Due to the influence of the Yellow River's mouth, the seabed foundation at the Shengli shallow waters is extremely unstable. As the service life of pipelines and cables extends, along with the effects of sea current erosion, hollowing, excavation, and the influence of foundation settlement, as well as unexpected accidents, severe damage to the pipelines and cables can occur. This can lead to the closure of oil wells, affecting normal crude oil production at sea and even polluting the marine environment. The inspection and maintenance of seabed pipelines and cables have become increasingly urgent issues to address. Therefore, based on extensive research and verification, the Shengli Petroleum Administration has proposed the research and development project of the "Shallow Seabed Pipeline and Cable Inspection and Maintenance Device" (hereinafter referred to as the "Device"). The purpose of this project is to utilize the "Device" for timely inspection and maintenance of the pipelines and cables, ensuring their normal operation and saving nearly one billion yuan in annual investment. The project is jointly undertaken and completed by the Shengli Petroleum Administration, along with domestic universities and research institutions.
Ensuring the safety of personnel working underwater is crucial. In this regard, underwater inspections are a vital task. Not only do they provide safety, but they also serve as a method to assess the actual underwater conditions, which is beneficial for workers to conduct their tasks. So, what are the methods of underwater inspections?
Regarding underwater inspection methods, today we introduce the integrated underwater camera inspection. Based on the actual workload and inspection location on-site, inspectors can choose to use the integrated underwater camera inspection method, diving inspection method, or underwater robot inspection method for inspecting the underwater portion of pier foundations.
The Modular Underwater Camera Inspection System is composed of an underwater camera, underwater illuminator, transmission cable, monitor, voice-over system, specialized hoisting equipment (used for the up and down movement of the camera lens), and a barge (used as the operational platform).
During the inspection, secure the working vessel to the inspected pier with ropes, and mark each shooting point below the water level on the foundation. Use a specialized hoisting device to attach the camera to the starting point of the area to be inspected, shooting vertically. Maintain a distance of approximately 20-30cm from the target surface (as clear visibility is key), and ensure smooth and uniform movement. After completing a vertical shooting, slide or circle along the foundation surface at the specified intervals and continue shooting in the opposite direction. During the shooting process, make detailed records and descriptions.
The advantages of the modular underwater camera inspection method lie in its fast inspection speed, low cost, and relatively safe operation for inspectors. However, the drawback is that it requires a high-quality environment for inspection, meaning it performs best in clear water conditions with no aquatic vegetation or microorganisms on the base surfaces, and where the base is submerged to a depth of no more than 5 meters. Therefore, it is more suitable for inspecting the foundations of bridges in mountainous areas and medium to small-span bridges in plains, but not for the foundations of large-span bridges in plains or sea-crossing bridges.
