Fault diagnosis and maintenance of marine hydraulic equipment_ Fault treatment of hydraulic system of ship windlass

Fault diagnosis and maintenance of marine hydraulic equipment_ Fault treatment of hydraulic system of ship windlass

(1) Accident overview

When the typhoon struck in summer, a ship dropped double anchors outside the port to avoid the wind due to business needs. Two days later, the typhoon left, but it was found that the double anchor chain was knotted when lifting the anchor. After 4 hours of anchor lifting operation, the left anchor was reluctantly recovered, but the right anchor could not be pulled up due to mechanical failure. Due to the shipping schedule constraints, we had to tow the right anchor to the destination—— ×× Port, request land support. After careful inspection by the factory, it was found that the main bearings of two windlasses were worn, and the blades and cylinder walls of two windlasses were seriously scratched and partially broken, resulting in inconvenient operation of the company, huge repair costs and heavy losses.

(2) Emergency handling of accidents

The ship's hydraulic system is manufactured in Norway and is basically designed for use in the cold zone, so the cooler is very small. Generally, the time for taking off and landing anchor and entering and leaving the port is 30 ~ 45min. Therefore, the hydraulic oil temperature has not increased significantly, resulting in the engineer's negligence and forgetting to start the cooling seawater pump for a long time. However, this action is very important, especially when lifting anchor, entering port and berthing at the wharf, the windlass should not only lift anchor, but also be used for wharf operation winch, and the temperature rise is an inevitable phenomenon. Therefore, the seawater cooling system must be turned on to cool the hydraulic oil.

After an urgent request for instructions from the company's headquarters, it was decided that the ship's engineer should deal with it first. During treatment, it was found that the hydraulic oil in the system was slightly reduced. After supplementing the hydraulic oil and cleaning the filter, it was found that the hydraulic oil temperature was 70 ℃, which was too high, but there was no significant harm in short-term use. After repeated tests, it was found that everything was normal during startup and warm-up, but the sound of the hydraulic pump was abnormal when the lifting output reached 3Mpa, and the output of the hydraulic motor was insufficient and the sound was abnormal during lifting.

In addition, the following maintenance and inspection were carried out: cleaning the filter and replenishing hydraulic oil; Remove the hydraulic motor control handle to ensure that all internal actions are normal; Remove the hydraulic motor pressure regulating valve and make sure that all internal and spring actions are normal.

This round uses a three screw pump and is equipped with a vane hydraulic motor. After repeated tests, it is determined that the two hydraulic pumps and two hydraulic motors have serious faults, and then it requests the support of the public works Department of the company.

With the consent of the captain, the headquarters of the company towed the ship for about 25m without recovering the anchor chain and anchor to make the ship sail slowly to the port of destination. Then contact the company according to the international safety management rules and procedures, and preliminarily decide to fasten the anchor mark signal at the outer port and cut off the anchor and anchor chain before entering the port in order not to delay the shipping schedule. After the master contacted with the port authority, the navigator agreed to bring the ship into the port with anchor. The master, navigator and the whole ship cooperated with each other, and finally landed smoothly without causing any loss of shipping schedule.

The ship protection engineer of the company arranged maintenance engineers, Ship Surveyors of classification association, water 400t floating crane and diving engineers to recover the anchor chain and anchor within one working day and make a maritime report.

The surveyor of the classification society shall sign the maritime report and instruct: unless necessary, anchoring shall be avoided when sailing offshore, and anchoring shall be carried out after complete repair, so as to avoid the accident that the anchor cannot be recovered due to the further deterioration of the situation; The hydraulic pumps and motors of the two windlasses shall be disassembled and sent to the factory for maintenance in sequence. The other group shall be disassembled after repair and test. Although this has not caused any shipping schedule loss in the operation business, it has caused a significant increase in the amount of maintenance.