FIELD OF INVENTION
[001] The present invention relates to method of welding (SAW) of Steam
outlet nozzle with secondary dished end in Sub assembly-13 (SA13) for
Steam Generators. In particular, the invention relates to an automatic
method of welding of Steam outlet nozzle with tori-spherical secondary
dished end butt joints by suitably changing the welding process for steam
generator sub-assemblies.
BACKGROUND OF THE INVENTION
[002] Steam generator generally have multiple nozzles like Feed water
nozzle, Secondary man hole nozzle, Hand hole nozzle, PDHRS nozzle,
Instrumentation nozzle, Level tap nozzle, Primary inlet nozzle, Primary
outlet nozzle, steam outlet nozzle, etc. All these nozzles have different
purposes and they are welded on the pressure boundaries, either on the
shell or on the dished end.
[003] The steam which is produced inside the pressure vessel (steam
generator) is passed through the steam outlet nozzle to the turbine. Steam
outlet nozzle is having a welding edge, prepared with a thickness of
81.5mm. The steam outlet nozzle welding edge is matched with tori-
spherical secondary dished end for butt welding. During this butt joint,
root gap of 10mm between the parent materials is bridged by a backing
ring. The original welding sequence of steam outlet nozzle with secondary
dished end butt joint starts with full SMAW on the groove side till its

completion on outside. After completion of the first side (outside) weld, the
other side (inside) is gouged and ground to make a groove for defect free
welding. This is to remove the probable lack of fusions in the root- the
most probable area for slag entrapment. Manual gouging and grinding at
shell inner side are being done for a length of about 4.2m. After the
completion of back groove, then new weld layer by SMAW is filled on the
back side groove. All these welding are done with 1500C preheat and inter-
pass temperature of 2000C. Four hours soaking is done for weld joints
during any interruption in welding or completion of welding. During
gouging, 1500C temperature is maintained.
[004] In the earlier method, after fit-up of steam outlet nozzle with
secondary dished end, two welders sit opposite to each other for steam
outlet nozzle with dished end groove butt welding. The welding
circumference is approximately 4.2m. So each welder has to cover a
welding length of approximately 2m. Due to the wider range of weld
circumference, welders has to often change their seating locations to cover
the 2m span. Similarly, after back groove completion, one welder at a time
has to complete the inside welding span of 4.2m and multiple Arc starts
and stops in these manual weldings which results in repairs and rework.
[005] Manual welding (SMAW) at outside and inside with 1500C preheat
create problems. Additional protective and monitoring equipment is
normally necessary when welding is performed in a confined space
(welding inside the dished end). Due to the isolation, more welding area,

difficulty of access and hot work operations (upto 2000C inter-pass
temperature) in confined spaces pose additional hazards. Weld smoke
accumulation, narrow weld groove, etc. are inevitable consequences. All
these resulted in delay in welding and also led to more weld repairs. So
there has been a need for alternate method to establish a change in
welding process to improve productivity and also to avoid repairs.
[006] Therefore, there has been a demand for welding process with better
quality productivity and that is easy to perform. No similar prior art is
available relevant to the present invention.
OBJECTIVE OF THE INVENTION
[007] It is therefore an object of the present invention is to propose a new
automatic welding process Submerged arc welding (SAW) for nozzle with
tori-spherical secondary dished end with steam outlet nozzle butt welding
for sub assembly.
[008] Another object of the present invention is to eliminate Noise and
Smoke at the site during welding process.
[009] Another object of the present invention is to reduce cycle time and
to improve weld quality.

