FIELD OF THE INVENTION
The present invention generally relates cycle time reduction in
manufacturing of mixing vessels/spheres. More particularly, this
invention presents an apparatus and method for plugging of nozzles on a
mixing vessel before conduction of the hydraulic test without welding of
dummy plates on the nozzles.
BACKGROUND OF THE INVENTION
A hydraulic test is a method of testing a product for strength and leaks.
The test involves filling the vessel or pipe system with a liquid, usually
water at ambient room temperature, which may be dyed to aid in visual
leak detection, and pressurization of the vessel to the specified test
pressure. Hydraulic testing is done with test pressure 1.5 times that of
the design pressure.
All the nozzle openings of the Mixing sphere at present are plugged by
welding dummy plates before conducting hydraulic test. Once the
hydraulic test is completed the dummy plates are cut down and the
nozzle ends are Edge prepared to the drawing requirement.
The welding of the dummy plates, cutting the same after hydraulic
testing and Final Edge preparation constitutes about 5% of the total
cycle time of the Mixing Sphere. Hence, there is a dire need to devise
techniques for reducing the cycle time and to save the resources while
conducting hydraulic testing.

OBJECTS OF THE INVENTION
An object of the invention is to overcome the aforementioned and other
drawbacks existing in prior art systems and methods.
More particularly, it is an object of the invention to develop a fixturing
apparatus for plugging of nozzles on a mixing vessel so as to withstand
the Hydro static test pressure without any leakage during
hydro/hydraulic testing of mixing vessel/sphere.
Still another object of the invention is to develop a fixturing apparatus
capable of obviating the need for welding of dummy plates on nozzles and
their Edge preparation machining after hydro test.
Yet another object of the invention is to develop a fixturing apparatus
that can withstand the high pressure while performing the hydro test,
thus ensuring safety.
These and other objects and advantages of the present invention will be
apparent to those skilled in the art after a consideration of the following
detailed description taken in conjunction with the accompanying
drawings in which a preferred form of the present invention is illustrated.
SUMMARY OF THE INVENTION:
The present application discloses an improved reusable fixturing
apparatus for plugging of plurality of nozzles located on a mixing sphere
(1) before conducting hydraulic testing of the mixing sphere. The
fixturing apparatus includes a stem (7) welded to a bottom plate (6). In
one aspect, the bottom plate (6) has a groove and a seal (11) fastened to
the groove without discrete sealing. In another aspect, the stem (7) has a

rod with threaded end. In another aspect, the fixturing apparatus has a
stopper plate (8) with a hole arranged on a surface of the stopper plate (8)
for tightly holding the bottom plate (6) and stem (7) via a nut (10).
Further, the apparatus includes an inlet and gauge point tube (9)
inserted into the bottom plate (6).
In another aspect, the present application discloses a method for
plugging of plurality of nozzles located on a mixing sphere (1) before
conducting hydraulic testing of the mixing sphere. The method includes
welding a stem (7) to a bottom plate (6) and forming a groove thereto for
fastening a seal (11). Further, the method includes inserting said steam
(7) welded to the bottom plate (6) inside each of the plurality of nozzles
via a man-hole door assembly. In an aspect, the steam (7) is welded to
the bottom plate (6) is tightly positioned inside the nozzle by tightening
the said steam (7) welded to the bottom plate (6) to a stopper plate (8) via
a nut (10). Further, the method includes inserting into each of the
plurality of nozzles an inlet and gauge point tube (9).
The above and additional advantages of the present invention will
become apparent to those skilled in the art from a reading of the
following detailed description when taken in conjunction with the
accompanying drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The drawings refer to embodiments of the invention in which:
Figure 1 illustrates a schematic view of conventional nozzle design with
dummy plate welding.
Figure 2 illustrates a schematic view of conventional nozzle with hydro
dummy welded.
Figure 3 illustrates a schematic view of Mixing Vessel with hydro
fixturing apparatus/fixture.
Figure 4 illustrates the modified nozzle facilitating plugging of a fixturing
apparatus/fixture.
Figure 5 illustrates a front view of a fixturing apparatus/fixture.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
Although the disclosure hereof is detailed and exact to enable those
skilled in the art to practice the invention, the physical embodiments
herein disclosed merely exemplify the invention which may be embodied
in other specific structure. While the preferred embodiment has been
described, the details may be changed without departing from the
invention, which is defined by the claims.
It will be apparent, however, to one of ordinary skill in the art that the
present invention may be practiced without specific details of the well

