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Self- unloading bulk carriers cargo hold/ tunnels preparations, maintenance and check items

Hold and tunnel sweeping / washing

Hosing down of holds can be minimised by the following:-

  1. Thorough draining down of the holds
  2. Optimum usage of vibrators
  3. Guiding the gate operators during draining
  4. On completion of discharge and if hosing down is required, the following is to be carried out:-
  5. All conveyors must be stopped with their emergency switches operated and motors isolated.
  6. Every effort must be made to bring down the sweepings onto the gates prior to hosing down
  7. A responsible person must be delegated to act as a supervisor during the hosing down operation
  8. The entry into the holds checklist must be completed prior to entry into the holds
  9. All the hold gates must be set cracked open, to allow water and fine residue to drain onto the belt
  10. Bulky and heavy residue must only be allowed onto the belt providing that it will not become overloaded.

If there is a risk of the belt being overloaded, and once it is confirmed that all Crew members have evacuated the holds then the conveyor may be started, and the heavy residue run out onto deck It is very important that the hold and tunnel hosing, is planned and a schedule is agreed upon between the Chief Officer and Chief Engineer. A person must be delegated to pump out the water draining into the tunnel through the gates. The vessel will normally have sufficient trim in the ballast passage, but if it is required to list the vessel slightly, the Chief Officer must inform the Master and the Duty Officer on the bridge of his intentions to list the vessel.

self unloader components
Fig:self unloader ready for operation

The Chief Officer is to inspect all holds after cleaning/washing, and ensure their cleanliness. The Chief Engineer is to inspect the tunnel, belts, hoppers, etc. and all related spaces for cleanliness. It is not unusual for residual cargo or spillages to adhere to the supporting structures in the tunnel after discharging, and become loose later. This may fall onto the belts during any subsequent discharge and cause contamination. Every effort must be made to identify these areas and include them in the inspections.

The inspections must be carried out in good light. If the condition is unsatisfactory, the space must be re-washed prior to arrival, taking into account the drying time required.

The use of trash pumps must only be when essential, and care must be taken not to pump any hard residues which may damage their impellers.

After completion of seawater hosing, a fresh water rinse must always be carried out, providing that there is adequate quantities of fresh water available on board. Salt deposits are corrosive and will damage the coatings, and subsequently the steelwork. If any of the UHMW sheets have been loosened such that they may trap or retain water between them and the steel surface, it must be re-fitted and the edges sealed.

The tunnel bilges must be cleaned after each hose down, and the bilge alarms tested. When disposing of waste or residual materials, reference is to be made to the MARPOL regulations, and they must be complied with.

Sufficient drying time and ventilation must be allowed after hosing down. The hold gates must be shut and isolated, and regular inspections made to ensure that any accidental opening of a gate has not occurred. Again, after commencement of loading, inspections of the Tunnel must be made, to ensure that a gate has not opened due to the pressure of cargo being loaded). The Holds, Tunnel and Spaces, must be ready and presented to the shippers for approval and certification.

Checks to be performed after each discharge

The following checks are to be carried out on the unloading gear after each discharge and the vessel has been cleaned and spillage run off. The head tunnelman is to perform these checks but the Chief Engineer must also check the system and satisfy himself that no problems have been overlooked.

  1. Visually inspect all the belts for mechanical damage, paying particular attention to the splice area.
  2. Vibrators are to be test run, loose units tightened, and defective units changed.
  3. Visually inspect all belt scrapers, and adjust tension as required.
  4. In the case of Flexowell Lift Belts, run each belt on manual (slow speed) and inspect all belt edges for damage.
  5. Carry out cold repairs to belt edge damage immediately to prevent water permeating the inside of the belt, and resulting in corrosion to the steel core cables. In the case of Flexowell Lift Belts, check all rubber side guide wheels are free to run, and repair any which are seized as soon as possible.
  6. Change out any defective rollers, noted during the previous unloading.
  7. Replace any leaking hoses.

Maintenance and conditions of cargo holds

It is of the utmost importance that all the vessel’s cargo holds are maintained to the highest possible standard. The condition of the UHMW lining is to be assessed after every discharge, and replacement of missing sheets carried out as required, to maintain intact linings in the holds. The ‘flow ability’ of the bulk cargoes are dependent on this to improve the discharge rates, and also to prevent the potentially dangerous time consuming man-entry into holds, for the clearing of cargo hang-ups.

