Oil Tankers & Pollution Prevention PDF

**[UNIT-3: OIL CARGOES, OIL TANKER OPERATIONS AND RELATED POLLUTION- PREVENTION REGULATIONS]** **COMPILED BY: CAPT YOGESH SHAH** **ASSISTED BY: CADET RUDRANSH CHOUBEY (8821)** **3.1 TANKER ARRANGEMENT** Naval architecture - Design, Hull, Shipbuilding \| Britannica The **cargo oil tanks** are us...

**[UNIT-3: OIL CARGOES, OIL TANKER OPERATIONS AND RELATED POLLUTION- PREVENTION REGULATIONS]** **COMPILED BY: CAPT YOGESH SHAH** **ASSISTED BY: CADET RUDRANSH CHOUBEY (8821)** **3.1 TANKER ARRANGEMENT** Naval architecture - Design, Hull, Shipbuilding \| Britannica The **cargo oil tanks** are usually equally sized, and the dimensions of each are decided by the designer in the initial stage of design, depending on the total weight of oil to be carried by the ship. The access to each cargo tank is separate, and is provided by means of rung ladders or hoist-able steps from the main deck. **Pump room** contains the largest concentration of cargo pipelines of any space within the ship. Leakage of a volatile product from any part of this system could lead to the rapid generation of a flammable or toxic atmosphere. **Slop tanks** are present onboard tanker to store oily water mixture from cargo tank washing. The number of slop tanks depends on the Dead weight Tonnage (DWT) of the vessel. Located in engine room, this tank is used to store sludge produced after treating fuel or lube oil through purifiers. **Cofferdam** is a void or empty compartment is provided between the tanks to prevent two different liquids from mixing with each other. The space avoids intermixing of two different liquids when there is a leak from the boundary separating the two liquids. The cofferdam is provided with manholes for entry and inspection. It is also provided with a sounding pipe. **Segregated Ballast Tanks (SBT)** are used for carrying ballast water in a manner that does not mix with the cargo. These tanks are usually located in the double-bottom area of the ship and sometimes also in the wing tanks or along the sides of the hull. The primary purpose of SBTs is to ensure that ballast water is separated from the cargo tanks, reducing the risk of contamination and environmental pollution. This also helps maintain the stability of the vessel during ballast operations. On crude oil carriers, SBTs are especially important due to the potential for crude oil contamination if ballast is allowed into the same tanks. Product tankers, like crude carriers, have segregated ballast tanks, but these may also be used for carrying products that require a certain level of separation (e.g., lighter refined products from heavier products). **Peak Tanks** are located at the bow and stern of the ship and are used to manage the trim and stability of the ship when loading and discharging cargo. Peak tanks often contain ballast water when the ship is not carrying cargo or they may be used for storing residual cargo or slops when necessary. The tanks near the bow are often used to adjust the ship\'s balance during loading and unloading operations. **Ventilators** are critical components for ensuring proper air circulation, safety, and reducing the buildup of flammable vapours in various spaces on the ship, particularly the cargo hold, machinery spaces, and accommodation areas. **Cargo Tank Ventilation:** Cargo tanks, especially those carrying volatile products like crude oil or refined petroleum products, require a well-ventilated system to allow the release of vapours and prevent dangerous pressure buildups. Cargo tank vent line may lead to the deck or the mast for safe release of gas. **Accommodation Ventilation:** Accommodation spaces need a constant supply of fresh air to ensure the comfort and health of the crew, as well as to ensure that any flammable vapours from the cargo area are vented safely away from living spaces. **Machinery Space Ventilation:** Machinery spaces also require proper ventilation to ensure that heat and exhaust gases are removed and that there is adequate airflow for the engines and systems. **3.2 DEFINITIONS** **Crude Oil:** Crude Oil is a naturally occurring, unrefined petroleum composed of hydrocarbon deposits and other organic materials. A type of fossil fuel, crude oil can be refined to produce usable products such as gasoline, diesel and various other forms of petrochemicals. The petroleum in its raw form is called a crude oil. Crude oil is a natural material in which the hydrocarbon is a principal ingredient and which contains a small amount of sulphur, nitrogen, oxygen and the metal etc. The chemical composition of crude