Chapter 2 Preparations for Tank Cleaning Work Preparatory Procedures for Tank Cleaning Work Make preparations for tank cleaning work according to the procedures given below. 1. Formulating the tank cleaning plan (P.2-2 to P.2-3) The Chief Officer should formulate the plans given below. 1) Schedule 2) Line diagram 3) Co-ordinate various plans. 2. Holding shipboard work meetings (P.2-4) Thoroughly familiarize the crew members the flow and the contents of the work according to the plan formulated by the Chief Officer, focusing on special work not implemented during usual cargo handling operations, and hold meetings to prevent accidents and enhance work efficiency. Particular care is necessary to ensure that gas-freeing work is thoroughly understood by the crew members. The Chief Engineer should confirm the tank cleaning plan formulated by the Chief Officer before the work meeting and offer assistance as required. 3. Inspection and maintenance of machinery and equipment (P.2-5 to P.2-6) Perform inspection and maintenance of machinery and equipment used in the tank cleaning work. 4. Checks and preparations of equipment, accessories and consumables (P.2-7) Check the quantity of equipment, accessories and consumables to be used for tank cleaning work on board the ship, and make the necessary preparations. 1
1. Formulating the tank cleaning plan 1.1 Schedule (refer to P6-1 and P6-2 of the Documents Section ) The Chief Officer should prepare the schedule of the entire tank cleaning work from the time of departure from the last discharging terminal to the removal of slop and sludge at the anchorage before entering dry-dock. 1.1.1 Items to be entered Enter the items mentioned below in the schedule. a) Entire work flow b) Time required for each stage of work c} Precautions for each stage of work 1.1.2 Items to be considered when preparing the chart Consider the items below when preparing the schedule. a) In principle, tank cleaning work should be completed during the time the ship travels at its normal cruising speed from the discharging terminal to the dry-docking yard. b) If the ship s speed is high, the time of travel from the discharging terminal to the dry-docking yard becomes short. Therefore, all the work stages should be adjusted so that the cleaning work is completed by the time the ship reaches the dry-docking yard. 1.2 Line diagram The Chief Officer should prepare detailed line diagrams of the items mentioned below from the overall process (Chapter 1, Section 3) mentioned in the time sequence to be implemented during the series of stages of the tank cleaning work 1} Filling of washing water 2} Rough washing of cargo line and cargo pump 3) Line washing (removal of oil traces in the ODM line) and valve flushing 4) Tank washing 5) First discharge of water from slop 6) Collection of washing water (shift from secondary slop tank to primary slop tank) 7) Washing of secondary slop tank 8) Final line washing (including line stripping) 9) Discharges after the second discharge of water from slop 10) Slop removal 11) Washing of primary slop tank 12) MARPOL line washing and final line stripping 1.3 Co-ordinating various plans 1.3.1 Voyage plan The voyage plan is to be formulated similar to plans for normal voyages but the plan should be made while considering the points mentioned below and adjusting the schedule of the tank cleaning work. a) If the dry-docking yard is close to the discharging terminal, back calculate the time available for tank cleaning work and then prepare the voyage plan. b) Select the route of the ship such that sea area navigated by the ship during the discharging of washing water and the final line washing lies more than 50 nautical miles away from the coast. (Refer to Section 8 of Chapter 3 for details of standards for discharging washing water). 2
c) Lightning should be avoided during tank cleaning work, particularly during gas-freeing of tank since flammable gases are likely to be discharged and to accumulate on the deck during such work. Formulate the voyage plan considering the weather and sea conditions beforehand especially in the sea area and the time when rough weather is expected. 1.3.2 Ballasting plan Consider the stripping efficiency during tank washing and adjust the ballast so that the trim is generally about 6 m. As preparations for rough weather, estimate beforehand the ship conditions that enable safe forward draught to be maintained and check the hull strength. 1.3.3. Replenishing plan The consumption of fuel oil during the tank cleaning operation may be much higher than during normal voyage. In the normal case, add this increased fuel quantity, estimate the consumption after leaving the dry-dock to the replenishment site and replenish with the appropriate quantity during the voyage before entering the dry-dock. Decide the replenishment site and the replenishing quantity based on the instructions from the charterer or the sales in-charge. 3
