Page 234 - International safety guide for oil tankers and terminals

INTERNATIONAL SAFETY GUIDE FOR OIL TANKERS AND TERMINALS

representative tank. Otherwise, the tests referred to above should be
carried out for each tank.
---ใช้เพื่อการศึกษาเท่านั้น---
Consideration should be given to using purge pipes for inerting ballast
tanks, to facilitate gas freeing the remoter corners of the tanks.
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี

11.4.8 Gas Freeing in Preparation for Hot Work
In addition to meeting the requirements of Section 11.4.2, the
requirements of Chapter 9 must also be complied with.

11.5 Crude Oil Washing

11.5.1 General
A crude oil tanker fitted with an inert gas system and approved fixed
washing equipment in its cargo tanks can use crude oil from the cargo as
the tank washing medium. This operation may take place either in port or
at sea between discharge ports. It is most frequently carried out while the
tanker is discharging cargo and permits the removal of oil fractions
adhering to, or deposited on, tank surfaces. These deposits, which would
normally remain on board after discharge, are then discharged with the
ึ
cargo. As a consequence, the need to water wash the discharged tanks
during the ballast voyage for the removal of residues is much reduced
and, in some cases, entirely eliminated.

Reference should be made to the IMO publication ‘Crude Oil Washing
Systems’ and the tanker’s approved ‘Operations and Equipment Manual’
for further detailed guidance on the procedures involved.

11.5.2 Advance Notice

When it is required to carry out crude oil washing (COW) during cargo
discharge, the Master should inform the competent authority and the
terminal (or other ship when ship-to-ship transfer is involved) at least
24 hours in advance, or in such time as is required. Crude oil washing
should only proceed when their approval is received.

11.5.3 Tank Washing Machines

Only fixed tank washing machines may be used for crude oil washing.

11.5.4 Control of Tank Atmosphere
The oxygen content of the tank must not exceed 8% by volume as
described in Section 7.1.6.9.

11.5.5 Precautions Against Leakage from the Washing
System
Before arriving in a port where it is intended to crude oil wash, the tank
washing system should be pressure tested to normal working pressure
and examined for leaks.

200 © ICS/OCIMF/IAPH 2006