Claims:We claim:
1) A carrier plate (400) comprising:
a rectangular block having converging slant faces (400(a)) joined by a rectangular plate (400(b)) at its bottom portion (400(c)), said rectangular block adapted to held in position over a pipe (200) with said rectangular plate (400(b)) facing against said pipe (200) and welded thereon.

2) The carrier plate (400) as claimed in claim 1, wherein the angle of slope of said converging slant faces (400(a)) is 30 degree.

3) The carrier plate (400) as claimed in claim 1, wherein the thickness of said rectangular plate (400(b)) is 80mm.

4) A method of assembling of a carrier plate (400) on to a pipe (200), said method comprising the steps of:
a) performing Tungsten Inert Gas (TIG) welding by placing said carrier plate (400) against said pipe (200) to form a weldment (402);
b) performing Shielded Metal Arc Welding (SMAW) on both sides of said carrier plate (400);
c) carrying out heat treatment of said carrier plate (400) welded to said pipe (200); and
d) conducting Non Destructive Examination (NDE) on said weldment (402).
, Description:FIELD OF THE INVENTION:
The present invention relates to a carrier plate used in high pressure and high temperature steam equipment. Particularly, the present invention relates to a carrier plate for effective weldment.

BACKGROUND OF THE INVENTION:
The carrier plates are used in boiler piping for lifting and clamping purpose.

Referring to the figure 1(a) & 1(b), a plurality of carrier plates 100 are welded on to a pipe 200 equidistantly spaced. The carrier plates 100 are rectangular blocks having converging slant faces 100(a) joined by a flat face 100(b) at their bottom portion 100(c).

The method of assembling of the carrier plates 100 on to the pipe 200 is as follows:
The carrier plates 100 are adapted to held in position over the pipe 200 and the following process is carried out in sequence for joining the carrier plates 100 to the pipe 200.
1) Firstly, root pass welding is carried out on all the plurality of the carrier plates 100 by Tungsten Inert Gas Welding (TIG) or GTAW to form a weldment 102. The TIG welding is supposed to produce full penetration weld between the plurality of the carrier plates 100 and the pipe 200.
2) Secondly, Shielded Metal Arc Welding (SMAW) is performed on one side of the plurality of the carrier plates 100.
3) Thirdly, the plurality of the carrier plates 100 welded on to the pipe 200 are heat treated in a furnace for stress relieving.
4) Fourthly, back grinding is done on the other side of the plurality of the carrier plates 100 to prepare the weldment 102 for Magnetic Particle Inspection (MPI).
5) Fifthly, Magnetic Particle Inspection (MPI) is done to ensure 100% penetration of the weldment 102.
6) Sixthly, Shielded Metal Arc Welding (SMAW) is performed on the other side of the plurality of the carrier plates 100.
7) Finally, the plurality of carrier plates 100 welded on to the pipe 200 are heat treated in the furnace once again for stress relieving.

It has been observed from various experiments that the profile shape of the bottom portion 100(c) of the carrier plate 100 is the cause for the following drawbacks.
a) Less Deposition rates
b) Multiple number of passes
c) Frequent change of electrode/filler wire
d) Requirement of highly skilled weld operator
e) Slag interruption in the weld
f) More rework.

Further, the process carried out for welding of the plurality of the carrier plates 100 on to the pipe 200 requires heat treatment operation for two times which increases the cycle time of the welding process.

Therefore, there is felt a need for development of a carrier plate with new profile shape to overcome the drawbacks of the prior art and thereby reduce the cycle time of the welding process.

OBJECTS OF THE INVENTION:
An object of the present invention is to provide a carrier plate of profile shape which reduces the cycle time of welding it on to a pipe.

Another object of the present invention is to provide a carrier plate of profile shape which ensures full penetration and good quality weld.
One more object of the present invention is to provide a carrier plate of profile shape which minimizes the steps involved in assembling of the carrier plate on to a pipe.

