FIELD OF THE INVENTION
The present invention relates to Marking, Drilling, fit up of hemispherical dish
end during fabrication of high pressure boilers. More particularly, the invention
relates to a device for pre-welding fit up of line pipes with a hemispherical dish
end during fabrication of high pressure boilers.
BACKGROUND OF THE INVENTION
In the manufacturing of high pressure boilers (both sub critical and super critical)
in the main steam line, hot reheat line and cold reheat line, fit-up of pipe with
hemispherical dish end is difficult and because of its handling. Moreover, the
lifting or moving of the dish end by a of crane is not possible without welding of
external jig or fixture along its surface. After completion of marking, drilling and
fit-up, the external jig or fixture is to be removed from the surface of the
assembly by hammering. This results in damaging of the raw material which in
turn has to be corrected by re-welding. Moreover, this jig or fixture is attached
along the curved surface of the dish end, so fit-up of the dish end with the pipe
takes longer time to maintain the root gap evenly along its circumference, which
is done by moving the dish end manually and maintaining the dish end in that
position and a bridge plate is welded. So to avoid this type of unsafe method, a
device is designed for taking fit-up without usage of crane.

OBJECTS OF THE INVENTION
It is therefore an object of the present invention to propose a device for pre-
welding fit up of line pipes with a hemispherical dish end during fabrication of
high pressure boilers.
Another object of the invention is to propose a device for pre-welding fit up of
line pipes with a hemispherical dish end during fabrication of high pressure
boilers, which reduces the usage of overhead cranes and cost.
SUMMARY OF THE INVENTION
According to the invention, a Hemispherical dish end of a line pipe for example a
main steam line is placed on a device having a Tilting base plate and a clamping
ring, which end is tightened with the clamping ring, the dish end of the pipe is
moved near to the pipe, to which fit up is going to be done by a movable base.
Then the dish end is brought to pipe height and its center is made to coincide
with the pipe axis with the help of an adjustable screw and jack provided in a
strand of the device. Then, face of the dish end is made parallel to the pipe face
with the tilting base plate, which is rested on a supporting channel. Once this
adjustment is done, a root gap between the pipe and the dish end is maintained
by moving the movable base to complete the fit-up.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 shows the front view of a device to carry out the inventive method.
Figure 2 shows the side view of the device of Figure 1.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
According to invention, a the Hemispherical dish end is placed on a Tilting base
plate (2) and tightened by a clamping ring (1), which can freely rotate on a
rotatable guide channel (5), provided in the device to hold the dish end in
position and the dish end is moved near to the pipe, to which a fit up is done by
a movable base (7). Then, the dish end is brought to pipe height and its center is
made to coincide with the pipe axis with the help of an adjustable screw (4) and
a jack (6) provided in the device. Then, face of the dish end is made parallel to
the pipe face with the tilting base plate (2), which is rested on a supporting
channel (3). Once this adjustment is done, a root gap between the pipe and dish
end is maintained by the moving movable base (7) to complete the fit-up.

Since the tilting base plate (2) is detachable, same can be used as base for both
marking and drilling. After completion of the drilling, the tilting base plate (2) can
be repositioned in the supporting channel (3) with the help of an over hand
crane. Since the tilting base (2) plate has rotatable guide channel (5), the dish
end can be moved axially and vertically.
The tilting Base plate (2) can free rotate about its axis which is rested on the
supporting channel (3).
The clamping ring (1) is attached to the base plate (2) through the rotatable
guide support (5). Thus, the device is enabled to hold different sizes of dish
ends. For each dish end, separate clamping ring is provided. The clamping ring
(1) being freely rotatable about the axis and rested on the rotatable guide plate
(5), the device allows the base plate (2) to act as a base for both drilling and fit
up. The rotatable guide support (5) is rotatable from 0 to 180 degree to allow
both drilling and fit up. The adjustable Screw (4) and jack (6) is provided for the
adjustment of height during fit up and the movable base (7) has rolllers.

WE CLAIM :
1. A device for pre-welding fit up of line pipes with a hemispherical dish end
during fabrication of high pressure boilers, comprising :
a tilting base plate (2) to accommodate the Hemispherical dish end, the
end being tightened by a clamping ring (1), which freely rotates on a
rotatable guide channel (5), the assembly holds the dish end in a desired
position and moved by a movable base (7) near to a pipe to be fitted
with the dish end, an adjustable screw (4) on a Jack (6) locating the dish
end at pipe height and its center is made to coincide with the pipe axis;
the tilting base plate (2), which is rested on a supporting channel (3);
positioning the face of the dish end parallel to the face of the pipe; and
a movable base plate (7) maintains a root gap between the pipe and dish
end to complete the fit-up.