Prewash Requirement Check (Annex II Reg 13)
Decision support for whether a prewash is required after discharging a Category X/Y cargo.
High-viscosity (> 25 mPa·s at unloading T)
Yes
Solidifying (MP > 15 °C)
No
Prewash requirement
Required (high-viscosity or solidifying Y)
Formula, assumptions, and limits
MARPOL Annex II Reg 13.6: Category X always prewash; Category Y only if cargo meets the HV (> 25 mPa·s at unload temperature) OR solidifying criterion. Prewash residues → shore reception facility.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| High viscosity, > 25 mPa·s at unloading T | boolean | BDN / CoA | |
| Melting point > 15 °C | boolean | CoA |