Bits-1

  • July 2020
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Precaution to be taken to reduse or prevent build up static electricity: 1.initial rate during discharge should not be more than meter per sec. 2. antistatic additive may be put into the cargo. 3. ullaging / sounding shall always be done through sounding pipe. 4. during and after 30 min. after loading of cargo, no metallic dipping, ullaging sampling shall be done, other than trough sounding pipe. 5. any equipment used for ullaging / sampling shall properly earthed to ship’s structure.6. non conductive equipment with no metal parts may always be used. 7. natural fiber rope used for lowering equipment and not synthetic, polymer. Reason for static electricity development: 1. liquid flowing through the pipeline 2. steam slowing through the pipeline 3. break in liquid column while freeflow 4. solid particals settling in liquid 5.bubbling of gas through liquid 6.discharge of CO2 through liquid 7. inert gas through pipe 8.tankcleaning jet disturbing liquid surface 9. running a manmade fiber rope through rubber gloves.IMDG code:- It had divide in to these classes.1. explosive, 2.gases.3 flammable liquid. 4 flammable solid. 5 organic substance 6. toxic substance. 7 radio active substance. 8 corrosive. 9 miscellaneous substances Supplement:-it has divided in to two volume and 1 supplement 1. Emergency schedule number:- in case of fire and spill the action procedure and equipment to be carried. 2. Medical first aid guide:- in case of accident involving dangerous goods, it gives the symptoms treatment and other advices as per the effects of goods under that table.3. Reporting procedure:- it gives the procedure of reporting in case of accident. C. Merchant shipping regulations and amendments, MSN-755, MGN-159 D. Chemical supplement to ship master medical guide. General procedure when loading dangerous cargo:- 1. To check any damage or leaking from leakage.2.To store package in a protective location.3.combustible materials to be kept away from sources of ignition.4.all cargo to be loaded as per IMDG-international maritime dangerous goods.5.all DG emsno. (Emergency schedule no) to be checked.6. before loading DG - IMO declaration certificate for dangerous goods must be received from the shore personnel.7. the DG class sticker must be pasted on the four sides of the DG container.8. “no smoking” , “no naked light” board must be posted. Situation aborting crude oil washing:- 1.inert gas failure 2. high oxygen alarm 3. low pressure IG alarm 4. failure of oxygen analyzer 5. leak of any sort of piping on deck or in pump room 6. 98% alarm in any tank 7. any emergency fire alarm 8. failure of gauging 9. any other unsafe/unacceptable situation developing. Document required to supply to a vessel loading DG:- 1.technical name of the DG, 2. the class of DG which it belongs to. 3. UNNo preceeded by letter UN. 4. number and type of package, 5. gross weight of consignment. 6. net weight of the dangerous cargo content, 7. packing group when assigned. 8. any special requirement. 6. IMO declaration of Dangerous goods. Publication should be consulted when loading/discharging/carrying bulk chemicals:- 1.Code of safe working practices for solid. 2. Bulk cargo code (B.C code) 3. IMDG code 4. BLU code. Main hazard associated with carriage of bulk chemical:1.chemical reaction 2. corrosion on cargo space 3. vessel stability 4. local stress 5. fire hazard. Advantage of carrying cargo on pallets:- 1. faster operation between ship and shore. 2. space can be utilized efficiently 3. reduced risk of pilferage or theft 4. easier tallying cargo. 5. reduced labour requirement 6. reduced damage to cargo 7. make more effective use of vertical storage spaces. 8. less breakage 9. standarised securing arrangement can be used 10. less insurance cost. 11. equipment used for loading is less. Disadvantage :- 1. loss of space below deck , were space of the vessel is not compatible with that of unit. 2. extra cost for pallet, wrapping and securing of cargo to the pallet, disposal of empty pallet after discharge. 3. loss of space equal to the outside dimension of each pallet base. 4. care is required of cargo in the lowest pallet is not crushed. Advantage of crude oil washing:- 1.reduces sea pollution. 2. reduces tank corrosion. 3. more cargo discharged. 4. more time for maintenance 5. less salt water discharged to refinery 6. less desludging time for dry docking. 7. less deadweight. 8. easier tank drainage. 9. greater cargo capacity.de-sludging cost reduced. Disadvantages:- 1. more risk of pollution in port. 2. more dishcharge time. 3. more work during discharge 4. more personnels required. 5. more equipments required. 6. installation cost. Advantages of union purchase:- 1.cheaper to install than other crane. 2. easier to maintain 3. faster operation 4. derrick can be rigged on both side of the ship. 3. greater reliability 4. winches are more flexible in case of break down drums. Disadvantages:- 1. adjustment of derrick is more time consuming. 