What are Precautions while loading Grain Cargo on ships?

Prior loading:

1. Get cargo information from the shipper.
2. Calculate the stability criteria complies with the requirement of International grain code.
3. Planning, calculation and loading to be made for ship’s stability at all stages of loading.
4. Clean  cargo holds for loading grain.
5. Test cargo hold bilges.
6. Check weather tightness of hatches.
7. Initial draft survey to be carried out before loading grain.

During loading:

1. Check stresses on hull are within the limit.
2. Trimming of cargo to be carried out as per loading plan
3. Check cargo for any sort of damage.
4. Check moorings at frequent intervals

Prior sailing:

1. Securing cargo as per grain code, to reduce grain heeling moment.
2. All cargo holds to be closed and properly secured.
3. Prevent entering of sea water during adverse weather condition.
4. Calculate final state of stability after completion of loading

Points to pounder for grain loading:

1. Most grains have an angle of repose (slip angle) of about 20° from the horizontal, which means that if the ship rolls more than 20° the cargo will shift. Then this happens the ship will develop a large list, lying on her side and still rolling will obviously cause a greater shift of cargo which in turn will capsize the vessel.
2. To avoid shifting of cargo, the grain surfaces must be reasonably trimmed:
   • Filled compartment, trimmed ­ the cargo should be trimmed so that all spaces under deck and hatch covers are filled to the fullest extent possible.
3. If the cargo is stowed only in the lower compartment, the lower compartment hatch covers should be secured in the approved manner.
4. In partly filled compartments, the surface of bulk grain should be secured by over-stowing except in cases where heeling moments due to grain shift have been calculated and taken into consideration for stability of the vessel.
5. Longitudinal divisions may be fitted to reduce heeling moments due to shift of grain in filled compartments, trimmed, filled compartments, untrimmed and partly filled compartments.

Note :-

This Code applies to ships regardless of size, including those of less than 500 tons gross tonnage, engaged in the carriage of grain in bulk, to which part C of chapter VI of the 1974 SOLAS Convention, as amended, applies.
The term grain covers wheat, maize (corn), oats, rye, barley, rice, pulses, seeds and processed forms thereof, whose behavior is similar to that of grain in its natural state.
For the purpose of this Code, the expression “ships constructed” means “ships the keels of which are laid or which are at a similar stage of construction”.
The term filled compartment, trimmed, refers to any cargo space in which, after loading and trimming as required under grain code, the bulk grain is at its highest possible level
The term filled compartment, untrimmed, refers to a cargo space which is filled to the maximum extent possible in way of the hatch opening but which has not been trimmed outside the periphery of the hatch opening either by the provisions of grain code  for all ships or  for specially suitable compartments.
The term partly filled compartment refers to any cargo space wherein the bulk grain is not loaded in the manner prescribed in grain code i.e(neither filled compartment, trimmed nor filled compartment , untrimmed).

Stability requirements for Grain Loading: –

The intact stability characteristics of any ship carrying bulk grain shall be shown to meet, throughout the voyage, at least the following criteria after taking into account in the manner described in part B of this Code and, the heeling moments due to grain shift:

• The angle of heel due to the shift of grain shall not be greater than 12° or in the case of ships constructed on or after 1 January 1994 the angle at which the deck edge is immersed, whichever is the lesser;
• In the statical stability diagram, the net or residual area between the heeling arm curve and the righting arm curve up to the angle of heel of maximum difference between the ordinates of the two curves, or 40° or the angle of flooding (01), whichever is the least, shall in all conditions of loading be not less than 0.075 metre-radians; and
• The initial metacentric height, after correction for the free surface effects of liquids in tanks, shall be not less than 0.30 meter.
• Before loading bulk grain the master shall, if so required by the Contracting Government of the country of the port of loading, demonstrate the ability of the ship at all stages of any voyage to comply with the stability criteria required by this section.
• After loading, the master shall ensure that the ship is upright before proceeding to sea.

 

Stowage of bulk grain as per grain code

 All necessary and reasonable trimming shall be performed to level all free grain surfaces and to minimize the effect of grain shifting.

• In any filled compartment, trimmed, the bulk grain shall be trimmed so as to fill all spaces under the decks and hatch covers to the maximum extent possible.
• In any filled compartment, untrimmed, the bulk grain shall be filled to the maximum extent possible in way of the hatch opening but may be at its natural angle of repose outside the periphery of the hatch opening. A filled compartment may qualify for this classification if it falls into one of the following categories:
  1. The Administration issuing the document of authorization may, under grain code , grant dispensation from trimming in those cases where the underdeck void geometry resulting from free flowing grain into a compartment, which may be provided with feeder ducts, perforated decks or other similar means, is taken into account when calculating the void depths; or
  2. The compartment is “specially suitable” as defined grain code, in which case dispensation may be granted from trimming the ends of that compartment.

• If there is no bulk grain or other cargo above a lower cargo space containing grain, the hatch covers shall be secured in an approved manner having regard to the mass and permanent arrangements provided for securing such covers.
• When bulk grain is stowed on top of closed ‘tween-deck hatch covers which are not grain-tight, such covers shall be made grain-tight by taping the joints, covering the entire hatchway with tarpaulins or separation cloths, or other suitable means.
• After loading, all free grain surfaces in partly filled compartments shall be level.
• In filled compartments, trimmed; filled compartments, untrimmed; and partly filled compartments, longitudinal divisions may be installed as a device to reduce the adverse heeling effect of grain shift provided that:
  1. The division is grain-tight;
  2. The construction meets the requirements of raincode.