2. Holding shipboard work meetings Hold shipboard work meetings related to tank cleaning work to discuss the points mentioned below on safety aspects and prevention of oil pollution that the workers should always be aware of. 1) Restrictions on smoking and use of flames About specifying smoking places, measures against static electricity, and sources of ignition such as soot from the smokestack and lightning bolt 2) Fire extinguishing equipment and rescue appliances About the necessity of fire extinguishing hoses and portable fire extinguishers, quantity of the same to be kept ready for each process, and method of usage of breathing apparatus, air cylinders, life lines and oxygen resuscitation equipment 3) First aid About first aid measures in the event of injuries to personnel 4) Ventilation control of accommodation spaces About the status of control of openings, access openings and mechanical ventilation intake openings and the effects of inert gases on the human body 5) Procedures for entering enclosed spaces Essential measures such as stationing of required personnel and continuous ventilation and gas detection should be adopted when entering enclosed spaces for performing work such as sludge removal. Workers should not enter enclosed places, which they are prohibited from entering. 6) Tank pressure in each process About correct tank pressure and tank pressure adjustments in each process of the tank cleaning work, and measures to prevent damage due to abnormal tank pressure 7) Atmosphere within the cargo tanks About atmosphere within each tank (oxygen concentration, concentration of combustible gases, etc.) during each process of the tank cleaning work and sampling points during measurements within the tank 8) About periodically confirming safety based on the Safety Check List 9) About checking the closure of scupper plugs on the upper deck 10) About equipment and accessories required for oil removal 11) About communication system in an emergency and method of using the transceiver 12) About usage, calibration of various detectors and precautions when using them Particularly, education and training should be imparted beforehand on the method of using and handling gas detectors. Precautions are specially required when calibrating the detectors during the work to ensure that calibration is not performed in an area where gas has accumulated. 4
3. Inspection and maintenance of machinery and equipment 3.1 Preparations and functional checks of each machinery and equipment Make preparations of machinery and equipment required for tank cleaning and perform functional checks of the same at the appropriate period. Guideline for implementation period: Before the 2 nd voyage 1) Working test of portable fan using water Before performing the working test of portable fan using water, check the portable fans and the number of hoses required, whether any hose is holed, the specifications and sizes of hose couplings, and order the deficient items, if any. Perform the working test of the portable fan and confirm its operation. Portable fans may also be rented from tank cleaning subcontractors. In case of shortage of fans, make arrangements beforehand to rent them. 2) Working test of sludge lifter The sludge lifter brought by the shore subcontractor is generally used for sludge removal at the anchorage before entering dry-dock. Check the operation of the harness and the breathing apparatus together with the operation of the sludge lifter when performing the internal inspection of the sludge lifter, since these equipment may need to be used for rescue during toxic accidents. 3) Working test of portable washing machine (if necessary) If this machine is expected to be used, perform the continuity test of hose and check for holes in the hose. 4) Preparations for removal of IG spectacle flange, cargo sea chest and overboard spectacle flange (confirm visually whether they can be removed, keep ready tools for removal if necessary) 5) Try fitting the bolts of spool piece for connecting ballast/ cargo line and confirm that they can be fitted. 6) Preparations for removal of bolts on the blind plate of branch line for portable COW machine (If portable machine is expected to be used. Confirm visually whether they can be removed, keep ready tools for removal if necessary) 7) Inspection of slop tank heating coil and tank cleaning heater Generally, the heating coil in the primary slop tank and the tank cleaning heater are used jointly for heating the washing water used for tank cleaning. However, since both are not used for a long period, the air test of these heating devices should be performed, and maintenance and inspection should be carried out beforehand. 8) Working test of ODM (Oil Discharging Monitoring System) Although functional confirmation tests are carried out periodically, this system is not used for a long period. Past records show that there have been many cases when the system could not be used because of functional defects. Thus, in additional to the shipboard working tests, inspection and maintenance by the manufacturer should also be considered. However, adequate discussions should be held with the manufacturer on inspection and work plans if the manufacturer s inspection is to be received at the discharging terminal. Explanations and permission for performing the work should also be received from the terminal. 