known components and techniques. In other instances, well known
components or methods have not been described in detail but rather in
Figures in order to avoid unnecessarily obscuring the present invention.
Further specific numeric references should not be interpreted as a literal
sequential order. Thus, the specific details set forth are merely
exemplary. The specific details may be varied from and still be
contemplated to be within the scope of the present invention. The
features discussed in an embodiment may be implemented in another
embodiment.
Moreover occasional references to the conventional plugging techniques
are made in order to better distinguish the present inventive disclosure
discussed later in greater detail. Few of the details pertaining to the
locking mechanism are well-known in the art, and therefore, are
described herein only in the detail required to fully disclose the present
invention.
Improving upon the conventional techniques discussed at length above
(background), in the present disclosure the improved and reusable
fixturing apparatus as shown in Fig. 3-5 clearly makes the technique of
plugging of nozzles present on the surface of a mixing vehicle/sphere (1)
as disclosed in the present application advantageous over the existing
arts as would also become clearer to the knowledgeable in the art with
the particulars of the aforesaid techniques being described below in
greater detail.
Turning now to Figures, Fig. 1-2 shows the existing technique of welding
the Dummy plates to the nozzles. In the conventional technique of
welding the Dummy plates to the nozzles, the dummy plates are cut
down and the nozzle ends are Edge prepared to the drawing requirement
once the hydraulic test is completed.

Fig.3 illustrates a schematic view of Mixing Vessel with hydro fixturing
apparatus. In an embodiment, the fixture consists of a Bottom Plate (6)
with a Stem (7) welded to it. Further, the Bottom Plate (6) is taper
machined to an angle which is same as the angle available in the nozzle.
To aid the use of the claimed fixturing apparatus a small design
modification in the ID of the nozzle has been made as shown in Figure 4.
The taper provided in the nozzle and the base plate of the fixture
provides a tight fit during Hydraulic testing. In an aspect, fixturing
apparatus as proposed in the present invention is hardened before use in
the hydraulic testing of the mixing sphere. Hardening is a metallurgical
metalworking process used to increase the hardness of a metal. The
hardness of a metal is directly proportional to the uniaxial yield stress at
the location of the imposed strain. A harder metal will have a higher
resistance to plastic deformation than a less hard metal.
Furthermore, in an embodiment the bottom plate (6) has a groove for
fastening the seal which in a preferred embodiment is a neoprene rubber.
In a preferred embodiment, the groove is formed in a center of the bottom
plate (6).
Further, in an aspect, before assembling the fixture, the neoprene rubber
is fastened on the groove available in the fixture bottom plate (6). Before
making the Mixing Sphere ready for hydro test, the fixture (6, 7) may be
inserted through the Man-hole Door Assembly (4) and may further be
fixed suitably by tightening the Stopper Plate (8) with Nut (10). The inlet
and gauge point tube (9) is used for filling the Mixing Sphere (1) with
water and for pressurizing where in an aspect, pressurizing is performed
by connecting the inlet point to a centrifugal pump)
In another embodiment, the Man-Hole door Assembly (4) is closed before
filling water. Further, in an aspect, the man hole door assembly has a

door plate and a flange arrangement. Further, the door plate has
attachments for fixing the same with the sphere. Herein, the door is
manually closed and assembled with the flange assembly using bolts).
Water is filled through any one of the inlet points and the other hole shall
be used for fixing the pressure gauge. In another aspect, water may be
filled through the gauge point as well as the inlet point. Once the vessel
is totally filled with water, guage is fixed in the guage point and
pressurizing may be done through the inlet point connected to the pump)
When the water is being pressurized, the neoprene rubber O-ring (11)
expands due to load and thus providing a tight seal to the opening. The
fixture assembly has a neoprene rubber O-Ring which has a property to
expand and thus shall seal the leak. Working of the neoprene rubber O-
Ring may be considered similar to the rubber washer in a pressure
cooker. After the hydraulic testing, the fixture (6, 7, 8, 9, 10, and 11) is
removed in a preferred embodiment and stored for future use. Only the
neoprene rubber O-ring (11) is replaced while using the fixture during
the next hydraulic test.
Further, the feasibility of change in ID (Inner diameter) of nozzle to a
localized length as shown in Figure 4 is analyzed with respect to flow
area and velocity variation.
Further, analysis was made for force acting on the fixture. Sample
analysis for an 800 MW mixing sphere fixture is as follows.
The major criteria for the Plate to withstand the forces are the thickness
(t) of the plate, which should be able to withstand the allowable yield
stress (CT) which is 260 N/mm2 for SA515 GR70 Steel. Force acting on
the circular surface of the Fixture Bottom Plate can be calculated as,
F = P X A,
(4.1)

KD2
Where, A = 4 mm2, surface area of the plate
P - Pressure in kg/mm2, which is 485.25 kg/cm2 for 800 MW Mixing
sphere
D - Diameter of the plate in mm.
Force acting on Inlet Nozzle, FD1 = 7 X 376' X 4-8S2S x 9B1 =5285670.94
N
Force acting on Outlet Nozzle, FD2 = * X 3662 X 4852S x 9m
=5008256.96 N
Force acting on Recirculation Nozzle, FD3 = 4 X 2S22 X 4BS2S X 9S1
=2374244.9 N
The criteria for minimum thickness of the Fixture bottom plate is as
follows

Thus, the thickness of the fixture bottom plates should be greater than
the following values

where t1, t2 & t3 are thickness of the fixture bottom plates (6) of Inlet,
Outlet and recirculation nozzles respectively.

