Fie]-d of the Invention
[0001] The present invention relates to devices and
methods for controfling flow of liquid, and more
particularly, to an apparatus and a method for preventing
liquid from overtopping a bund waff built around one or
more tiquid storage tanks.
Background of the Inwention
[0002] Liquid storage tanks or reservoirs at petroleum
industries are generally used to contain petroleum
products in the form of liquids. The petroleum products
such as crude oil, petrol, diesel, aviation fuel, turbine
fuel- etcetera are stored in huge tanks. Spillage of the
stored liquid may be hazardous to the environment and may
give rise to flre incidents. Hence, a retention means is
required around the storage tank for retaining the leaked
liquid within a permissibl-e area.
[0003] GeneralÌy, dike assemblies or bund waIIs are
constructed around the storage tanks to retain the
spilled Iiquid. A dike or a bund is constructed using
various materials including earthen masonry materials and
cements to confine the inadvertently spilled liquid. The
dikes or bunds are constructed such that the entire
volume of the tiquid stored in the tank can be retained
within the retention means in the event of tank leakage.
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:-:..::- - J:-:.i.!r:,ìr'..:;:.,
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[0004] However, in the event of a catastrophic rupture in
the storage tank, such as sudden cracking in the walls of
the storage tanks, the existing designs of bund walls may
not f acil-itate in retaining the huge vol-ume of the
released liquid, whlch is refeased in short time, within
the permissible area. This is because the sudden rupture
in the tank induces a substantial- amount of kinetic
energy in the spilled liquid and the liquid coming out of
the tank overtops the bund wafls. This resul-ts in
spreading of the spitled J-iquid in the area adjoining the
outside of the bund wal-1. This not onJ_y af fects the
environment but also incur huge ross to resources and
revenues and may also resuft in fire.
[0005] rn light of the above, there is a need for an
apparatus and a method for preventing liquid from
overtopping a bund wal-r in the event of catastrophic
rupture in the storage tank. Further, there is a need for
an apparatus and a method for minimizing the overtopping
20 of liquid by reducing the chance of generating high
energy Surge I^/ave
Summary
[0006] rt is an object of the present invention to
provide an apparatus and a method for preventing J-iquid
from overtopping a bund wafr- in the event of catastrophic
rupture in the storage tank. Another object of the
present invention is to minimize the overtopping of
liquid by reducing the chance of generating hiqh energy
surge wave.
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[0007] Tn accordance with the objects of the invention,
an apparatus and a method for preventi-ng liquid from
overtopping a bund wall- built around a liquid storage
tank are discl-osed herein. rn one embodiment of the
present invention, the apparatus comprises a first fÌat
wafl having a first wall--end and a second wall-end; and a
second f lat wall having a f irst wal-l--end and a second
wafl-end. The first wal-l-end of the first flat wall is
bonded with the first walf-end of the second ffat walf at
an angle 'e' for diverting fl_ow of liquid in an event of
a catastrophic rupture of the liquid storage tank. The
angle'e'is less than 180 degrees when it is facing
towards the bund waff. A pair of angul-ar pillars are afso
constructed adjacent to the corresponding second walf-end
of the first ftat wall and the second ftat wall_
respectively for preventing the formation of any surge
r¡rave due to the catastrophic rupture. The angular pillar
is an eì-ongated pilJ-ar having tri-angular cross section.
[0008] fn various embodiments of the present invention,
the apparatus is constructed on an area between the
liquid storage tank and the bund wafl-. The height of the
first fl-at walf and the second flat are equal or
marginalÌy lower to the height of the bund wall
t0009] fn one embodiment of the present invention, the
method for preventing liquid from overtopping a bund wall
buift around a liquid storage tank, comprises the steps
of: constructing a first ffat wall having a first warrend
and a second wa11-end; constructing a second flat
wall bonded to the first flat walf, wherein the first
wal-l--end of the f irst f lat waf l- is bonded wit,h a f irst
wal-f -end of the second f lat wall, ât an angJ_e . e, f or
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4
diverting ffow of liquid in an event of a catastrophic
rupture of the liquid storage tank; constructing a pair
of angular pillars adjacent to the corresponding second
wal-l-end of the f irst waf r- and the second warl
respectively, for preventing formation of any surge rivave
due to the catastrophic rupture.