oil is generally as follows. Most crude oils contain carbon and hydrogen though the physical and scientific properties of the crude oil are affected by the soil of the production region. a\) Carbon: 83-87% b\) Hydrogen: 11-14% c\) Sulphur: 5% or less d\) Nitrogen: 0.4% or less e\) Oxygen: 0.5% or less f\) Metal: 0.5% or less **Refined Products:** These are products derived from the refining of crude oil, such as gasoline, diesel, kerosene, and jet fuel. Process involved in refining petroleum products includes catalytic cracking and fractional distillation. These products have chemical characteristics that differ according to the type of crude oil and subsequent refining processes. **Spiked Crude:** Crude oil that has been blended with other substances, such as lighter hydrocarbons, to alter its properties for specific purposes. **Sour Crude:** Crude oil containing a high amount of the impurity sulphur, which requires more processing to remove the sulphur and make it suitable for use. When the total sulphur level in the oil is more than 0.5% the oil is called "sour". **True Vapour Pressure:** Also known as bubble point vapour pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid phase at a prevailing temperature. It\'s a measure of a liquid\'s volatility. As the temperature of a petroleum mixture increases, its TVP also increases. The TVP provides a good indication of its ability to give rise to gas. **Reid Vapour Pressure:** Reid Vapour Pressure (RVP) is a standardized measure of the vapor pressure of a liquid, commonly used to describe the volatility of gasoline and other petroleum products. It is determined under specific conditions. A sample of the liquid is introduced into the test container at atmospheric pressure so that the volume of the liquid is one fifth of the total internal volume of the container. The container is sealed and immersed in a water bath where it is heated to 100°F (37.8°C) and measured with a Reid-type apparatus. RVP is used as an indicator of how easily a substance will evaporate or form vapours. In general, RVP is useful for comparing the volatilities of a wide range of petroleum liquids. **Upper and Lower Flammable Limits (UFL and LFL):** Upper Flammable Limit (UFL): The maximum concentration of a vapor in air that is still flammable. Above this limit, the mixture becomes too rich to ignite. Lower Flammable Limit (LFL): The minimum concentration of a vapor in air that will ignite. Below this limit, the mixture is too lean to support combustion. ADB - Hydrocarbon gas/air mixture (No Inert Gas Content) CDE -- Flammable Envelope C -- Lower Flammable Limit (LFL) (1% by volume) D -- Upper Flammable Limit (UFL) (10% by volume) E -- Minimum O2 required for combustion (\~11% by volume)  A mixture of hydrocarbon gas and air cannot be ignited and burned unless its composition lies within a range of gas in air concentrations known as the "flammable range". The lower limit of this range, known as LFL and upper limit, known as UFL. **Pour Point:** Pour point is the lowest temperature at which a liquid, such as crude oil or a refined petroleum product, will flow under standard test conditions. In simple terms, the ability of oil to pour down from a beaker at minimum temperature. It is an important property for determining the suitability of a fuel for transportation and use in cold climates. **Flash Point**Fire**:** Flash point is the lowest temperature at which a liquid produces enough vapor to form an ignitable mixture with air. It is a key safety measure to assess the flammability of fuels and chemicals. Below the flash point, the substance will not ignite. **Threshold Limit Value (TLV):** Threshold Limit Value (TLV) refers to the maximum concentration of a substance in the air that a worker can be exposed to over a specified period (usually 8 hours a day, 5 days a week) without experiencing harmful effects. **Permissible Exposure Limits (PEL):** Permissible Exposure Limits (PEL) are legally enforceable standards set by regulatory agencies, that specify the maximum allowable concentration of a hazardous substance in the workplace air. PELs are designed to protect workers from harmful exposure to chemicals, gases, and vapours. **Volatile Liquid:** A volatile liquid is one that evaporates or vaporizes quickly at normal temperatures. These liquids have a high vapor pressure and tend to release significant amounts of vapor into the air, which can be flammable or hazardous. Examples include gasoline and other light refined petroleum products. **3.3 HAZARDS OF OIL CARGOS, FLAMMABILITY DIAGRAM** **Hazard Associated with Oil