697 - 05/10 - Carriage of Cement Cargo - USA
A number of factors will determine the outcome of the cargo discharge of cement in bulk and subsequent hold cleaning that follows. Some of these factors include:
Condition of the cargo holds (cleanliness) prior to loading
1. Condition of the cargo holds (cleanliness) prior to loading2. Local weather at time of loading
3. Open or closed hatch loading
4. Moisture content of cargo at time of loading
5. Hatch leakage or ingress of water (sea or ballast) during the voyage
6. Local weather at time of discharge
7.Taking on relatively cold ballast water during cargo discharge/sweat condition possible
Some of the above-mentioned conditions are unavoidable to vessel owners, such as local weather at the load or discharge ports and moisture content of cement at time of loading. The voyage instructions or CP dictates other factors, such as open (gravity feed) or closed hatch (blown in) loading. And then some carriage conditions may or may not be preventable by owners, i.e. hatch leakage (heavy weather) or loading ballast water to minimize vessel stress during discharge operations.
In this particular case it was found that local weather at time of loading, and especially during the 7 day discharge, played a significant role in the adverse condition of the cargo holds subsequent to cargo discharge; cement residue ROB (remaining on board) was partially hardened at completion of cargo discharge. Additionally, the actions of the shore based cleaning crew exacerbated the condition and further delayed cleaning efforts and departure of the vessel by attempting to clean the partially hardened cement residue by inadequate means and by not immediately reporting the adverse hold conditions found to charterers.
At the completion of discharge of cement in bulk on uneventful "normal" voyages, a thin dry residue and small pockets of cement remain loosely adhered to exposed surfaces in the cargo hold including shell frames, shell plating, bulkheads, gusset plates and pipe brackets, ladder wells, hopper tank tops and tank tops. The residues are best removed by use of manlifts utilizing brooms, brushes and air guns to knock down the loose dry cement to the tank tops where the loose cement can be collected and bagged for removal from the cargo hold. Once all the loose dry cement has been removed, a pressure washer (2500 psi) is used to fresh water rinse each cargo hold from top to bottom to remove any remaining cement dust.
The time to clean a typical 5 hatch Handy Max bulk carrier after the carriage of cement in bulk, with the use of manlifts, shore based labour assisted by the ship's crew, is approximately 48 to 60 hours, at an approximate cost of US 42,000 to US 50,000 in labour and equipment.
The below photo was taken after the initial cleaning operation was completed (sweep, blow and pressure wash). Note remaining residues of semi-hardened cement on all surfaces. Under normal conditions all cement residue would have been removed.