Page: 1 of 7 12.1. COMPLIANCE WITH MARPOL 12.1.1. Retention of Oil on Board Oil tankers are provided with facilities to enable them to control operational pollution by cleaning cargo tanks using re-circulatory washing; discharging dirty ballast and decanting slop tanks in a manner which enables the vessel to remain within the statutory limits for permitted discharge of oil at sea. These facilities also enable crude oil vessels to operate the load-on-top (LOT) system of loading cargo on top of the recovered oil remaining in the slop tanks from deballasting and tank washing operations and subsequently discharging the recovered oil to shore with the cargo. In product vessels, LOT is not normally practiced as the recovered oil is usually discharged to shore reception facilities. 12.1.2. Use of the Oil Discharge Monitoring Equipment (ODME) The equipment shall be operated and tested strictly in accordance with the manufacturer s instructions / PMS and prior to each operation. The control console shall be kept locked when not in use and the key shall be retained by the Chief Officer. The ODME is designed to measure and react to small quantities of oil (in ppm) suspended in water. Reaction time will depend upon the length of sample line between the over side discharge line and the detector cell mounted in the skid assembly and will generally be slow compared to the reaction time of a person observing the water discharged. It cannot react quickly to slugs of very oily mixtures which may inadvertently be discharged during a decanting operation. Slop tanks which contain fuel oil, lubricating oil or engine room sludge are particularly susceptible to the formation of light sludge which will float at or near the tank floor and be easily disturbed either by movement of the vessel or movement of water towards the suction. This sludge may be drawn into the suction without any previous indication that the oil content of water discharge is about to rise and will contaminate the overside discharge line before the ODME is able to react. This oil or sludge may then contaminate the vessel s hull, either if the overside valve is left open after completion of decanting or when the overside valve is opened prior to the next decanting operation. It is therefore essential that slop tanks are routinely Crude Oil Washed or water washed to control the accumulation of sludge and a visual watch is maintained on the water discharged during decanting 12.1.3. Discharge Limits Marpol 73/78 Annex 1 requires that discharges of oil to sea remain within the following maximums for discharge rate and the total quantity of oil which may be discharged:
Page: 2 of 7 Instantaneous Discharge Rate: 30 litres per mile. Oil discharged at rates not exceeding 30 litres per mile quickly spreads into a thin film which disperses within a few hours leaving no discernible pollution. The oil discharge rate in litres per mile is given by the calculation: effluent discharge rate in m³/hour x ppm of oil in the effluent vessel s speed in knots x 1,000 The three elements of effluent discharge rate, effluent oil content and vessel s speed must be matched to remain within the same maximum instantaneous discharge rate of 30 litres per mile; for example, an increase in effluent oil content must be matched by a reduction in effluent discharge rate, as shown in the table below: Effluent Effluent Oil Ship s Speed Oil Discharge Discharge Rate Content Rate (M3/hour) (ppm) Knots (litres/mile) 200 2250 15 30 2000 225 15 30 2000 150 10 30 7500 40 10 30 Total Quantity Discharged: 1/30,000 of the total quantity of the cargo of which the discharged residue formed part This figure applies to the total quantity of the relevant cargo carried and not to the essel s total cargo carrying capacity. It includes the amount of oil in heavy weather ballast discharged from cargo tanks and the amount of oil in water discharged from the slop tanks after tank cleaning. The total quantity of oil which may be discharged from a single cargo is given by the calculation: Total litres = m3 of cargo x 1,000 30,000 The total quantity of oil which may be discharged is entered into the Oil Discharge Monitoring Equipment (ODME) which will then automatically control an effluent discharge to ensure that the Instantaneous discharge rate of 30 litres per mile and total oil discharged limitations are not exceeded. 12.1.4. Sludge and Scale Solid residues and sludge may give off flammable gas and may contain rags or waste liable to spontaneous combustion. If kept in drums before being disposed of, it must be stowed on deck and kept wetted down. All scale from tanks that have contained leaded petroleum or cargo containing H2S must be safely contained. All disposals of sludge, scale or sediment from cargo tanks must be recorded in the Oil Record Book or Garbage Record Book, as appropriate to the type of waste.
