FIELD OF THE INVENTION
The present invention relates to a method of producing nozzles welded in steam
drums of Heat Recovery Steam, Generators (HRSG). More particularly, the
present invention relates to an improved method of producing a nozzle fixable in
fully compensated steam drums of Heat Recovery Steam Generators (HRSG).
BACKGROUND OF THE INVENTION
The HRSG is an environment friendly and efficient system of utilizing exhaust
heat of Gas turbines to generate steam for power and process. The principal
heat transfer surface for example, super heater, reheater, evaporator and
economizer are placed in a duct along the gas flow path.
A plurality of steam drums, for example, High Pressure (HP), Intermediate
Pressure (IP), and Low Pressure (LP) steam drums are used in the system to
provide storage facility, water circulation, and separation of the steam from
steam-water mixture.

The drum generally consists of a plurality of nozzles welded to the drum-shells. A
typical arrangement is shown in Fig. 1.
Welding methods of nozzles in fully-compensated steam drums in HRSGs are
known, however such welding methods are applicable for socket seat and set-in
type nozzles on the steam drums. The prior art welding methods have been
extensively used in HP, IP and LP steam drums of various HRSGs. However, the
socket seat type nozzles in the existing form cannot be used for fully
compensated steam drums, and wherein the set-in type nozzle design cannot be
used cost effectively for fully compensated steam drums.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to provide an improved method of
producing nozzles fixable in fully-compensated steam drums in HRSGs.

Another object of the invention is to propose an improved method of producing
nozzles fixable in fully-compensated steam drums in HRSGs, which adapts forged
nozzles with hydro-tested taper.
A still another object of the invention is to propose an improved method of
producing nozzles fixable in compensated steam drums in HRSGs, which
eliminate the use of dummy plates for hydro-testing of the nozzle after fixing on
the steam drum shell.
Yet another object of the invention is to propose an improved method of
producing nozzles fixable in fully compensated steam drum in HRSGs, which uses
a re-usable device for hydro-testing of the nozzle-shell assembly.
A further object of the invention is to propose an improved method of producing
nozzles fixable in compensated steam drum in HRSGs, which allows adapting
fully-compensated steam drums in HRSGs.

A still further objected of the invention is to propose an improved method of
producing nozzles fixable in compensated steam drum in HRSGs, which enables a
fast start-up of HRSGs by adapting the fully-compensated steam drums.
SUMMARY OF THE INVENTION
Accordingly, there is provided an improved method of producing nozzles fixable
in fully compensated steam drum in HRSGs, comprising the steps of: providing
forged nozzles with thickness corresponding to the compensation requirement of
fully compensated drum prescribed by the statutory codes; characterized in that
the welding between the nozzles and the steam drum is implemented through
providing backing rings, and in that the backing rings provide a positive root
fusion and their easy removal after the welding.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure-1 shows a typical arrangement of nozzle in the steam drums of HRSGs.
Figure-2 shows a cross sectional view of a nozzle produced and fixed to the
steam drum shells according to the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
With the above and other objectives in view, the present invention provides an
improved method of producing nozzles fixable in fully compensated steam drum
in HRSGs,
As shown in Fig.l, the present invention provides an improved method of
producing nozzles fixable in fully compensated steam drum in HRSGs. A plurality
of forged nozzle having an inside tapering enables welding of the nozzles with
less

time and cost-on the shells of the steam drums, which produces fully
compensated drums. According to the present invention, the nozzles can be
welded In the steam drums to match low thickness of the fully compensated
drums, and simultaneously maintaining in the compensation requirement
prescribed by the statutory codes.
The nozzle (4) is welded on the drum shells (2) using backing ring (03) to ensure
positive root fusion.
The profile of the backing ring (03) is designed and provided for ease of removal
of the backing ring (03) and at the same time ensuring the root fusion.
A re-usable device for hydro-testing the nozzles (04) having tapers (01) is
provided. The device (not shown) is having an external taper matching with the
internal taper of the nozzle.

A plurality of rubber seal rings (not shown) are used to provide suitable sealing
between the nozzle taper and hydro test device. This device eliminates the prior
art practice of welding dummy plates with the nozzles for hydraulic testing of the
fully-compensated steam drum and subsequent removal of these dummy plates
after the hydro test.

WE CLAIM:
1. An improved method of producing nozzles fixable in compensated steam
drum in HRSGs, comprising the steps of:
providing forged nozzles with thickness corresponding to the
compensation requirement of fully compensated drum prescribed
by the statutory codes;
characterized in that the welding between the nozzles and the steam drum is
implemented through providing backing rings, and in that the backing rings
provide a positive root fusion and their easy removal after the welding.
2. The method as claimed in claim 1, wherein the nozzles are provided with
inside taper which corresponds to an outside taper configured on a re-usable
hydro-testing device.

3. The method as claimed in claim 1 or 2, comprising a step of hydro-testing
of the assembly of the nozzles and the steam drum.
4. The method as claimed in claim 3, wherein a plurality of rubber seal rings
during the hydro-testing of said assembly in said re-usable device.
5. An improved method of producing nozzles fixable in compensated steam
drum in HRSGs, substantially as herein described and as illustrated in the
accompanying drawings.

An improved method of producing nozzles fixable in fully compensated steam drum in HRSGs, comprising the steps of: providing forged nozzles with thickness corresponding to the compensated requirement of fully compensated drum prescribed by the statutory codes; characterized in that the welding between the nozzles and the steam drum is implemented through providing backing rings, and in that the backing rings provide a positive root fusion and their easy removal after the welding.