To develop a tool to inspect riser pipes under operating conditions, the tool should be suitable to enter the riser pipe to 300 metres from the launch-retrieve trap and use umbilical/rescue cable.
A special cable and winch unit were built and worked satisfactorily. Ultrasonic probes were selected and a prototype ultrasonic system constructed. Prior to a high pressure system a tool was constructed to inspect open pipelines to a distance of 500 metres using the constructed ultrasonic device. The field test showed its good performance and justification of the project. Attention was also paid to high pressure free swimming tools, as such the rtd-caliper was designed.
The integrity of riser pipes is of paramount importance. To prove its condition the ultrasonic method was selected to measure pipe wall thickness and quantify corrosion, if present. Inspection from the outside if often impossible, therefore tools are required which can enter the riser pipe system, preferably under operating conditions.
Typical riser operation conditions are pressures up to 150 bars and oil or gas velocities up to 5m/sec.