It is the Chief Officers responsibility to ensure that work is carried out in the holds whenever possible during ballast passages. He is to liase with the Chief Engineer for the replacement of missing, or loosened UHMW sheeting. It is the Masters overall responsibility to inspect Cargo Holds on a regular basis, and to report their condition to the relevant Management Office. This report is to be made on the Company Hold Condition Form provided, at quarterly intervals. Additionally, a report of the condition of UHMW lining is to be attached, as required or be incorporated in the report. The requisition for spare UHMW sheets and studs etc, is to be made timely.

The report must be unbiased and any deterioration of the cargo holds since the last report, must be reported to the relevant Management Office and before the next quarterly report.

The continuous employment of the vessel is dependent on the condition of the Holds and their upgrading. However, under no circumstances is any upgrading work to be carried out in a cargo Hold, which contains cargo. Many claims have been made against Owners for cargo damage and/or contamination by rust, paint, grease, even though there appeared to be no damage at the time. In addition, any paint applied prior to loading a cargo must be applied in time to allow sufficient drying and hardening.

When fitting UHMW sheets, all necessary fire precautions must be taken. The steel surface condition under the sheets can be assessed by an estimation of the exposed area in way of a missing or loosened sheets, and a suspect areas may be examined by removing the sheets in a way.

During routine inspections of the cargo Holds by the Master or Chief Officer, special attention must be given to the safety aspects such as, conditions of Hold ladders, hand rails and platforms. Any defects are to be repaired immediately, and inspected by the Master or Chief Officer, to authorise them safe for use. When cleaning the Holds, it is the duty of every Crew Member present to report to the Chief Officer any defects that they may notice.

It is recognised that access to the underside of hatch covers for maintenance is difficult, however, the inspection and any subsequent remedial repair work, rust removal, and the rectification of flaking paintwork is essential to avoid cargo contamination.

It is advisable, to avoid the washing down of holds unless absolutely necessary. When the next cargo is similar and compatible with the previous cargo carried, Hold and Tunnel washing can be avoided, unless there is an express requirement.

A good clean out of the holds by the optimum use of vibrators and guidance of gate Operators from the deck by the Duty Officer, will considerably reduce the residual cargo in the holds.

The watertight integrity of the hatch covers is of the utmost importance and concern. All hatch cover packing, compression bars, battening down arrangements etc. must be inspected and repaired or renewed as necessary.

At points where sealing rubber sections are joined, gaps may begin to appear and this must be remedied. The sealing rubbers must be free of rust and paint flakes. The trackway channels must be cleaned out after every loading and any obstruction between the compression bars and the sealing rubbers removed. The inter-pontoon hinge-ways and sealing rubber are to be clean, and clear of obstruction. All hatch covers and coaming drain channels must be clear, to allow water to drain out freely.

All battening down clamps, G-bolts, cleats etc must be adjusted correctly, to maintain the water-tight integrity, and ensure the safety of the ship and her cargo.

The application of hatch sealing tape, such as Ramneck, as an extra precaution against water ingress is fully recommended by the Company, regardless of the age and condition of the vessel, and particularly in the case of delicate and susceptible cargoes. An adequate supply of sealing tape is to be maintained onboard at all times.

The machinery and associated equipment required for the opening and closing of hatch covers, must be kept in good working order at all times, and any defects which may hinder the operation and cannot be rectified immediately by the ships crew, must be notified to the relevant Management Office. Claims can result from hatch-covers not being opened in time, or the vessel being ordered off the berth due to delays caused by opening/closing systems, not operating efficiently.

Where hydraulic systems are employed, care must be taken to avoid leakage of hydraulic fluid, which may cause hazardous conditions on the deck, and possible injury to the ship or shore personnel. In the case of hydraulic fluid escaping over side, the Coast Guard or such authority are to be notified, and clean-up procedures implemented.

Due to possible claims for cargo damage by water ingress through hatch covers owing to poor sealing, it is necessary to chalk test all seals when possible. The suspect areas are to be marked and hose tests carried out during a ballast passage. The findings of this test are to be reported to the relevant Management Office.

Particular attention is drawn to examination for fractures, cracks, or corrosion in the structure of the cargo holds. Reference is to be made to the guide issued by Lloyds Register of where to look, and what to look for. Masters must be aware, and make others aware of the contents of these guidelines.

Related information

Cargo holds readinesss, maintenance requirement, preventing stevedore damages & safety aspects

Watertight integrity for cargo holds & hatch cover strength requirements for bulk carriers

Maintenance procedure for mechanical steel hatch covers

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Our detail pages illustrated many safety aspects of Bulk carrier

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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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