To extend the service life of the water intake pump vessel to over 50 years—and given that the underwater portion of the hull's outer plating cannot be maintained throughout its entire lifespan—we require that the thickness of the vessel’s entire underwater outer plating (≥8mm) meets the durability standards for its intended service life. Additionally, we recommend using advanced marine anti-fouling and corrosion-resistant materials (designed to prevent the attachment of algae, barnacles, and other aquatic organisms) along with state-of-the-art processing techniques.

　　Our company uses CCSA steel plates for the ship hull. After the hull is completed, we conduct weld seam ultrasonic non-destructive testing and a comprehensive tightness test as per industry standards: Inside the hull, compressed air is supplied at a pressure of 0.2 MPa, held for 30 minutes; meanwhile, external weld seams are coated with lime water, while internal seams are thoroughly soaked with kerosene, allowing us to visually inspect for any leaks. All welding work on the ship’s structural components is carried out by qualified welders.

　　Before welding, the surfaces of the components to be welded should be carefully cleaned to remove rust, paint, moisture, and oil stains. Welding should be carried out in a specific sequence to prevent deformation of the steel plates and avoid stress concentrations in the material.

　　After welding is completed, water-fire straightening is performed on the necessary areas to ensure the smoothness of the hull's contours, and welding specifications are strictly followed according to the requirements outlined in the welding specification sheet.

　　1. Surface Treatment

　　1) Use clean, dry air free of oil and other contaminants to blast the anti-corrosion surface. The abrasive grit selected for sandblasting must have a maximum particle size of no more than 75 μm and a minimum size of at least 25 μm within the blasting area. After rust removal by sandblasting, the surface cleanliness must meet the requirements of SSPC-SP5-1966 (Swedish Standard SIS 05 5900-1967 Sa3), CP3012-1972, or relevant international standards.

　　2) Use manual tools such as angle grinders, polishing machines, etc., to carefully remove all burrs, weld spatter, sharp edges, and rough surfaces.

　　3) Use a handheld electric wire brush or similar tools to clean the edges and surfaces, removing rust spots, oxide scale, oil stains, and residual paint.

　　4) Clean the surface of oil stains using the same solvent that matches the one provided by the paint manufacturer.

　　5) For components with higher brightness and bearing surfaces, apply anti-corrosion varnish or a similar protective coating, followed by thorough polishing to prevent corrosion.