Page 214 - International safety guide for oil tankers and terminals

INTERNATIONAL SAFETY GUIDE FOR OIL TANKERS AND TERMINALS

Where the design of the ship does not allow admittance of air via
the vapour system at a sufficient rate, air may be admitted via a
Cargo discharge must not be started until:นั้น---
sighting or ullage port, provided it is fitted with a permanent flame
screen. In this situation, the ship is no longer considered to be

All relevant cargo tanks, including slop tanks, are common withย์นาวี
11.1.14.4 closed discharging.
Inert Gas Procedures
Ships using an inert gas system (IGS) must have the system fully
operational and producing good quality (i.e. low oxygen content)
inert gas at the commencement of discharge. The IGS must be
fully operational and working satisfactorily throughout the
---ใช้เพื่อการศึกษาเท่า
discharge of cargo or deballasting. Section 7.1 gives details on
All other cargo tank openings, including vent valves, areิช

the operation of the IGS.
the inert gas (IG) main.

connection is fitted, also from the cargo main.าณ
งานห้องสมุด ศูนย์ฝกพ
securely closed.
The IG main is isolated from the atmosphere and, if a cross

The IG plant is operating.
The deck isolating valve is open. ึ

A low but positive inert gas pressure after completion of discharge
will permit the draining of the manifold drip tray into a tank and, if
required, allow manual dipping of each tank.

11.1.14.5 Pressurising of Cargo Tanks
When high vapour pressure petroleum (e.g. natural gasoline and
certain crude oils) reaches a low level in cargo tanks, the head of
liquid is sometimes insufficient to keep cargo pumps primed. If an
inert gas system is installed, it can be used for pressurising cargo
tanks in order to improve pump performance.

11.1.14.6 Crude Oil Washing
If the ship needs to crude oil wash all or some of its tanks during
discharge, the Responsible Officer should incorporate a crude oil
washing plan in the required discharge plan set out in Section 22.6.

A full description of the requirements relating to crude oil washing
is given in Section 11.5.

11.1.14.7 Commencement of Discharge Alongside a
Terminal
Shore valves must be fully open to receiving tanks before the
tanker’s manifold valves are opened. If there is a possibility that,
owing to the elevation of the shore tanks above the level of the
ship’s manifold, pressure might exist in the shore line and no
non-return (check) valves are fitted in the shore line, the ship must
be informed and the tanker’s manifold valves should not be
opened until an adequate pressure has been developed by the
pumps.

180 © ICS/OCIMF/IAPH 2006