Cargoes are as follows:** - **FIRE AND EXPLOSION-** Most oil cargoes, especially crude oil and petroleum products, are highly flammable. Vapours from volatile oils (like gasoline or jet fuel) can form explosive mixtures with air. A spark or heat source (such as a hot surface, static discharge, or equipment malfunction) can ignite the vapours. - **TOXIC GASES-** Some oil cargoes, particularly crude oil, may contain H₂S, a toxic and flammable gas that can accumulate in tanks or other confined spaces. In high concentrations, H₂S can be fatal if inhaled. - **STATIC ELECTRICITY-** The flow of oil during loading and unloading creates the potential for static electricity build-up. A discharge of static electricity can cause sparks and ignite flammable vapours. Proper grounding and bonding of equipment and tanks are essential to prevent static-related incidents. - **CORROSIVE DAMAGE-** Some oils (e.g., sour crude) can contain corrosive components like hydrogen sulphide (H₂S) or acidic compounds. These substances can damage the internal structure of the tanker, including the hull and pipelines, if not handled correctly. - **CARGO SHIFT-** Improper loading, unstable tank conditions, or uneven distribution of cargo can cause the cargo to shift during transit. This can destabilize the ship, especially in rough seas, and increase the risk of capsizing or causing damage to the ship's hull. - **STRUCTURAL FAILURE-** Excessive cargo weight or improperly balanced cargo can lead to stress on the ship\'s hull. If the hull is compromised, it could lead to leaks, especially in the double-hull designs used for oil tankers. - **ENVIRONMENTAL POLLUTION-** Spills of oil cargoes during loading, unloading, or in the event of accidents (like collisions, grounding, or hull breach) can lead to significant environmental damage. Oil spills affect marine life, coastal ecosystems, and can cause long-term environmental harm. - **HUMAN HEALTH RISK-** Crew members may be exposed to toxic vapours such as benzene, H₂S, or other chemical residues when working with or around oil cargo. This can lead to short-term health effects (headaches, nausea, dizziness) and long-term health risks (cancer, organ damage) if protective measures are not followed. **Flammability Diagram**  A Flammability Diagram shows the flammability region in mixtures of fuel, oxygen and an inert gas. It is known that for any fire to start, it requires a minimum presence of 3 components: Air, Fuel and Source of heat. In the above diagram CDE represents the Flammability mixture. - Flammable range: The flammable range of CH gas is between 1% and 10%. - For oxygen the minimum is 11.5%. At 10% CH O~2~ should be at least. - Dilution must not follow the path FA. It should be done using the line FH and then HA. - Path through FA can cause explosion when the mixture is in the flammable range. **3.4 Cargo Piping System, Pollution Prevention Arrangements** **Cargo Piping System** **Free Flow System:** This system is usually found on large crude carriers, where the cargo piping is not used for the discharge of cargo. Instead, gate valves are provided on the bulkheads of the tanks which when opened; allow the oil to flow freely in the aft most tank and into the COP. The advantages of this system are primarily the cost factor, it allows for fast drainage and efficient means of pumping the cargo tanks. Disadvantages are of single crude being shipped. **Advantage:** - Main pipe line is not used for discharge. - Less pipe line. - Less bend. - Less friction & more pressure cause very high discharge. **Disadvantage:** - Is not flexible. - One grade is dischargeable if more risk of contamination exists. - Risk of overflow exists if level of all tank doses not carefully monitoring. **Ring Main System:** It is generally of a square or circular layout. It is used mostly on product tankers, as segregation of cargo is required. The system is expensive because more piping and extra number of valves are used. However, if the vessel is carrying many grades of cargo, the advantages compensate for the extra cost of the original outlay.  **Advantage:** - In this system any tank can be discharged by any pump. Thus, different grade of the cargo can be loaded. **Disadvantage:** - It is expensive to build due to the extra length of the piping required. - Extra bend is required. Thus, decreasing in rate. - Risk of leakage from radius of bend exists. **DIRECT FLOW SYSTEM:** This system is mainly found on crude oil carriers where up to 3 grades of cargo can be carried as most of the direct pipeline systems is fitted with three direct lines. This system is cheaper to construct. The disadvantages over the ring main system, is that line washing is more difficult, the system has fewer valves which make pipeline leaks difficult to control, as the system lacks versatility there is problem with line and valve segregation. This system provides the vessel to carry as many grades as there are tanks. The disadvantage is the cost factor having a multitude of pumps on board.   