FIELD OF THE INVENTION
The present invention relates to a fixture of simplified clamping method used
for positioning and fit up of bend tubes to water wall panels used in furnace
of steam generation power plants for power generation. More particularly the
invention relates to method of clamping the bend tubes for root welding
without bridge pieces welding on the bend tubes.
BACKGROUND OF THE INVENTION
In power plants, the water wall panels are used for carrying water and its
conversion into steam in furnace to rotate the turbine for power generation.
The water wall panels are assembled in side walls and on the top of the
furnace which carries and supplies water along with steam interconnecting
headers and separators. These water wall panels are manufactured by
welding flat fin and water wall tubes in series of required diameter and
specification of grade in 20 torch welding machine. These panels are
manufactured in straight for welding in 20 torch welding but the bend tubes
cannot be fed in the rollers of machine for carrying out the process.
These water wall panel bend tube attachments are welded by fit up
positioning in the shop by arresting with channel and angles. This fit up and
welding consumes excess time to do the grinding and rework operations. This
poses a serious problem during positioning, fit up, finning and final inspection
stages. The dimensions of the water wall panel is generally 24000 mm height,
2500 mm width and tube outside diameter ranging from 44.5mm to 75.00
mm and the weight of the panel varying from 1000 kg to 5000 kgs. The
dimensions of the bend tube is generally 500mm length with offset distance
of 120mm with same panel tube outside diameter of 44.5mm and its weight

is around 100kgs. 750mm length of two no's of tubes having outside diameter
are welded on either side of the panel with 650 mm projecting outside to tack
weld a standard channel to provide a basement to place bend tubes. After
placing the bend tubes, leveling was checked with spirit level and bridge
pieces were tack welded for all 25 no's of bend tubes with panel. The number
of bend tubes may vary from 25 to 50. Now root welding is carried out for
one half of the panel and the operation is repeated by reversing the panel to
complete the joint. The bride pieces, channel and 750 mm length tube are
removed by grinding and gas cutting. This operation of welding the bridge
pieces and channels and again removing after root welding was found highly
time consuming to the workmen for fit up and rework operations.
It takes about 4 shifts for the entire operation for one panel assembly.
There are 18 panels per boiler and 5 boilers / year are to be manufactured.
Hence there is a need to find out a simplified and easy clamping platform
method for handling, dismantling and fit up without arresting the bent tubes
by conventional welding with channels or L-angles.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a simplified clamping
platform for positioning and fit up of bent tubes to water wall panel.
Another object of the invention is to propose a clamping platform for easy fit
up and dismantling without bridge pieces which are to be welded on the bend
tubes to connect with straight water wall panels.
A still another object of the invention to do the root welding of bend tubes
with water wall panels in safe condition to reduce cycle time and fatigue to
operator.