[0010] Other features and advantages of
10
invention will_ be apparent in the following
claims and accompanying drawings.
Brief Description of Èhe Accompanying Drawíngs
l5 [00111 The present invention is
illustrated in the
the present
description,
described by way of
accompanying drawings
20
[0012] FrG. 1 ilrustrates schematic of an apparatus
comprising diversion wal]s and angular piJ-lars for
preventing liquid from overtopping a rectanguÌar bund
wal-1, in accordance with an embodiment of the present
invention;
25 [0013] FIG. 1a iflustrates schematic of the angular
accordance with an embodiment of the present
embodiments
wherein:
pillars, in
invention;
[00f 4] Ff G. 2 illustrates schematic of
preventing liquid from overtopping a ci
in accordance with an embodiment
invention; and
the apparatus for
rcu.Iar bund wa11,
of the present
30
. -,, : -,,:.:, - : -:: : :.; : :,, "::. -. ; ::-)1.> ::-.
[0015] FIG. 3 is rhe
liquid overtopping a
catastrophic rupture of
schematic representation of the
bund wal_I in an event of
tank; and
10
[00161 FIG. 4 is a table showing resuf ts of various
experiments carried out with and without the apparatus
within a tank and bund-wall environment.
DetaiJ-ed description of the invention
[0017] An apparatus and a method f or preventi-ng riquid
from overtopping a bund wafr- is disclosed. The invention
provides a method for preventi-ng liquid from overtopping
a bund wal1 built around one or more liquid storage
tanks. Further, the invention provides an apparatus and a
method for minimizing the amount of overtopping of liquid
by preventing the sudden stoppage of liquid wave and
diverting in different direction thereby minimi zinq the
probability of generation of hiqh energy surge wave, in
the event of a catastrophic rupture or a large feak in
the storage tank.
l00r8l The following discl-osure is provided in order to
enab]e a person having ordinary skil_l in the art to
practice the invention. Exemplary embodiments are
provided only for iflustrative purposes and various
modifications wil-l be readiry apparent to persons skitled
in the art. The general principres defined herein may be
applied to other embodiments and applications without
departing from the spirit and scope of the invention.
Also, the terminology and phraseorogy used is for the
purpose of describing exemplary embodiments and should
not be considered limiting. Thus, the present invention
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is to be accorded with the wi-dest scope encompassing
numerous afternatives, modifications and equivalents
consistent with the principles and features disclosed.
For purpose of clarity, detaifs relating to technical
material- that is known in the technical fields related to
the invention have not been described in detaif so as not
to unnecessarily obscure the present invention.
[0019] The present invention would novr be discussed in
context of embodiments as ilfustrated in the accompanying
drawings.
[0020] FrGs. 1 and 1a- il-f ustrate schematic of an
apparatus comprising diversion walls ro2 and angular
pillars 106 for preventing tiquid from overtopping a
rectangular bund wall- 108, in accordance with an
embodiment of the present invention. rn one embodiment of
the present invention, the diversj-on walf ro2 comprises
two fl-at walJ-s, a first flat waÌr ro2a, and a second flat
wal-r 702b. Each flat wal-l- r02a, ro2b comprises two walfends
' a first wafl-end and a second wafl-end. The
diversion wall- r02 is a 'v' shaped structure and is
constructed by j oining or bonding the first walf-end of
the first flat wafr ro2a with the first wal_l-end of the
second f l-at wal-1 702b. f n various embodiments of the
present J-nvention, the first flat wall ro2a and the
second fl-at walf r02b are joined or bonded at an angle
"e". The vafue of angJ-e o is less than 1Bo degrees and
can vary according to various requirements. However, very
less angle measurement of angle o (for example 10
degrees) should be avoided as it may result in a number
of complex anqular spikes instead of angular wall-s as
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desired. Also, in such a scenario, construction of
10
angufar pillars may not be required and it may
consequently resuf t in a non-ef f ect j-ve preventJ-on of
liquid overtopping. Further, the val-ue of angre e more
than 180 degrees may not be effective in preventing bund
overtopping. rn the preferred embodiment of the present
invention, the angle e measures 160 degrees to provlde
optimum reduction in liquid overtopping.
