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Cement is considered to be a troublesome cargo for sea carriage. Ships are naturally supposed to be at sea - in the water - & cement is damaged in contact with water as well as in humid atmosphere. There are many other reasons such as cleaning, damage to deck & engine machinery, bilge line plugging & so on.
Cement cargoes, which account for about 5% of the dry bulk trade, can prove to be extremely problematic when carried in conventional bulk carriers as opposed to specialized cement carriers. If not dealt with in an appropriate manner, cement carriage can result in cleaning expenses of over USD 100,000 and delay the vessel for a significant period of time.
The following notes are aimed to be used as guidelines for safe &efficient maritime transportation of cement.
►Prior loading:
The main problems with cement cargo arise when holds are not initially dry, clean and watertight. The majority of claims arising from cement cargo are caused by the following factors:
Solidification when wet
Contamination by residues of previous cargoes
Retention of heat when loaded warm
Packaging:
Cement, if not carried in bulk, is usually shipped in 50 kg paper bags or one/two tonne polypropylene bags.
These must be further packaged in water-proof material as absorption of moisture or carbon dioxide from the air can significantly deteriorate cement over time.
The deterioration may not be visible but it significantly reduces its performance.
Solidification:
It is crucial to ensure all holds and bilges are completely dry prior to loading.
It is also of paramount importance that all valves in the drain and bilge systems are thoroughly checked and confirmed to be operational. Dysfunctional valves can allow water to seep into holds through the bilge line system causing the cement in the holds to solidify.
An ultrasonic test before loading must be conducted in order to ensure the hatch covers are weather tight. The ultrasonic test saves a lot of trouble in comparison with other conventional methods (hose test, chalk test) of checking weather- tightness and has become the international standard in recent years. If seawater leaks though the hatch covers, the cement can harden and result in damage to the vessel, unloading equipment, loss of cargo, additional removal work and possible damages to the terminal.
Cargo in good condition
Partially wet cargo (to be rejected)
Contamination:
Cargo holds must be clean and odour-free.
It must be clarified in the charter-party what level of cleanliness is required on delivery and an independent surveyor can be employed to make sure the vessel is ready to load cement.
Cargo residues such as sugar and fertilizers may result in the contamination of cement cargoes. Raw sugar reacts with cement and even small amounts seriously affect the setting and hardening performance of cement. As little as 0.001% of sugar, if mixed with cement, renders it worthless. Some cement companies do not allow cement to be carried on vessels which have carried previous sugar cargoes.
Temperature:
It is important to check the temperature of cement before loading, as its temperature can be as high as 110°C when leaving the production site. This should especially be considered when loading takes place alongside the factory and cargo is loaded as soon as it is passed through the kilns.
Loading cement at high temperatures (over 100°C), not only damages hold coatings, but also leads to the production of water vapour within the holds.
Conducting pre-loading surveys to ensure all cargo is below 100°C can prevent cargo and vessel damage
When incoming air has a lower temperature than the cargo in the holds, the surrounding air cools and produces vapour which condenses. This results in the solidification of cement in the cargo holds. The wet cement dries in the holds and hardens, leading to troublesome cleaning problems.
Good ventilation can reduce the occurrence of this, but only when the weather is not extremely humid.
The temperature can also be raised and the cargo damaged due to heat transfer from the Double Bottom Fuel Oil Tanks. High viscosity, low quality, heavy fuel oil is unpumpable at low temperatures and so heating of the oil becomes necessary. The extent of damage varies with the moisture content of the cargo and the duration of the heating. A common cause of this problem is the lack of communication between the Engine and Deck Departments. Another common cause of overheating of fuel oil is the incorrect operation and poor maintenance of steam values, which if not completely closed result in a continuous flow of steam through the heating lines, leading to unnecessary prolonged heating.
Precautions:
There are special chemicals that may be applied to the cargo holds before loading that serve to protect the surface from the cargo and subsequent cleaning processes. However, these chemicals must be applied according to the manufacturer’s recommendations as they may prove to be difficult to remove and cause problems when the holds are repainted.
Wet cargo, due to rain, must be separated from sound cargo before the commencement of loading.
The loading process into holds results in the creation of large amounts of cement dust settling on all exposed areas. All areas must be swept and/ or washed down after the completion of loading to prevent loose cement from hardening if exposed to seawater or rainwater during the vessel’s journey.
