|Operation • Hazardous Cargoes • Dangers • Handling • Cleaning • Gas Blanketing • Heating • Miscellaneous • Fault Finding|
|Tank cleaning is standard
requirement and should be carried out by specialist cleaning facilities.
Before accepting any cargo for transport, the operator should obtain information concerning the recommended method of cleaning and determine whether it is possible to clean and dispose residues at the destination. Environmental regulations might restrict the cleaning of certain cargoes. Operators should ensure that the tank is fully discharged by the consignee and that responsibility for the disposal of excess cargo is confirmed.
Cleaning is principally carried out by the use of rotating pressurised hot (or cold) water jets, commonly referred to as a spinner head, lowered into the tank through the manlid. Additives such as detergents, solvents and caustics are introduced through the spinner as required. Consideration of the effect of the cleaning method on the tank shell material is important. Many products release free chloride if heated. Steam vapour cleaning systems are also in common use. Preheating the tank is used for certain cargoes to facilitate cleaning. The heat from high temperature cleaning processes naturally dry the tank, but to speed the process hot air blowers are recommended. Dismantling and cleaning of valves and syphon tubes is not always undertaken unless specifically requested. Sterilisation and removal of stains are sometimes required, as an addition to the standard cleaning process.
Tests for cleanliness are normally carried out when specified. An independent inspector may be employed to ensure a tank is cleaned to the required specification and should issue a certificate of cleanliness.
Make arrangements for cleaning prior to discharge of the cargo, agree specification
2. Identify the last cargo
3. Establish the cleaning procedure and environmental regulations regarding cleaning and disposal of residues and vapours.
4. Ensure that discharge procedures are confirmed with the consignee and transporter and that the tank is fully discharged.
5. Determine the next cargo to be loaded in order to specify any special instructions at the time of cleaning.
6. Cleaning of valves and top outlet syphon tubes and renewal of gaskets or seals should be specified as required.
7. Stubborn stains or cargo film might need to be removed by polishing with nylon pads. No other form of abrasive material should be inside the tank without expert advice.
8. Dry the tank on completion of cleaning.
9. Ensure inspection is completed and that the tank is cleaned to the specified quality. The cleaning station should issue a cleanliness receipt confirming the cleaning process carried out. An independent surveyor should be employed where a Cleanliness or Safety Certificate is required.
10. Remove all redundant labels
11. The exterior of the tank should be cleaned to remove any cargo residue and to ensure that mandatory markings are legible. The ladder and the walkway should be kept clean to ensure safety of personnel.