I. Preface
When the ship enters and leaves the port, if the mechanical and electrical equipment (main propulsion device, main power supply, emergency power supply, boiler, steering device) fails, the ship's operation is restricted, which is very easy to cause accidents.
From April 7, 2024, the Maritime Safety Administration of the Ministry of Transport has launched a nationwide special action to prevent the failure of ship mechanical and electrical equipment, with the aim of improving the awareness of all sectors of shipping on the importance of inspection and maintenance of ship mechanical and electrical equipment through rectification, so as to strengthen management to reduce the risk of failure of ship mechanical and electrical equipment and improve the safety level of ships.
The following is combined with a case study to analyze the harmfulness of the failure of the safety valve of the ship's auxiliary boiler, hoping to arouse the attention of the majority of enterprises, ships and crews, and conscientiously do a good job of self-examination and self-correction.
2. Overview of the ship
3. Check the situation and raise questions
On April 15, 2024, the Fangchenggang Maritime Safety Bureau organized security inspectors to carry out port state supervision and inspection of the ship "J**" berthed at berth No. 103 of Liugang in Fangchenggang, and found 7 defects in the inspection, among which the failure of a safety valve of the boiler of the ship is typical.
(1) Description of the defect
ONE BOILER SAFETY VALVE OUT OF ORDER 锅炉的一个安全阀故障
4. Analysis of relevant laws and regulations and defects
(i) The original text of the Convention shall apply
SOLAS chII-1/32
Steam boilers and boiler feed systems.
Every steam boiler and every unfired steam generator shall be provided with not less than two safety valves of adequate capacity. However,having regard to the output or any other features of any boiler or unfired steam generator,the Administration may permit only one safety valve to be fitted if it is satisfied that adequate protection against overpressure is thereby provided.
Each steam boiler and each non-combustion steam generator shall be equipped with at least two safety valves with sufficient displacement. However, it is permissible to have only one safety valve after the competent authority has taken into account the steam production or any other characteristics of any boiler or non-combustion steam generator, if it is satisfied that there is adequate protection against overpressure.
Regulatory analysis: Check the technical specifications of the boiler, the manufacturer's design is to be equipped with 2 safety valves, and the ship's failure of one boiler valve and the ship's failure to provide the competent authority to approve the installation of only one safety valve related documents, obviously does not meet the requirements of the Convention. If the boiler safety valve is not repaired, the boiler will not be able to be used at all, which will cause the ship to be unable to sail normally. In summary, the defect is prescribed.
(ii) Analysis
1. The function of the safety valve: the safety valve is the most important safety protection device for the marine steam boiler, which will automatically open when the boiler pressure exceeds the safety value, discharge the steam and relieve the pressure, and ensure the safety of the boiler operation; When the pressure drops back to the base pressure, it will automatically shut off to prevent excessive steam loss and ensure the economy of boiler operation.
2. Lifting the function of the transmission device: in addition to the automatic steam discharge and pressure relief, the safety valve can also lift the transmission device through the rope linkage to achieve the effect of manual pressure relief, when operating the boiler, if the engineer finds that the internal pressure of the boiler exceeds the design pressure and there are potential safety hazards, the device can be manually operated to achieve the effect of release.
3. Defect discovery process and specific performance: when the boiler equipment of the ship is inspected, the boiler of the wheel is in a state of stop working, and the security inspector requires the crew to test the operation of the boiler safety valve of the ship, during which when the pull rope is pulled to test the two safety valves, one of the lifting transmission devices can not be reset after being lifted into place (Figure 1), and the other normal safety valve (Figure 2) can be restored to the initial position after multiple attempts.
By comparing the working conditions of the two safety valves, it was found that one of them was obviously stuck and could not be restored to the original position, and the engineer tried to press back to the reset position with auxiliary tools, and found that it could not be operated at all, and the security inspector preliminarily judged that the safety valve was in poor working condition and may not be able to operate due to internal stuck.
In order to further verify the defects, the crew was arranged to find technical documents such as boiler safety valve drawings for comparison and analysis (as shown in the figure below), and determined that the safety valve was a spring-type safety valve.
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Causes of defects: By consulting the information and viewing the safety valve section of the boiler, it is found that the safety valve is completely different from other valves, the internal structure is more complex, and the lifting transmission device can not be reset after being lifted into place, and the preliminary judgment is caused by the internal valve stem rust or the spring is stuck, etc., and in the later stage, the wheel is confirmed to be the internal spring rust and stuck when repairing.
If not corrected, after the internal heating of the ship's boiler generates pressure, the internal steam is directly discharged into the engine room through the valve, resulting in the engine room being filled with water mist, if not repaired, the boiler can not be used normally. Secondly, the ship is 22 years old, the overall appearance of the ship is poor, and there are a number of serious defects in other equipment in the engine room.
5. Defect handling and correction
Handling decision: In view of the importance of the safety valve for the safe operation of the boiler and even the safety of the ship, and if the defect is not corrected, it may lead to the normal use of the ship's boiler, the security inspector requires the ship to carry out comprehensive maintenance of the safety valve, and after communicating with the captain and chief engineer, the ship party said that it accepts the decision to deal with the defect and organizes rectification.
Defect correction: After the defect is found, the ship actively contacts the company to carry out rectification, inspects and repairs the safety valve, and after the rectification is completed, the security inspector reviews and confirms that all defects are closed after the rectification is completed.
6. Safety management suggestions
Boiler equipment in the ship belongs to high pressure and high heat equipment, itself has high risk attributes, has always been related to boiler fire, explosion and other accidents of ships are not uncommon, every accident is a bloody lesson. Combined with the requirements of ship safety supervision and regulations, several suggestions are put forward:
One
Increase investment in safety and improve the quality of crews. From the perspective of inspecting ships, companies should strengthen the control of human factors when implementing the main responsibility of safety management, and increase the management of ship facilities and equipment maintenance by seafarers.
Two
The construction of the ship safety management system of each company has been further refined. Optimize the inspection and maintenance measures of boiler safety valves, oil supply pipe quick closing valves, water level indication devices, boiler steam main pressure gauges, boiler burners and related alarm devices, regularly strengthen the safety self-inspection and self-correction of related projects, and strengthen the necessary training for crew members in boiler safety to ensure the safe operation of boilers.
Three
All companies should seize the opportunity of this special action to prevent mechanical and electrical equipment failures, organize a comprehensive self-inspection and self-correction of their ships, and effectively improve the intrinsic safety of ships.
Four
The ship security inspectors of various maritime safety management agencies have in-depth study of the working principles of mechanical and electrical equipment, equipment operation precautions, regulatory requirements, common faults and their inspection and testing methods in combination with typical cases, increase inspection efforts, urge ships to correct defects in a timely manner, and effectively improve the quality and efficiency of water traffic safety supervision.
Source: Guangxi Maritime
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