FIELD OF INVENTION
The invention relates to a fixture for perfect alignment of inter-connecting
nozzles of two tanks of a Deaerator in a Power Plant and the process for
assembling the tanks.
BACKGROUND OF THE INVENTION
Deaerator is a direct contact heat exchanger which is used in a steam heating
cycle either in a power plant or in a process steam generating industry.
Deaerators are used to remove any non-condensable gases mainly Oxygen and
Carbon Di-Oxide.
A conventional spray cum Tray type Deaerator consists of two tanks which
constitute the Deaerator assembly. They are:
1) Deaerator Heater: It houses the spray valves and Trays installed for achieving
deaeration (this tank is mounted on Deaerator Feed Storage Tank).
2) Deaerator Feed storage Tank (FST): for storing the water already deaerated
in Deaerator Heater.
The two constituent tanks - Heater and Feed storage Tank (FST) are connerted
by inter-connecting nozzles namely:

1. Down comer (for deaerated water to flow from Deaerator Heater to FST)
and
2. Equalizer (for steam to flow from Heater to FST, in-order to equalize the
pressure between the two tanks).
The Deaerator Heater and the Feed Storage Tank are manufactured separately
at the manufacturer's facility. After fabrication of each of the tanks, there arises
a need to inter-connect them. For this purpose, openings need to be created in
each of the vessels. These openings serve the purpose of fitting in the inter-
connecting nozzles, namely the Down Comer and the Equalizer.
Any one of the vessels, either Heater or the Storage Tank is taken up as
reference for making the opening. At first, the center line of the chosen vessel is
precisely marked using the dimensions mentioned in the drawing. Taking this
center line as reference, the openings are made at the identified locations of the
vessel and the nozzles are welded into them. In the same way, the openings are
made for the other vessel too and the nozzles welded to it based on dimensions
mentioned in the drawings. The two vessels i.e. Heater and Storage Tank are
then interconnected at their nozzles and welded thus completing the assembly.

PROBLEMS FACED IN THE EXISTING SYSTEM (PRIOR ART)
With the two tanks being fabricated separately, matching the location of inter-
connecting nozzles becomes a problem. There is always a possibility of human
error in identifying the exact location for welding of inter-connecting nozzles and
also in the making of the opening. Any such mismatch becomes a serious
problem at site. Resulting modification and rework for perfect alignment takes a
lot of time, manpower and resources.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a fixture for perfect
alignment of Inter-connecting nozzles of feed storage tank and heater of a
Deaerator and the process for assembling the same which is capable of aligning
the inter-connecting nozzles of two tanks for welding the Deaerator assembly.
Another object of the invention is to propose a fixture for perfect alignment of
Inter-connecting nozzles of feed storage tank and heater of a Deaerator and the
process for assembling the same which is able to eliminate site rework in
Deaerators so that there is adequate saving in respect of manpower and
resource utilization.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1 - shows a line diagram of Deaerator Heater with down comer and
equalizer.
Fig.2 - shows a line diagram of Deaerator Feed storage Tank with down
comer and equalizer.
Fig.3 - shows a Deaerator Assembly of the heater and the storage tank
joined together by inter-connecting nozzles.
Fig.4 - shows a line diagram of the fixture according to the invention in
plan and elevation view.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
Fig.1 shows Deaerator heater (12) with inter-connecting nozzles down comers
(3H, 6H) and equalizer (4H, 5H) and Fig.2 shows Deaerator Feed storage tank
(13) with inter-connecting nozzles down comer (3F, 6F) and equalizer (4F, 5F).
The assembly of these two units is made with the help of the Fixture.

The present invention proposes the use of an ingenious procedure of using a
novel fixture (11). Any of the Deaerator vessels (12, 13), either the Heater (12)
or the Storage Tank (13), is taken as reference. The center line of this vessel is
marked precisely.
The position of the down comers (3H, 6H) and the equalizer (4H, 5H) of the
heater (12) is marked as per the drawing dimension and with the help of the
centre line taken as reference.
The inter-connecting nozzles, the Down Comer (3H, 6H) and the Equalizer (4H,
5H) are welded onto the vessel (12) at the marked openings taking into account
the dimensions provided in the drawing. Each of these inter-connecting nozzles
(3H, 6H; 4H, 5H) is provided with extra material for development of the fixture
at site. This novel fixture (11) is developed by taking a pair of channels (43)
(1,2) as the structure for handling and then based on the position of the inter-
connecting nozzles, the extra material (ring shaped pipe pieces) (7, 8) are then
welded onto this channel as a mirror image of its position. This procedure is
repeated for both the Down Comer as well as the Equalizer. In cases where the
sizes of the inter-connecting nozzles are unequal, the pipe piece (ring) with
larger diameter (7) is taken up first and welded to the parallel set of channels (1,
2). The pipe piece (ring) with smaller diameter (8), which corresponds to the

