When cargo holds are presented for loading cargoes in bulk and they are not sufficiently clean for the intended cargo, delays, off-hire and charter party disputes can arise. Insufficient cleaning can also cause cargo contamination and infestation, leading to cargo damage claims from cargo receivers. Due to the importance of the preparation and cleaning of cargo holds prior to loading, personnel on vessels involved in preparing cargo holds, and also those ashore involved in fixing and operating vessels, should be familiar with the various issues surrounding the cleaning of holds in order to prevent the possibility of delays, disputes and claims.
Operational guidance addressing the preparation and cleaning of holds between cargoes should be available to both seagoing and shore based staff. The extent of the cleaning operation and the steps required between two dissimilar cargoes will depend on the properties of the previous cargo. When a break bulk cargo such as steel coils has been discharged, the cleaning task may be limited to the removal of old dunnage and lashing materials and a final sweep of the cargo spaces. If a petroleum coke (petcoke) cargo has been carried, the subsequent cleaning operation will be conversely lengthy and involved due to the “dirty” and possibly oily nature of this cargo.
External factors beyond the control of the vessel may also limit and hinder a cleaning operation and these will need to be allowed for; there may be a requirement to ballast a hold at the discharge port, or limited time prior to loading the next cargo, or washing down may not be possible due to freezing temperatures. In general terms holds should be cleaned so that there are no residues of previous cargoes, no loose rust scale, paint flakes or blistering of paint coatings, no evidence of insect or rodent infestation when foodstuffs are to be carried and no odours present, including those from cleaning chemicals and paint. Holds should be thoroughly dried prior to loading though some cargoes may be loaded damp from open stockpiles possibly negating this requirement.
Cargo Hold Inspection and Maintenance
Some cargo contamination issues and the failure of holds by surveyors stem from insufficient hold and hatch cover maintenance. It is recommended that regular inspections and preventative maintenance of cargo holds and hatch covers be carried out as part of a documented planned maintenance system, ideally following the discharge of each cargo. The periodic inspections should be carried out by a responsible officer, ideally the Chief Officer, and cover all structures, surfaces and fixtures and fittings within the holds.
The scope of the hold inspection should include underdeck framing, pipework and guards, access ladders and supporting framework, manhole covers, bilges as well as bulkheads, stools, side framing and tanktops. Similarly, hatchcovers, coamings and associated fixtures and fittings should be periodically inspected and repaired as necessary to maintain weathertightness. Areas of loose rust scale which can be removed without chipping should be eliminated. Areas of flaking paint and paint blisters should also be attended to promptly and made good. Consideration should be given to the chipping or high pressure sandblasting of hard rust scale on the tanktop; thick rust scale can be dislodged by the buckets and tracks of bulldozers etc. during discharge, leading to cargo contamination. If the vessel is principally engaged in the carriage of clean cargoes the paintwork should, so far as possible, be kept fully intact.
Where pipework is found corroded and holed it should be cropped and replaced, as temporary repairs will not be accepted by some surveyors. Holed handrails on access ladders and platforms can retain residues of previous cargoes and should also be cropped and renewed. It should be borne in mind that the type of paint applied may affect the ease with which the holds can be cleaned and epoxy paints are easier to clean than alkyd based paints. Cosmetic touch-up of paintwork over rust may appear an easy short term solution but this is not recommended and may lead to holds being rejected by some hold surveyors as the paint may have, or appear to have, been applied over loose scale.
When steel fixtures and fittings within cargo holds are damaged during cargo operations, these should be promptly repaired. In addition to any safety considerations, contamination claims due to pieces of steel from the hold structure coming loose and being found within the cargo may be encountered. Fixed hold air sampling fire detection systems and fixed CO2 systems should be periodically blown through with compressed air when the holds are free of cargo as a routine task included in the planned maintenance system, so that any debris is blown out and the pipes remain clear for their intended purpose and debris cannot migrate into the hold.
Hold Cleanliness Standards and Requirements
Cleaning commences at the discharge port. All cargo residues should be removed so all that remains are those residues which cannot be recovered using normal methods for unloading which comply with MARPOL Annex V requirements and any local regulatory requirements governing the disposal of cargo residues. Since cargo receivers will normally want a maximum outturn of their cargo it is anticipated that a vessel will usually be re-delivered swept clean, rather than shovel clean. However, in some ports the stevedores may need reminding and encouraging to remove as much of the cargo residues as possible. The cleaning regime to then be used in preparing for the next cargo will depend on a number of factors:
a) The nature of the previous cargo
The previous cargo may be incompatible with the next cargo and which will necessitate particular care when cleaning the holds. Manganese ore, for example, is rendered worthless by the presence of chrome ore, and even small traces of sugar can affect the properties of subsequent cement cargoes.
b) Shipper’s and / or Charterer’s cargo hold cleanliness requirements / contractual hold cleanliness requirements, as specified in the voyage instructions / charter party
Shippers and / or charterers may specify their hold cleanliness requirements or the cleaning regime to be employed to prepare the holds for the next cargo in their voyage instructions / orders.
