Accurate pipeline inspection transforming underwater engineering

Louise Smyth

An innovative pipeline survey project demonstrates how advanced inspection technology is transforming underwater engineering

In a novel inspection project, CCC Underwater Engineering has resumed the second phase of a 2,000km pipeline survey in the Arabian Gulf, totalling 316 pipelines.

The operator is inspecting the final 102 pipelines using its Saab Seaeye Leopard underwater robot, which CCC says is the best vehicle for the task.

The objective is to achieve the most precise repeatable survey data possible, to a baseline accuracy below 0.5m. This kind of accuracy, whilst working in extremely shallow water along different sized pipelines for extended periods, requires a large array of high-definition filming and sensing equipment.

Abu Dhabi-based CCC Manager, Tavis Letherby, says that position repeatability accuracy is essential to secure a solid baseline for future surveys. The necessary array aboard the Leopard includes three HD cameras with movie quality 1080i interlacing, two Kongsberg M3 profiling sonars, Sonardyne Mini-Ranger and Sprint-Nav 500 Hybrid INS, Valeport bathy suite including altimeter, Valeport mini sound velocity profiler, MCS’s photo-realistic 3D cloud system, laser line generator, CP and UT probes.

Pipeline inspection achieving accurate data in strong currents

“For accurate data acquisition,” says Letherby, “only a Leopard has the manoeuvrability, control and payload to stay steady and on course without problems in shallow water when faced with strong cross currents and wave motion – sometimes working in less than 6m of depth.”

He points to the vehicle’s specification of 11 thrusters, 500kgf of forward thrust, 200kg payload and iCon intelligent control architecture, as making it suitable for very shallow water working whilst fully loaded with equipment.

When long excursions are necessary the operating vessel must stay around 70m clear of platforms for safety reasons. On those occasions the Leopard needs to navigate for up to 100m to fulfil the pipeline inspection, which is a particular challenge in shallow water.

Letherby says that the Leopard has advanced underwater robotics further into the digital world and offers operators a work vehicle costing half that of an equivalent hydraulic system.

A large open payload within the chassis allows for the installation of specially designed sliding trays equipped with survey sensors or tooling options. A range of tooling skids make it a versatile system capable of performing a variety of work tasks in even the harshest of environments at depths of up to 3,000m.

What’s next for the offshore subsea inspection industry?

Letherby believes that the next stage in the digital evolution for data acquisition offshore inspections will be the adaptation of remote operations.

He says, “The advent of low latency, encrypted video/data streaming from offshore vessels to onshore facilities directly or cloud based media streaming platforms using either HEVC or H.264 encoding of video images, is driving the way for remote operations to become more mainstream for offshore subsea inspections.

Companies are already establishing remote operation centres (ROC), where, utilising VSat communication, they are either minimising or removing personnel from the offshore vessel and controlling operations from a remote location (contractors main office) either in the same country or in another part of the world (contractors satellite office).”

Due to recent worldwide pandemic, companies are now accelerating their plans for adapting to remote operations, instead of the conventional way of undertaking offshore subsea inspections.

Letherby comments that, “This shift to remote operations will also highlight new challenges for contractors and manufactures to overcome, namely the reliability of the subsea vehicles, sensors and tooling to operator for long durations without maintenance or human intervention.”

He adds: “A once, long established (analogue) practise is now being rewritten and a new digital, high-definition, real-time normal is coming to the offshore subsea inspection industry.”