With respect to the cycle time following is the data obtained as a result of
the experimentation.
Table 3.5 Activities and Cycle time in manufacturing of the mixing
sphere

Fit up and welding of the dummies constitutes around 5 % of the total
manufacturing cycle time of the product. An improvement in the existing
process may result in cycle time saving as well as material savings.
Furthermore, the fixturing apparatus is designed as illustrated in Figure
5. In an aspect, said fixture with neoprene rubber O- ring (11) around its

taper portion provides the perfect sealing by virtue of centrifugal force
due to hydraulic test pressure. Instead of having a flat surface contact
between the fixture/fixturing apparatus and the nozzle, a taper contact
or an angular contact reduces the stress concentration
Advantages
i. Usage of dummy plates and their machining for welding on nozzles
is completely avoided.
ii. Welding of dummy plates as shown in Figure 1 and requisite
resources for welding is completely eliminated.
iii. Need for movement of vessel to machining work center for final
machining after hydraulic test is eliminated.
iv. The proposed techniques have also helped in reducing the raw
material length of nozzle by at least 100 mm.
v. The fixture can be stored and can be used in the future just by
replacing the neoprene O-ring rubber.
vi. The proposed technique facilitates reduction in the existing cycle
time by about 5%.
Economic Significance
The proposed fixture eliminates the use of the dummies that are to be
welded and also eliminates the manual labor required for welding the
dummies, leading to huge savings with respect to the cost. The cost
details associated with the use of dummies are mentioned in following
tables respectively.
Cost details of Dummy raw materials

Thus the total savings for 1 mixing sphere – Rs. 88,887
Net savings per year for approximately 6 mixing spheres (per year) - Rs.
5, 33, 323).
The foregoing is considered as illustrative only of the principles of the
invention. Furthermore, since numerous modifications and changes will
readily occur to those skilled in the art, it is not desired to limit the
invention to the exact construction and operation shown and described.
While the preferred embodiment has been described, the details may be
changed without departing from the invention, which is defined by the
claims.

We Claim:
1. An improved reusable fixturing apparatus for plugging of plurality
of nozzles located on a mixing sphere (1) before conducting
hydraulic testing of the mixing sphere, said fixturing apparatus
comprising:
a stem (7) welded to a bottom plate (6), said bottom plate (6)
having a groove, a seal (11) fastened to the groove without
discrete sealing, said stem (7) having a rod with threaded
end;
a stopper plate (8) with a hole arranged on a surface of the
stopper plate (8) for tightly holding said bottom plate (6) and
stem (7) via a nut (10); and
an inlet and gauge point tube (9) inserted into the bottom
plate (6).
2. The fixturing apparatus as claimed in claim 1, wherein the bottom
plate (6) is taper machined to an angle identical to an angle at
which each of the plurality of nozzles is positioned on the mixing
sphere.
3. The fixturing apparatus as claimed in claim 1, wherein the bottom
plate (6) and the stem (7) is housed in each of the plurality of
nozzles via a man-hole assembly (4).
4. The fixturing apparatus as claimed in claim 1, wherein the seal is
of neoprene rubber O-ring (11) type.
5. The fixturing apparatus as claimed in claim 1, wherein the stopper
plate (8) is a rectangular plate.
6. The fixturing apparatus as claimed in claim 1, wherein the bottom
plate (6) and the stem (7) is made of carbon steel.

7. The fixturing apparatus as claimed in claim 1 is hardened before
used in the hydraulic testing of the mixing sphere.
8. A method for plugging of plurality of nozzles located on a mixing
sphere (1) before conducting hydraulic testing of the mixing
sphere, said method comprising:
welding a stem (7) to a bottom plate (6) and forming a groove
thereto for fastening a seal (11);
inserting said steam (7) welded to the bottom plate (6) inside
each of the plurality of nozzles via a man-hole door
assembly, wherein said steam (7) welded to the bottom plate
(6) is tightly positioned inside the nozzle by tightening the
said steam (7) welded to the bottom plate (6) to a stopper
plate (8) via a nut (10);
inserting into each of the plurality of nozzles an inlet and
gauge point tube (9).
9. The method as claimed in claim 1, wherein the bottom plate (6) is
taper machined to an angle identical to an angle at which each of
the plurality of nozzles is positioned on the mixing sphere.