Marine Construction
Table of Contents
Operation concept of stress calculation equipment used on board
The principle of work
IMO requirements
Benefits of stress monitoring systems
Differences between conditions and permissible stress limits
Conclusion
References
Operation concept of stress calculation equipment used on board
a) In the late 1980s was noticed an increase in the number of bulk carriers lost due to the lack of safety equipment and continuous overloads. This fact forced the IMO organization to take some steps to provide the safety of the bulkers. In this regard all vessels should have special devices on board, which would monitor, control and organize the process of loading.
This way, according to IMO vessel requirements: “All vessels should be fitted with hull stress calculation equipment in order to avoid emergencies caused by hull overloads.” (IMO recommendations, 1999)
Special Equipment Used on Board to Plan, Monitor and Control Loading/Unloading Operations
The IMO recommends installing stress calculation equipment on bulk carriers of 20,000 dwt (dead-weight tons) and above. (IMO recommendations, 1999) Moreover, the organization is responsible for completing revisions and examinations of the equipment.
There are different components, which enable the crew to control the loading level to avoid emergencies before and during transportation:
Standard components:
1) Strain sensors
Strain sensors check the pressure of the cargo on the deck and allow to “disperse” it so that neither shipboard overweight the other. Sensors consist of an insulating flexible backing which supports a metallic foil pattern.
Operational concept:
Resistive strain gauge reacts on differences in resistance. These differences as a rule are caused by overloads. As a result the pressure on the sensor is modified into an electrical signal of alarm, which is shown on the main computer.
2) Bow accelerometer
This sensor is used to monitor the intensity of the head waves. Bow accelerometer is a great feature for the ships, which have to travel across the oceans. It allows avoiding excessive wave-induced oscillation. As a rule bow accelerometers are installed at the bow of the ship.
3) Temperature and motion sensors
It is an additional option for the hull stress monitoring system. These sensors control the temperature of the place where the cargo is and inform the bridge if there is a change in position or temperature of the cargo.
b) IMO requirements for stress monitoring equipment on bulk carriers of 20,000 dwt and above.
As it was mentioned earlier the IMO recommends installing stress-monitoring equipment on bulk carriers of 20,000 dwt and above. This equipment gives the master an opportunity to get real-time information during loading, unloading and transportation. What is more, according to the IMO recommendations software and hardware of the stress calculating equipment should be approved and observed by the Administration. It means that the owners of the ships should give the executives of the Administration access to the data concerning loading and unloading stored in the system. Furthermore, equipment itself, software and hardware should fit the standards produced by the Nominated Bodies and the owners of the ships should inform the appropriate organs about their experience of the use of the systems.
c) Benefits of the stress monitoring equipment
Stress …