9) Preparations for various record sheets including rough copies of record sheets for Oil Record Book (Refer to 6-3 Various recording forms of the Documents Section.) 3.2 Detectors Detectors are very important especially for preventing human injuries. In addition to routine inspections, which should naturally be performed, inspections, functional checks and preparations of the items mentioned below for each detector should be carried out before the tank cleaning work. If necessary, perform adjustments and maintenance at shore facility when time permits. 3.2.1 O 2 meters (including tube for measurement) 1) Filter cloth 2) Spare sensor and effective lifetime 5
3) Calibration of meter 4) Use a black-colored sampling tube. Mark the ullage height to be measured by sheathing or plastic tape so that the tube position can be adjusted easily by visual observation. 3.2.2 HC gas meters (including tube for measurement) 1) Filter cloth 2) Spare sensor and effective lifetime 3) Calibration of meter 4) Use an orange-color sampling tube for measurements of VOL% and green-color sampling tube for measurements of LEL%. Tue tube should be marked similar to the marking of the O 2 meter. (For instance, marking 5 m, 15 m and 25 m as top, middle and bottom positions) 3.2.3 H 2 S (hydrogen sulfide) meters Perform the working tests. 3.2.4 MMC oil-water interface detector 1) Working tests 2) Cleaning 3) Charging 3.2.5 API gauge/ thermometer 1) Confirm that the measurement range is appropriate and that the measurement is performed satisfactorily since these instruments will be used to measure the final SLOP quantity. 2) Keep spares ready since these instruments are liable to break easily when dropped. 6
4. Checks and preparations for equipment, accessories and consumables Perform checks and preparations for the equipment, accessories and consumables mentioned below that are used for tank cleaning. The equipment and accessories for tank cleaning should include those rented from the sub-contractor in addition to the quantity on board the ship. 1) IG branch line blind plates Mark the blind plates of each tank used and confirm that the required quantity of blind plates are available. 2) Grating to prevent falls through the tank manhole All manholes are to be opened up when the ship enters dry-dock. Therefore, gratings should be kept ready for fitting on all the manholes to prevent falls through them. 3) Nuts for tank manholes Keep spare nuts for tank manholes ready since it is likely that some of them may be lost or damaged when they are removed for opening the tank manholes. It is recommended that empty paint cans be modified for use as containers for storing bolts and nuts. 4) Batteries Study the specifications of detectors as required and keep in the store an adequate number of spare detectors because they may be of a special variety (with built-in batteries). During tank cleaning, a large number of dry batteries used in explosion-proof flashlights are likely to get used up during internal inspections of the tank. A large number of dry batteries are necessary since tanks need to be entered many times both after entering and after leaving the dry-dock. Thus, replenish dry batteries and ensure that an adequate number is available before performing tank cleaning work. If dry batteries are required for explosion-proof flashlights, then they may be replenished when the ship is in dry-dock. 5) Cotton waste, cotton gloves and working uniform Sludge remains after the washing of tanks. A large quantity of cotton waste will be used when entering the tank since the equipment, accessories and maintenance parts will become dirty. Therefore, order for plenty of cotton waste, hand gloves and working uniforms and keep them in the store. 6) Detergents The deck becomes dirty after sludge removal. Moreover, oil sticks to the body and the clothes of persons performing tank cleaning work. Therefore, keep ready detergents for various applications. Also keep adequate quantities of detergents and kerosene ready since they are likely to be used in cleaning work after leaving the dry-dock. 7) Fresh water During tank cleaning, an unexpectedly large amount of fresh water is likely to be used up because of the increase in the number of uniforms to be washed or used up by the workers during sludge removal. Thus, adequate amount of fresh water should be replenished beforehand. Distilled water for the boiler should also be made available, therefore, plans should be made at that time to replenish tanks for this purpose. 8) Plastic cover sheets During tank cleaning work, the passages in the C.O.C and accommodation spaces are likely to get dirty. These passages need to be covered by plastic sheets before starting the tank cleaning work. Keep ready the required number of plastic sheets for this purpose. Thick plastic sheets should preferably be used. 7