Final ROV deployment LRUT system and operation trials
The final configuration for the LRUT/ROV integration system regarding the communications system, power supply and physical interface such fixations and hydraulics was achieved successfully.
Work Class ROV from the Underwater Centre Service Provider.
(a) The Underwater Centre Vessel equipped with Work Class ROV (b) SubCTest System ready to be integrated with the ROV.
Final LRUT/ROV configuration
To demonstrate the capabilities and simplicity integration of the SubCTest system, the consortium agreed to demonstrate the integration using the hydraulic power and valve controls of the ROV. With this configuration the consortium tried to present a more simplistic version of the SubCTest system, reducing the number of components and giving the operations of the LRUT manipulator to the ROV operations team (all hydraulics: reservoir, hydraulic valves and pump of the original SubCTest are not used for this final integration but demonstrated as operational in initial trials, using his own hydraulics the system only needs communication and 24V power supply from the ROV). This configuration required an hydraulic compatibility between both systems LRUT/ROV, which was pretty straight-forward to achieve. In addition, this configuration served as a confidence check that SubCTestDemo system can be easily integrated with existing ROVs with minor hardware modifications directly through connecting to their hydraulic system.
Next figure presents the Work Class ROV (TRITON XL) that was used during the field trials and the LRUT base installation.
Work Class ROV – Triton TXL, from the Underwater Centre
The ROV base was specially conceived to attach the plate base of the manipulator.
(a) LRUT base fixation assembly at the rear of the ROV, (b) detail of the lift-off to allow the correct movement of the LRUT tool
Next figure presents the three-point fixation of the plate base of the LRUT manipulator.
Three point fixation between LRUT tool and the base installed on the rear ROV
Next figure presents the hydraulic cables that were used for connecting the LRUT manipulator to the ROV hydraulic system.
Hydraulic cables connecting the LRUT manipulator to the ROV hydraulic system
Optical fibre multiplexer and the customised cable developed to connect the power and communications. The communications uses four pins Ethernet standard connection and power supply two pins for 24V power source.
(a) Fibre Optic Multiplexer and (b) Costumized cable for power and communication connection
Once the integration activities were finalised the SubCTestDemo LRUT system could be remotely controlled from the control room of the ROV; while data acquisition from the LRUT system was remotely performed by the laptop running the Teletest Focus software.
(a) Navigation system of ROV – Triton TXL, from the Underwater Centre, and (b) SubCTest system connected remotely from navigation ROV room
A pipeline mock-up was built to validate the operation and deployment performance of the LRUT and EMAT SubCTest tool. Real defects were developed in the 12’’ diameter steel pipe to evaluate the defect detection performance of the NDT tools.
Pipeline mock-up preparation pier Loch Fort William to be deployed underwater
The pipeline mock-up was placed underwater at 40m depth, in order to facilitate subsea tests.
Pipeline mock-up deployed at 40m depth, and presenting the EMAT manipulator clamp locking on the pipeline
ROV - System mobilisation
Two ROVs were used during the operation trials; the Work Class ROV was the main vehicle where the NDT tools were integrated, whereas the Observation Class ROV was used to provide a secondary camera view of the LRUT clam on the Work Class ROV.
(a) The Observation Class ROV and (b) Its' control room
(a) The Work Class ROV and (b) Its' control and operation room.
The subsea deployment procedure of the Work Class ROV was performed using a special crane located on the vessel.
Subsea deployment procedure of the Work Class ROV
Once the ROV deployed under water the objective was to perform the validation of the operational SubCTest system. Next figures present two different subsea views of the LRUT tool from the ROV camera. At this stage the ROV operation team was checking that the manipulator was working and the hydraulic controls were correctly adjusted to give enough controllability to the tool.
Different subsea views of the LRUT tool from the ROV camera
The operation of the manipulator and procedure to clamp the collar around the pipe didn’t present any difficulty to the ROV team operation, resembling to a normal underwater work class ROV procedure.
Subsea views of the LRUT tool as the manipulator clamp locks on the inspected pipe
Once the NDT collar was in place and the ROV stable the following task pass to the NDT engineers at this stage the objective was to perform the NDT inspection of the pipeline with the software interface of Teletest Focus.
(a) Teletest Focus software interface and (b) LRUT data acquisition
During the underwater operation trials, various technical and operational challenges were encountered. It was identified that the SubCTest system can be easily connected with the hydraulics, power, and communications of the Work Class ROV without requiring any hardware modifications. In addition, it was presented that the SubCTest system can be directly operated by the ROV pilots from the control room of the ROV, while remote LRUT data acquisition can be performed through the laptop hosting the Teletest Focus software.
Despite the challenges very promising conclusions could be drawn from the operation trials. Specifically, the fact that the SubCTestDemo system complies with the industrial standards for the hydraulics systems of Work Class ROVs will greatly facilitate the wide adoption of the system. Towards this direction, important contribution was provided by the straightforward integration of the system with the main chassis of Work Class ROVs and its’ compatibility with their hydraulics and communication systems.