Unique technologies and equipment for underwater welding that allow work to be performed at any time of the year, including under ice, under high pressure and other complex factors. At the same time, we guarantee high quality and reliability of welded seams and joints of low carbon and low alloy steel. Technologies and means of mechanization of underwater welding processes have been developed, which is especially important for emergency rescue operations and working in hazardous conditions. They can significantly increase the productivity of welding, reduce the consumption of welding consumables and energy consumption due to the optimization of the entire production process. We have developed and tested welding technologies, which provide new opportunities for the implementation of particularly important projects in underwater welding:
- hull repair of floating vessels
- performing rescue procedures when lifting sunken ships
- restoration of fixed and floating bunk beds and platforms
- repair of metal structures and other metal structures without disassembly, directly in the water
In the last century, thousands of submarine infrastructures have been built and technical spaces are very important for society (starting with the first cable between Europe and America and continuing with the submarine oil and gas pipelines).
The current underwater infrastructure is from important to critical for many areas of human life, especially for small islands, as in the case of Greece.
Another important infrastructure is related to port infrastructure and offshore gas and oil platforms. Most of these structures were prefabricated on land and later placed in water, which required solving complex R&D challenges. Unfortunately, the problem of repairing and maintaining these structures is quite difficult. In many cases divers, submarines, etc. must be used.
Even in ship maintenance, their maintenance and repair is performed on a dock – another expensive service.
Given these events and, at the same time, the huge development of robotics, we decided to start designing, building and integrating into a camera a sensor that can simplify and reduce the cost of many of the above tasks.
The sensor is designed to inspect surfaces from a distance of 200 mm to 1000 mm below the water surface.
The inspection is performed using a laser beam with green or blue light, so that the underwater penetration is as much as possible.
The first version of the sensor – U.Wel..Cam.-Sea camera – is programmed to operate at a depth of 100 m, mounted on a drone or underwater robot.
The sensor can scan any surface that reflects the light of a laser beam providing an accurate profile (from 0.5 mm to 0.05 mm depending on the range of the sensor visibility).
This type of fine-grained scan is of great interest because it detects premature cracks and damage, thus allowing timely corrective and preventive damage prevention measures to be taken.
The scanned profile is analyzed for defects and, if necessary, alarms are activated so that the operator on the service vessel can decide on any further action.
The various surface profiles are recorded and can be analyzed by specialized personnel. In the event of an emergency, evacuation or shutdown measures or other special measures may be taken to prevent serious damage.
The U.Wel..Cam.-Sea camera can also be used to determine the size of defects that are not noticeable with traditional underwater ultrasound technology.
Because U.Wel..Cam.-Sea is conceptually derived from the well-known laser scan air chambers, it inherits the ability to control and detect a “seam” between two parts (as in welding).
With a robot capable of underwater welding, U.Wel..Cam.-Sea can provide path correction data, which is very important for underwater welding, as the possibilities of mounting and mounting in water are limited.
Of course, after welding it is possible to check the quality of the welds.
Principle of operation and open issues
U.Wel..Cam.-Sea is based on the principle of triangulation of the reflection of a laser beam from the surface being examined.
Here the well-known Scheimpflug principle, used in many off-water laser scanning systems, is applied to maintain the correct visual behavior of the camera.
But in the case of underwater operation, there are many mechanical complications due to different visual behavior of water and air.
These require special design of the underwater device, so as to reduce distortions and maintain the right results.
Underwater, the laser beam is initially emitted behind a protective glass, so we have the steps: air, glass, water (reflection), glass and again air.
Therefore, special design of the optical system is required and, consequently, appropriate correction of the distortions.
Particular attention should be paid to resistance to high pressure (10 atm.), Humidity and corrosion.
The wavelength of the laser source must be selected according to the maximum penetration into the aquatic environment (blue or green light area)
Advantages and applications
In conclusion, the U.Wel..Cam.-Sea camera:
– detects and corrects with high accuracy possible defects in underwater objects, such as the propeller or the bottom of a ship.
For example, because the cost of a propeller is high and its maintenance is about 5% of the original price (eg $ 500,000), maintenance and replacement should only be done when you require it.
If a submarine drone is equipped with a grinding tool, a polisher and the U.Wel..Cam.-Sea system, controlled propeller polishing can be achieved even in underwater conditions, which would result in a significant cost reduction.
– inspects defective underwater structures: offshore platforms, ports, underwater installations, other equipment operating below the water level. This scan can be critical for early detection of defects and avoidance of accidents.
– Monitoring and quality repair of pipelines. The pipes are produced in parts which are welded (sealed) before being placed in water. Once installed, infrastructure repairs and maintenance can only be done underwater with the help of divers or expensive submarines. With the U.Wel..Cam.-Sea camera, mounted on a drone with appropriate equipment, you check the quality, evaluate the defects and the possible repair of the equipment.
– Check and correct “track” near scanning and underwater inspection surfaces, monitor seams, find initial position for scanning, manage welding parameters – amount of material, current, inflation, etc. (adaptive welding), underwater welding inspection.
– Scanning of archeological sites and high resolution objects in gentle conditions to keep the obsolete material (eg wood) intact before the natural extraction of the sections for exploration and certification.
It is worth noting that scientists from the University of Sofia (Bulgaria) with many years of experience in the field also participate in the project.
The second includes an extensive market research and participation in relevant events – exhibitions, forums, etc.