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Cargo work safety - Self-unloaders procedure

Self unloading bulk carriers uses horizontal and vertical conveyor systems to discharge bulk cargoes. Originally developed to allow ships to handle cargoes at ports not equipped with their own gear, they are also used to reduce handling costs by minimising the need for stevedores.

Preventing/Dealing with Spillage’s and Overloads:

It is absolutely essential to avoid any spillage, and belt overload by taking the following measurements and precautions:-

  1. Correct training and belt tensioning.
  2. Adjustment of scrapers.
  3. Proper control of cargo flow onto the belt.
  4. Maintaining proper hydraulic line pressures on the gates.

  5. Careful monitoring of the belt load meter settings in the CCR when operating at maximum capacity.
  6. Frequent inspection of the system to identify any malfunction.
  7. Maintaining a shore hopper/boom watch to prevent overloading the shore system.


Cargo on the Return Belt

When spillage occurs or pieces of cargo bounce off the carrying side of the hold conveyor belt and falls onto its return side, this cargo will get in between the carriage components and cause damage to them. Proper control of the cargo flow onto the belt and good belt tracking will prevent this occurrence. If spillage occurs, the hold conveyor must be stopped, using the pull chord to clear the spill.

self unloader alongside terminal
Fig: self unloader alongside terminal

Max Dimension of Cargo per C/P

The C/P states that the maximum size of a stone/rock/piece of cargo, which is allowable is 10 cm in any direction. Oversized cargo may cause damage to the belt cover, or get stuck in the system causing further damage. If oversized pieces are noted, samples must be kept aside, and a protest issued to the Shippers. The relevant Ship Management Office and Owners must be informed immediately.

Danger in the Loop Area:

No unauthorised persons are allowed in the Loop area and the CCR must be informed prior to entry. Crew entering this area must wear protective clothing and exercise caution, as there is danger of falling cargo, which may have slipped through the loop belt, or fallen off the elevator belt. The Chief Engineer can restrict entry as necessary.

Loop Water Sprinkler

A water-sprinkler arrangement is provided to protect the Loop House. It is not an automatic arrangement, and must be turned on immediately in the event of a fire. The water output from this sprinkler may prove inadequate and is basically to cover the period until fire hoses are ready. The water sprinkler arrangement must be tested regularly to ensure that the nozzles are not blocked.

ND Ultrasonic Testing of the Boom

Regular and thorough visual checks of the Boom structure are to be carried out. If excessive deflection or fractured welding is sighted, then the Boom structure must be subjected to dye penetrant testing of all suspect welding. Evidence of cracking of any welding etc is to be followed by an Ultrasonic examination of the entire Boom Structure by an accredited Company.

Entry Procedure to clear Hang-Ups

Cement carrier KEDAH CEMENT II
According to The Motor Ship May 1996 )

The self-loading/discharging cement carrier KEDAH CEMENT II was built by Pan-United Shipyard, Singapore. The ship has four holds, each centrally divided by a longitudinal bulkhead. The cement-handling plant has been supplied by the German Company IBAU and is designed to handle two different grades of Portland cement, based on a specific gravity of airless cement of 1.1/1.4t/m3. There is a central loading station located amidships on the main deck with four fluidslides. Cement is loaded at a rate of about 1000 t/h, using air slides and gravity. High-pressure fans supply fluidisation air to the loading slides and distributors. Four electrically-driven piston blowers supply the aeration of the cargo holds.

Discharge of the cargo is from the bottom of the sloping holds through cement pumps onto a conveyor belt. The cargo hold bottoms are sloped 7° athwartships and 11° in the fore and aft direction. Each of the four electrically-driven cargo pumps has a capacity of 200t.

Again, fluidisation of the cargo is necessary during discharge, especially since the cargo tends to settle and consolidate during transit. In this case, it is achieved by fluidisation air channels in the holds, which move the cargo towards the flow gate. The rate of discharge from each hold is controlled by the flow gate connected to the cargo pumps. The total distance covered by the conveyor belt is about 590m. This includes lifting the cargo up to 50m and eight 90deg bends are included in the belt run. Discharge at the ship side is through four cargo hoses, stowed on the main deck, when not in use and handled by a MacGregor-Haglund 15t crane. Propulsion is by twin engines with a total output of 5279kW to give a service speed of 13.5knots.

The engines drive through a double input/single output gearbox driving a 4-bladed 4.7m diameter CP propeller with a gear ratio of 1:4.2 to give a propeller speed of 135rpm. The gearbox is also equipped with two A van Kaick PTO rated at 2160kW each. To aid manoeuvrability the ship is fitted with a 640kW Wärtsilä Lips CP bow thruster rated at 10t.

Length, oa: 145.0m, Length, bp: 136.1m, Beam, mld: 22.0m, Depth, mld to the main deck: 12.20m, Draught design/scantling: 9.0/9.50m, Deadweight design/scantling: 16,000/17,300dwt, Cargo capacity: 3600m3, Output: 2x2650kW, Speed: 13.5 knots.

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Safe working practice onboard self unloading bulk carriers

Our detail pages illustrated many safety aspects of Bulk carrier

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Related information

  1. Self unloader components

  2. Function of loop & bucket belt elevators

  3. Various type boom conveyor belts - How the belt sytem practically works ?

  4. Dealing with self unloaders stalled lift belt

  5. Conveyor belt construction & troubleshoot guide

  6. Conveyor belt installation guide

  7. Conveyor belt repair & maintenence guide

  8. Safe working practice onboard self unloading bulk carriers

  9. Preventing conveyor belt fire onboard self unloading bulk carriers

  10. Cargo work safety precautions

  11. Various bulk cargoes - free flow ability

  12. Various bulk cargoes & dealing with cargo hang ups

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  15. Preparations for cargo planning, handling & stowage

  16. Maintaining safe stability onboard self-unloading bulk carriers

  17. Procedure for bulk cargo handling prior to and during loading

  18. Loading operations - voyage orders, draft restrictions, various grades and rates

  19. Loading sequence and other related considerations

  20. Preparations for discharging & related guideline

  21. self-unloaders-discharging-operation

  22. Safety precautions for boom operation

  23. Directing gate operation, gate problems & crew duties

  24. Cargo holds/ tunnels cleaning, maintenance and check items

  25. Procedure for transporting coal on self- unloading bulk carriers

Operation of sea going bulk carriers involved numerous hazards . Careful planning and exercising due caution for all critical shipboard matters are important . This site is a quick reference to international shipping community with guidance and information on the loading and discharging of modern bulk carriers so as to remain within the limitations as specified by the classification society.
It is vital to reduce the likelihood of over-stressing the ship's structure and also complying with all essential safety measures for a safe passage at sea. Our detail pages contain various bulk carrier related topics that might be useful for people working on board and those who working ashore in the terminal. For any remarks please Contact us

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