Europe · High-Pressure Graded Air Supply & Sandblasting System Retrofit for Large Ship Repair Yard

Project Background: A large coastal ship repair yard in Europe undertakes hull sandblasting, pneumatic grinding, welding fixture driving, pressure vessel testing and pre-coating purging. Sandblasting is an intermittent peak-load process with sudden massive air demand when multiple nozzles operate together. The original single-pressure network with fixed-speed compressors responded slowly. Pressure dropped sharply when sandblasting started, causing uneven blasting strength, inconsistent rust removal and high rework rate. After blasting stopped, compressors kept loading and excess air vented through relief valves, wasting energy. Coastal salt spray accelerated corrosion of compressor housings, piping and valves, creating numerous hidden air leaks. Tight dock schedules meant delayed blasting directly slowed block delivery, so the owner targeted stable blasting pressure, shorter treatment cycles and lower corrosion-related maintenance cost.

Solution: A graded air supply architecture was implemented with separated high-pressure circuits for sandblasting and low-pressure circuits for grinding and instrument purging. High-pressure side uses VSD screw compressors matched with large buffer air receivers to absorb instantaneous peak flow and stabilize nozzle working pressure. Independent low-pressure units serve hand tools and purging to avoid energy waste from overpressurization for low-demand applications. All pressure vessels, flanges and pipe fittings receive salt-spray resistant coating plus supplementary cathodic protection. An online leakage monitoring system automatically locates leak points. The control logic prioritizes pre-loading compressors upon sandblasting activation and reduces load during idle intervals. Refrigerated dryers remove moisture to prevent flash rust on cleaned steel plates after blasting. Safety interlock pressure relief devices comply with shipyard high-pressure codes.

Results: Combined buffer tank and VSD stabilization delivers consistent blasting pressure, improving rust removal uniformity and reducing rework, shortening processing time per hull block and lifting dock turnover rate. Graded supply eliminates overpressure waste and cuts compressor energy consumption by roughly 21%. Anti-corrosion treatment slows salt spray degradation and pipe leakage, lowering annual spare parts expenditure. Dry air prevents flash rust and reduces secondary surface treatment work before coating. This solution addresses the typical intermittent peak-load feature of sandblasting at coastal shipyards and offers a practical upgrade reference for marine and ship repair operators across Europe.