smaller of the inter-connecting nozzles is then placed in between the channels
and is welded onto the fixture by the help of supporting ribs (9, 10) at the
required position.
After marking the position of the inter-connecting nozzles, the position of the
center line (12,13,14,15) in the vessel is also marked onto the fixture (11). The
fixture (11) thus developed leads to an exact imprint of the positions of the
nozzle as well as the center line of the vessel taken as reference.
This fixture (11) developed is then transferred to the other manufactured vessel
(13). The center line of this vessel (13) is matched precisely with the position of
the center line marked in the fixture (11). Locking the fixture (11) at this
position, based on the imprints obtained from the previous vessel (12), the
positions of openings for inter-connecting nozzles (3F, 6F; 4F, 5F) are marked for
this vessel (13). Subsequently, the openings are made and the nozzles welded at
the exact locations ensuring a perfect match in between them.
The novel fixture (11) comprises an assembly of two parallel channels (1, 2)
which are placed at a specific distance depending on diameter of the nozzle. The
pipes (7, 8) corresponding to the specific positions of the Down Comer (3H, 6H,
3F, 6F) and the Equalizer (4H, 5H, 4F, 5F) are welded on to this structure (11).

It thus acts as the structure for handling. In cases where the nozzle diameters of
the down comer (3H, 6H, 3F, 6F) and the equalizer (4H, 5H, 4F, 5F) are unequal,
the pipes (7, 8) corresponding to the larger of the two nozzles is welded onto the
fixture (11) at first. Subsequently, the pipe (8) for the smaller fixture is placed
and welded onto the fixture with the help of ribs (9, 10) to hold them in the
marked position dimension Marked with (15, 16, 17, 18) are taken from the
vessel which is fabricated first. The same is then transferred to the second
vessel. The fixture (11) obtained is then used to transfer these dimensions to the
second vessel so that the nozzles are placed in tandem ensuring a perfect
positioning and subsequent matching during assembly of the Deaerator (14).
The nozzles (3F, 4F, 5F, 6F) are then welded at the exact location. As shown in
Fig.3 the Deaerator assembly (14) constituting of the heater (12) and the
storage tank (13) is then made by joining the inter connecting nozzles, namely
the down comer and the equalizer.
The Deaerator (14) manufactured using the above procedure and consisting of
the above novel fixture (11) ensures to eliminate the probability of misalignment
and mismatch issues in between the inter-connecting nozzles of a Deaerator
(14).
Furthermore, site rework in Deaerators (14) is eliminated saving adequate
manpower, resources as well as reducing erection time.

WE CLAIM
1. A fixture (11) for perfect alignment of inter-connecting nozzles of Feed
storage tank (13) and heater (12) of a Deaerator in a Power Plant
comprising:
two parallel channels (1, 2) joined to each other by pipe rings (7, 8);
at least two supporting ribs for accommodating each of the smaller pipe
rings (8) for welding in the channels (1, 2);
Characterized in that,
the welded pipe rings (7, 8) are disposed on the channels for specifying
the exact position of down comer and equalizer already welded on a
vessel of the Deaerator.
2. A process for perfect alignment of inter-connecting nozzles of feed storage
tank (13) and heater (12) of a Deaerator and joining them by a fixture
claimed in claim 1 comprising:
marking the centre line of any one of the vessel (12/13) precisely;
marking the position (12, 13, 14, 15) of the inter-connecting nozzles,
down comer (3H, 6H) and equalizer (4H, 5H);

welding the down comers (3H, 6H) and the equalizers (4H, 5H) with the
vessel at the marked openings;
welding the pipe rings (7, 8) in between two channels (1, 2) exactly in the
same position of the down comers (3H, 6H) and equalizers (4H, 5H);
welding the smaller pipe rings (8) with supporting ribs (9,10);
marking the centre line of the vessel onto the fixture (11) for taking
reference and creating an exact imprint of the positions of the nozzle;
transferring the developed fixture (11) onto the other manufactured
vessel (12, 13) for matching the centre line of the vessel precisely with
the centre line marked on the fixture (11);
locking the fixture (11) at this position;
marking the positions of the openings for inter connecting nozzles (3F, 6F;
4F, 5F) are welded at the exact locations ensuring a perfect match in
between the two vessels (12, 13) so that Deaerator (14) is assembled
without any misalignment or mismatch.