The routine docking repair of ships is according to the rules of classification society. It is necessary to inspect the ships in the dock after the certain operation cycle of ship maintenance in zhejiang province. Docking repair operation process includes: (1) propeller operation process; (2) shafting operation process; (3) rudder system operation process; (4) the seabed valve, sea valve operation process.

Prepare before docking

As for the hull, the ship shall request the ship to prepare the general arrangement plan, linestyle plan, docking pier plan, bottom plug arrangement plan and outer board symbol plan, etc. In terms of the turbine, the chief engineer shall, upon request, prepare the submarine valve box layout and the sea valve layout; Assembly drawing and part drawing of rudder, rudder stock, rudder pin and rudder bearing, equipment technical drawing and accounting statement of rudder stock and rudder stock; Spare parts drawing and assembly drawing of stern shaft, shaft sleeve, stern shaft seal, stern bearing and propeller; Parts drawing and assembly drawing of fishing net equipment; Stern tube arrangement drawing and structural drawing; Drawing of stern peak tank or stern tube cooling water tank and piping drawings of heating pipe, ballast pipe, air sounding pipe and other equipment to be installed in dock; Propeller disassembly and assembly technology and equipment accounting; Assembly drawing of thruster; Log, sounding equipment diagram. It is necessary to know and refer to the historical data of the vessel in detail. Please note that if there is impressed current cathodic protection, please turn off the power. If want to tear open check stern shaft, still should tear open the join flange of stern shaft before entering dock, measure its offset and bend value and make a record, see with what make repair equipment and contrast.

Before entering the dock, it shall clearly observe regulations and sign relevant agreements with the ship during the dock period with the ship, requesting the ship to level the ship as far as possible, and the draught and floating dock before and after draught shall not exceed 1% as far as possible. First avoid pier sitting when the hull additional fracture stress. But floating dock if reach less than 1% for some reason, can enlarge a bit, be in 1.5% less. Horizontal QingShi point also request not beyond 1.5 ° (foreign request is 0.5 °), will also request the ship double bottom together, deep oil tank, sewage water, fat and clay to remove such as clean, especially the average boat, try to avoid pollution to the dock.

2. Key practice of engineering project and quality control in dock

2.1 appearance inspection of hull, rudder and propeller

After dry-docking, the dry-docking repair supervisor shall inspect and acknowledge the sitting condition of the ship's pier together with the owner, chief engineer and chief officer, as well as the external appearance of the hull plate, rudder and propeller together, so as to determine whether there is any unplanned repair project. Together should also be the main parts of the propeller, rudder photography for storage and reserve.

2.2 inspection of submarine valve box and repair of submarine valve

High pressure water cleaning in the hull should be opened before the bottom of the valve box grille, so as to wash the valve box internal. Upon completion of the scour, the repair supervisor shall immediately check the internal condition of the valve box together with the chief engineer and acknowledge the contents of the repair project. The bottom of the valve box, especially the bottom of the sludge deposition is necessary to completely wash clean, remove the valve box surface of all Marine organisms. Since all the seabed valves are closed when entering the dock, check whether there is water dripping.

If have illuminate these valve leak, want key follow - up record.

Although the repair of the seabed valve is relatively brief, but a little neglect will cause a big delay in the docking period, so it is necessary to check the key quality of its repair. The usual inspection method for the disc and seat of the touch ring for the color of the development of the view, such as all disassembled can be carried out hydraulic test.

2.3 shaft system and propeller overhaul and repair

No matter it is not to draw stern shaft, it is necessary to measure stern shaft subsidence to determine whether the wear and tear of stern bearing and bearing clearance are normal. Measurement values should be recorded in the form of factory rules. Pay attention to check whether the sealing device is surrounded by fishing nets and oil seepage scene.

The disassembling and assembling process of shafts and OARS takes a long time. It is necessary for the repair supervisor to follow and participate in the whole process. Please pay attention to the following points.

1) measure the sinking amount of stern shaft and the number of shaft heads before shaft removal.

2) if stern bushing is grooved by sealing ring, it shall be repaired by naked car or by electroplating or spraying. When the lining set is reassembled, the circumferential run-out should be adjusted. If the diameter of the liner is less than or equal to 670mm, the run-out should be less than 0.20mm. For bushing diameter greater than or equal to 710mm, its runout is less than 0.30mm, the smaller the runout is the better.

3) check whether there are cracks and other damage scenes at the taper of front and rear bearings and stern shafts.

