04 / Apr / 2023

Seeing Through the Splashzone

Back to blog

Martin Longmuir, Non-Destructive Testing Technical Authority

Martin Longmuir is the Non-Destructive Testing (NDT) Technical Authority at AquaTerra. Beginning his working life in the armed forces, Martin moved into the offshore inspection industry in 2006 as an NDT Technician, working all over the world on offshore projects and in shipyards. In 2014 he moved into a role focussed on the development of NDT personnel and the technical management and development of NDT, before joining the AquaTerra team in August 2021. To follow up on our most recent blog, we asked Martin to share his knowledge of the challenges of NDT in the Splashzone, and to talk us through AquaTerra’s industry-leading solution, the AquaCLAM®.

“At AquaTerra, we often talk about the Splashzone; it’s the area between the topside and subsea structures of a marine structure. It’s often in a position where it’s never fully submerged, but on the other hand it’s never really clear of the sea. The structures that sit in this area are intermittently subject to harsh weather conditions and to seawater, due to the motion of waves and tides. This exposes the area to a variety of integrity threats including corrosion, erosion, fatigue, marine growth and risks of impact damage.

On their own, or as a combination, these issues can have serious safety critical consequences to the structural integrity of the whole platform.

We explored the Splashzone in detail in our last post so with this article, I wanted to dive further into the way asset teams manage these challenges and how AquaTerra’s specialist inspection tools can support them.

In the Zone

There are three main discussion points that I come across with clients when we’re talking about inspecting in the Splashzone:

  1. Asset integrity management is one of the most important ways that asset owners can monitor and assess the condition of these structures.
  2. Removal of soft and hard marine growth to expose the material underneath is critical to carry out thorough visual inspections but also to help maintain the integrity of the structure.
  3. Carrying out non-destructive testing, such as ultrasonic wall thickness gauging using divers or ROV to gather a quantifiable volume of data for analysis and assessment is difficult when there is so much motion from the water in the area.

Teams that operate on marine structures are hardy and highly adaptable to the challenges that their various environments present. However, carrying out inspection and testing in an area where conditions are constantly changing, battered by waves, sea spray and wind is difficult, unpredictable work. Add in the need to maintain safe communications and operating the equipment needed to carry out the tasks and teams are faced with a whole new dimension of challenges.

Is There Another Way?

AquaTerra offers a suite of solutions that avoid the requirement for personnel to be in the water, safely away from the risks and challenges associated with working in the splash zone.

AquaCLAM® Cleaning & Inspection

AquaCLAM® is a remotely operated tool for the cleaning and inspection of tubular structures such as conductors, caissons and marine piles. It is made up of two main parts: The main carriage and the utility belt.

The main carriage houses a hydraulically controlled clamp which allows the tool to secure itself onto the structure opposing the forces from the waves and tide.

The utility belt is the heart of the tool and houses the cleaning and inspection spread.

Weighing in at less than 1000kg the tool can be rapidly deployed using a specialised team of rope access technicians. Once deployed, it can be controlled from the topside, safely avoiding the splash zone to carry out cleaning and inspection operations.

Cleaning operations are conducted using a high-pressure water jetting system and two Barracuda jetting heads fitted to the utility belt. The system can clean up to a pressure of 15k PSI, allowing the removal of even the most stubborn marine growth.

Building a Clear Picture: Visual Inspection & Ultrasonic Testing

Visual inspection is carried out using a high-definition subsea camera and LED light mounted onto a pan-and-tilt unit to deliver close visual inspection of the structure. This can identify surface corrosion, erosion, and other forms of surface problems such as impact damage, even in dark or cloudy subsea conditions. This system can be used to capture both photographic images and video footage that can be reviewed on completion of inspection.

The condition of the structure can also be tested for corrosion and erosion using the subsea ultrasonic testing system, fitted via a custom-built delivery system.

With a bespoke software package, AquaCLAM® takes information collected by an A-scan wall thickness gauge and two positional encoders to generate a C-scan corrosion map. This offers the client a clear picture of the condition of their structures with detailed information and references to problem areas.

To read more about our work in the Splashzone, visit our case studies page here.

Integrating with Integrity Systems

We understand the importance of integration with our clients’ integrity management systems. When the AquaCLAM® is used to carry out ultrasonic corrosion mapping in an area, it generates countless quantities of valuable data on the condition of the vital structures in the splashzone.

The software that is built into the tool generates a detailed heatmap of the area tested as well as a .CSV table containing all of the survey information that can be extracted and analysed by AquaTerra. This can then be used for detailed reporting and distributed to the client for integration into their integrity management systems.

Final Thoughts

I think that it’s hard to overstate the need for detailed and reliable inspection and maintenance strategy. It ensures that critical infrastructure meets safety standards and regulations, and helps asset owners avoid expensive and potentially tragic accidents whilst maintaining asset integrity. AquaTerra’s expertise, combined with its innovative technology can deliver highly accurate, safe, and efficient inspection and maintenance options, saving asset owners time, money and helping to ensure the safety of their vital personnel working in the Splashzone.”