2. can only be used for lifting light weight (1.5 to 2.5ton) 3.labour intensive 4. skilled winch operator required 5. cannot be used for unitization method 6. cannot be used for spot loading. 7. maximum runner tension occurs at an angle of 120’(between runner & load) 8. maximum load should never exceed SWL of runner wire. 9. sling length governed by head room limitation. 10. tension in guys is 2 to 3 times load lifted. When angle between runner wire reaches 120’. 11. angle between boom and guys have to be sufficient to prevent jack knifing 12. siting of deck fittings limits the position of guys. Precautions taken b4 and during loading of heavy cargo using ships crane:- 1. stability of ship should be adequate, taken into account of the COG of weight to be lifted, act from derrick head, when weight is lifted, a shift of COG. 2. the angle of list a vessel will assume should be calculated. 3. free surface effect should be eliminated. 4. the rigging plan should be employed 5. check the condition of the derrick, equipment and lifting gear, check SWL of shackle, block, and wire as per the certificate. 6. check the weight mark on lift and weight on documentation 7. competent winch driver and the signal man must be in atterndance. 8. sufficient power required (generators must be in good working condition) 9. all winch affecting the load should be put into low gear. 10. heavy lift capacity plan should be consulted, check the deck is capable of supporting the weight, timber, should be layed as required. Lashing points to be checked. 11. mooring should be tended as required 12. one person must monitor gangway and adjust as per cargo loading/discharging. 13. fenders must be used as required 14. portable shipside railings must be refitted 15. barge and boat alongside must be cast-off 16. steady line should be attached to lift & block 16. to check whether correct sling is in use. 17. check all lashing from load have been removed and cleared. 18. to take the weight slowly as the lift is just clear off. Stop & check all around b4 continuing.Dangerous involved in carriage of cargo which may liquefy:- 1. liquefying cargo in its viscous fluid state may shift in one direction as the ship rolls but not completely returned as the ship rolls back to the other way. The ship may heel progressively further and eventually capsize 2. liquify cargo may be dangerous to the ship hull may cause corrosion. A ship which are not specially constructed to carry cargoes having moisture content above the TML (transportable moisture limit) it may be difficult to discharge. Six items used for separation of parcel:- 1. plastic ropes in various colour 2. different colour paint 3. plastic or rope net 4. plywood sheet 5. mats or nylon 6. mooring rope. Deck water seal:- deck water seal acts as a non return valve, during normal flow condition the inert gas passes through the water trap , through the demister plates (to takeout the water vapour or moisture) to IG main deck line. In case of back flow flammable gases from the tank, pressure acting on the sealing water surface creates water plug & back flow is prevented. Alarm fitted in IG system:- 1. High IG temperature 2. high efficient level 3. low deck seal water 4. high oxygen content. Scrubber tower in IG system:- flue gas inerted scrubber tower at the lower part of the tower. Gas is made to pass through water trap were initial cooling and washing takes place. Solid particles and sulphur components are washed out and drained out at bottom of tower. Rubber lamination at the bottom protect it from corrosion of steel. Then gas passes through the water sprays were further cooling and impegment plates which prevents remaining particles , cool clean gas passes through the demester plates which removes the water particles which removes the water particles and moisture in gas and allows only clean inert gas. Bale capacity: capacity of the cargo space inside cargo battens, ceiling and the underside of the deck beams. Grain capacity: the cubic capacity available for cargo that flows to the shipside. Stowage factor: it is the space occupied in m3 per / one ton cargo. Broken stowage: it is the space unused, wasted while loading cargo due to its structure. Angle of repose: the maximum slope angle of non-cohesive (free flowing) granular material. It is the angle between horizontal plane cone slope of such material. Flammable range: the region between lower flammable limit and upper flammable limit is known as flammable range. Upper flammable limit : it is the highest concentration of hydro carbon gas in air to support combustion. Lower flammable limit: it is the lower concentration of hydrocarbon gas in air to support combustion. TEU: twenty foot equivalent unit. MCTC- moment to change trim by 1 cm. List: is the transverse inclination caused due to not uniform loading or discharging or shifting. Trim: is the