[010] A further object of this invention is to eliminate fatigue of the task
performer in completion of manual welding of tori-spherical secondary
dished end with steam outlet nozzle.
[011] Yet another object of this invention is to remove difficulty in Narrow
groove welding (Less visibility and more chance for Side wall lack of fusion
defect) and back groove welding.
[012] Yet another object of this invention is to avoid frequent stop and
starts to change electrode, high metal wastage (electrode stubs) during the
said welding process.
[013] These and other objects and advantages of the present invention will
be apparent from the ensuing description.
SUMMARY OF THIS INVENTION
[014] This invention relates to an automatic welding process modification,
in particular, from SMAW to SAW to overcome the issues faced in tori-
spherical dished end welding with steam outlet nozzle butt joint at outer
groove side and inner back groove side. In the present invention, adapters
for both inside and outside welding is fabricated and implemented for the
welding automation of steam outlet nozzle with secondary dished end
welding to ensure defect free welds and high yield production.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[015] Various objects, features, aspects, and advantages of the inventive
subject matter will become more apparent from the following detailed
description of preferred embodiments, along with the accompanying
drawing figures in which like numerals represent like components.
[016] The foregoing summary is illustrative only and is not intended to be
in any way limiting. In addition to the illustrative aspects, embodiments,
and features described above, further aspects, embodiments, and features
will become apparent by reference to the drawings and the following
detailed description.
[017] The figures depict embodiments of the disclosure for purposes of
illustration only. One skilled in the art will readily recognize from the
following description that alternative embodiments of the structures and
methods illustrated herein may be employed without departing from the
principles of the disclosure described herein.
[018] Figure 1: Side view of the tori-spherical dished end (01) in sub
assembly.
[019] Figure 2: Side view of the steam outlet nozzle (02) in sub assembly.
[020] Figure 3: Cross sectional view of tori-spherical dished end (01) with
steam outlet nozzle (02) in sub assembly.

[021] Figure 4: Cross sectional view of tori-spherical dished end (01)
bridged with steam outlet nozzle (02) weld groove by backing ring (06)
[022] Figure 5: Cross sectional view of submerged arc welding machine
with rotating welding head (07), placed over the adapter (03) during outer
side welding.
[023] Figure 6: Cross sectional view of submerged arc welding machine
with rotating welding head (07), placed over the fixture (05) during inner
side welding
[024] Figure 7: Cross sectional view of Steam Outlet Nozzle (02), holding
submerged arc welding machine (04) with adapter (03) during outer side
welding.
[025] Figure 8: Cross sectional view of Steam Outlet Nozzle (02) holding
submerged arc welding machine (04) with fixture (05) during inner side
welding.
[026] Figure 9: Top and side view of Backing ring (06)
DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH
REFERENCE TO THE ACCOMPANYING DRAWINGS OF PREFERRED
EMBODIMENTS
[027] While the embodiments of the disclosure are subject to various
modifications and alternative forms, specific embodiment thereof has been
shown by way of example in the figures and will be described below. It
should be understood, however, that it is not intended to limit the

disclosure to the particular forms disclosed, but on the contrary, the
disclosure is to cover all modifications, equivalents, and alternative falling
within the scope of the disclosure.
[028] Although embodiments for the present subject matter have been
described in language specific to package features, it is to be understood
that the present subject matter is not necessarily limited to the specific
features described. Rather, the specific features and methods are disclosed
as embodiments for the present subject matter. Numerous modifications
and adaptations of the system/device of the present invention will be
apparent to those skilled in the art, and thus it is intended by the
appended claims to cover all such modifications and adaptations which
fall within the scope of the present subject matter.
[029] Each sub-assemblies (shells) are having operations like marking,
buttering welding, attachment welding, nozzle welding, grinding, NDE,
machining, etc. After the completion of each sub assembly, it goes for
integration with its next sub assembly (shell). An arc is moved along the
line of a weld (circular profile with respect to center) by the motion of an
automatic welding machine. The welding machine is having a rotating arm
with respect to center with traveling drive motor mechanism. Automatic
welding has the advantages as

