Arrangements for Floating and Stationary Inflammable Oil Storage Tanks.
Year: 1892

page_text: Date of Application, 13th July, 1892
Complete Specification Left, 13th Apr., 1893-Accepted, 13th May,
1893
PROVISIONAL SPECIFICATION.
Safety Arrangements for Floating and Stationary Inflammable Oil
Storage Tanks.
BENJAMIN HOWARTH THWAITE of 37 Victoria Street Liverpool Civil
Engineer do hereby declare the nature of this invention to be as follows:-
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This invention relates to improvements in a former invention for which Patent
right was granted and numbered 9180, 1891, by which the method of carrying oil
in bulk in tank steamers is much reduced if not altogether removed.
The essential characteristics involved in this, improved invention are first, the use
of gas escape pipes by which the gas evolved from the more volatile portions of
the oil can escape without permitting on the contraction of the oil, the ingress of
air into the space over the oil. This I effect in the following manner, I lead the
pipe from the upper surface of the tank deck level, for a certain height, and then
either lead it into a hydraulic or oil seal box, or preferably lead the pipe on the
outside of the vessel below the level of the flotation water, allowing for conditions
of water and the motion of the vessel.
may use a
When the gases evolved from the oil accumulate so as to establish a pressure
greater than the depth of water in the hydraulic seal box or greater than the dip
of the outlet pipe in the sea, or equivalent to both depths because I
combination. The gas bubbles through the water until the pressure is reduced;
in the event of extreme condensation the reduction of volume of oil in the tank
may require an additional supply of oil or gas to make up for this reduction.
Glass gauges are so fixed as to indicate when such an abnormal reduction takes
place so as to enable this displacement to be compensated for, I may provide bottles
of compressed carbondioxide for this purpose..
In the event of drawing the oil from the oil tank, I connect the latter with
either the compressed (CO₂) cylinder or with the steam generator, so that
there will not be any accumulation of an explosive mixture possible, 1 may
provide CO2-producing generators at the oil tank installations for the purpose
described.
For new oil tank vessels I provide separate and destinctive tanks, the bottom
and sides of which are all approachable and are distinctive from the structure of
the vessel proper.
I also provide special inclined floors under said tank, provided with wells to
accumulate any oil that may escape. By this means the leaks are soon located and
can be repaired.
may
maintain a
I may supply the tanks with annular or hollow sides, in which I
flow of water which said water, in hot climates I pass through a refrigerating
apparatus so as to maintain the oil at a temperature below that of volatilisation.
For existing tanks I place refrigerated water coils inside the tanks.
1000
COMPLETE SPECIFICATION..
Safety Arrangements for Floating and Stationary Inflammable Oil
Storage Tanks.
BENJAMIN HOWARTH THWAITE of 37 Victoria Street Liverpool. Civil.
Engineer do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement :-
This invention relates to improvements in a former invention for which Patent

page_text: .
right was granted and numbered 9180-1891, 'by. which the method of carrying oil
in bulk in tank steamers is much reduced it not altogether removed.
The essential characteristics involved in this improved invention are first, the
use of gas escape pipes, by which the gas evolved from the more volatile portions
of the oil can escape, without permitting on the contraction of the oil, the ingress
of air into the space over the oil. This effect in the following 'manner, I lead
the pipe from the upper surface of the tank deck level, for a certain height, and
then either lead it into a hydraulic or oil seal box or preferably lead the pipe on
the outside of the vessel, below the level of the flotation water, allowing for the
conditions of water and the motion of the vessel.
When the gases evolved from the oil accumulate so as to establish a pressure
greater than the depth of water in the hydraulic seal box or greater than the dip
of the outlet pipe in the sea, or equivalent to both depths, because I may use a
combination, the gas bubbles through the water until the pressure is reduced.
In the event of extreme condensation the reduction of volume of oil in the tank
may require an additional supply of oil or gas to make up for this reduction.
Glass U gauges are so fixed as to indicate when such an abnormal reduction takes
place; so as to enable this displacement to be compensated for, I may provide
bottles of compressed carbondioxide for this purpose.
In the event of drawing off the oil from the oil tank, I connect the latter
with either compressed (CO2) cylinders or with the steam generator, so that
there will not be any accumulation of an explosive mixture possible, I may
provide CO, producing generators at the oil tank installations for the. purpose
described.
2
For new oil tank vessels I provide separate and distinctive tanks, the -bottom
and sides of which are all approachable and are distinctive from the structure of
the vessel proper.
I also provide special inclined floors under said tank, provided with wells to
accumulate any oil that may escape. By this means the leaks are soon located and
can be repaired.
I may equip the tanks with annular or hollow sides in which I may maintain a
flow of water which said water, in hot climates I pass through a refrigerating
apparatus so as to maintain the oil at a temperature below that of volatilisation.
For existing tanks I place refrigerated water coils inside the tanks.
By the use of my invention it will be clearly realised that the temperature of the
oil in tank steamers, when passing through the Suez Canal or through geographic
localities, characterised by very elevated temperatures, can be exactly controlled.
The method of refrigeration enables this to be done quickly and effectually, so that
the accumulation of explosive mixtures need never occur. And there need be no
loss of the more valuable parts of the hydrocarbons by volatilisation. On with-
drawing the oil from the tank the use of carbondioxide. Steam or refrigerated air
will absolutely remove any probability of danger now so conspicuously associated
with the work of discharging a petroleum cargo from an oil steamer.
I will now elucidate by illustrations on annexed sheet of drawings, the method
by which I may apply my invention. But before doing so I wish it to be understood
that I do not intend to be confined to the use of the details exactly as shown, as
they may be modified without departing from the nature of the Specification.
Referring to this sheet of drawings,
Figure 1 is a vertical section of the oil gas or vapour, hydraulic escape box.
Figure 2 is a plan of the vessel.
Figure 3 is a longitudinal section of a part of an oil tank steamer, shewing the
tanks.
Figure 4 is a plan of the vessel shewing four tanks.
Let us in the first instance refer to Figure 1. The rising pipes A are connected
to the expansion boxes or to the empty space above the oil in the tanks.
Water is maintained in the vessel as shewn by dotted lines B, at a uniform level,
to enable this to be done, water gauges C are provided.

