Page 133 - International safety guide for oil tankers and terminals

SHIPBOARD SYSTEMS

non-return valve. The design of the flange should be compatible with the
design of other connections in the ship’s cargo piping system.
---ใช้เพื่อการศึกษาเท่านั้น---

7.1.10 Product Carriers Fitted with an Inert Gas System
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
7.1.10.1 General

The basic principles of inerting are exactly the same on product carriers
as on crude carriers.

There are, however, some differences in operational detail, as outlined in
the following Sections.

7.1.10.2 Carriage of Products Having a Flashpoint
Exceeding 60ºC

SOLAS implies that tankers may carry petroleum products having a
flashpoint exceeding 60ºC (i.e. bitumens, lubricating oils, heavy fuel oils,
high flashpoint jet fuels and some diesel fuels, gas oils and special boiling
point liquids) without inert gas systems having to be fitted or, if fitted,
without tanks containing such cargoes having to be kept in the inert
condition.

flammable condition may occur. ึ
However, when cargoes with a flashpoint exceeding 60ºC are carried at a
cargo temperature higher than their flashpoint less 5ºC, the tanks should
be maintained in an inert condition because of the danger that a

It is recommended that, if inert gas systems are fitted, cargo tanks are
maintained in an inert condition whenever there is a possibility that the
ullage space atmosphere could be within the flammable range. (See also
Section 2.7 regarding the carriage of residual fuel oils.)

When a non-volatile cargo is carried in a tank that has not been
previously gas freed, the tank should be maintained in an inert condition.

7.1.10.3 Additional Purging and Gas Freeing

Gas freeing is required on product carriers more frequently than on crude
carriers, because of the greater need both for tank entry and inspection,
especially in port, and for venting the vapours of previous cargoes. On
inerted product carriers, any gas freeing operation has to be preceded by
a purging operation (see Section 7.1.6.10).

It should be recognised, however, that purging is not essential before gas
freeing when the hydrocarbon gas content of a tank is already below 2%
by volume.

7.1.11 Cold Weather Precautions for Inert Gas Systems

The inert gas system may be subject to operational faults when operating in
extreme cold weather conditions.

7.1.11.1 Condensation in Inert Gas Piping
SOLAS requires that the piping system shall be so designed as to prevent
accumulation of cargo or water in the pipeline under all normal

© ICS/OCIMF/IAPH 2006 99