Page: 3 of 7 12.2. PREVENTION OF OPERATIONAL OIL SPILLS 12.2.1. Pollution Avoidance The Master will appoint the Chief Officer as Pollution Prevention Officer. As with matters relating to safety, the Master is responsible for leading by example in ensuring that procedures designed to avoid pollution are meticulously followed and rigorously enforced. 12.2.2. Priority of Actions Measures to prevent or minimize pollution damage take priority over cargo segregation and quality issues. Measures to prevent pollution do not however take priority over the safety of individuals or the vessel. 12.2.3. Cargo Tank Leakage In the event of suspected tank leakage, the head in the cargo tank involved must be reduced, either by internal transfer or discharge ashore. Oil will continue to flow from the tank until a hydrostatic balance is achieved between the head of oil in the tank and the ballast or sea water pressure exerted on the outer skin of the tank. If it is not possible to identify the specific tank from which the leakage is occurring, the levels of all tanks in the vicinity should be reduced, taking into account the effect on hull stresses and stability. If it is suspected that leakage is from a fracture in the bottom plating, the level of oil in the tank, if full, should be reduced and water pumped into the damaged tank to form a water bottom to prevent further leakage of oil. In a tidal stream or river, any leakage from the hull or a sea- valve may be carried by the tide or current to another part of the vessel before it surfaces and is noticed. This is particularly so in the area of the bilge keels. For example, oil leaking from a sea-valve may be carried forward by the current, entrapped below the bilge keel, to surface at the fore end of the vessel. 12.3. REQUIREMENTS FOR CARGO PUMPROOM SEA VALVES 12.3.1. Locking and Blanking Arrangements To prevent pollution through incorrect or inappropriate operation of the valves, the following arrangements must be maintained. Outer manual valves must be equipped with a physical locking device such as a chain and padlock. The device must incorporate a substantial lock and the key must be retained by the Chief Officer. The locking device must be fitted in such a manner that it is not easily by-passed by disconnection or removal of an extended spindle or hand wheel.
Page: 4 of 7 The operation of the sea valves (either suction or overboard discharge) shall only be carried out under the direct supervision of the Chief Officer or the Master. The valves will be kept locked at all times except when it is specifically required that they be open for operational purposes. 12.3.2. Testing Of Cargo Pumproom Sea Valves Valves must be tested as detailed in Prevention of Oil Spillages through Cargo Pumproom Sea Valves. Testing shall be carried out as per interval provided in PMS (maximum interval of a month). Drain test for the sea chest to be carried out as part of the pre arrival check for the port. The space between the inboard and outboard valves shall be drained down by means of the drain cock fitted in the section of pipeline between the two valves and confirmed as being dry and at zero pressure as measured by the pressure gauge fitted in the same section of line. The section of line between the valves shall then be pressurised with compressed air (suction valves to 3.5 Kg/cm2) injected through the connection fitted for the purpose. The pressure is to be monitored for a period of 15 minutes. Any pressure drop is likely to indicate a leak. If the outboard sea chest valve is leaking then this can be confirmed by appearance of bubbles in the sea surface due to escape of air to the sea. If there are no such bubbles observed then the inboard sea chest valve could be leaking. This test is to be performed while the vessel is stationary and in calm waters, so as to sight the bubbles if outboard sea chest valve is leaking. A record of testing of the sea valves shall be entered in the Oil Record Book (Cargo) and signed by the Master and Chief Officer. 12.3.3. Monitoring of Cargo Pumproom Sea Valves During Cargo Operations Sea valves shall be checked during the deck rounds of the OOW and shall also be checked while taking over watches. 12.4. POLLUTION RESPONSE Every vessel is required to carry either a Shipboard Oil Pollution Response Plan (SOPEP) or a Shipboard Marine Pollution Emergency Plan (SMPEP). The SOPEP is for oil tankers or any type of vessel which carries oil whether as cargo or fuel, and the SMPEP is for vessels which carry NLS or chemicals, but in practice the two plans are the same. Vessels which may trade to American ports are also required to carry a Vessel Response Plan (VRP) approved by the USCG. The VRP is very similar to a SOPEP or SMPEP but is specific to operations in US waters.
