Basic Knowledge Of Ship Repair And Maintenance

Basic knowledge of ship repair and maintenance, according to the Ministry of Communications' Ship Repair Regulations and Ship Repair Work Meeting Minutes, has made a clear classification and grading of ship repairs according to the causes, repair scope, and interval years of ship repairs. The maintenance department of the shipping enterprise shall formulate plans for the repair time and cost of each specific ship. The heads of various departments on the ship who are online should be familiar with the scope of various ship repairs, so as to prepare a ship repair project application form (hereinafter referred to as the ship repair list) according to the type of ship repair, so as not to expand the repair scope indiscriminately, resulting in time, Waste of energy and funds. The ship repair list is the basic technical document for ship repair work proposed by the ship and maintenance department to the shipyard. It is the basis used by the maintenance department and the shipyard to arrange ship repair plans and allocate ship repair costs. Therefore, the ship repair list should be compiled to make the ship's repair parts clear, accurate, and technically reasonable. Only in this way can the repair work proceed smoothly and meet the technical quality requirements.

(1) Types of ship repair

1. Plan maintenance repairs

The hull and equipment will have natural losses during operation, and some defects will be exposed over time, and large or small damages will occur. In order to continue to use safely, it must be repaired in a planned manner. Planned maintenance repairs include aviation repairs, minor repairs, and overhauls (or intermediate repairs and overhauls).

Air repair: during the operation period of the ship, the general repair work and general accident repairs that need to be assisted by the shipyard or the air repair station occur during the operation of the ship. The air repair should be carried out using the berth time of the voyage at the port, and the shipyard or air repair station should be accumulated. Pay attention to the aviation repair work, arrange repairs upon receiving the notice, and follow the ship for an overhaul when necessary, so as not to affect the transportation and production of the ship.

Minor repair: It is a factory repair project that is carried out according to the prescribed cycle and regularly combined with the periodic inspection. The purpose of minor repairs is to eliminate the transitional wear and tear that occurs during operation and to ensure the safe operation of the ship until the next scheduled repair period. Minor repairs are generally carried out simultaneously with dock repairs. During minor repairs, the main inspection, and repair of the hull, rudder, shafting, sea valve, main and auxiliary machinery, boilers and special equipment for engineering ships, etc., generally only adjust, grind, replace parts, clean and maintain the original equipment Except for ships in navigation engineering, paint decoration is not allowed. The scope of minor repairs is as follows.

(1) Remove rust paint when the hull is corroded (if there is no corroded part and the paint is good, do not remove the rust and paint randomly), repair a small number of hull components, and make appropriate repairs to the partially worn outer plates, decks or other plates Or patch up.

(2) The host is partially disassembled and adjusted, the clearance is adjusted, and the bearing is cast with lead. Without special circumstances, the main engine of the ocean-going ship does not hang the crankshaft, the main engine of the Dajiang ship does not leave the cabin, and the large diesel engine generally does not disintegrate.

(3) Auxiliary machines and piping systems are generally inspected and repaired, and parts can be replaced, but they are not painted or shifted.

(4) Cleaning the inside of the boiler, repairing the accessories, and repairing some furnace tubes, small strips, and welding cracks, but without peeling the furnace coat or disintegrating. Not due to special needs, do not randomly conduct a hydraulic test.

(5) Check and repair the special equipment of the project, and replace the vulnerable parts such as dredging tools, mud pumps, pile hammers, and winches.

During minor repairs, motor ships, engineering ships, refrigerated barges, and food barges are 12 to 18 months for first-class oil barges, 18 to 24 months for stranded barges and barges, and 24 to 36 for cargo barges and below second class oil barges. Months, some barges have no minor repairs. The upper and lower limits of the interval are determined by the technical department of the shipowner based on the navigation area, operating conditions, and equipment status, but the upper limit cannot be exceeded.

The overhaul is a factory repair project that is carried out with 2-3 minor repairs at regular intervals and combined with regular inspections. The purpose of the overhaul is to conduct a comprehensive inspection of the hull, main and auxiliary machinery, and other equipment, focusing on repairing larger defects that cannot be resolved during minor repairs, maintaining the strength of the ship and the safety and operating conditions of the main equipment. The problems found during the inspection should be repaired if they need to be resolved, but the joint projects can be safely used until the next minor repair, and they can be recorded and continued to be used and repaired in the future minor repairs. The scope of overhaul basic engineering includes:

① Periodic inspection of the prescribed disassembly and assembly works;

② Derusting paint when the hull is corroded;

③Repair part of the hull, deck, and skeleton;

④The main machine is allowed to be dismantled and repaired, and the main parts can be replaced; the auxiliary machine can be repaired out of the cabin, or the whole machine can be replaced;

⑤The boiler is allowed to be withdrawn from the furnace, and the combustion chamber is to be replaced, and the water pressure test shall be carried out within the time limit specified in the inspection;

⑥ Generally, paint renovation is not carried out during maintenance, but reconstruction projects with small engineering volume and significant benefits in operation can be combined with maintenance after being verified and reported to the superior for approval;

⑦ The special equipment of the engineering ship should be fully dismantled and inspected, and it is allowed to change the main parts of the equipment such as dredging, pile driving, lifting, and special electrical equipment.

The overhaul is a major overhaul of planned repairs. The determination of repair items must comply with the principles of safety and diligence. Generally, the superstructure is not replaced, and the main ship and boiler are not replaced by the large ship. ,

Intervals for maintenance: 4 to 6 years for motorboats, engineering ships, beach badges, refrigerated barges, food barges, first-class oil barges, offshore steel barges; 6 to 9 years for river steel barges; cargo barges and There is no maintenance for oil barges below level two.

The above repairs are mainly arranged at intervals, and the scope of the project is only divided in principle. Due to the complicated ship type and model and the different technical conditions of the ship, if problems are found, they should be resolved realistically according to the specific situation and minor repairs. Works within the scope of individual repairs are allowed.

2. Accident repair

Accident repair refers to the repair of the damaged parts of the ship due to an accident. Such repairs can generally be carried out along with aeronautical repairs if the scope of the project is not large. However, if the scope of the project is large and the aviation repair is incompetent, the repair plan still needs to be arranged

Draw. The items, scope, and duration of accident repairs shall be based on the actual damages and

Fix requirements to determine. Before repairing the accident, the ship repair list still needs to be issued to the shipyard under repair. For minor

The accident damage can be recorded on the premise that it does not affect the airworthiness performance and does not hinder the safe operation and will be maintained until the planned maintenance and repair

Timely repair. Accident repair projects should focus on the preparation of ship repair bills and indicate "accident repair", requiring the shipyard to pay for this part of the repair

Another invoice is issued, and the stamp of "accident repair" is stamped on the invoice as proof of the claim.

3. Basic recovery repair

For ships that can no longer be used, repairs to restore seaworthiness and hull strength are required, such as repairs to the wreckage of sunken ships and fire ships. This type of repair works is huge, requires huge amounts of money, has a longship repair period, and has poor economic results. It is now rare.