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Best Practices & Design Improvement Items (Part III
from Wavelength #77
By Natassa Sakellariou and Christina Toki
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Following “Best Practices & Design Improvement Items – Part I and Part II” described in the two previous issues of Wavelength, there are some additional items which have been implemented on fleet vessels as design improvements for the following systems and onboard areas in order to ensure safer and more efficient operations corresponding to the highest marine industry standards and recommendations.
• Navigation & Communication Systems • Cargo and Ballast Systems • Inert Gas System • Engine Room • Deck Area & Ballast Tanks
Navigation & Communication Systems
Navigation and Communication systems used on vessels are vital for the safety, protection of life at sea and marine environment. They increase the efficiency of voyage planning, operations and trading. The Company has adopted the following improvements in the equipment on board:
a. Independent magnetic off course alarm
This equipment operates as an independent heading monitor with an off-course alarm. It is designed to integrate with a ship's existing magnetic compass installation and generates an audible and visible alarm when the vessel deviates from a chosen course by more than a pre-set amount (in degrees). Figure 1: Independent magnetic off course alarm
b. Two (2) gyro compasses Many vessels of our fleet are fitted with two gyro compasses for back-up purposes in order to determine, display and transmit heading information.
Figure 2: Two (2) Gyro compasses
c. Echo sounder with recording capability Vessels are equipped with a depth finder that has the capability of recording and setting the alarm set point according to ExxonMobil Criteria.
Figure 9: Cargo tanks pressure readings in CCR d. Two (2) Inmarsat-C satellite communication systems Two Inmarsat-C systems are fitted for redundancy purposes. They allow vessels to send and receive data, including email, SMS, telex, navigational warning and meteorological information. SSAS and LRIT are incorporated into the systems.
Figure 4: Two Inmarsat-C systems
e. V-Sat satellite communication system Satellite communication equipment capable of sending and receiving data and voice communication is installed on board. The system is interfaced with the vessel’s computer network system and auto telephone system.
Figure 5: V-Sat system
f. Radar mast of the foldable type (tilting type) Some fleet vessels are fitted with Radar Mast's top part of the collapsible/foldable type that allows compliance with air draft requirements of various ports and enhancement of their trading profile.
Figure 6: Radar mast of foldable type
Cargo and Ballast Systems
Improvements applied to the design of Cargo and Ballast Systems have enhanced and upgraded vessel operations in terms of efficiency and safety, thereby having a positive effect on a vessel’s operating and trading profile. a. Temperature Alarm & Monitoring System for Cargo and Ballast Pump bearings, casings and stuffing boxes
This design prevents explosions or fire incidents in the cargo pump-room, and acts as a predictive maintenance method for pump parts. The bearings and casings of Cargo and Ballast Pumps are fitted with high-temperature alarms and trips. Furthermore, all Cargo and Ballast Pump drive shaft bulkhead bearings and glands located in the pump room are fitted with a high-temperature
alarm monitoring system. Figure 7: Cargo and Ballast pumps temperature readings in CCR A temperature alarm and monitoring system is installed in the Cargo Control Room
b. Remote indication of cargo manifold pressure in the CCR Modifications for remote readings of cargo manifold pressure in the Cargo Control Room have been carried out on board vessels for the remote and efficient monitoring of cargo operations, as strongly preferred by ExxonMobil.
Figure 8: Remote readings of cargo manifold pressure in CCR
c. Cargo tank pressure monitoring and alarm system in the CCR The Cargo tank pressure monitoring system uses pressure sensor technology to provide accurate information concerning the pressure in the tanks through direct measurement. Vapour Pressure Sensors enable the accurate measurement of the cargo vapour pressure and 4 alarm limits which help to monitor and detect Hi/Low pressure. In particular, the system includes the manufacturer’s set high and low-pressure alarms as detailed within OCIMF SIRE 6 VIQ CH. 8.33, and additionally a minimum of two adjustable, user-defined, alarm limits. These alarms should provide an audible and visual alarm through a visual display installed in the CCR if the set limits are exceeded.
Figure 9: Cargo tanks pressure readings in CCR
d. Fixed vibration system of Cargo pumps and P/R exhaust fans
Fixed vibration monitoring equipment is provided on all centrifugal cargo pumps and P/R exhaust fans and includes a remote alarm facility in the CCR.
