As a routine practice, the planned maintenance system of these vessels includes the assessment of the condition of cargo holds after every discharge and cleaning operations with the aim of identifying possible defects, and damage to coatings, etc.
The environmentally sound management of cargo residues and cargo hold wash water is regulated by the revised Annex V of MARPOL which became effective on January 1st, 2013. The regulations of the Annex differentiate the management of cargo residues and the cargo hold wash water, in terms of whether the cargo is considered to be harmful to the environment (HME) or not. It is the responsibility of cargo shippers to test and classify their cargoes according to certain criteria and declare whether or not their cargoes should be considered as HME. These criteria have been set in the Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS) that deals with the classification of chemicals by type of hazard and proposes harmonized hazard communication elements including labels and Safety Data Sheets.
Cargo residues or cargo hold wash water originating from HME cargoes might require special handling not normally offered by port reception facilities designed for ship-generated waste. The discharge of residues and washing water from HME cargoes (as shown in the following table) is prohibited within or outside Special Areas, with the exception of dust from surface areas remaining after sweeping.