Carriage of Grain in Bulk

 

Carriage of Grain Safe Procedure - Bulk Carriers Recommended Guideline

  

Grain

One of the most difficult and dangerous cargoes to carry in bulk are grain cargoes. 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.

Most authorities therefore request that the master proves that his ship is capable of remaining stable even if the grain cargo shifts. This is done by the compiling of the Grain Loading Form which fully outlines the ships stability at the worse condition on passage.

Because grain cargoes are liable to shift, heavy emphasis is placed on the stability of ships that carry them. The main reason is the variation in the types of grain, including its size and its ability to develop a free flow state when loaded in bulk. Each ship carrying grain has to provide grain specific stability information, including grain heeling moments, to the terminal. This section looks at various problems, methods and precautions that must be taken when carrying grain cargoes. Grain cargoes carried in bags are not considered as bulk cargo.

The bulk carriers' grain loading manual contains Volumetric Heeling Moments (VHM), which are values based on an assumed surface grain shift of 15° (for a full compartment) and 25° (for a partially full compartment).

 

1. To avoid shifting of cargo, the grain surfaces must be reasonably trimmed:

a) Filled compartment, trimmed ­ the cargo should be trimmed so that all spaces under deck and hatch covers are filled to the fullest extent possible.

b) Filled compartment, untrimmed ­ the cargo should be trimmed within the hatchway but may be left at its natural angle of repose on the surrounding area of the hatchway. The same can be applied for a filled compartment, trimmed if:

 

Dispensation is granted from trimming by the authority issuing the Document of Authorisation on the basis that the cargo can flow freely to underdeck empty areas through feeder ducts, perforated decks, etc, or

The compartment is designated a `Specially Suitable Compartment', in which case exemption may be granted from trimming the compartment ends.

 

2. If the cargo is stowed only in the lower compartment, the lower compartment hatch covers should be secured in the approved manner.

3. If the cargo is stowed in the upper compartment above a tween deck whose covers are not grain- tight, the covers should be made grain-tight using sealing tape, tarpaulins or separation cloths.

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, provided that each division:

a. Is made grain-tight.

b. Is constructed according to the Grain Code standards.

c. Extends from deck to deck in tweendecks.

d. Extends downwards from the underside of the hatch covers.

6. The Master shall ensure that the ship:

a. Before loading, can comply with intact stability criteria at all stages of the voyage.
b. Is upright before proceeding to sea.
c. Has all the paperwork completed and onboard.

 

Terminology Used in the Carriage of Grain in Bulk Carrier

 

The following definitions are from the IMO International Grain Code

The term grain covers wheat, maize (corn), oats, rye, barley, rice, pulses, seeds and processed forms thereof, whose behaviour is similar to that of grain in its natural state.

The term filled compartment, trimmed, refers to any cargo space in which, after loading and trimming as required under A 10.2, 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 A 10.3.1 for all ships or A 10.3.2 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 A 2.2 or A 2.3.

The term angle of flooding (1) means the angle of heel at which openings in the hull, superstructures or deckhouses, which cannot be closed weathertight, immerse. In applying this definition, small openings through which progressive flooding cannot take place need not be considered as open.

The term stowage factor, for the purposes of calculating the grain heeling moment caused by a shift of grain, means the volume per unit weight of the cargo as attested by the loading facility, i.e. no allowance shall be made for lost space when the cargo space is nominally filled.

The term specially suitable compartment refers to a cargo space which is constructed with at least two vertical or sloping, longitudinal, grain- tight divisions which are coincident with the hatch side girders or are so positioned as to limit the effect of any transverse shift of grain. If sloping, the divisions shall have an inclination of not less than 30° to the horizontal.

The Document of Authorisation certifies that a ship is capable of loading grain in accordance with the requirements of the International Grain Code.

 

Grain Loading Standards for Seagoing Bulk Carriers - Limitations Involved

 

Grain is the collective name for the edible seeds of various plants. Many of them are also called cereals, e.g. wheat, barley, although products like maize and rice are also considered under this heading. Most grain, especially wheat and maize (corn), is carried in bulk.