Page: 5 of 7 Persons arranging spill response exercises on board should utilize the checklists contained in these plans. 12.5. DISPERSANTS All vessels are supplied with approved oil dispersant and one or more portable sprayers. This dispersant must not be used for any purpose other than dealing with oil spills. For spillages on board, dispersant may be sprayed on the oil covered surfaces, which are then hosed down with sea water. This should only be done with scuppers sealed and under no circumstances should emulsified oil and dispersant be washed off the deck into the sea. Dispersant must not be used on the surface of the sea without the prior approval of the Local Port Authority or Coastal State Authority. 12.6. MATERIALS AND EQUIPMENT FOR OIL SPILL CLEANUP ON DECK Wilden pumps should be deployed at the aft end of the main deck during cargo operations, connected up to their air lines and oil hoses ready for immediate use in recovering spilled oil and pumping it to a slop tank. 12.7. MINIMISATION OF ATMOSPHERIC POLLUTION FROM CARGO OPERATIONS Cargo vapour emissions to atmosphere shall be minimised by strictly complying with VOC Management Plan. 12.8. GUIDANCE ON THE USE OF ABSORBENT MATERIAL Booms should be laid down on deck to direct the flow of oil away from scuppers or to create a pool to prevent the oil running the full length of the deck and to assist recovery. Booms may also be laid on the water to contain oil in the vicinity of leaking scuppers or similar small scale spills. It is important that however small the spill; an effort must be made first to contain it on the deck; then to contain it within the smallest possible area; then to recover it. Absorbent granules should be used on deck to protect scuppers or to plug gaps between booms or between parts of the vessel s structure. Loose absorbent materials must never be thrown into the water. Pom poms are balls of absorbent material in a shredded form that can be rolled in the oil. They have more surface area available to mop up oil than flat pads which, although they can be turned over, are less efficient. Mops are made of material similar to that used for pom poms but with long strands. These can be used with a wringer bucket to repeatedly mop up oil and collect oil.
Page: 6 of 7 Pads should be turned over to allow both sides to absorb oil. Oil-soaked absorbents must be placed in the heavy duty plastic sacks supplied for storage until disposal ashore is possible. Oil-soaked absorbent material must not be incinerated. It must be landed ashore as Oily Waste. 12.9. PRESSURE TEST OF CARGO LINES Prior Arrival Discharge port, vessels are required to test the Cargo, COW, Stripping lines to the working Pressure. It shall be logged in the port log. Precautions shall be taken to strip all the lines after completion of the operation. The Chief Officer shall have a ship specific procedure made and approved by Master. Cargo pipelines should be tested to the normal working pressure prior every discharge operation. In this case the normal working pressure is defined as the maximum expected discharge pressure the vessel would attain during the corresponding discharge. In situations where vessels are involved in frequent discharge operations, such pressure testing shall be carried out to the maximum expected discharge pressure, at periodic intervals as per master s discretion however not exceeding 3 months. All cargo discharge pipelines (including Marpol line) and tank cleaning lines must be tested to their Maximum Allowable Working Pressure (MAWP) annually and also after any repairs to the cargo line system. All cargo discharge pipelines must be pressure tested to 1.5 times their MAWP at least twice every five years i.e. each dry docking or repair period. Those vessels with longer drydock intervals must make arrangements to conduct the 150% MAWP tests at least twice in any five year period. Pipelines must be marked with the date of test and test pressure. Accurate records should be maintained in the PMS. These tests are to be carried out in accordance with the SIRE-VIQ / ISGOTT / USCG Marine Safety Manual (Vol: II) recommendations. Detailed risk assessment should be carried out and suitable safety precautions undertaken prior commencing the pressure testing. Pressure testing above the MAWP should not be carried out with oil or other cargoes which can cause pollution. Fresh water shall be used for tests whenever possible so as to avoid undue corrosion. Alternatively, seawater may be used. All lines should be immediately drained and blown through after the test. A piping system for liquid is to be tested by a static, hydraulic pressure using a cargo pump, stripping pump or a hydraulic test pump to produce the required pressure. During such tests it is important to ensure that the piping system is full of liquid and free from air locks. The test pressure shall be held for 10minutes and all exposed section of the pipe lines shall be inspected for any leaks. During the test procedures crew should be warned of possible gas hazard in pump room and tanks & precautions should be taken. When carrying out the test on board, ensure the gauges to be used are calibrated prior use on board and the tolerance of the gauges taken into consideration. During the inspection of piping systems particular attention should be given to expansion joints, flanges & valves. Any defects found during the test shall be corrected & re-tested.
Page: 7 of 7 Pressure testing of piping in cargo tanks may be carried out in conjunction with the tank-cleaning programme to permit the inspection of the piping in those tanks, which are gas- free for entry. Both sides manifolds should be fitted with pressure gauges having valves or cocks on the outboard sides of the manifold valve. Steel Blank flanges fitted to the manifold pipelines should be of the same thickness or certified rating as that of the pipeline to which they are fitted. Pipelines should be marked with the date of test and the test pressure