http://thenauticalsite.com/NauticalNotes/CargoWork/MyCargoWk-Lesson11a-Oil%20Tanker\_files/image024.jpg **Advantages:** - Each tank is isolated from others, reducing the risk of contamination between different cargoes. - It allows for precise control over the transfer of cargo into or out of specific tanks. - Direct loading and unloading can be faster, especially for ships carrying a single type of cargo. **Disadvantages:** - Requires more individual piping and valves, increasing installation costs. - Takes up more space inside the vessel, which could be a limiting factor on smaller tankers. - More piping and valves can increase the risk of leaks or failures, requiring more frequent maintenance. **Pollution Prevention Arrangements** **[1. Segregated Ballast Tank (SBT)]**- A Segregated Ballast Tank (SBT) is a ballast tank that is entirely separate from the cargo tanks. It is used to carry ballast water to maintain the vessel's stability without mixing it with oil cargo residues. **Advantages:** - Pollution control: Prevents contamination of ballast water with oil residues, ensuring that ballast water can be discharged without contamination. - Compliance with regulations: SBTs are mandated by international conventions such as MARPOL (Annex I), which requires tankers to use segregated ballast to avoid oil pollution. **Disadvantages:** - Space consumption: SBTs occupy valuable cargo space, reducing the capacity of the tanker to carry oil. - Operational complexity: The separation between cargo and ballast requires careful operational procedures to avoid mistakes in ballast management. **[2. Clean Ballast Tank (CBT)]**- A Clean Ballast Tank (CBT) is used to carry ballast water that has been cleaned or treated to remove any oil residues before being discharged. CBTs are typically used when segregated ballast tanks are not available or practical. **Advantages:** - Flexibility: Can be used in vessels where segregated ballast tanks are not feasible. - Allows for ballast operations: Enables vessels to load and discharge ballast in an environmentally safe manner by preventing oil contamination. **Disadvantages:** - Risk of contamination: Without proper treatment, ballast water in CBTs could still be contaminated with oil residues, potentially violating pollution regulations. - Operational costs: Cleaning and treating ballast water can add to operational costs. **[3. Slop Tank and Handling of Slops]**- Slop tanks are special tanks used to store waste oil and water mixtures (slops) that result from cleaning the cargo tanks, or from cargo spills during loading/unloading. The handling of slops involves managing these residues safely and preventing their release into the environment. **Advantages:** - Waste containment: Slop tanks contain waste products, preventing them from being discharged into the sea. - Regulatory compliance: Ensures that waste oil and cargo residues are properly stored and disposed of, in compliance with MARPOL Annex I regulations. **Disadvantages:** - Storage limitations: Slop tanks have limited capacity, and their contents must be disposed of at port facilities, which may involve additional handling costs and time delays. - Potential for overflow: If slop tanks are not properly managed, they could overflow, potentially leading to pollution. **[4. Load-on-Top (LOT) System]**- The Load-on-Top (LOT) system allows tankers to load new cargo on top of residual oil in slop tanks. This method is used to minimize the risk of oil pollution and to optimize tank cleaning. **Advantages:** - Reduced cleaning requirements: By loading new cargo on top of residual oil, the need for extensive cleaning between cargoes is minimized, reducing the risk of spills. - Pollution reduction: Reduces the amount of residual oil that needs to be disposed of as slops. **Disadvantages:** - Cargo segregation: The system is only applicable for cargoes that are compatible, and contamination can occur if the two cargoes are not suitable for mixing. - Operational limitations: Not all oil products can be loaded on top of one another, and this system requires careful management to avoid cross-contamination. **[5. Oil Discharge Monitoring and Control System (ODMCS)]**- The Oil Discharge Monitoring and Control System (ODMCS) is a system used to monitor the discharge of oil from the ship and ensure that it complies with international pollution prevention standards. The system includes sensors, meters, and alarms to detect and prevent illegal oil discharges. **Advantages:** - Compliance with regulations: ODMCS ensures that oil discharges are within acceptable limits, as specified by MARPOL. - Real-time monitoring: Provides real-time data on oil discharge, which can prevent accidental pollution. **Disadvantages:** - System complexity: The system requires regular calibration, maintenance, and testing to ensure accuracy. - False alarms: Improper calibration or malfunction can lead to false alarms, potentially delaying operations. 5. **INERT GAS SYSTEM**  Inert gas system is the most important integrated system for oil tankers for safe operation of the ship. Inert gas is the gas which contains insufficient oxygen (normally less than 8 %) to suppress combustion of flammable hydrocarbon gases. Inert gas system spreads the inert gas over the oil cargo hydrocarbon mixture which increases the lower explosion limit LEL simultaneously decreasing the Higher explosion limit HEL. When the concentration reaches around 10 %, an atmosphere is created inside tank in which hydrocarbon vapors cannot burn. The concentration of inert gas is kept around 5% as a safety limit. **Parts of Inert Gas System:** 1. **Boiler uptake valve: is opened and the exhaust is taken to a Scrubber.** 2. **Scrubber: Here the flue gas is washed with sea water after passing it through filters. Gases of SOX and NOX are removed. Scrubber is subject to salt water corrosion. Hence it is epoxy coated.** 3. **Demister: Normally made of polypropylene, it is used to absorb moisture and water from the treated flue gas.** 4. **Blower: The flue gas is pumped into the tanks using blowers.** 5. **Deck seal and Non-Return Valve: Purpose of the deck seal is to stop the gases to return back which are coming from the blower to cargo tanks. Normally wet type deck seals are used. Non return valve serve the same function.** 6. **I.G pressure regulating valve: The pressure within the tanks varies with the property of oil and atmospheric condition. To control this variation and to avoid overheating of blower fan, a pressure regulator valve is attached after blower discharge which re-circulates the excess gas back to scrubbing tower.** 7. **Pressure Vacuum (PV) breaker: The PV breaker helps in controlling the over or under pressurization of cargo tanks. The PV breaker vent is fitted with flame trap to avoid fire to ignite when loading or discharging operation is going on when in port.** 8. **Mast riser: Mast riser is used to maintain a positive pressure of inert gas at the time of loading of cargo and during the loading time it is kept open to avoid pressurization of cargo tank.** 1. **Oxygen Deficiency: Inert gas displaces oxygen, and in confined spaces, this can lead to asphyxiation. Crew working in such spaces may lose consciousness or even die due to low oxygen levels.** 2. **Toxicity of Gases: Inert gas mixtures can contain carbon dioxide (CO₂), which can be toxic in high concentrations, causing respiratory problems and asphyxiation.** 3. **Pressure and Leaks: Over-pressurization in the inert gas system or leaks can cause oxygen depletion in the surrounding areas, increasing the risk of asphyxiation or explosion.** 4. **Explosion Risk: Improper handling of inert gas during cargo discharge or tank cleaning can lead to flammable vapours being mixed with oxygen, creating an explosion hazard.** 5. **Disrupted Gas Flow: Faulty inert gas systems or improper gas pressure can lead to unsafe oxygen levels in the cargo tanks, increasing the risk of fire or explosion.** 6. **CRUDE OIL WASHING (COW)** Earlier oil tanks on crude oil tanker were cleaned by water, but this increased marine pollution and required bigger slop tanks to store leftover residue and oily water mixture. In order to prevent this problem, a better non pollutant way was introduced where in oil cargo of the tank itself was used to clean the cargo tanks. This system virtually eliminates the requirement of slop tanks on ships and almost all cargo can be transferred to the shore. This process is known as Crude oil Washing or **COW**. **Hazards of COW** - Need for additional equipment for COW and its regular maintenance as per PMS (planned maintenance system) - Specialized man power required. - Increased stay in the discharge port. - Increased work load. - Potential safety and pollution risk during COW operation as line pressure is 10 bar. **Benefits of COW are:** - Much less oil-contaminated water is handed throughout the ballast passage. - Increased cargo out turned. - Decreased storage tank rust caused by water washing. - Reduction in time and cost of tank cleaning. - Less ROB (remaining on board) quantity, so higher freight can be earned by loading more cargo at next port - Reduced sludge accumulation. - Reduced gas freeing time. - Reduced manual cleaning **ITEMS OF COW CHECKLIST** 1. Are all pre arrival checks and conditions completed. 