination volume of the weld. The AUT data is displayed using a traditional A-Scan, B-Scan (Side View), C-Scan (Top or Plan View) and D-Scan views (End View).
The pictures below show a completed three weld drilling riser, with and without floatation installed.