4) whether stern tube lubricating oil is emulsified or not, if so, it is necessary to request the owner to find out the cause of leakage. If shaft seal leakage is excluded, check the inlet and outlet pipelines and connecting flange of stern tube in stern shaft cooling water tank.

5) before the stern shaft equipment, the repair supervisor and chief engineer shall check whether the cleaning inside the stern tube is reliable and whether the sealing tubing is reliable. Request electrical engineer or electrician to measure whether stern bearing temperature sensor is normal.

6) when the stern shaft of the equipment is sealed, the concentricity of sealing ring box body and stern bearing shall be maintained. Measure the sink of stern shaft after installation. When sealing the stern shaft of the equipment according to the technical requirements, a fixed bracket shall be provided to connect the shaft sealing box with the white steel sleeve (avoid the lip of the apron not in place), and shall be inserted into the stern shaft equipment together. Install check to see after normal, fill oil to send out air, see rear axle seal again whether to have ooze oil, need to roll stern shaft a few viewpoint to check. Unscrew the rear leak detection screw plug to check whether there is oil leakage. After admitting that it is normal, pour on the lubricating oil and seal. In case of oil tank passing through the pipeline, the crew should be prompted to close the valve to prevent oil leakage caused by pressure difference.

7) most ship propellers are of fixed pitch. According to the equipment method of propellers, there are key propellers and keyless propellers. There are key OARS and divided into wet and dry, mostly for the selection of old ships, pay attention to the mark before demolition and shaft head value measurement and record; As for keyless wet propellers, the equipment should pay attention to the corresponding propellers' pushing amount and pushing force at various temperatures, and monitor the results of the equipment on site. The ship repair supervisor and chief engineer shall supervise the progress on site and strictly follow the equipment procedures specified in the drawings.

After the completion of the equipment to pay attention to the large nut safety equipment.

2.4 rudder system overhaul and repair

Even if the rudder system is not completely disassembled, rudder rod bearing and pintle bearing should be inspected to measure and record the void value to determine whether the wear and void of rudder bearing are in the normal range. Note that the rudder rod and rudder blade connection bolts are not outstanding, check the rudder rod, rudder

There is no electrochemical corrosion of the leaves. On ships with sacrificial anode protection, check the quality, quantity, and dispersion of the anode, and on ships with impressed current cathodic protection, check that the shafts and rudder rods are properly grounded. Theoretically, the potential difference between rudder, propeller and hull with excellent grounding should be less than 0.1v.

The rudder of the ship sees be half suspension type and suspension rudder more, if the measurement of vane of rudder bearing exceeds limit, want to consider to change rudder bearing or add thick rudder lever or the bushing of rudder sleeve. Before rudder fitting, it is necessary for the repair supervisor to acknowledge that epoxy resin should be used to cover the two ends of rudder bushing and the interval between bushing and cone surface. It is necessary to trim and smooth the sealing ring area, the diameter of the selected sealing rubber ring is necessary to be higher than the depth of the ring groove, check the jump stop is safe, measure the rudder rod jump stop gap, jump stop gap at the mercy of 1~3mm.

3. Key operation before docking

1) upon completion of docking repair, the docking repair supervisor of the shipyard shall, together with the chief engineer and chief officer, inspect the dock in full, admit that there is no missing project and that there is no local accuracy, and check whether the seals protecting some of them will be removed together.

2) the repair supervisor shall clear up and file the completion data of docking repair, guarantee and repair the full list of requirements for the ship to be out of dock, so as to verify the ship can be out of dock. Should establish a dock to prove a book, record mends concise content among them, add necessary measurement data to be like: before and after stern bearing gap, stern shaft subsidence, rudder bears gap, pin bears gap to wait, check before docking end when mutual visa, serve as next docking repair material.

3) the water outlet and roof brace shall be removed before discharging water in the dock. Remove all service equipment and equipment (such as welding rectifier, heater, ground wire of welding machine, power and oxygen, acetylene, etc.) supply pipeline. Remove scaffolding and remove trash.

4) when water is released from the dock and the ship enters the floating state, the supervisor should urge the engineer to open the filter cover and other methods to check whether the submarine valve is leaking when the repaired submarine valve has been repaired. Dock water, so that the surface of the sea beyond the seabed valve, should carefully check the leakage of the sea valve, and the bottom of the ship to change the plate some of the welding seam tightness, tightness of the bottom plug