page_text: This water level is 2 or 3 inches above the termination of the central gas outlet
or escape pipe E, forming a hydraulic seal equal to this depth.
Once a pressure of volatilised oil vapour or oil gas is established in excess of
this hydraulic seal, the gas or vapour bubbles through to the atmosphere.
This escape vessel is preferably placed exactly over the centre board of the oil
tank steamship, so that its oscillations are reduced to a minimum. A water gauge
is attached to this vessel to shew the pressure of gas established.
The position of this vapour escape vessel in relation to the tanks is shewn on.
Figure 3 at F.
Referring to Figure 2, it will be seen that the oil gas or vapours connecting pipes
are 4 in number one being connected to each tank.
This vapour escape vessel being placed at the intersection of the division plates
of the four tanks, the outlet escape tube being placed in the centre of the vessel.
The central outlet or escape pipe E may be laid down on the deck, and with its
termination, dipping down into and below the surface of the sea, the terminal end
of this pipe being formed of a flexible tube, with a float box, that whilst floating
upon the water permits the vapour to escape by bubbling through a depth of sea
water, not exceeding 3 inches.
Referring to Figures 3 and 4, the oil tanks I are provided with coil or other
refrigerated water or air, circulating pipes H through which a supply of refrigerated
water or air is constantly kept flowing. The tanks may also have water jacketted
sides through which a constant flow of refrigerated water is established, or air
refrigerated to the degree desired.
After passing through these pipes this refrigerated air-if this medium is used—
escapes into the space over the oil or into the expansion tanks, and from thence
through the connecting pipes of hydraulic gas escape box F, but when refrigerated
water is employed a constant circulation of the refrigerated water is established,
the pipes H for circulating such water being endless.
The refrigerating machine preferably the Haslam or any other type of equal
efficiency, is shewn at J.
The outlet or escape pipe E, of vessel, is shewn as connected up to a pipe K,
passing up to the mast L, so that the vapour is emitted at a sufficiently high level
to ensure safety.
Thermometers are fixed at various positions in the tanks, so that the temperature
can be accurately noted, so that the refrigerated medium production can be
adjusted to the requirement to maintain the temperature of the oil below that of
volatilisation.
If necessary, and by electrical means, this regulation of temperature can be
automatically adjusted, the rise and fall of mercury starting or cutting off an electric
current that controls the motion of the refrigerating engine.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same may be performed, I declare that what I
claim is embodied in the following paragraphs.
Claim 1st. The method of introducing steam or carbondioxide into oil tanks, of
tank steamers, during the pumping out or clearance of such oil, for preventing
a dangerous accumulation of vapour of oil, or a mixture of such oil vapour and air.
Claim 2nd. The employment of a refrigerated medium introduced in pipes or
otherwise, through the oil in circulating pipes, and over the surface thereof, or
through water jackets for the purpose of maintaining such oil at a temperature
below that of volatilisation or below the flash point of such oil.
Claim 3rd. The vapour or oil gas hydraulic escape box in vessel for the purpose
of permitting the oil vapour to escape and preventing the introduction of ordinary
atmospheric air into the oil tank, substantially as described and shewn in Figures 1. 2.
and 3.
Claim. The jacketting of such oil tanks with water filled compartments or
hollow sides, which may be maintained at a little above freezing temperature

page_text: degree or any other temperature degree necessary to prevent the oil from
attaining such a degree of heat as to evolve inflammable gases, substantially as
described.
Claim 5. The employment of special inclined floors with oil catch compartments,
substantially as described.
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Dated this. 19th dow of Annil 1005
B. H. THWAITE.