[0021] Further, a pair of angular pillars or the
diversion pilJ,ars are constructed for preventing
formãtion of any surge wave due to the catastrophic
rupture in the liquid storage tank. The angular pitrars
706, herein after 'pi]lars' 106 are constructed adjacent
to the diversion walls ro2 which facilitate in directing
the flow of the J-iquid gushing out from the tank 110.
Each of the pillars 106 is an elongated pitlar having a
trianguJ-ar cross section wherein the base of the triangle
has two extended segments 106a, 1o6b as shown in figure
1a. The height of the extended segments 106a and 106b are
equal to the height of the angular pilJ-ar 106. Further,
the extended segments 106a and 1o6b may have optimum
length to allow sufficient space for the divert.ed J-iquid
to flow and enough passage for movement of operating
persons. The diversion wal-l-s r02 and the pillars 106 are
constructed ahead of the inner side of the bund wal_l 1oB,
wherein each angular pillar of the two angul_ar pilJ_ars
stands adj acent to the corresponding second wal_l--end of
the first wall- and the second warl respectively for
preventing f ormation of any surge vvave due to sudden
stoppage of approaching J-iquid by the bund wall- 108 in
the event of the catastrophic rupture. Thus, the
diversion wafls 702 and the pillars 106 are constructed
within the encfosed bund area, between the storage tank
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110 and the bund wal-l 108, to prevent the liquid from
overtopping the bund walf 1oB in case of large feak or
rupture in the storage tank 110. The height of the
elongated pillars 106 and the extended segments 106a &
106b can either be equal to the diversion wafl_ , or can be
higher than the height of the diversi_on wall. rn one
embodiment of the present inventi_on, for a rectangular
type of bund as shown in the figure, four pairs of
diversion walls r02 and four pilJ-ars 106 may be
constructed- Each pair of the diversion wall_s 102 may be
constructed ahead of the corresponding side of the
rectangular bund 108. Further, the four pillars 106 may
also be constructed ahead of the respective corners of
ihe rectangular bund, according to the exempiary
embodiment of the present invention as shown. The
diversion wal-rs r02 and the pillars 106 are solid and
opaque structures made up of masonry or RCC (Reinforced
cement concrete) materia.l-s. The ffat wal_f s ro2a, ro2b of
each of the diversion wal-ls ro2 do not have any hole or
openi-ngs on the wal-l surfacer so as to prevent the l_eaked
liquid f rom f J-owing directry towards the bund wal_l 1oB.
The ffat wall surface with no hores or openings
facilitates in preventing any direct striking of the
l-eaked liquid with the bund wal-l- 108 in the event of a
catastrophic rupture of the tank 110.
100221 Furtherr âS shown in figure ra, the pirrars 106
are constructed in vicinj_ty of the corners of the
rectangular bund wal-l 108 and between the two consecutive
paì-rs of the diversion waf l-s r02 f or f acilitating the
leaked liquid in flowing away from the bund walÌ corners.
The leaked liquid is thus directed towards the inner side
of the bund itself rather than striking to the bund wafl-
108 directly and thereby producing a surge wave. The
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surge wave if produced due to any catastrophic leakage,
can otherwise be very difficul-t to stop and it may
overtop the bund wal-fs 108. However, due to the angular
divers j-on provided by the dj-version waf l_s ro2 and the
pillars 106, the liquid flows to the corners of the bund
wall-s, through the space formed between the diversion
walf s r02 and the pilJ-ars 106, and therefore the l_eaked
liquid may be easlly retained by the bund walf 1oB and it
may not overtop the bund.
[0023] rn various embodiments of the present invention,
the pi-1J-ars are either sol-id or holl-ow. The sotid pirlars
can provide strong structures but reduces the liquid
.^¡..,^L: jñ-.i-^
corì;aÌnrng capa^jc-L.r= ry o.-- r !¡r^n- e bund wall. on the oiher hand,
holLow pillars may not reduce the liquid holding capacity
of the dike, âs when the hol-low pillars are left
uncovered at the top, they help in accommodating some
liquid inslde the hol_low space.