SUMMARY OF THE INVENTION
Accordingly, the water wall panel is placed on the base plate form and the
other end is supported by means of two or more supporting stand ( not
shown) depending on the length of the water wall panel to make a simply
support with counter weight to avoid distortion. Referring to the Figure 1,
there is provided an ‘A’ Frame provision to build a clamping platform with
three numbers of bottom channels (12) at equal distance welded
perpendicularly to ‘A’ Frame. Three numbers of inclined angles (8) are welded
at an angle 45˚ connecting with channels to form bracket assembly. One
number of horizontal angles (13) is welded in the middle portion of the
bracket assembly for reinforcement.
Four No's of M24 Hexagonal nut (10) is welded perpendicular to ‘A’ Frame at
4 corners to utilize as levelers at ground floor with assembly of M24
Hexagonal screw (11) for adjusting upwards and downwards for perfect
leveling. The base platform (2) mounted on the top of the A-Frame was
interlocked with bottom channel (12) by means of fasteners (05, 06 & 07) .
The base platform and top channel are provided with four numbers of
identical slots of 150 x 16 mm for holding four number of bolt , nut , square
washer and round washer for perfect clamping and better seating during
root welding. The pitch distance between the bend tubes varying from 54mm
to 100mm can be accommodated by this method of clamping. Thus the
arresting of bend tubes for fit up with water wall panel is properly locked by
the above arrangement and the tack welding carried out by conventional TIG
welding for the upper half and the panel reversed by simply dismantling the
fasteners to carry out the remaining half of the root welding. Counter weight
is placed on the panel assembly for perfect leveling on the other end. The
entire operation is carried out in one shift with the elimination of the
drawbacks said in the prior art.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 — is a block diagram of clamping platform used for positioning and
fit up of bend tubes to water wall panels according to the invention.
Figure 2 — shows the isometric view of the apparatus with work pieces in
position for root welding.
Figure 3 shows the supporting stand to use on the straight water wall panels
nearer to counter weight.
Figure 4 shows the top channel with slots provided for clamping the bend
tubes.
Figure 5 shows the base platform with slots provides corresponding to the
slots of top channel for clamping the bend tubes. The figure shows the
counter bore for interlocking the bottom channel.
Figure 6 shows the assembly of bolt, nut, square washer and round washer
for connecting the base platform and channel.
DETAIL DESCRIPTION OF THE INVENTION
Accordingly, the water wall panel (16) is placed on the base plate form (02)
and the other end is supported by means of two or more supporting stand
(17) ( not shown) depending on the length of the water wall panel (16) to
make a simply support with counter weight (14) to avoid distortion. Referring
to the Figure 1, there is provided an A-Frame (01) provision to build a
clamping platform with three numbers of bottom channels (12) at equal
distance welded perpendicularly to A Frame (01). Three numbers of inclined

angles (08) are welded at an angle 45˚ connecting with channels (12) to form
bracket assembly. One number of horizontal angles (13) is welded in the
middle portion of the bracket assembly for reinforcement.
Four No's of M24 Hexagonal nut (10) is welded perpendicular to A-Frame (01)
at 4 corners to utilize as levelers at ground floor with assembly of M24
Hexagonal screw (11) for adjusting upwards and downwards for perfect
leveling. The base platform (02) mounted on the top of the A-Frame (01) was
interlocked with bottom channel (12) by means of fasteners (03). The base
platform (02) and top channel (04) are provided with four numbers of
identical slots of 150 x 16 mm for holding four number of bolt (07), nut (06),
square washer (05) and round washer (09) for perfect clamping and better
seating during root welding. The pitch distance between the bend tubes
varying from 54mm to 100mm can be accommodated by this method of
clamping. Thus the arresting of bend tubes for fit up with water wall panel is
properly locked by the above arrangement and the tack welding carried out
by conventional TIG welding for the upper half and the panel reversed by
simply dismantling the fasteners (05), (06), (07) and (09) to carry out the
remaining half of the root welding. Counter weight (14) is placed on the panel
assembly (16) for perfect leveling on the other end. The entire operation is
carried out in one shift with the elimination of the drawbacks said in the prior
art.

WE CLAIM:
1. A simplified clamping platform apparatus comprising :
a base platform (2) for providing basement of water wall panels (16),
the said base platform (2) being placed over a plurality of bottom
channels (12) which are at equal distance and interlocked to each
other, the said assembly being mounted on top of A-frame assembly
(01), the A-frame comprising legs (1) forming trusses and reinforced
by inclined angles (08) placed at 450 position and welded connecting
bottom channel (12) with vertical stand by welding wherein a plurality
locking mechanism comprising bolt (7), nuts (6), square washer
(05)and round washer (09) are used for locking the top channel (4)
with base platform (2) when the bent tubes (15) placed in between
perfectly positioned side by side and afront the water wall panel (16)
which is mounted taking platform (2) base as support in one side and
on the other side resting over supporting stand (17), the set up being
ready for performing root welding of bent tube;
2. The clamping platform apparatus as claimed in claim 1 wherein the
leveling of the platform base (2) is done by a mechanism welded at the
bottom of A-frame assembly with the help of 4 Nos of hexagonal nut
(10) and screw (11) at the four corners.
3. The clamping platform apparatus as claimed in claim 1 wherein a
counter weight (14) is placed on the panel assembly (16) for perfect
leveling and matching with the bent tube faces.

4. The clamping platform apparatus as claimed in claim 1, wherein a
single number of horizontal angle (13) is welded in the middle portion
of bracket assembly for reinforcement.