Heavy wall MFL – Stretch the boundaries

Pipeline Description:

Two 10″ heavy wall offshore pipelines running parallel from platform to platform required a metal loss inspection. The length is 1.9 miles (3 km). There are heavy wall riser sections with 0.719″ (18.2mm) wall thickness at the foot of the platforms. The pipelines are located offshore in California, USA.

Why is it challenging?

With common MFL tool designs, the wall thickness of 0.719″ (18.2mm) cannot be sufficiently magnetized in a 10″ pipeline. Therefore, an MFL inspection seemed not feasible. In addition, the previous 3rd party MFL inspection wasn’t successful because of this. Ultrasonic inspection tools failed to get good data because of debris issues. The high cleanliness requirements for UT technology could not be met.

Target of the inspection:

Perform a high-resolution metal loss inspection for internal and external corrosion. Due to the project circumstances the inspection was to be carried out under urgency.