PROTECTION MEANS FOR LOW TEMPERATURE LIQUID LEAK

PROTECTEUR ADVENANT DES FUITES DE LIQUIDES TRANSPORTES A TRES BASSE TEMPERATURE

English Abstract

ABSTRACT
In a device for catching leaked liquid for use in a ship
carrying a low temperature liquid in a storage tank which is supported
on the bottom of a ship's hold by means of tank supporting structures
which prevent horizontal displacement, a leaked liquid receiving pan is
disposed below an engaging member which extends downwardly from the bottom
of the tank. The low temperature liquid leaked from the tank and falling
between the engaging member and a heat insulating layer surrounding the
tank is received by the leaked liquid receiving pan and does not reach
the bottom of the ship's hold. Thus the bottom of the hold is prevented
from being cooled. Prior to this invention, the problem of super cooled
liquids leaking on a ship's hold and causing structural weakness was
overcome by either constructing ships of special steel or providing an
extra insulating jacket around the tank. Both these measures were
uneconomical. Because such structural steel members are cooled by
the leaked liquid locally and at extremely low temperature, the strength
of the ship is adversely affected. The present invention provides a
simple economical solution.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In combination with a ship's low temperature liquid
storage tank carried in the ship's hold having pairs of horizontal
displacement preventive tank supporting structures disposed
between the bottom of the ship's hold and the bottom of the tank,
a heat insulating layer surrounding the tank, and an engaging
member extending from the bottom of the tank and through said heat
insulating layer to between said supporting structures, whereby
gaps exist between said engaging member and said heat insulating
layer, a leaked liquid receiving pan means disposed below the
engaging member for receiving leaked liquid falling from said gaps,
thereby to prevent the bottom of the ship's hold from being cooled
by the leaked liquid.
2. The combination according to claim 1 wherein said leaked
liquid receiving pan means is heated by heating means.

Description

This invention relates to a device for ca-tching leakecl
liquid for use in a ship carrying a low -tempera-ture liquid in a
storage -tank which is supported on -the bottom of a ship's hold by
means of tank supporting structures which prevent horizontal dis-
placement.
Prior to -this invention, the problem of super cooled
liquids leaking on a shipls hold and causing structural weakness
was overcome by either constructing ships of special steel or pro-
viding an extra insulating jacket around the tank. Both -these
measures were uneconomical. Because such structural steel members
are cooled by the leaked liquid locally and at extremely low temp-
erature, the strength of the ship is adversely affected. The
present invention provides a simple economical solution by provid-
iny a device ~hich is simple in structure.
This invention provides in combination with a ship's low
temperature liquid storage -tank carried in the ship's hold having
pairs of horizontal displacement preventive tank supporting struc-
tures disposed between the bottom of the ship's hold and the
bottom of the tankl a heat insulating layer surrounding the tank,
~0 and an engaging member extending from the bottom of the tank and
through said heat insulating layer to between said supporting
structures, whereby gaps exist between said engaging member and
said heat insulating layer, a leaked liquid receiving pan means
disposed below the engaging member for receiving leaked liquid
falling from said gaps, -thereby to prevent the bottom of the ship's
hold from being cooled by the leaked liquid.
The invention is more fully described by way of example
only, with reference to the accompanying drawings which illustrate
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embodiments of -the invention and whereln:
Fi~ure 1 is a cross sectional view of an LNG carrierj
Figure 2 is a view, on enlarged scale, of an encircled
portion A indicated in Figure l;
Figure 3 is a vi.ew of a second embodiment of the present
invention;
Figure 4 is a sectional view taken along the lines B-B
in Figure
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5i~
3; and
Figure 5 is a view of a third embodiment o the present inven-tion.
Figure 1 shows ln section, ~n LNG carrier. Within a ship's hull
1, a tank 3 which is surrounded with a heat insulating layer 2 is supported
on a bottom 4 o a hold by tank supporting structures 5 and 6. If a crack
7 is produced through the wall of the tank 3, the low temperature LNG
leaks and the leaked liquid 8 flows down along the heat insulating layer
2. A li~uid-tight layer may be provided, as a countermeasure therefor,
along the heat insulating layer 2. However, the tank 3 is supported on the
hold bottom 4 by the tank supporting structures 5 and 6 which are extended
through the heat insulating layer 2 such that clearances or gaps exist
between the members of each of the tank supporting structures 5 and 6 and
the heat insulating layer 2. The leaked liquid 7 flows down through these
clearances or gaps and cools the structural steel members of the bottom ~.
In Figure 2, an engaging member 9 extends downwardly from the
bottom of the tank 3 through the heat insulating layer 2. The tank supporting
members 10 are securely anchored to the bottom ~ of the hold in such a way
that they are opposed to the engaging member 9 with a small lateral clearance.
Below the lower end of the engaging member 9 is disposed a leaked liquid
receiving pan 11 which is substantially larger in area than the cross sectional
area of the engaging member 9. The peripheral edge of the leaked liquid
receiving pan 11 is bent upright so that a predetermined quantity of the
leaked liquid may be received. The pan 11, is supported by legs 12 which
are made of either a heat insulating material or steel for use in low tem-
peratures.
The leaked liquid ~ flows through the heat insulating layer 2 and
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4~
along the engaging membeT 9 and is received in the leaked liquid receiving
pan 11 so that the bottom 4 of the hold can be prevented from being
directly exposed to and excessively cooled by the leaked liquid 8.
In Figures 3 and 4 the engaging member 9 is surrounded with heat
insulating members 13 and 14. The heat insulating members 13 which engage
with the tank supporting members 9, are made of a material having a relatively
high mechanical strength. A plurality of vertical grooves 15 spaced apart
from each other are formed in the inner surface of each of the heat insulating
members 13 which face the engaging member 9, so that the leaked liquid
may flow down through such grooves 15 to the leaked liquid receiving pan 11.
According to a second embodiment, the bottom 4 can be prevented
from being cooled by the thermal conduction through the tank supporting
members 9.
In Figure 5 heating means 16 are disposed below a leaked liquid
receiving pan 11 so that the leaked liquid dropped on the pan 11 evaporates
immediately. Consequently, it is not necessary to fold the peripheral edge
portion of the pan 11 upright.
The leaked liquid receiving pan may be in the form of a ring or
doughnut whose inner diameter is substantially equal to the outer diameter
of the engaging member 9.
It is also possible to attach the leaked liquid receiving pan
directly to the lower end of the engaging member ~not shown).
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