• Great intensities of heat can be generated and kept concentrated
to weld thicker sections with deep penetrations.
• High metal deposition rates can be achieved.
• Welding is carried out without sparks, smoke, flash or spatter.
• Very neat appearance and smooth weld shapes.
• Faster welding speed, Less risk of user error and More consistent
weld
[030] To overcome from all the difficulties faced by manual welding and to
achieve a defect free weld joint, the present disclosure provides a method
of automatic welding of secondary dish end (01) with steam outlet nozzle
(02) in SA13 assembly.
[031] Butt joint of tori-spherical dished end (01) as shown in Figure 1,
with steam outlet nozzle (SON) (02) as shown in Figure 2, is a critical
activity in sub assembly-13 (SA13) of steam generator. During the process
of butt joint, root gap of 10mm between the parent materials is bridged by
a backing ring (06) (referring Figure 4). 20MnMoNi55 (Quenched and
Tempered steel - High strength low alloy material is the raw material for
both secondary dished end (01) and Steam outlet nozzle (02). During fit-
up, the tori-spherical dished end (01) is levelled after the completion of
integration with backing ring (06). Then steam outlet nozzle (02) is placed
over the backing ring (06) for butt welding. The wall thickness and weld
length per pass is around 82mm and 4.2m respectively. Total number of
weld passes involved for completion of this weld joint is around 250 weld

passes by SMAW. Because of these reasons, the total time involved for
completion of one weld joint took more welder man shift. Total number of
welder involved for one shift is 4. Further, due to manual welding, the
rework rate is around 10% which significantly reduces the quality of
product and increase of delivery time. Under this circumstances, it is well
understood that, fully automatic welding procedure for welding of
secondary dish end (01) to steam outlet nozzle (02) in SA13 assembly
(Figure 3) is very much required. Cross sectional view of the said dished
end with the said steam outlet nozzle weld groove bridged with backing
ring (06) is shown in Figure 4. The configuration of backing ring (06) is
shown in Figure 9.
[032] Once the object is ready for welding, an adapter plate (03) is placed
on the free end of the SON (02) as shown in Figure 5. Over the said adapter
plate (03), SAW welding machine (04) embedded with welding head (07) is
mounted for circular profile groove butt welding (Figure 5). The
continuous circular profile SAW welding machine has the like features of
parameters setting unit, wire feeding mechanism, flux serving hopper as
conventional SAW machine. The adapter (03) and welding machine (04) is
clamped in such a way that, it is not disturbed during welding. Cross
sectional view of Steam Outlet Nozzle (02), holding SAW machine (04) and
adapter (03) during performance of outer side welding is shown in Figure
7. By the method disclosed herein, outer side welding of the steam outlet
nozzle (02) with secondary dished end (01) assembly gets completed by
continuous circular rotation of welding head (07).

[033] The welded object is flipped upside down after the completion of
outside groove welding and adapter (03) and SAW welding machine (04)
are removed thereafter. Then back gouging and back grinding are carried
out for back side (inner side) welding. A specially designed fixture (05) as
shown in Figure 6, is placed on the inner sider of the steam outlet nozzle
(02) for mounting the SAW welding machine (04). The Cross sectional view
of Steam Outlet Nozzle (02), holding SAW machine (04) and fixture (05)
during performance of inner side welding is shown in Figure 8. The fixture
(05) and welding machine (04) are clamped in a way to ensure undisturbed
condition during welding. The inner side welding of the steam outlet nozzle
(02) with secondary dished end (01) assembly is completed with
continuous circular rotation of welding head (07) thereafter.
[034] Circular profile groove welding machine with adapter (03) during
outer side welding and with fixture (05) during inner side welding
performs operation with rotating welding head (07) (referring Figure 5 and
Figure 6) and the object remains stationary during welding. Welding plane
also do not have any rise or fall, hence welding is performed without any
adjustments of welding torch.
[035] Process modifications to SAW welding disclosed herein in the dished
end with steam outlet nozzle welding is done based on the aim to remove
the difficulties like Less productivity (Consumed 2070 electrodes & took
30 days), Frequent stop/starts to change electrode, Relatively high metal
wastage (electrode stubs), Greater reliance on skill of operators, More