[0024] f n various embodiments of the present invent j_on,
the cross sectional shape of the diversion wall ro2 is a
square, rectangfe, or a trapezoidal shape. Further, the
width of the diversion wal-fs ro2 may vary according to
the bund area and capacity of the storage tank 110. very
thick width of the wall may affect the totar retention
vol-ume of the bund or the dike. Hence an optimum
thickness of the diversion wall- s ro2, varying from 10 cm
to 50 cm may be chosen depending upon the requirement.
Furthermore, the height of the diversion wal_r ro2 may be
equal to or sJ-ightly lower than the height of the bund
wal-] 108. The height of the diversion wal_ls ro2 may also
be kept higher than the height of the bund wa]r 108.
However, the increased height of the diversj_on wal_l- ro2
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may not provide any further advantage. on the contrary,
it adds cost in the construction of the diversion wafl of
increased height, without improvising in the bund
overtopping prevention. Furthermore, a diversion wall ro2
much higher than the bund wall 1oB may obstruct in the
firefighting tasks. As per the OfSD standards (Oil
rndustry safety Directorate standards), the height of the
bund waffs may vary from 1 m to 2m (orsD std.11B). The
height of the diversion wafl-s ro2 and pillars 106 are
equal to that of the bund wall 108. The width and height
of the diversion warl s 702 are required to have the
optimum measurements i-n order to provide sufficient
strength to the warfs thereby faciritating in
withstanding the force exerted by the approaching liquid
waves in the event of a J-arge leak or any catastrophic
rupture of the storage tank 110. Metatric steef
structures are not used in the construction of the
diversion wafls and pirJ-ars as metals fike steef are
usually prone to corrosions and graduaÌ deteriorations.
For exampJ-e, steel structure may lose its strength when
engulfed in fire.
t00251 FlG. 2 shows the apparatus for preventing riquid
from overtopping a circul-ar bund wafl-, in accordance with
an embodiment of the present i-nvention. The circular bund
wafl- 206 as shown in the figure, ilây have three or more
pairs of diversion walf s 202 and pillars 204. Based on
the shape and size of the bund wal-l 206, the number of
diversj-on wafls 202 and the angle of the diversion walls
202 may vary. rn one embodiment of the present invention,
the at least three diversion waÌl_ s 202 and pilrars 204
may be constructed for a circul-ar bund wafl 206. rn
another embodiment of the present invention, the total
number of the diversion wafls and pillars may be three or
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more depending on the size of the storage instaffation
and dike or bund area. The exempl-ary embodiment of the
present invention as shown in the figure comprises six
diversion wall- s 202 and six angular pillars 204 .
[0026] FrG. 3 is the schematic representation of the
liquid overtopping a bund walf in an event of
catastrophic leakage. rn the event of any J-arge leak or
catastrophic rupture of the storage tank, a large volume
of J-iquid 302 is rel-eased with a hiqh velocity in a very
short time- This high velocity riquid wave frows towards
the bund wafl- 304. rn the absence of any diverting means,
the high velocity liquid wave 302 strikes the bund warl-
304 that offers a sudden stoppage or barrier to'L.he wave.
This results in formation of a surge of waves having
substantial amount of force to overtop the bund 306.
Í00271 According to the embodiments of the present
invention, the diversion wal-ls facilitate in preventing a
sudden stoppage of the high veJ-ocity liquid vvave. The
diversion walls and the angular pillars divert the liquid
\,v_ave in dif ferent directions. This diversion of the
J-iquid waves arso cause division of v/ave j-n two or more
directions. This wây, the liquid wave wifl not face
obstruction which causes sudden stoppage and generation
of surge wave but it wil-l al-low the wave to f low in
another direction. rn other words, the mechanisms of the
present invention as discussed above, facilitate in
gradually reducing the momentum of the fl-ow of the leaked
liquid thereby preventing the tiquid vvaves to overtop the
wal-l-.
