Heavy Weather Ballast


FOM 1.2	Fleet Operations Manual General 1.2 Heavy Weather Ballast	Doc No.: FOM 1.2 Revision: 01 Date: 15 Oct 2024 Issued by: DPA Approved by: MD

1 TAKING HEAVY WEATHER BALLAST IN CARGO TANKS

1.1 Stresses calculation

Vessels Trim and stability booklet/loading manual should be referred, all recommendations on dedicated Heavy weather ballast tanks to be adhered to.
At the planning stage, stresses experienced by the vessel should be calculated (using loadicator). Calculations must be for SEA condition and for a minimum of 4 stages for ballasting/de-ballasting operations. Stresses should be monitored during the entire operation and must confirm to stability criteria/limitations.
On chemical tankers, factors such as sloshing restrictions and adjacent cargo compatibility should be considered.

1.2 Limitations

Cargo tanks other than segregated ballast tanks may be ballasted only in the following cases:

In adverse weather conditions, for safety of the vessel.
To safely pass under a bridge or other overhead obstructions.
When local port or canal regulations require specific draft.

Note:

Before taking heavy weather ballast, ship specific risk assessment must be carried out as per standard model template ‘Heavy Weather Operations’.

1.3 Procedure of taking heavy weather ballast

If ballasting cargo tank as mentioned in above limitations, follow below procedures. Consider the following when loading ballast in cargo tanks:

A plan to take heavy weather ballast must be prepared. (If the heavy weather ballast plan is not included in BWMP – company approval is required before plan is followed) Plan should include, but not limited to:
- Sequence of operation/Valves to be operated/Stresses
Follow closed loading procedures, when taking ballast into tanks containing hydrocarbon vapour. In consultation with the terminal, observe all safety precautions required for loading of volatile cargoes.
On crude oil tankers, crude oil wash the tank before ballasting.
When ballasting cargo tanks, vent out the mixture of hydrocarbon gas via the recognised venting system only.
Follow closed loading operation.
Take ballast via the bottom line.
Before opening the sea chest valves comply with procedure DK-01 - 6.3 Sea chest valves – tankers.
When ballasting non-inerted cargo tanks containing hydrocarbon vapour:
- First valves to be opened should be the tank valve.
- Maintain a controlled flow rate of about 1m/sec until the longitudinal are covered or a sounding of 1.5 meters is achieved. (cargo drop line/cargo drop valve to be fully immersed before increasing the flow rate)

CAUTION:

Avoid free falling liquid in the tanks as this causes a spraying effect and leads to build up of electrostatic charge. Electrostatic charge is a source of ignition and may cause an explosion.

Appropriate entries must be made in the oil record book.

Note:

Cargo tanks with last cargo categorized as Marpol ANNEX 2, must be cleaned to water white standards in accordance with their P&A manual prior to commencement of ballasting operations. Post ballasting Entries must be made in cargo record book.

2 DISCHARGE OF HEAVY BALLAST FROM CARGO TANKS

If not discharging to a reception facility, discharge of ballast from cargo tanks according to below conditions:

CAUTION:

Discharge criteria as per MARPOL annex 1 is complied with:

Discharge ballast water MUST be through ODME only. Bypassing ODME is not acceptable, except in case of an emergency. Risk assessment should be carried out and Managers, local port state and flag state should be informed/consulted.

Prior commencement consult “Oil discharge monitoring equipment manual” and “Crude Oil Washing Operation & Equipment Manual”.
The procedures must be in accordance with MARPOL 73 / 78, Regulation 9 of Annex I. Limits of quantity allowed by MARPOL: 1/30.000 of the total volume of the cargo tanks involved by the previous loading, max.30L / mile and max15ppm.
Check/Test the ODME (Simulation test) and ensure all data is appropriately entered.
Cargo line and Cargo pump used during operation, must be flushed to slop tank, prior commencing discharge overboard.
Check line up of all cargo tanks/pumps and inert gas valves before start of operation.
Inert gas plant should be operational and O2 content verified.
Before starting discharge, check oil - water interface and estimate time of switching over recovery to slops. ODME system automatically activates transfer to slop when oil content is reached, however it should always be monitored.
Reduce the discharge rate, when water sounding in the tank is 20% / 1 Meter of the total tank depth. Reduce the rate by slowing down the pump to avoid surface oil being sucked in.
When about 30 cm ballast remaining in cargo tank, STOP overboard discharge and transfer remaining quantity into Slop tanks.
Always check overboard discharge ballast from deck and monitor oil content.
Tank ullages, pressures and stability of the vessel should be logged on hourly basis.
After a settling time of about, 24 hours, the remaining ballast contained in slop tank can be discharged through O.D.M.E.
The quantity of oil remaining in the slop tank, must be calculated by measurement of the interface. 50cm above interface stop decanting/de-ballasting via ODME and transfer the remaining of Slop to ROT, which should later be discharged ashore.
Once Discharge is complete, fill up Oil Record Book / Cargo Record book (as appropriate) reflecting the operation.

Note:

If the last cargo in nominated cargo tank is classed as per Marpol Annex II, Ballast disposal must be in accordance with vessel’s P&A manual and same must be recorded in the Cargo record book.