Page 273 - Ship Construction.DJ Eyres 6Ed

Ch22-H8070.fm Page 262 Wednesday, October 18, 2006 6:59 AM
262 Ship Construction
Chemical Tankers

The structural configurations and arrangements of chemical tankers often
are basically similar to those described for oil tankers, particularly where
the chemical product is not required to be carried in an independent tank.
Where the chemical product is required to be carried in an independent
tank the structure and arrangements may be similar to ships carrying lique-
fied gases described in Chapter 23.
Carriage of Dangerous Chemicals in Bulk’.าเท่านั้น---
Regardless of size, ships built or converted on or after 1 July 1986 and
engaged in the carriage of bulk cargoes of dangerous or noxious liquid
งานห้องสมุด ศูนย์ฝกพาณิชย์นาวี
chemical substances, other than petroleum or similar flammable products,
are required to comply with the International Code for the Construction
and Equipment of Ships Carrying Dangerous Chemicals in Bulk (IBC
Code). Such ships built or converted before that date are to comply with
the earlier Code for the Construction and Equipment of Ships Carrying
Dangerous Chemicals in Bulk (BCH Code). Ships that comply with these
--- ใช้เพื่อการศึกษ
requirements are issued with an ‘International Certificate of Fitness for the

Under the IBC Code chemical tankers are designed and constructed to
one of three specified standards. A type 1 ship is a chemical tanker
ึ
intended for the transportation of products considered to present the great-
est overall hazard. It is to be capable of surviving the most severe standard
of damage and its cargo tanks should be located at the maximum prescribed
distance inboard from the shell plating. Type 2 and 3 ships carry products of
progressively lesser hazards. Where a ship is intended to carry a range of
products it is assigned the standard applicable to the product having the
most stringent ship type requirement.
The IBC Code also defines cargo tank types. Tank Type 1 is an inde-
pendent tank which is not contiguous with, or part of, the hull structure.
Tank Type 2 is an integral tank i.e. it is part of the ship’s hull structure.
A gravity tank (G) is an independent or integral tank that has a design
pressure of not more than 0.7 bar gauge at the top of the tank. A pressure
tank (P) is an independent tank that has a design pressure of more than
0.7 bar gauge.
The IBC Code specifies for each individual product to be carried the ship
type and required tank type, e.g. sulphuric acid – ship type 3 – tank type 2G.
Also requirements for the materials of construction, freeboard, stability,
general arrangement, piping arrangements, electrical and environmental
arrangements, tank venting and gas freeing, fire protection etc of chemical
tankers are covered by the IBC Code.
Figure 22.4 shows a 130m LOA Type II oil products/chemical tanker of
12,700 tonnes deadweight. The 130 metre length overall by 20 metre
breadth by 9.75 metre depth vessel has 12 cargo tanks, equipped to carry six
different types or grades of cargo simultaneously. Each tank has a deepwell