Prior to loading grain, all ships are usually subject to a survey by an approved independent surveyor. The surveyor will require the ship’s particulars, and details of at least the last three cargoes carried. He will then inspect the holds for cleanliness and infestation, and the presence of any material that could lead to infestation or contamination.
When the surveyor is satisfied, he will issue the ship with a certificate to confirm that the holds are clean. However this is not a guarantee that the holds are perfectly clean and that no cargo claim will result.
In the dry bulk trades, there are essentially five grades of hold cleanliness:
1. hospital clean, or ‘stringent’ cleanliness
2. grain clean, or high cleanliness
3. normal clean
4. shovel clean
5. load on top
Hospital clean is the most stringent, requiring the holds to have 100% intact paint coatings on all surfaces, including the tank top, all ladder rungs and undersides of hatches.
The standard of hospital clean is a requirement for certain cargoes, for example kaolin/china clay, mineral sands including zircon, barytes, rutile sand, ilmenite, fluorspar, chrome ore, soda ash, rice in bulk, and high grades of wood pulp. Generally, these high standards of cleanliness will only be met by vessels trading exclusively with such cargoes. It will rarely be required in the tramp trades.
Grain clean is the most common requirement. A ship will be required to be grain clean for the majority of bulk and break bulk cargoes, such as all grains, soya meal and soya products, alumina, sulphur, bulk cement, bauxite, concentrates, and bulk fertilisers. Some ports and shippers may allow a different standard of cleanliness.
Normal clean means that the holds are swept clean, with no residues of the previous cargo, and washed down (or not, depending on charterer’s requirements), that is, cleaned sufficiently for taking cargoes similar to or compatible with the previous shipment.
Shovel clean means that all previous cargo that can be removed with a ‘Bobcat’ or a rough sweep and clean with shovels by the stevedores or crew. The master should clarify what standard is expected.
Load on top means exactly what it says – the cargo is loaded on top of existing cargo residues. Usually, this means ‘grab cleaned’.
This standard will commonly be required where a ship is trading continuously with the same commodity and grade of that commodity.
This will typically occur when a ship is employed under a Contract of Affreightment to carry, for example, a single grade of coal over a period. With such a trade, there is no commercial need for holds to be cleaned between successive cargoes, and each cargo is simply loaded on top of any remaining residues from the previous cargo.
With load on top, guidance may be necessary for the master on any cleaning requirements, including the use of bulldozers and cleaning gangs.
The most common cleanliness requirement for bulk carriers is that of grain clean.
The usual instructions a master of a tramping conventional bulk carrier will receive, particularly if his ship is unfixed for next employment, is Clean to grain clean on completion of discharge. This guideline is aimed at the majority of bulk carriers engaged in the carriage of ‘usual’ bulk cargoes in conventional ships, which are cleaned to a grain clean standard. As noted above, there are certain cargoes, such as kaolin, which require the higher standard of cleanliness or hospital clean.
The industry accepted definition of grain clean is provided by the National Cargo Bureau (NCB).
“Compartments are to be completely clean, dry, odour-free, and gas-free. All loose scale is to be removed.”
The definition is clear:
1. all past cargo residues and any lashing materials are to be removed from the hold
2. any loose paint or rust scale must be removed
3. if it is necessary to wash the hold, as it generally will be, the holds must be dried after washing
4. the hold must be well ventilated to ensure that it is odour-free and gas-free.
What is ‘loose scale’? It is important to differentiate such scale from oxidation rust (i.e. light atmospheric rusting). Loose scale will break away when struck with a fist or when light pressure is applied with a knife blade or scraper under the edge of the scale. Oxidation rust will typically form on bare metal surfaces but will not flake off when struck or when light pressure from a knife is applied.
Generally, the presence of hard-adhering scale within a hold is acceptable in a grain clean hold. The scale should not fall during the voyage or during normal cargo operations.
Countries apply different standards to what constitutes an acceptable amount of loose scale or loose paint. While in some countries, no such material is permitted, the United States Department of Agriculture permits a single area of loose paint or loose scale of 2.32 sq m, or several patches that in total do not exceed 9.26 sq m, before a hold is deemed to be unfit. In practice, the hold should be free of loose scale as each surveyor’s interpretation of the required ‘standard’ may vary.
Swept clean or shovel clean
The quantity of cargo residues remaining in a hold at the completion of discharge may vary considerably, for a variety of reasons. The master may have control over some of these; for example, after discharging a steel cargo, it may be possible to persuade the stevedores to remove lashing materials, which will greatly assist the crew in their hold cleaning. Often a charterparty will specify that the ship is to be redelivered ‘swept clean’ or ‘shovel clean’. If it is ‘swept clean’, the stevedores the discharge port should sweep the holds before completion of discharge in order to minimise the remaining residues; if it is ‘shovel clean’, the stevedores need do no more than discharge cargo that can be easily accessed with a mechanical shovel or a Bobcat.
If a ship is redelivered with holds that are shovel clean, several tonnes of cargo, might remain in each hold. This must all be swept up by the crew and brought on deck for disposal as permitted. Hold cleaning and cargo removal might take weeks, depending on the amount remaining onboard and available resources.
During the sweeping operation, care should be taken to ensure that:
1. any residues that may be trapped in places such as accessible pipe guards, access ladder trunkings, behind frames and frame knees, are removed
2. hatch cover undersides, if not boxed in, are swept to remove any residues that have accumulated under the covers
3. hatch coamings, hatch trackways, hatch access ladders and internal ladder spaces are cleaned
4. during this sweeping process, the hold bilge wells should be opened and cleaned to remove any residues that may have fallen into them
The parts of the hold that crew can access for cleaning may be limited, particularly in the larger handymax, panamax and capsize ships, because of the dimensions of the holds. Some high-level access may be possible only with scaffold towers, if these can be safely rigged. Even with such equipment, there will still be areas that are inaccessible.
Source: BULK Cargoes – HOLD PREPARATION AND CLEANING by The Standard.