Navy researchers have developed a novel ship coating inspection process that is designed to be far safer, faster, cheaper and more accurate than current methods.
Underwritten by the Naval Sea Systems Command (NAVSEA) under the Paint Center of Excellence Program, the streamlined process developed by the Chemistry Division at the Naval Research Laboratory (NRL) is expected to yield “impressive savings” for the U.S. Navy and limit the “highly subjective” results of the current process, researchers say.
Photos: Naval Research Laboratory
|Developers say the technology can replace the slow, dangerous and subjective process of personally visually inspecting a ship's hull and superstructure, as demonstrated by researcher James Tagert.|
“Current methods of performing inspections of ship surfaces are slow, labor intensive and highly subjective,” said John Wegand, program team member at NRL's Center for Corrosion Science and Engineering Branch.
“These inspections require significant time-consuming manual processes to measure dry coating thicknesses, check color metering, as well as the visual inspection for corrosion damage and blistering below the surface of coating materials.”
NRL’s new process, which can also be used to inspect civilian vessels, uses two specified digital cameras with a coatings analysis software application developed by the NRL.
The process, developed by a team led by Paul Slebodnick and James Tagert, involves an image-collection protocol that provides detailed images of a vessel's structural zones as collected by a two-person team in only three days.
|Researchers Kimberly Santangelo and John Wegand use the AFTCAT approach to gather data.|
The images can be collected either pier-side or from a patrol boat 100 to 200 feet from the ship. Further advancements will eliminate the need for a patrol boat, and all images will be captured from the adjacent pier, the team reports.
Team members collect the image sets with the lightweight camera while walking perpendicular to the surfaces being inspected. The images are then uploaded to the NRL’s application, known as the Automated Freeboard and Topside Coatings Analysis Toolset (AFTCAT).
The application consists of a grouping of advanced image processing and data interpretation algorithms that are used to quantify the condition of the coatings.
One algorithm, the Topside Corrosion Detection Algorithm (TCDA), is used to automatically assess the extent of corrosion damage and coating degradation. Other algorithm prototypes assess color uniformity and the extent of coating failures from flaking, delamination and blistering as shown in individual images.
From 65 Days to 4 Days
Researchers compared the traditional manual and new digital approaches in head-to-head inspections of the USS Nimitz in 2009.
Manual inspection of the entire topside coating required a 65 man-day effort, with four additional weeks needed to complete the inspection report. The process involved both human visual inspection and physical measurements performed over a five-day period by five NACE-certified and S-CAT-trained engineers and technicians.
Six personnel lifts (two pier-side and four on barges) were required, as were eight to 10 ship personnel to support barge/JLG logistics during the inspection.
Using the new process and technology, the same inspection took less than four days and provided immediate access to more than 3,000 images of the ship's surface condition for in-depth inspection, researchers reported.
‘Greatly Less Expensive’
In the end, the team expects that the new process will require a team of two trained technicians to collect image sets over a three-day period. Logistical support will include access to an adjacent pier to photograph surface zones opposite the ship's Quarter Deck. An additional technician will be required to run the AFTCAT on the image sets and automatically generate and complete the inspection reports over two days.
|Coating non-uniformity is evaluated in digital images taken from 417 yards away.|
In all, inspecting all vessel surfaces, including catwalk zones, on an aircraft carrier should take 10 man days, including generating the inspection report, researchers say.
“Our new method represents a quicker, more accurate and greatly less expensive alternative to the present inspection process now used,” said Wegand. “An added bonus is the system can be adopted for the inspection of civilian vessels with no change in procedures or protocols.”