Requirements may also be included in the charter party and it may well be that reference is made to one of a number of industry standard cleanliness requirements, such as:
1. Load on Top
When the same cargo is to be carried on a successive voyage, it may be possible for the next shipment to be “loaded on top” of the cargo residues remaining in the holds following a grab discharge, provided the charterers are happy with this arrangement. Although loading on top will save considerable cleaning time and effort, the presence of cargo residues in the holds will not permit a thorough inspection of the hold steelwork for damage. Efforts should therefore be made to move the residues to one side so that the hold structures can
be inspected. When load on top is utilised, it may still be worthwhile periodically cleaning the holds after a number of cargoes to prevent staining of paintwork (e.g. by coal), or the build-up of hardened residues (e.g. cement), which will make the cleaning process more demanding the longer they are left.
2. Shovel Clean
Typically, the cargo will be removed by grab with the assistance of a bulldozer / wheel loader / bobcat and shovels, and several tonnes of cargo may remain in each hold requiring the crew to dispose of these residues. However, since the need to comply with MARPOL Annex V limits the scope for the discharge of cargo residues overboard, this cleanliness requirement has become less common.
3. Normal Clean
In the event of no specific requirements being advised by the charterer or contained within the charter party, it is recommended that the following steps be taken, as a minimum:
- Cargo residues be removed
- Double sweep the holds clean
- Seawater wash down
- Fresh water rinse
- Allow the holds to thoroughly dry
Typical bulk cargoes requiring normal cleaned holds may include:
- Iron ore
4. Grain Clean / High Cleanliness
This is the most commonly required standard of cleanliness with the holds free of all traces of previous cargo residues and transferable stains, free of loose rust scale, loose paint flakes, paint blisters and any other contaminants, thoroughly dry and without any trace of infestation or strong odour.
Typical bulk cargoes requiring grain clean holds may include:
- Grain (corn/maize, barley, soybeans, wheat etc.)
- Mineral concentrates
- Seed cake
5. Hospital Clean / Stringent Cleanliness
The cleaning regime is the same as for grain clean, with the added requirement that the holds have fully intact paintwork on all hold and hatch cover surfaces, including the tank top, and on all fixtures and fittings within the hold. Some inspection regimes may permit a small percentage of the total hold surface area with a non-intact paint coating.
Typical bulk cargoes requiring hospital clean holds may include:
- Chrome ore
- Mineral sands
- Rice in bulk
- Soda ash
- Wood pulp
c) Exporting / importing country mandatory requirements
Some exporting and importing countries have detailed hold cleanliness requirements for certain commodities. Australia has particularly strict requirements for the inspection and cleanliness of holds prior to loading fertilizer, as any foreign pests or diseases affecting the cargo could be directly introduced when the fertilizer is applied to the soil. If a single grain of a foreign cargo is found in the fertilizer at an Australian discharge port, this could be sufficient for the entire shipment of fertilizer to be condemned and an order imposed that it be re-exported.
d) International Maritime Solid Bulk Cargo (IMSBC) Code “Hold Cleanliness” requirements
When determining the cleaning requirements for the next cargo the “Hold cleanliness” requirements in the applicable IMSBC Code schedule should also be considered, as compliance with IMSBC Code requirements is mandatory under SOLAS. Many cargo schedules either specify “No special requirements” or “Clean and dry as relevant to the hazards of the cargo”. However, some cargoes have more detailed cleanliness requirements, for example holds being prepared for sulphur UN1350 should be “Clean and dry as relevant to the hazards of the cargo and should be thoroughly clean and washed with fresh water”, and for Direct Reduced Iron (A) the Code advises “The cargo spaces shall be clean, dry and free from salt and residues of previous cargoes” and “Prior to loading, wooden fixtures such as battens, loose dunnage, debris and combustible materials shall be removed”.
The steps taken on the ballast voyage to clean the holds will depend on the foregoing cleanliness standards and requirements. The cleaning requirements should be realistic, as, for example, it will take considerable time, effort and resources to prepare a bulk carrier that has been employed in the log trade ready to load a cargo of mineral sand. Where a Master is any doubt as to the capability of the vessel to prepare the holds to the required standard in the timescale available, they should contact their managers at the earliest opportunity. Cargo hold cleaning will normally consist of one or more of the following steps:
- Removal of dunnage, lashing material and / or cargo residues
- Holds swept down
- Holds swept down a second time (double swept)
- Cargo residues that have set hard removed
- Cleaning chemicals applied to hold surfaces and allowed to penetrate / react with stains prior to being washed off
- Holds sea water washed down
- Holds washed down with detergents mixed in fresh water
- Holds fresh water rinsed to remove all traces of chlorides and detergents
- Bilge wells and plates / strainers cleaned
- Holds air dried
- Loose paint flakes, loose rust scale and paint blisters removed
- Paintwork touched-up
- The application of a barrier coat
Some vessels are equipped with fixed cargo hold washing machines, however, these vessels are in a minority and most vessels carrying solid bulk cargoes will need to manually wash the cargo holds. Where fixed washing machines are used, manual cleaning of shadow sectors within the holds may still be required.
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Source: West of England P&I Club