longitudinal inclination caused when a weight is loaded or discharged or shifted in forward or aft of centre of floatation. Longitudinal centre of floatation (LCF) or Tipping centre: it is the centre of water plane area and the point about which the vessel will trim. Longitudinal metacentric height: it is the vertical distance between the longitudinal centre of gravity and longitudinal metacentre GM. Flash point: the lowest temperature at which a liquid gives off sufficient gas to form a flammable gas mixture near the surface of liquid. Earthing: the electrical connection of equipment to the main metallic structure of ship. Bonding: the connection together a metal part to ensure electrical continuity. Non-volatile : flash point of 60’c or above. Volatile: flash point below 60’c. Centre of Gravity: it is the point through which the weight of the body said to act vertically downwards. Centre of Buoyancy: it is the point through which the force of buoyancy is consider to act vertically upwards. Ship sweat: when ship moves from warm place to cool place the air in the cargo hold is warm, but the air surrounding the ship is cool. The cold air cools ship structure. The warm air in the hold contact with ship side and deck get cooled below its dew point . this causes water vapour which condenses in form of water droplets. Cargo sweat: mostly occurred when ventilation is carried out while going from cold to warm places. When cargo is cold, and incoming air is warm. Which come its contact cargo, cooled below its dew point and water droplet condensation on the cargo. To prevent :- 1. a careful watch should be kept on wet and dry bulb temperature of the air. 2. If the dew point of the outside air is less than the temperature of the air inside the hold. Then only ventilation must be carried out. 3. the ventilation should replace the air in the hold with colder, drier, which has lower dew point to prevent sweat 4. the dew point of the outside air should be less than or equal than the dew point of air inside. Then ventilation can carried out. Metacentric height: it is the height measured from centre of gravity to the metacentre. Metacentre : this is the point at which a vertical line through the centre of buoyancy at a small angle of heel cut the centre line. Stable equilibrium : when a ship turn to return to the upright position when inclined, for this to occur G must be below M. she has positive GM. Unstable equilibrium: when a ship inclined to an angle and tends to heel over still further. She is in a state of unstable equilibrium, for this to occur the ship must have a negative initial GM. Neutral equilibrium: when G and M are co-ordinant no movement exist. When inclined to a small angle the ship will remain in that angle until another external force is applied. Angle of Loll: when buoyancy moves to a position vertically below centre of gravity in a ship with a negative GM the capsying movement disappear. The angle at which this occur is known as angle of loll. Factors affecting the free surface effect: 1. Density of the liquid, 2. ships displacement 3. tank dimentions 4. depth of tank. 5. position of the tank. Tanker loading procedure: 1. all manifold valves closed 2. tank, deck and drop lines correctly set 3. pumproom valves correctly set 4. initial loading tank valve open 5. vent valves open 6. ship/shore communication verified 7. open manifold valves on loading arms 8. inform shore, ready to load 9. initial tank loading rate max 1m/sec 10. watch pressure gauges 11. advise shore oil being received in tank 12. check off shore manifold 13. check pumproom 14. check other tanks 15. maintain slow loading rate until bottom. 16. stringers covered and turbulence ceased 17.if all is in order inform shore to increase loading rate to agreed maximum check all valves/connections for leaks. Tanker dishcharging procedure: 1. all valves closed. 2. advise engine room to run IG plant 3. maintain IG pressure 4. warm through pumps 5. discharge plan agreed with terminal 6. set valves as per the discharge plan 7. ensure sea valves closed and sealed 8. manifold valves kept closed until terminal ready to receive 9. double check the valve settings 10. when shore ready to receive, open tank valve and start pump slowly 11. if back pressure allows open manifold. 12. check tank level dropping 13. check IG pressure maintained or if no IG, vent valve open.14. check for any leaks, manifold, pumproom and over the sides. 15. if all going to plan and shore confirm receipt of cargo then slowly increase rate of discharge to agreed maximum with all pumps 16. watch the back pressure and do not exceed maximum agreed (slow down). MSS=W*GZ , GZ=GM*SIN THETA , GM=KM-KG , UPRIGHT CONDITION : DIS*GM*SIN THETA , HEELED ANGLE: MSS=W*GZ=DIS*GM*SIN THETA TM. CALCULATE GM:-(MOMENT OF WEIGHT) GG1=W*d / W (FOR A WEIGHT SHIFTED) , GG1=