2. Has COW operations been discussed with both ship and shore staff. 3. Has communication link between the Deck / Control room and Control room / Shore been set up and working satisfactorily. 4. Have Crude Oil Wash abort conditions and procedures been discussed and agreed by both Ship and Shore staff. 5. Have fixed and portable oxygen analyzers been checked and working properly. 6. Is the I.G. system working properly and is the oxygen content of the delivered I.G. bellow 5% by volume. 7. Have all cargo tanks got a positive I.G. pressure. 8. Have valves and lines for COW operations both on deck and in pump room been checked. **MARPOL regulation for COW** - Crude oil washing was made mandatory for new tankers by the 1978 Protocol to the MARPOL Convention. - Regulation 33 of MARPOL Annex I requires every new crude oil tanker of 20,000 tons deadweight and above to be fitted with a cargo tank cleaning system using crude oil washing. - COW installation and arrangements should comply with at least all of the provisions of the Specifications for the Design, Operation and Control of Crude Oil Washing Systems. -  Every crude oil washing system required to be provided in accordance with regulation 18.7of this Annex.  7. **ITEMS OF PRE-ARRIVAL CHECKLIST, LOADING AND DISCHARGING OPERATIONS ON A TANKER, CARE OF CARGO DURING TRANSIT** **Items of pre arrival checklist** a. Do all devices related to cargo work such as gauging systems, hydraulic valves and pressure gauges function properly? b. Check that unused valves such as sea suction and overboard discharge valves are sealed and blanked. c. Check to see that the IG supply valves of all tanks are padlocked open. d. Check the proper function of the IG and the cleanliness of the inert gas. e. Are crew members familiar with proper regulations of the berth and port? f. Has firefighting equipment and oil pollution equipment and materials been prepared? g. Have emergency hydraulic pumps been prepared? h. Have fixed and portable gas detectors and oxygen analyzers been inspected and maintained? i. Does the gas alarm system function properly? j. Has the oxygen content of the tanks been measured and recorded? k. Are lights on the deck and in the pump room Working? **Loading Operations** 1. **Preparation Before Loading**: - **Tank Inspection**: Ensure cargo tanks are clean, dry, and free from residues or water. This includes checking for any residual chemicals or oil from the previous cargo. - **Inerting**: Before loading, inert gas is introduced into the tanks to reduce the oxygen level and prevent the formation of a combustible mixture with cargo vapours. - **Ventilation**: Venting systems must be ready to avoid pressure buildup in the tanks during loading. 2. **Loading the Cargo**: - **Rate of Loading**: Load the cargo at a controlled rate to avoid overfilling and to prevent tank damage. Ensure that the cargo does not cause excessive pressure or temperature changes. - **Continuous Monitoring**: Monitor cargo levels during the process to avoid overfilling and spills. - **Venting and Inerting**: Ensure proper venting to avoid excessive pressure buildup in the tanks while continuing to monitor inert gas levels. 3. **Safety Checks**: - **Pressure and Temperature Monitoring**: Ensure that cargo pressure and temperature are within safe limits during loading to avoid risks of overpressure or cargo vapor release. **Discharging Operations** 1. **Preparation Before Discharge**: - **Pre-Discharge Inspection**: Inspect cargo tanks, discharge piping, and valves for leaks or damage. - **Tank Venting**: Ensure proper venting to avoid pressure build-up during discharge. - **Monitoring Instruments**: Confirm that all monitoring equipment (such as flow meters and temperature gauges) are in proper working condition. 2. **Discharging the Cargo**: - **Rate of Discharge**: Discharge the cargo at a controlled rate to avoid tank damage or pressure fluctuations. The cargo must be removed efficiently without generating harmful vapours. - **Cargo Monitoring**: Continuously monitor the discharge for any signs of leakage or irregularities. If residual oil is left, it should be removed using slop tanks. 