repairs - Approx. 10% volume rework, Generation of Welding smoke
(Welder discomfort), Narrow groove welding (Less visibility and more
chance for Side wall lack of fusion defect), Difficulty in back groove manual
welding (Dish heated to a temp. of 1500C, Suffocation due to heat &
welding smoke) faced in the existing process. The said SAW welding
produces high productivity beads compared to manual welding, smoke free
and faster completion of joint with 100% defect free weld joint. Welders
performing the welding have found the work as comfortable due to this
process change.
[036] Each of the appended claims defines a separate invention, which for
infringement purposes is recognized as including equivalents to the
various elements or limitations specified in the claims.
[037] Groupings of alternative elements or embodiments of the invention
disclosed herein are not to be construed as limitations. Each group
member can be referred to and claimed individually or in any combination
with other members of the group or other elements found herein. One or
more members of a group can be included in, or deleted from, a group for
reasons of convenience and/or patentability. When any such inclusion or
deletion occurs, the specification is herein deemed to contain the group as
modified thus fulfilling the written description of all groups used in the
appended claims.

[038] The above description does not provide specific details of
manufacture or design of the various components. Those of skill in the art
are familiar with such details, and unless departures from those
techniques are set out, techniques, known, related art or later developed
designs and materials should be employed. Those in the art are capable of
choosing suitable manufacturing and design details.
[039] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of the
present disclosure. It will be appreciated that several of the above-
disclosed and other features and functions, or alternatives thereof, may be
combined into other systems or applications. Various presently
unforeseen or unanticipated alternatives, modifications, variations, or
improvements therein may subsequently be made by those skilled in the
art without departing from the scope of the present disclosure as
encompassed by the following claims.
[040] The claims, as originally presented and as they may be amended,
encompass variations, alternatives, modifications, improvements,
equivalents, and substantial equivalents of the embodiments and
teachings disclosed herein, including those that are presently unforeseen
or unappreciated, and that, for example, may arise from
applicants/patentees and others.

[041] It will be understood by those within the art that, in general, terms
used herein, and especially in the appended claims (e.g., bodies of the
appended claims) are generally intended as “open” terms (e.g., the term
“including” should be interpreted as “including but not limited to,” the
term “having” should be interpreted as “having at least,” the term
“includes” should be interpreted as “includes but is not limited to,” etc.).
It will be further understood by those within the art that if a specific
number of an introduced claim recitation is intended, such an intent will
be explicitly recited in the claim, and in the absence of such recitation no
such intent is present. For example, as an aid to understanding, the
following appended claims may contain usage of the introductory phrases
“at least one” and “one or more” to introduce claim recitations. However,
the use of such phrases should not be construed to imply that the
introduction of a claim recitation by the indefinite articles “a” or “an” limits
any particular claim containing such introduced claim recitation to
inventions containing only one such recitation, even when the same claim
includes the introductory phrases “one or more” or “at least one” and
indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically
be interpreted to mean “at least one” or “one or more”); the same holds
true for the use of definite articles used to introduce claim recitations. In
addition, even if a specific number of an introduced claim recitation is
explicitly recited, those skilled in the art will recognize that such recitation
should typically be interpreted to mean at least the recited number (e.g.,
the bare recitation of “two recitations,” without other modifiers, typically

means at least two recitations, or two or more recitations). Furthermore,
in those instances where a convention analogous to “at least one of A, B,
and C, etc.” is used, in general such a construction is intended in the sense
one having skill in the art would understand the convention (e.g., “a
system having at least one of A, B, and C” would include but not be limited
to systems that have A alone, B alone, C alone, A and B together, A and C
together, B and C together, and/or A, B, and C together, etc.). In those
instances where a convention analogous to “at least one of A, B, or C, etc.”
is used, in general such a construction is intended in the sense one having
skill in the art would understand the convention (e.g., “a system having at
least one of A, B, or C” would include but not be limited to systems that
have A alone, B alone, C alone, A and B together, A and C together, B and
C together, and/or A, B, and C together, etc.). It will be further understood
by those within the art that virtually any disjunctive word and/or phrase
presenting two or more alternative terms, whether in the description,
claims, or drawings, should be understood to contemplate the possibilities
of including one of the terms, either of the terms, or both terms. For
example, the phrase “A or B” will be understood to include the possibilities
of “A” or “B” or “A and B.”
[042] It will be further appreciated that functions or structures of a
plurality of components or steps may be combined into a single component
or step, or the functions or structures of one-step or component may be