►During loading:
If it is warm and humid at the port of loading, hatch covers should be closed as soon as loading has been completed to retain dry air inside the holds.
Hatch covers should also be kept closed during intervals in loading, especially if there is a possibility of rain.
Closed loading systems:
Closed loading systems entail pumping cargo under high pressure into the holds through a loading chute, while the hold covers remain closed.
When loading cement in this manner it could result in a large amount of cement dust sticking to the hatch cover undersides, hatch track-ways, hatch coamings, drain holes and drain channels. Incorrect loading equipment could worsen the situation. If this cement dust is not cleaned, it would harden and result in the blockage of the drain holes and channels on coming into contact with rainwater or seawater during the voyage.
►After loading (before departure):
The main deck, hatch covers, hatch coamings, drain holes and draining channels should be swept and washed down before departure of the vessel.
If not forbidden by the port due to anti-pollution regulations, these areas should be cleaned with compressed air. This prevents any loose cement in these areas from hardening if exposed to water.
Before loading Cement After loading Cement
►During discharge:
Discharge should not be undertaken during periods of bad weather.
Charterers may be asked for a LOI if they insist on discharge. This would usually serve to place all liability and damage risks on charterers.
►After discharge:
After discharge, dry residue and pockets of cement remain loosely adhered to exposed surfaces in the hold, including bilge wells, cargo hold bulkheads, hatch cover undersides and hatch coamings.
The cement dust in these areas should be cleaned using brooms, brushes and air guns with the help of Cherry Pickers. When all cement dust has been swept away, all areas should be washed with seawater using high pressure hoses (2,500 psi).
If there is semi-hardened cement visible on the hold surfaces, a more aggressive approach should be employed from the start. Stiff bristle brushes and hand scrapers should be used to remove as much as the cement as possible. If hardened, pressure hoses will not successfully remove the cement and only worsen the situation. Water will aid in the hardening process of the cement, causing more damage and further delaying the cleaning process.
If manually sweeping and scraping the surface does not remove the hardened cement, additional equipment such as very high pressure washers (20,000 psi) may have to be loaded on board. These are expensive, extremely heavy and cause delay.
If the hard residues can still not be removed by high pressure water/air, it may become necessary to remove the hardened cement with acid cleaners or specialized machines. The acid may cause damage to the hold paint and thus must be diluted with freshwater. Check the hold paint manufacturer’s recommendation as to which acid cleaners they suggest be used. Acid cleaners must be used with great precaution as they can cause harm to the cleaning crew. Material Safety Data Sheets should always be consulted.
► Contractual Requirements:
Hold Cleanliness on Delivery:
Most charter-parties provide for the holds to be clean-swept on delivery.
CEMENT VOY - Clause 6
“At loading port before tendering notice of readiness, the Owners and the Master shall ensure that the Vessel’s holds are clean and dry and in all respects suitable to receive the cargo.
If, after tendering of notice, the Vessel is nevertheless found by the Charterers’ Surveyors not to be clean and dry, the time from the Vessel being found not to be clean and dry until she is in fact clean and dry shall not count as lay-time or, if the Vessel is already on demurrage, as time on demurrage. The Owners shall be responsible for unavoidable standby charges for trucks, railcars, barges and gangs incurred directly due to the resulting delay in loading.
If, in the Owners’ opinion, acceptance of the holds is unreasonably withheld, the parties shall appoint jointly an independent Surveyor whose decision shall be final.”
NYPE ’93 form
“The vessel on her delivery shall be ready to receive cargo with clean-swept holds and tight, staunch, strong and in every way fitted for ordinary cargo service, having water ballast and with sufficient power to operate all cargo-handling gear simultaneously.”
***It is important to remember, however, that this obligation of owners does not usually extend to subsequent loading ports. Charterers must clearly specify the degree of cleanliness required in the charter-party, as once accepted at the time of delivery, charterers cannot reject an 'unclean vessel’ at a subsequent loading port.
Intermediate hold cleaning:
Owners do not have an obligation to warrant clean holds at every load port subsequent to the port of delivery. However, some charter-parties contain express intermediate hold cleaning and/or customary assistance clauses, which oblige the crew to undertake the cleaning of holds in preparation of the next cargo.
NYPE ’93 – clause 8
a) The Master shall perform the voyages with due dispatch, and shall render all customary assistance with the Vessel’s crew.
