ROV for Inspection and Repair

Fluor Marine Propulsion LLC (FMP), Naval Nuclear Laboratory

Problem Statement Description

Identification Number: FMP-NNL-0028

Title: Remotely Operated Vehicle for the Inspection and Repair of Ship Structures Request for Proposal
Problem Statement
U.S. Navy vessels require periodic dry dock sessions where repairs, preventative maintenance, and modernization are performed to keep ships seaworthy. Part of this inspection and maintenance process is performed within onboard fluid tanks where human inspection and repair bear a high financial cost and an onerous labor challenge due to labyrinthine tank layouts.
To improve dry dock efficiency and improve the safety posture, overhaul facilities must be able to supplement human-performed maintenance functions with remote and/or autonomous capabilities. Remotely Operated Vehicle (ROV) solutions are being sought for the inspection and repair of the ship structures.

Background
The metal housing of these fluid tanks corrodes slowly over its lifespan and presently receives time-based maintenance via human entry for visual inspection and measurement of paint system health, cracks, and corrosion/pitting. After draining the tanks, a worker transits through a small horizontal portal (18 x 18 circle or 15 x 23 oval), then navigates many tall, partitioned bays both horizontally and vertically through portals of the same small size. This task takes hundreds of hours to assess and many more hours for inspector concurrence. Preparation and execution for paint and welding repair then requires arduous ventilation setup and equipment movement.

Desired Capabilities
Solutions are being sought for commercially proven ROV technologies that may accomplish all, or parts, of the following:
1. Routine inspection and defect categorization of internal ship structures to assess repair necessity

2. Defect repair

Desired Capabilities Expanded

1. Routine inspection and defect categorization of ship structures to assess repair necessity:
o Develop an automated scanning capability to accurately inspect and gauge defect dimensions without the need for manual comparison or manual measurement of collected data (e.g., laser scanning, sonar 3D mapping, etc.).
ROV technology should allow for 3D mapping with digital overlay capability to allow analysis of new and historical ship structure scans.
ROV technology should incorporate a method of geolocation to allow for manual ROV navigation with a potential for fully autonomous navigation.

2. Defect repair:
o Provide an ROV, or a means for an ROV, to make repairs.
Examples of repairs include epoxy repair for corrosion mitigation, corrosion crack repair via welding, excavation/drilling/filling of crack tips, etc.
o ROV technology should have ability to manipulate fasteners.
o ROV technology repair services may be provided via tether (e.g., weld gas or weld wire).

Functional Attributes
ROV to fit minimum dimensions (openings) of the ship structure, as well as internal navigational dimensional restrictions.
o Typical U.S. Navy tank navigational restrictions are 18 x 18 circle and 15 x 23 oval openings. This size limitation applies to both initial ROV placement into the tank and also horizontal transit through vertically oriented portals of the same side inside the tank.
o Solutions that do not fit the standard naval openings above may still provide some benefit in separate future applications.
For swimming specific ROVs, the ability to ascend/descend, traverse/strafe, and pitch without the use of thrust is desirable so as to minimize the ROV kicking up debris that compromises visibility.
If tethered, ROV thrust should be sufficient to transverse with full tether length around multiple obstacles or bends (e.g., the ROV must be able to have enough power to handle tether drag).
o Sufficient tether length for most U.S. Navy applications is 300 ft or less.
For swimming, and/or flying ROVs, the ROV must be self-stabilizing.
o Able to hover at specified point without user input.
o Swimming ROVs should, at minimum, have manual buoyancy control (e.g., ability to add or remove weight to achieve neutral buoyancy without supplementary use of thrust).
ROV should have auto and manual camera focus options.
o Manual camera focus is desirable in situations where the autofocus erroneously identifies intermediate debris.
o Effective combined camera field of view (e.g., 270 ) to minimize the ROV movement required to correctly self-orient inside the tank.
ROV should have sufficient variable lighting for live feed and camera use.
ROV should have the ability to gauge the length, width, and depth of defects.
If untethered, the onboard ROV power source should last for 12 or more hours.
While not prohibited, untethered ROV control complicates the approval process for U.S. Navy shipyard implementation (e.g., Wi-Fi, Bluetooth, network used, spectrum analysis, etc.).