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[0028] rn one embodiment of the present invention, a
method is provided for preventing liquid from overtopping
a bund walf built around a J-iquid storage tank. The
method comprises the steps of: constructing a first fl_at
wall having a first warr--end and a second war-r-end; and
constructing a second flat waff bonded to the first ffat
wall- - The f irst waf l-end of the f irst f lat wal-f is bonded
with a first waff-end of the second frat wafr-, ât an
angle 'e' for diverting flow of riquid in an event of a
catastrophic rupture of the liquid storage tank. The
method further comprises the steps of constructing a pair
of angular pirJ-ars adjacent to the corresponding second
wall--end of the f irst waf r and the second war-l
respectively, foç preventing formation of any surge wave
due to the catastrophic rupture.
[002e] Figure 4 is a tabl-e showing experimentar- resuf ts
of bund overtopping with and without the apparatus for
preventing liquid from overtopping a bund wa]r accordíng
20 to the embodiments of the present invention. The
experiments have been carri-ed out in folÌowing stages
using a facility of a storage tank and dike or bund walf
setup in the scale of 1:40.
[0030] stage 1: At stage r, the experiment was carried
out without using the apparatus of the present invention.
A tank modef was fifl-ed up to approximately 90å of its
capacity and 903 of tank height. The overtopping liquid
quantíty due to a sudden release of liquid from the tank
was measured around lrz of total liquid in the tank. when
the tank was fil-led approximately 50å of tank capacity
and up to 50ã of tank height, the u^vertopping riquid
quantity due to sudden rel-ease of liquid from the tank
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was measured around 452 of total liquid in the tank (i.e.
50å of tank capacity) . Further, when the tank was fiffed
approxj-mately up to 452 of tank capacity and up to 45eo of
tank height, the overtopping liquid quantity due to
sudden release of liquid f rom the tank \ivas measured
around 313 of total J_iquid in the tank.
[0031] Stage 2: At stage 2, the experJ-ment was carried
out on the tank model with the diversion wafls and
angular pillars. The tank modef was filfed up to
approximately 902 of its capacity and gOeo of tank
height, The overtopping quantity due to sudden rel-ease
\^/as measured around 20-22? of liquid in tank. rt was thus
observed that the angular wall-s and pirlars as discl-osed
in the present invention were capable of reducing the
overtopped quantity considerably. I,rlhen the tank model v/as
filled up to 50å of tank capacity with 50å of tank
height, the overtopping quantity due to sudden release
was negtigible. Similarly, a negligible overtopping \ivas
observed in a simil-ar manner when the tank model v/as
fif]ed up to approximately 452 of its capacity and 452 of
tank height
[0032] Further experiments were carried out to determine
the maximum capacity and height of the tank fitred up
vofume below which overtopping was negligible due to
sudden re-lease of liquid from the tank. rn a typicar case
of tanks having 152 of filled vo]-ume and ? height of same
order, it was observed that 15% of hofd up liquid
overtopped the bund due to sudden ref ease. rt vvas also
observed that in the case of tank filfed capacity and
tank height of approximately 632 and below, the
overtopped liquid quantity was negligible
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Further, by
10
increasing the bund walr height by 50å of initial height,
for tanks having j5z of firred vol-ume and ? height of
same order, it vvas observed that around 5? of hofd up
liquid overtopped the bund due to sudden refease. rt was
also observed that in the case of tank filled capacity
and tank height of approximatery ioz and below, the
overtopped liquid quantity was negligible. rt was
concl-uded that the overtopping can further be reduced by
increasing the height of bund wal-1. However, the total_
height of bund walf should be up to maximum of 2 meters
in line with the reguJ-atory guidelines. During the
experiments, it was afso observed that the maximum
overtopping takes place at the corners when the dike is
provided with the dlversion walls and prr-rlars. Therefore,
it was concl-uded that the prevention of bund overtopping
may afso be improved by optimally increasing the height
of bund wall at the corners, instead of i_ncreasing the
height of the enti-re bund wall-. The resuf ts of the
experj-ments are shown in the table of f igure 4.
