1. Failure maintenance of hydraulic system of spud of cutter suction dredger

 

  • In the process of repairing the fault of the hydraulic system of spud of cutter suction dredger, the staff should first confirm the initial position of the oil cylinder, and after there is no pressure in the oil cylinder body, remove the balance valve and the hydraulic control check valve, and the staff did not find any abnormality after remove.

 

  • Check the one-way throttle valve. After inspecting the oil cylinder, no abnormality was found, and then the staff was arranged to inspect the one-way throttle valve. Through deep inspection, it was found that the oil route was blocked mainly because the one-way throttle valve handle of the oil cylinder cavity on the left was closed. After reopening the handle, the system pressure was significantly reduced. The test run was carried out again under the condition of no load. After the test run, the oil cylinder lifting did not appear abnormal again.

 

  • After the pressure of the system is restored to the normal pressure, the return oil back pressure of the oil cylinder is 14 MPa under the condition of no load. When the pressure in the lower cavity of the oil cylinder is greater than the allowable pressure, the gravity of the spud acting on the oil cavity will increase. If spud dumping is carried out at this time, it will result in a very high risk factor of the hydraulic system of spud of cutter suction dredger. The one-way throttle valve in the lower chamber of the oil cylinder was adjusted, and then the second no-load test was carried out. After the re-test, the oil back pressure was found to drop to 7 MPa. The main reason is that the oil cylinder is far away from the pump and the pipeline is long, which increases the resistance along the way, resulting in greater hydraulic resistance of the components.

 

  1. Commissioning system

 

Through the analysis, if the auxiliary pile structure of the spud hydraulic system of the cutter suction dredger has been maintained, and the oil cylinder on the left side has been subjected to greater pressure, resulting in the oil cylinder’s tightness is reduced. In order to ensure the safety of construction, it is necessary to re-commissioning the system and test the performance of the hydraulic system of vertical piling, so as to ensure that the piling operation can be carried out smoothly. There are 5 specific test contents.

 

  • In order to prevent the occurrence of suction, the first to ask the staff to further check the oil level of the spud oil tank of cutter suction dredger.

 

  • In the case of no load spud hydraulic system of the cutter suction dredger, the staff is required to check whether there is abnormal vibration or mechanical jam of the spud oil cylinder. If there is no abnormality, it is necessary to remove the air in the oil cylinder after a full stroke of oil cylinder lifting.

 

  • The staff shall further increase the pressure in the oil cylinder system, and then check the tightness of the hydraulic system of spud of the cutter suction dredger and the pressure resistance of the system pipeline, etc., and check whether the oil cylinder has internal leakage and external leakage.

 

  • Lift the oil cylinder of the cutter suction dredger and check the synchronization of the spud oil cylinder.

 

  • Deal with the abnormal pile dumping immediately, and then evaluate the safety of the hydraulic system. The pile dumping construction can be carried out after it is delivered to the ship for use.