FIELD OF THE INVENTION
The present invention relates to a device for providing openings in the panels
of high pressure boilers. More particularly, the invention relates to a universal
device to support and maintain constant gap to avoid shrinkage during
welding of evaporator panels with bend tubes in high pressure boilers.
BACKROUND OF THE INVENTION
Generally high pressure boilers having two passes namely first pass and
second pass. The water wall panels are provided with openings during
manufacturing. The purpose of providing openings is to insert soot blower
manhole doors and observation ports.
The water wall openings are provided with three bend tubes on either side so
as to maintain an opening gap. During normal manufacturing of the pressure
boilers, water wall panels are welded with bend tubes by fit up welding.
The pitch distance from one centerline of the pipe tube to the centerline of
another pipe tube including the opening dimension, are critical which are to
be maintained during welding operation of connecting the bend tubes and
evaporator panels in order to avoid shrinkage during welding. In the existing
manufacturing process at least five bridge pieces are tack welded across said
gap and the height of the opening. Fin plates are welded in between the
tubes to maintain the pitch distance. During welding, the shrinkage is
arrested by the bridge pieces already welded. After completion of the both
the welding i.e. water wall panel to bend tubes including the fin plate
welding on both sides of the tubes, the bridge pieces are removed by
grinding. After removable of the bridge pieces, the rough surfaces of the
panel tubes are rebuilt with weld metal and non-distractive test are carried
out since those tubes are subjected to high pressure and high temperature

application. The above process is time consuming and more skill is required
for the fit-up.
OBJECT OF THE INVENTION
It is therefore an object of the present invention to propose a universal
device to support and maintain constant gap to avoid shrinkage during
welding of evaporator panels with bend tubes in high pressure boilers.
SUMMARY OF THE INVENTION
Accordingly, there is provided a universal device to support and maintain constant
gap to avoid shrinkage during welding of evaporator panels with bend tubes in high
pressure boilers. The universal device supports the bend tubes of water wall panels
with specified gap during welding process. According to invention the device is
disposed at the center of the panel opening and a handle of the device is oscillated
up and down so that the left and right clamps moves simultaneously in the opposite
directions.
The operation is carried out till both the clamps touch the left and right bend tubes.
Now the specified distance is maintained between the inner tubes of left and right
bend tubes, thereby a constant gap is maintained to carry out the following welding
process.
1. Welding of panels evaporator panels with bend tubes
2. Fin plate welding in between the tubes to maintain a specified pitch distance of
between centerline of the tubes.
Because of the perfect holding by the device shrinkage is eliminated and a constant
distance is maintained throughout the welding process.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIGURE 1-shows the assembly of the fit-up device of the invention with work piece
in position.
FIGURE 2-shows the fit-up device alone without work piece.
DETAILED DESCRITION OF THE PREFERRED EMBODIMENT OF THE INVENTION
As shown the figure-2 the device comprises:-
1. Handle (01) fitted with a locking pin (04) with a ratchet assembly (05) ;
2. Outer arms (03) both on the left side and right side of the ratchet assembly (05)
is fitted in such a way that it rotates in its own axis;
3. An external threaded stud (06) welded with a semicircular clamps on either side
in such a way that the outer arm (03) rotates the stud (06) will move
longitudinally ;
4. The diameter of the semicircular clamps (02) is selected to be more than that of
the tube diameter of the work pieces (07 & 08).
Initially referring to FIGURE-1 the outer arm is held by hand approximately at the
center of the work pieces (7&8). According to the invention the device is normally
disposed approximately at the center of two water wall panel opening and the
handle (01) is oscillated up and down so that the left and right clamps(02) moves in
symmetry in opposite directions.
The operation is carried out till both the clamps touches the left and right bend
tubes. Now the specific distance is maintained between the inner tubes (07 and 08)
there by a constant gap is maintained to carry out the following welding process.
1. Welding of panels evaporator panel with bend tubes
2. Fin plate (10) welding in between the tubes (09) to maintain a pitch distance
of 54mm between centers.

Because of the perfect holding by the device, welding shrinkage is eliminated
and the constant distance is maintained throughout the welding process.

WE CLAIM:
1. A universal device to support and maintain constant gap to avoid
shrinkage during welding of evaporator panels with bend tubes in high
pressure boilers, comprising :-
-a handle (01) with a locking pin (04) and a ratchet assembly (05) having
outer arms (03) on both sides of the ratchet assembly; and
- a plurality of studs (06) welded to a plurality of semicircular clamps (02),
wherein the rotation of the handle (01) allows the externally-threaded stud
(06) to simultaneously move longitudinally in opposite direction, and wherein
the plurality of the clamps corresponding to the movement of the stud (06)
firmly grip the work piece (07,08) to maintain a predetermined constant gap.
2. The device as claimed in claim 1 where in the constant distance is maintained
without shrinkage during the entire process of complete welding of the work-
piece (07,08) with water panels (09).
3. The device as claimed in claim 1, wherein the device allows maintaining of
constant gap during the welding of the work-pieces (07,08) to each other.
4. The device as claimed in claim 1, wherein the device allows maintaining of
constant gap during welding of fin-plates (10) in between the tubes (09).