Wheat flour is a powder made from the grinding of wheat used for human consumption. More wheat flour is produced than any other flour. Wheat varieties are called "clean," "white," or "brown" if they have high gluten content, and they are called "soft" or "weak" flour if gluten content is low. Hard flour, or bread flour, is high in gluten, with 12% to 14% gluten content, and has elastic toughness that holds its shape well once baked. Soft flour is comparatively low in gluten and so results in a finer or crumbly texture.[1] Soft flour is usually divided into cake flour, which is the lowest in gluten, and pastry flour, which has slightly more gluten than cake flour.

 

Contaminants

Contaminants are defined individually in these Standards and consist of the following:

  

1) Bread wheat (in durum deliveries only)

2) Cereal Ergot

3) Chemicals not Approved for Wheat

4) Chemicals in excess of the MRL

5) Earcockle

6) Earth

7)Foreign Seeds

8) Insects – Large

9) Insects – Small

10) Loose Smut

11) Objectionable Material

12) Other Non-Objectionable Material

13) Pickling Compounds

14) Ryegrass Ergot

15) Sand

16) Snails

17) Stored Grain Insects and Pea Weevil – Live

18) Contaminants may be referred to as foreign material, being all material other than whole or broken seeds or hulls of the wheat being assessed.


Defective Grains

Defective grains refer to wheat that has been damaged to some degree, as outlined in these Standards. They include the following:


1) Dry Green or Sappy
2) Field Fungi
3) Frost Damaged
4) Heat Damaged, Bin Burnt, Storage Mould Affected or Rotted
5) Insect Damaged
6) Non vitreous kernels (Durum only)
7) Over-Dried Damaged
8) Pink Stained
9) Smut
10) Sprouted
11) Stained

 

Take all Affected

Hazard: It may sift when aerated. This cargo is non-combustible or has a low fire risk

Hold cleanliness: Clean and dry as relevant to the hazards of the cargo

Stowage & segregation: No special requirement

Ventilation: The cargo spaces carrying this cargo shall not be ventilated during voyage.


Loading

The ship shall be kept upright during loading of this cargo. This cargo shall be so trimmed to the boundaries of the cargo space that the angle of the surface of the cargo with horizontal plane does not exceed 25 deg. This cargo shall be kept as dry as practicable. This cargo shall not be handled during precipitation. During handling of this cargo, all non working hatches of the cargo spaces into which the cargo is loaded or to be loaded shall be closed


Precautions

Appropriate precautions shall be taken to protect machinery and accommodation spaces from the dust of the cargo. Bilge wells of the cargo spaces shall be protected from ingress of the cargo. Person who may be exposed the dust of the cargo shall wear protective clothing, goggles or other equivalent dust eye protection and dust filter masks, as necessary. Bilge wells shall be clean. Dry and covered as appropriate, to prevent ingress of the cargo.


Carriage

After completion of loading of this cargo, the hatches of the cargo spaces shall be sealed as necessary. All vents and access ways to the cargo spaces shall shut during the voyage. Bilges in the cargo spaces carrying this cargo shall not be pumped unless special precautions are taken.


Discharge

No special requirement


Clean up

In the case that the residues of this cargo are to be washed out, the cargo spaces and the other structures and equipment which may have been in contact with this cargo or its dust shall be thoroughly swept prior to washing out. Particular attention shall be paid to bilge wells and framework in the cargo spaces. The fixed bilge pumps shall not be used to pump the cargo spaces, because this cargo may make the bilge system inoperative.

Example :
Loading Port - Geraldton / Australia

Discharging port - Phu May/ Vietnam


PnI Case

Members should be aware that there is a strong risk of spurious cargo claims being made on grain cargoes in Iraq. During the discharge of an Argentinean wheat cargo at Umm Qasr, the Iraqi receivers claimed that cargo in one hold was contaminated with e-coli bacteria. The cargo was analyzed three times by a local health authority laboratory and on each occasion the tests were positive. The Member had a cargo sample analyzed by Solomon and Seaber in the UK and the result was negative.

 

 

 

 SOURCE: 

http://bulkcarrierguide.com/carriage-of-grain.html

http://bulkcarrierguide.com/grain-terms-for-loading.html

http://bulkcarrierguide.com/grain-handling-precautions.html