Still another object of the present invention is to reduce the cost involved in assembling a carrier plate on to a pipe.

Further another object of the present invention is to eliminate back grinding requirement for welding a carrier plate on to a pipe.

SUMMARY OF THE INVENTION:
In accordance with the present invention a carrier plate welded on to a pipe is provided, the carrier plate comprises a rectangular block having converging slant faces joined by a rectangular plate at its bottom portion. The carrier plate is adapted to held in position over the pipe and welded thereon.

The method of joining the carrier plate to the pipe includes the following steps:
1) Firstly, root pass welding is carried out on the carrier plates by Tungsten Inert Gas Welding (TIG) or GTAW to form a weldment. The TIG welding produces full penetration weld between the carrier plate and the pipe.
2) Secondly, Shielded Metal Arc Welding (SMAW) is performed on both sides of the carrier plate.
3) Thirdly, the carrier plate welded on to the pipe are heat treated in a furnace for stress relieving.
4) Finally, Non Destructive Examination (NDE) is conducted to inspect full penetration weld and complete weld metal deposition.

BRIEF DESCRIPTION OF THE DRAWINGS:
The invention will now be described with reference to the accompanying drawings in which:
Figure 1(a) illustrates a perspective view of a plurality of carrier plates assembled on to a pipe according to the prior art;

Figure 1(b) illustrates a cross-sectional view of a carrier plate of figure 1(a);

Figure 2(a) illustrates a perspective view of a plurality of carrier plates assembled on to a pipe, in accordance with an embodiment of the present invention;

Figure 2(b) illustrates a cross-sectional view of a carrier plate of figure 2(a).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
A preferred embodiment will now be described in detail with reference to accompanying drawings. The preferred embodiment does not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.

Referring to fig 2(a) and 2(b), in accordance with the present invention, there is provided a plurality of carrier plates 400 welded on to a pipe 200 equidistantly spaced. The carrier plates 400 are rectangular blocks having converging slant faces 400(a) joined by a rectangular plate 400(b) at their bottom portion 400(c).

In an aspect, the rectangular plate 400(b) of the carrier plate 400 is thin with a thickness of 80 mm.

In an aspect, the angle of slope of the convergent slant faces 400(a) of the carrier plates 400 is 30 degree.

In an aspect, the angle of slope of the converging slant faces 400(a) of the carrier plates 400 is less in comparison to the prior art.

The method of assembling of the carrier plates 400 on to the pipe 200 is as follows:
The carrier plates 400 are adapted to held in position over the pipe 200 with the rectangular plate 400(b) facing against the pipe 200 and the following process is carried out in sequence for joining the carrier plates 400 to the pipe 200.
1) Firstly, root pass welding is carried out on all the plurality of the carrier plates 400 by Tungsten Inert Gas Welding (TIG) or GTAW to form a weldment 402. The TIG welding produces full penetration weld between the plurality of the carrier plates 400 and the pipe 200.
2) Secondly, Shielded Metal Arc Welding (SMAW) is performed on both sides of the plurality of the carrier plates 400.
3) Thirdly, the plurality of the carrier plates 400 welded on to the pipe 200 are heat treated in a furnace for stress relieving.
4) Finally, Non Destructive Examination (NDE) is conducted to inspect full penetration weld and complete weld metal deposition.

The carrier plate 400 of the profile shape disclosed in figure 2(b) eliminated heat treatment procedure for one time after performing SMAW on one side of the carrier plate 400. Also, back grinding operation is eliminated. This reduction in the process steps reduced the cycle time and cost.

The carrier plate 400 of the profile shape disclosed in figure 2(b) ensures full penetration of the weld and produces a good quality weld. The test reports certified that the carrier plate 400 of the profile shape disclosed in figure 2(b) met all the necessary statutory and design requirements.

Although the invention has been described herein above with reference to the embodiments of the invention, the invention is not limited to the embodiments described herein above. It is to be understood that modifications and variations of the embodiments can be made without departing from the spirit and scope of the invention.