Figure 10: Cargo pumps fixed vibration system readings in CCR
Inert Gas System
a. Two (2) Inert Gas Fans of 100% capacity each Two (2) Inert Gas Fans of 100% capacity each are provided in many tankers of our fleet for redundancy purposes. Each Inert Gas Fan is capable of delivering inert gas to the cargo tanks at a rate of at least 125% of the maximum rate of discharge capacity of the ship expressed as a volume. The main advantage of such a design is that if either Fan is defective, the other one is capable of maintaining a positive gas pressure in the cargo tanks without extending the duration of cargo discharge.
b. Two (2) IGS Oxygen Analysers In order to create an inert atmosphere, or in other words an atmosphere that is safe from explosion or fire, the oxygen content must be below 5%. So, for safety, accuracy and redundancy purposes a second oxygen analyzer is also installed as a back-up arrangement in all the tankers of our fleet.
Figure 12: Two (2) oxygen analysers
Engine Room
a. Two (2) Main Engine Turbochargers The Company’s HSHI Suezmaxes (George S., Yannis P., Mikela P., CE-Bermuda, CE-Hamilton) and NTS Capesize bulk carriers (Polymnia, Calliope P., Evgenia, Philippos A.) are equipped with two (2) M/E Turbocharges for redundancy purposes, so that in case of the malfunction of or damage to one unit, the Main Engine can run at 50% of the MCR load.
Figure 13: Two (2) Main Engine Turbochargers
b. Main Engine Water in oil detection system (Maker: Vaisala) This system enables the fast and reliable detection of moisture and water in the Main Engine system oil. The equipment provides real-time detection of water content without sampling and indicates the true margin to the water saturation point in all changing conditions, taking into account temperature changes and aging of oil.
Figure 14: M/E Water in oil detection system c. Shaft torque meter (power meter) The shaft power meter is an instrument for the continuous measurement of torque, revolutions, power and thrust for the monitoring of propulsion, main engine and vessel performance. Accurate information provided by the equipment allows proper propulsion parameters monitoring, which aims at fuel efficiency and ship reliability.
d. Distance ring for stern tube seals
Figure 15: Shaft power meter
After a certain period of service, the chrome liner is grooved by seal rings running on the outer surface. A deep groove may disturb oil or water tightness of the seal rings. In the case of seal ring renewal by a bonding method, skimming of the chrome liner surface is not feasible. In such a case, a split type distance ring is installed between the stern tube boss and AFT seal flange so that new seal rings run on the new surface positions with no grooves. In the case of the distance ring having been pre-installed, the same effect is achieved with the removal.
Figure 16: Distance ring
e. Bursting Disc for Vacuum Condenser Most tankers of our fleet are provided with a bursting disc on the Vacuum Condenser for protection of the Condenser against overpressure. The same design improvement is applied in all the Company’s newbuilding projects.
Figure 17: Bursting disc for Vacuum condenser
f. Two (2) air dryers Air dryers remove from the control air the coarse rust particles and dust and then the moisture, thereby eliminating the risk of damaging corrosion in pneumatic and air operated equipment. This protects and increases the lifetime of such equipment. So due to the air dryers’ importance, two (2) units are fitted onboard for redundancy purposes.
Figure 18: Air dryers
g. A/C Unit in E/R Workshop
Many fleet vessels are equipped with an Air Conditioning Unit in the Engine Room Workshop which facilitates crew tasks and creates a better working environment.
Figure 19: A/C Unit in E/R Workshop
h. Emergency foot stops for machinery of E/R workshop Foot stops have been placed in E/R workshop machinery, allowing for an immediate stop in case of emergency.
Figure 20: Emergency foot stops in various E/R workshop machinery
i. Store for Chemicals in Steering Gear Room The storage of chemicals in the Steering Gear Room keeps them protected from high engine room temperatures and exposure to open deck weather/sea conditions. In parallel, existing firefighting arrangements in the Steering Gear Room ensure that proper and timely procedures can be followed in case of a fire incident.
Figure 21: Chemicals locker in Steering Gear Room
j. Flame arrestors in way of funnel exhaust gas pipes The low load operation of marine engines tends to produce partially burnt carbon deposits and soot from the exhaust gas piping system of the engine. As the exhaust gases produced after combustion are rich with oxygen, these partially burnt carbon particles are discharged from the exhaust funnel as a highly dangerous spark. Flame arrestors placed in the funnel exhaust gas pipes allow gas to pass through but stop flame transmission over the deckhouse which prevents a larger fire or explosion, decreases the risk and improves the safety aspects.
Figure 22: Flame arrestors in exhaust gas pipes
Deck Area & Ballast tanks
a. Safe Access to Tanker Bow – Shelters with a sighting hole
Another design improvement that has been applied on deck shelters is the creation of a sighting hole of 200 mm at a height of 1,700 mm above deck. This arrangement allows safe access to the bow when weather and sea conditions are adverse.
Figure 23: Shelter with sighting hole