3. **Post-Discharge Checks**: - **Tank Cleaning**: After discharge, ensure proper cleaning of cargo tanks to remove any residues or contamination, especially before switching to a different type of cargo. - **Ventilation**: Vent the tanks properly to clear any residual cargo vapours and maintain safety. **Care of Cargo During Transit** 1. **Stability and Ballasting**: - **Ballast Management**: Ensure proper ballast to maintain stability during the voyage. This includes adjusting ballast tanks to balance the ship after cargo is loaded or discharged. - **Tank Monitoring**: Regularly monitor the condition of the cargo tanks, ensuring that they remain free from water or contaminants. 2. **Cargo Temperature**: - **Temperature Control**: For temperature-sensitive cargo (such as crude oil or chemical cargo), ensure that tanks are kept at the correct temperature using heating coils or other temperature control methods, as required. 3. **Tank Integrity**: - **Inspection**: Regularly inspect the cargo tanks for leaks or structural damage. The integrity of the tanks is crucial to prevent contamination or loss of cargo. - **Monitoring**: Continuously monitor the level and condition of the cargo, ensuring no shifting or settling that could compromise tank stability. 4. **Avoiding Cargo Shifting**: - **Cargo Securing**: Ensure that cargo is properly loaded and secured to prevent movement during rough seas. This prevents damage to the cargo and ensures vessel stability. 5. **Inert Gas Monitoring**: - **Oxygen Levels**: Throughout the voyage, monitor the inert gas system to maintain low oxygen levels in the tanks. This reduces the risk of combustion and keeps the atmosphere non-flammable. - **Gas Quality**: Regularly check the quality and pressure of the inert gas to ensure safety and compliance with regulations. 8. **USE OF OXYGEN ANALYSER, EXPLOSIMETER, TANKSCOPE, MULTIGAS DETECTOR AND DRAGGER TUBES** **Oxygen Analyzer:** An oxygen analyzer is a device used to measure the oxygen content in the air or gas mixture, typically in confined spaces or cargo tanks. The major uses of Oxygen Analyzer are as follows: - Monitoring oxygen levels in cargo tanks, pumprooms, and other confined spaces to ensure they are within safe limits (usually 21% oxygen in open spaces). - Ensures that oxygen levels are low enough during inerting operations to prevent combustion but not so low as to cause asphyxiation of personnel working in the area. - Used to monitor the effectiveness of the inert gas system during cargo operations. **Explosimeter (Flammable Gas Detector):** An explosimeter is a portable device designed to detect the presence of flammable gases or vapours in the air. It provides an immediate reading of gas concentrations in the atmosphere. It is: - Used to measure the concentration of flammable gases in cargo spaces, engine rooms, and other areas where volatile vapours may accumulate. - Crucial during cargo handling (loading and discharging) to prevent the buildup of flammable vapours that could lead to explosions. - Ensures that the atmosphere is safe for personnel working in or around tanks and confined spaces by detecting gas leaks and hazardous concentrations. **Tankscope:** A Tankscope is a visual inspection tool, typically a camera or fibre-optic device, used to inspect the interior of cargo tanks. - Provides visual inspection of cargo tanks without the need for human entry, which is especially useful for checking the condition of the tank, residual cargo, and tank cleaning before the next load. - Used to inspect tank walls, bottoms, and manways for contamination, corrosion, or other hazards before cargo operations. - Helps ensure that tanks are clean, dry, and free from dangerous residues before starting loading or inerting operations. **Multigas Detector**: A multigas detector is a portable device used to detect multiple gases simultaneously, including oxygen, flammable gases (such as methane, butane), and toxic gases (such as carbon monoxide, hydrogen sulphide). Its uses comprise of: - Simultaneous detection of multiple gases in cargo holds, tanks, and confined spaces to monitor the atmosphere and ensure that it is safe for crew members to work in. - Particularly useful during gas freeing, purging, and tank entry operations to monitor oxygen levels, flammable gases, and toxic gases all at once. - Provides early warning in case of gas leaks or hazardous conditions that could lead to fire, explosion, or poisoning. **Dragger Tubes:** Dragger tubes are chemical detection tubes used in conjunction with a hand pump to measure the concentration of specific gases or vapours in the air. It is majorly: - Used to detect and measure specific toxic gases such as hydrogen sulphide (H₂S), carbon monoxide (CO), or ammonia in confined spaces like cargo holds or engine rooms. - Provides a quick and accurate measurement of gas concentrations in the environment, helping to assess the risk of poisoning or explosion. - Essential for ensuring safety during cargo operations, gas freeing, and tank entry, especially when monitoring for gases that can be harmful at low concentrations. 