[0033] Thus, when the tiquid storage tanks are
facilitated with the apparatus and the method of the
present invention, reduced bund overtopping can be
effectively obtained in the events of sudden release of
liquid. The angular walfs and pillars may be constructed
between the liquid storage tank and the bund wall-.
Angurar wa1ls being constructed very cl-ose to the tank
may resurt high speed liquid fl-ow in the converging
passage towards the corners and may not be very effective
in reducing the liquid overtopping. construction of the
walfs very close to bund wafl may also not be very
effective in reducing overtopplng as surge waves are
generated when approaching liquid strikes on the angular
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r'- .,ì,.:.-:\...-.!:;:. ;1ì,:i.iä-'::;:;-i:..:--.*,ì.-':.::,,:-: -;,t:-::::,__:
\^/al-l-s, and the surge \,ùaves may jump out of the bund wal-l.
Thus, optimum l-ocation can be selected by keeping in view
the operational and maintenance requirements of the
storage tank facility.
[00341 While the exemplary embodiments of the present
invention are described and iflustrated herein, it will
be appreciated that they are merely illustrative. It wiff
be understood by those skil-l-ed in the art that various
modifications in form and det.ail may be made therein
without departing from or offending the spirit and scope
of the invention as defined by the appended .

claims.
claim:
1 " An apparatus for preventing liquid from
overtopping a bund wal-I buiÌt around a J-iquid storage
5 tank, the apparatus comprising:
a first fl-at wall having a first wall-end and a
second wall-end;
a second flat wall having a first wal-l--end and a
second wall-end, the first wall-end of the first flat
10 walÌ bonded with the first wafl-end of the second
fl-at waIl, ât an angle'e'for diverting fl-ow of
liquid in an event of a catastrophic rupture of the
liquid storage tank;
a pair of angula-r piIlars, each angular piIJ-ar
15 standing adjacent to the corresponding second wal-lends
of the first flat wall- and the second ffat wallrespectively
for preventing formation of any surge
wave due to the catastrophic rupture of the liquid
storage tank
20
2. An apparatus as cl-aimed in cl-aim 7, wherein the
apparatus is constructed on an area between the
liquid storage tank and the bund walf.
25 3. An apparatus as claimed in claim I, wherein the
angle 'e' is l-ess than 180 degrees facíng towards the
bund wall.
4. An apparatus as cl-aimed in cfaim L, wherein the
30 angular piJ-l-ar is an elongated pillar having
triangular cross section.
17
10
5. An apparatus as
height of the first
equal to the height
cl-aimed in claim
flat walf and the
of the bund wall.
I, wherein the
second fl-at are
wherein the
between the
6. An apparatus as claimed in cfaim I, wherein the
height of the first flat wall and the second ftat
wall- are marginall-y lower than the height of the bund
wal-l-
1. A method for preventing J_iquid from overtopping a
bund wal-l- buil-t around a liquid storage tank, the
method comprising the steps of:
constructing a first flat. wal_l having a first
wal-f-end and a second wal-f-end;
constructing a second fl_at wall bonded to the
first flat wal1, wherein the first wall-end of the
first ffat wall is bonded with a first wall-end of
the second flat wal-1, ât an angle .e, for diverting
fl-ow of liquid in an event of a catastrophic rupture
of the liquid storage tank;
constructing a pair of angular piJ_lars adjacent to
the corresponding second wall_-end of the first flat
wal-l- and the second f l-at wal-f respectively, f or
preventing formation of any surge wave due to the
catastrophic rupture of the liquid storage tank.
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B. The method as claimed
apparatus is constructed
liquid storage tank and the
1n claim J,
on an area
bund wal-l.
9. The method as claimed
angle 'e' is less than 180
bund wall -
ín cl-aim J , wherein the
degrees facing towards the
30
18
10. The method as cl-aimed in claim 7, wherein the
angular pí1Lar is an elongated pillar having
triangular cross sect j_on.
11- The method as cl-aimed in cf aim J , wherein the
height of the first fl-at wall and the seconQ ffat aïe
equal t.o the height of the bund waf Ì.
10 12. The method as cl-aimed in claim I , wherein the
height of the first flat wafl_ and the second flat
waf] are marginally Ìower than the height of the bund
waf l-