AISUS has successfully developed and deployed a new bespoke Clamshell Inspection Tool, designed specifically to overcome a complex riser inspection challenge on a North Sea offshore platform.
AISUS, inspection specialist created the new technology following a client requirement to inspect two 6-inch OD risers through the splash zone, where restricted access, heavy marine growth and thick passive fire protection (PFP) coating presented significant operational challenges.
A North Sea operator tasked AISUS with externally cleaning and inspecting the risers while maintaining the integrity of the existing 50mm PFP coating. Conventional inspection techniques were unsuitable for the application, requiring the company to engineer an entirely new solution.
The project highlights AISUS’ approach to solving complex asset integrity challenges through in-house innovation, combining engineering design, manufacturing and operational expertise to deliver a tailored inspection system.
Developing a Solution for a Unique Challenge
The inspection scope involved cleaning and assessing two splash-zone risers positioned in close proximity to both one another and a carrier caisson. Limited clearance around the structures meant any deployed technology needed to maintain an extremely compact profile while still delivering both cleaning and inspection capability.
The challenge was further compounded by thick marine growth on the risers, which prevented equipment from travelling along the structures, and by the presence of 50mm of passive fire protection coating that ruled out conventional ultrasonic testing methods.
Recognising that existing inspection systems were not optimised for the application, AISUS engineers developed a completely new Clamshell Inspection Tool designed specifically around the project’s requirements.
Designed, modelled, manufactured and tested entirely in-house, the new system was engineered to fit around the coated risers while remaining compact enough to avoid clashes with surrounding structures. The lightweight design also enabled safe installation and removal by Rope Access technicians operating offshore.
Combining Cleaning and Inspection in a Single Deployment
The Clamshell tool incorporates high-pressure dual spray bars that provide 360-degree cleaning coverage, removing marine growth while maintaining carefully controlled jetting pressures to protect the underlying coating.
Alongside visual inspection capability, the system was equipped with a multi-probe Pulsed Eddy Current Testing (PECT) payload, allowing AISUS to perform a full inspection through the existing coating without requiring coating removal or intrusive preparation work.
The modular design also allows the Clamshell system to accommodate alternative inspection payloads, providing flexibility for future applications and asset types.
Successful Offshore Deployment
The newly developed technology was successfully deployed in the North Sea, completing both cleaning and inspection operations across the two risers.
Marine growth was removed sufficiently to allow uninterrupted deployment down to the first subsea guide, while a full 360-degree PECT inspection was completed through the splash zone on both structures.
Inspection results identified no areas of concern, with corrosion rates aligning closely with measurements previously recorded elsewhere on the client’s subsea pipeline system, providing additional confidence in the findings.
Driving Innovation Through Client Requirements
The project demonstrates how client-specific challenges continue to drive innovation within AISUS’ inspection technology portfolio.
By maintaining full in-house design, manufacturing and testing capabilities, AISUS can rapidly develop bespoke technologies that address complex offshore inspection requirements where conventional solutions may be impractical or ineffective.
The successful deployment of the Clamshell Inspection Tool not only delivered the required inspection data for the client but has also established a proven new solution for future riser, tubular and restricted-access inspection applications.