FIELD OF THE INVENTION
The present invention relates to a method of welding a shorter length of pipe having high thickness in a SAW (Submerged Arc Welding) machine, More particularly the invention relates to a method of submerged arc welding of a shorter length steel pipe with elbows without any hindrance of welding torch movement by the rotor body of high pressure steam generators.
BACKGROUND OF THE INVENTION
Welding of shorter length of high thickness pipes of carbon steel and low alloy steel having outside diameter in the range of 219.1mm to 558mm having thickness in the range of 40mm to 80mm are to be welded with elbows and this assembly named as links used in high pressure boilers in the super heater and reheater regions. Figures 1, 2, 3, 4 shown as various type of links manufactured to use in the above said area. The length of the pipe (01) is always less than 2.5m and if it is to be welded with elbows (02) in SAW welding machine (13), the direct welding is not possible with the existing rotor body Welding torch can't be moved closed to the job because of the moving machine hits the rotor body base (14).

Normally one extra length pipe (Not Shown) named as adding pipe having 2.5m length is welded with the shorter length pipe (01) with stiffener plates to complete the job. Now the SAW welding can be carried out without any hindrance of the rotor base (14) with welding machine (13). The drawback in this method of manufacturing is the removal of said adding pipe and stiffeners, which involve gouging, grinding. Non destructive test methods are also involved which is more time consuming and additional man power is required. Hence there is a need to propose an apparatus to reduce cycle time, and man hour and enhance the welding quality.
OBJECTS OF THE INVENTION:
It is therefore, an object of the present invention to propose a method of submerged arc welding of a shorter length steel pipe with elbows without any of welding torch movement by the rotor body of high pressure steam generators.
Another object of the invention is to propose a propose a method of submerged arc welding of a shorter length steel pipe with elbows without any hindrance of welding torch movement by the rotor body of high pressure steam generators which eliminates welding of adding pipes which needs to be subsequently removed after job completion.
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SUMMARY OF THE INVENTION:
Accordingly, there is provided a method of submerged arc welding of a shorter length steel pipe with elbows without any hindrance of welding torch movement by the rotor body of high pressure steam generators comprising the steps of placing shorter length pipe concentrically on the outside diameter of a rotor body (07) with four screw rods (12) to hold the job firmly. The rotational movement of the shorter length pipe is arrested with a lock nut (11). A first end of the rotor body is weldably attached to a plate (08) of corresponding diameter plate (08) having at least one circular hole. A end of a guiding pipe (09) is inserted in to the plate and welded with stiffener plates (10). A second end of guiding the pipe (09) concentrically fixed on the rotor assembly (14). Both the work piece and the guide pipe (09) are supported with a support assembly (15) on either side of the rotor body (07). Now the setup is ready for welding to elbows without the need of welding of additional pipes.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING:
Fig. 1 Shows a shorter pipe with elbows. Fig. 2 Shows elbows with two shorter pipes. Fig. 3 Shows two elbows with one shorter pipe.

Fig. 4 Shows angular bend with two shorter pipes
Fig. 5 Shows the rotor.
Fig. 6 Shows the end plate.
Fig. 7 Shows the guide pipe.
Fig. 8 Shows the screw rod with lock nut.
Fig. 9 Shows the assembly view of rotor with rotor base for welding shorter length pipe with elbow in the SAW Machine.
Fig. 10 The flow diagram of prior art method.
Fig. 11 The flow diagram of the method of present invention
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION;
According to present invention, the method of welding is carried out for a shorter length pipe of less than 2.5m length. Elbow (02) is first tack welded (root run) by TIG welding carried out prior to moving to a SAW Machine (13). By referring to Fig (9) the shorter length pipe (01) is fixed inside the rotor (07) concentrically by

adjusting at least four screw rods (12) simultaneously and locked by lock nuts (11). Hence all the degree of freedom is arrested. The guide pipe (09) is placed concentrically with shorter length pipe (01) and welded with an end plate (08). At least four stiffener plates (10) 90° to each other are placed and welded with the end plate (08) and the guide pipe (09). The other end of the guide pipe (09) is fixed on the rotor assembly (14). The roller stand assemblies (15) are placed suitably on either side of the rotor body (07) so that they touch on the bottom of the shorter length pipe (01) and guide pipe (09) respectively. Now the welding operation is carried out without hindrance or interference between the rotor assembly (14) and the SAW Machine (13). Similarly referring to figures 02, 03, and 04, all the components shown can be welded in the SAW machine as described above and it has been found that as short as 500mm length of shorter pipe welding with 90°-elbow (02) and even angular pipe (04) can also be welded.
Because of this method of manufacturing, cycle time is reduced substantially by elimination of gouging, grinding, hammering of stiffener plates and avoiding subsequent testing in the high pressure boiler components there by increasing the productivity.

WE CLAIM :
1. A method of submerged arc welding of a shorter length steel pipe with elbows without any hindrance of welding torch movement by the rotor body of high pressure steam generators, comprising the steps of:
> placing a shorter length pipe concentrically in the rotor body by simultaneously adjusting at least four screw rods (12) and locking by a plurality of and lock nut (11), to arrest degrees of rotational freedom of the pipe (01);
> locating of guide pipe (09) concentrically with the shorter length pipe (01), a first end of the guide pipe (09) welded with an end plate (08) and four stiffeners (10) welded 90° to each other with end plate (08) and guide pipe (09);
> supporting a second end of guide pipe (09) by a rotor assembly (14);
> positioning roller stand assemblies (15) on either side of the rotor body (07) with the top portion resting on the shorter length pipe (01) and guide pipe (09); and
> welding of the elbows with the shorter length pipe in a submerged arc welding machine.

2. The method as claimed in claim 1, wherein the end plate (08) having at
at least one circular hole.
3. The method as claimed in claim 1, wherein the elbows are first tag-
welded by TIG welding before being loaded on the submerged arc
welding machine for final welding with the shorter length pipe.