NYPE ’93 – clause 36
“The Charterers shall provide and pay extra for sweeping and/or washing and/or cleaning of holds between voyages and/or between cargoes provided such work can be undertaken by the crew and is permitted by local regulations, at the rate of … per hold.
In connection with any such operation, the Owners shall not be responsible if the Vessel’s holds are not accepted or passed by the port or any other authority.
It is important to remember that the crew are not skilled cleaning operatives and charterers are expected to know when fixing, what cargoes the vessel can carry consecutively without the need of specialized intermediate cleaning. The extent to which a particular service is customary or not; will depend on the facts and circumstances but with regard to hold cleaning there are limits to what the crew can be expected to do.
In addition, the intermediate hold cleaning clauses in a charter-party must be specific. The extent of the intermediate hold cleaning by the crew will depend on the construction of the clause in the charter-party. The charter-party must specifically state the cleaning obligations of the crew and clearly identify Owners liability in this regard.
►Redelivery Obligations:
Charterers usually have an obligation to discharge all cargo before re-delivery of the vessel. Remaining cargo in the holds results in extra cleaning costs and time lost, which owners will seek to claim from charterers. Charterers must be aware of their re-delivery obligations under the charter-party.
CEMENT VOY - Clause 15
“After the Charterers’ shore discharging equipment or the Vessel’s grabs have removed as much cargo as possible, to facilitate the discharging of the remaining cargo residues, the Charterers shall supply free of risk, liability and expense to the Owners, suitable trimming equipment, including bulldozers, and labour. The discharging will be considered completed and lay-time shall cease when the Vessel has been shovel cleaned and all the Charterers’ equipment has been returned to the shore.”
As for cleaning of the holds on re-delivery, specific provisions in the charter-party either place this obligation on the charterers or the owners. The charterers may be required to re-deliver the vessel in a condition as it was on delivery or the charterers may have option to re-deliver the vessel with unclean and unswept holds for a fixed payment stated in the charter-party.
NYPE – Bulk Cement Protective Clause
“Charterers have liberty to carry bulk cement on following conditions…
h)Charterers undertake, after the loading and discharge of such cargo to clean the vessel with their labour time and expense and to bring the vessel in such a condition as was before the loading of this cargo
i)Charterers to be responsible and to pay for thorough cleaning up of all cargo residues from holds, removal/ disposal of residues and washing down/ pumping out of wash water, of all holds by fresh water, immediately after discharge, at their time and expense including equipment and machinery”
NYPE ’93 – clause 36
“The Charterers shall have the option to re-deliver the Vessel with unclean/ unswept holds against a lump sum payment of … in lieu of cleaning.”
►Cement Clinker:
Cement clinker is the semi-manufactured material which needs to be ground into powder to make ordinary cement. It may present fewer problems than the carriage of cement. Its biggest advantage is that it does not harden when in contact with water, reducing the damage it can cause to the vessel. It must, however, still be kept dry so as to prevent it from caking. Contamination with seawater also results in an increase in its chloride content, adversely affecting the cement produced from it.
►Safety:
Crew involved during the loading, discharging and cleaning process must always be provided with appropriate personal protective equipment (“PPE”) and trained on using it properly. Appropriate PPE will include chemical gloves, chemical body suits, eye goggles, breathing masks and boots. All crew must be trained in how to use them properly. Whereas dry cement dust can cause severe eye and respiratory irritation when it comes in contact with mucous membranes, wet cement can also cause severe skin burns if not washed off properly.
►Useful Tips:
Make sure the holds are clean and dry before loading
Be extremely careful if the vessel has previously carried a cargo of sugar
Conduct an ultrasonic test before loading to ensure hatch covers are weather tight
Discourage loading and unloading during periods of bad weather
Discourage loading cargo at very high temperatures as this could produce water vapor in the holds
After loading, ensure all cement dust is swept away from all exposed surfaces to prevent it from hardening on contact with rainwater or seawater
Always ensure crew dealing with cement are provided and trained in using the appropriate PPE
Consider carefully the cleaning method to be employed from the very start in the event of hardened cement on the hold surface. A wrong approach can exacerbate the situation, increase cleaning costs and cause significant delays
Aim to include extremely specific clauses regarding delivery, re-delivery and cleaning obligations in the charterparty
Know your obligations and liabilities under the charterparty.