9. **INTRODUCTION TO CARGO PUMPS** **Centrifugal Pumps:** Centrifugal Pumps are the most commonly used type of pump on oil tankers due to their efficiency and simplicity. They operate by using a rotating impeller to impart velocity to the liquid, converting this velocity into pressure to move the cargo. Centrifugal pumps are ideal for transferring large volumes of cargo at relatively low pressures. Their advantages include continuous flow, low maintenance, and reliability. However, they are not suitable for high-viscosity liquids, as the pump\'s efficiency decreases with thicker fluids. Centrifugal pumps - Useful Information **Reciprocating Pump:** Reciprocating Pumps, on the other hand, are used for pumping high-viscosity liquids or when high pressure is required. These pumps work by using a piston or diaphragm to create suction and push the liquid through the system. Reciprocating pumps provide a pulsating flow, which is often advantageous when precise control over the cargo flow is necessary. They are more complex and require more maintenance compared to centrifugal pumps, but they are effective for thick oils or slurries where centrifugal pumps would be inefficient.  **Eductor:** Eductors are a type of jet pump that operates on the principle of the Venturi effect, where a high-velocity jet of fluid creates a low-pressure zone that draws in and moves another fluid. Eductors are often used for emptying tanks and lines, or for slop recovery, as they can handle liquids with varying viscosities and can be operated with minimal maintenance. They are commonly used when a large amount of cargo needs to be displaced quickly or when no power source is available, as they rely on the flow of the cargo itself or the use of a high-pressure water jet. Water Jet Eductor \| Schutte & Koerting 10. **CONTENTS OF INTERNATIONAL SAFETY GUIDE FOR OIL TANKERS AND TERMINALS (ISGOTT)** ISGOTT was first published in 1978 and combined the contents of the \'Tanker Safety Guide (Petroleum)\', published by the International Chamber of Shipping (ICS), and the \'International Oil Tanker and Terminal Safety Guide\', by the Oil Companies International Marine Forum (OCIMF). - The purpose of the guide is to provide operational advice to assist personnel directly involved in tanker and terminal operations. - It is emphasized that the ship's operator should provide positive support, information and guidance to the master who is in charge of the day-to-day running of the ship. - It also emphasized that the terminal management should ensure that its concern for safe operating practices is known to the terminal personnel - This guide makes recommendations for tanker and terminal personnel on the safe carriage and handling of crude oil and petroleum products on tankers and at terminals.  - It was prepared originally by combining the contents of the 'Tanker Safety Guide (Petroleum)' **Contents of ISGOTT:** **Chapter 1. Hazards of petroleum\ Chapter 2. General precautions on tankers\ Chapter 3. Arrival in port\ Chapter 4. General precautions while a tanker is at a petroleum berth\ Chapter 5. Liaison between tanker and terminal\ Chapter 6. Precautions before and during cargo handling and other cargo tank operations\ Chapter 7. Handling of cargo and ballast\ Chapter 8. Double hull operations\ Chapter 9. Tank cleaning and gas freeing\ Chapter 10. Fixed inert gas systems\ Chapter 11. Enclosed space entry\ Chapter 12. Combination carriers\ Chapter 13. Packaged cargoes\ Chapter 14. Emergency procedures\ Chapter 15. Basic properties of petroleum\ Chapter 16. Toxicity of petroleum and associated substances\ Chapter 17. Hydrocarbon gas evolution and dispersion\ Chapter 18. Gas indicators\ Chapter 19. Electrical equipment and installations\ Chapter 20. Static electricity\ Chapter 21. Pressure surge\ Chapter 22. Fire-fighting - theory and equipment\ Chapter 23. Pyrophoric iron sulphide\ Chapter 24. The flammable hazards associated with the handling, storage and carriage of residual fuel oils**