Section 4: Dedicated Clean Ballast Tank Operation Procedures

  4.1.1 After completion of line flushing procedure and prior to arrival at the loading port the valves on the slop tanks, cargo tanks and dedicated clean ballast tanks are to be closed. The identification numbers of these valves are:

  4.1.2 Immediately before discharge of ballast an inspection is to be made of the surface of the CBT ballast to ensure there has been no oil contamination.

  4.1.3 In the loading port and prior to loading cargo the CBT ballast is to be discharged, by No.1 cargo oil pump and its associated piping, overboard through the starboard sea suction valve. The oil content meter must be calibrated and the system be ready to monitor the ballast discharge. During discharge, if there is any doubt on the cleanliness of the water, the discharge must be stopped and the remainder retained in the ballast tank. The valves to be opened for ballast discharge are:

  4.1.4 Discharge from No. 2 centre tank should be stopped when the tank innage is a half metre; this enables the branch pipes to be flushed when the lines are being cleaned.

  4.1.5 Discharge from No. 4 centre tank should be stopped when the tank innage is one and a half metres-see paragraph 5.1.3, section 1 of this Manual.

  4.1.6 To utilize the system for cargo loading, drain the piping into the port slop tank. After draining close all valves.

  4.2.1 Prior to departure from the loading port it should be ensured that:

• .1 all cargo lines are stripped and drained as far as possible;

• .2 all slop tank and cargo tank valves are closed.

  4.3.1 During the loaded voyage periodic checks must be made in the ballast tanks for any hydrocarbon content and if any gas is detected vent the tank until safe for entry and inspect for leakage in bulkheads and piping.

  4.4.1 After discharge of cargo it should be ensured that:

• .1 all cargo lines are stripped and drained as far as possible;

• .2 all slop tanks and cargo tank valves are closed.

  4.4.2 After cargo discharge the dedicated clean ballast system must be flushed with water from No. 4 centre tank. Using No. 1 cargo pump, flush its associated piping and No. 2 cargo suction main. Circulate water round the system and return the flushings to the port slop tank via No. 2 cargo suction main. Flushing should be continued for at least thirty minutes. Under no circumstances must flushings be returned to a dedicated clean ballast tank. The valves to be opened for flushing are:

  4.4.3 Before flushing, prime the system, establish suction, stop the pump and close all valves to allow oil to separate out from the pipe walls. After about half an hour, resume pumping at a moderate rate with the output throttled on the discharge side of the pump.

  4.4.4 After priming the system the branch suction pipe on No.2 centre tank is to be cleaned using No.1 cargo pump and its suction main and discharging via the port jet pump into the port slop tank. Continue this operation for three minutes, stop pump, close all valves and proceed to flush system as previously described. The valves to be opened for flushing branch pipes are:

  4.4.5 Before ballasting the tanks check for hydrocarbon content as outlined in paragraph 4.3.1 of this section.

  4.4.6 The tanks are ballasted using No. 1 cargo oil pump and its associated piping. The ballast suction is taken from the port sea suction and discharges over the deck to each respective tank via the suction main. The valves to be opened for ballasting are:

  4.4.7 When ballast tanks are full, stop the pump, drain the system to the port slop tank and close all valves.

  4.5.1 During the ballast voyage the slop tank contents must be processed in accordance with section 7 of this Manual.

  4.5.2 During the ballast voyage a visual inspection of the surface of the CBT ballast is to be made at regular intervals to ensure there is no oil contamination.