split among plural steps or components. The present invention
contemplates all of these combinations. Unless stated otherwise,
dimensions and geometries of the various structures depicted herein are
not intended to be restrictive of the invention, and other dimensions or
geometries are possible. In addition, while a feature of the present
invention may have been described in the context of only one of the
illustrated embodiments, such feature may be combined with one or more
other features of other embodiments, for any given application. It will also
be appreciated from the above that the fabrication of the unique structures
herein and the operation thereof also constitute methods in accordance
with the present invention. The present invention also encompasses
intermediate and end products resulting from the practice of the methods
herein. The use of “comprising” or “including” also contemplates
embodiments that “consist essentially of” or “consist of” the recited feature.
ADVANTAGE OF THE INVENTION
[043] The advantage of the present invention is that it develops a new
automatic welding process Submerged arc welding (SAW) for nozzle with
tori-spherical secondary dished end with steam outlet nozzle butt welding
for sub assembly.
[044] Another advantage of the present invention is that it eliminates Noise
and Smoke at the site during welding process.

[045] Another advantage of the present invention is it reduces cycle time
during welding process and improves weld quality.
[046] A further advantage of this invention is that it involves reduced time
taken for non-destructive testing during before and after heat treatment.
[047] A further advantage of this invention is that it generates great
intensities of heat and keeps that concentrated to weld thicker sections
with deep penetrations with high metal deposition rates.
[048] A further advantage of this invention is that it eliminates fatigue of
the task performer during manual welding of tori-spherical secondary
dished end with steam outlet nozzle.
[049] Yet another advantage of this invention is that it removes difficulty
in Narrow groove welding (Less visibility and more chance for Side wall
lack of fusion defect) and back groove welding.
[050] Yet another advantage of this invention is that it avoids frequent stop
and starts to change electrode, high metal wastage (electrode stubs) during
the said welding process.
[051] Yet another advantage of this invention is that it reduces production
costs, thus increases Competitive Advantage and reduces time to market.

We Claim:
1. A method of automatic Submerged Arc Welding (SAW) in tori-
spherical dished end attached to steam outlet nozzle butt joint
in steam generator at outer and inner back groove side, comprises
the steps of:
- Leveling of tori-spherical dished end (01) completing the
integration of backing ring (06) therewith;
- Placing steam outlet nozzle (SON) (02) over the backing ring (06)
for bridging with dish end (01) butt weld;
- Placing adapter plate (03) on the free end of the SON (02) for
securing placement of dished end (01) attached with (SON) (02);
- Mounting SAW welding machine (04) embedded with welding
head (07) for continuous circular profile groove butt welding;
- Clamping the said adapter (03) and the welding machine (04)
ensuring undisturbed condition during welding operation;
- Completing outer side welding of the steam outlet nozzle (02) with
secondary dished end (01) assembly with welding head (07);
- Removing adapter (03) and SAW welding machine (04) from the
set up;
- Flipping upside down the welded object;
- Placing a fixture (05) on the inner sider of the tori-spherical
dished end (01) for mounting the SAW welding machine (04) and
clamping the said fixture (05) on the inner diameter of the steam

outlet nozzle (02) for ensuring undisturbed condition during
welding;
- gouging and grinding for back side (inner side) weld;
- Completing inner side welding of the secondary dished end (01)
and steam outlet nozzle (02) assembly with welding head (07)
thereafter.

2. The method as claimed in claim 1, wherein it involves automatic
outer side and inner side Welding of tori-spherical secondary dished
end (01) with steam outlet nozzle (02) butt welding joint.
3. The method as claimed in claim 1, wherein it accomplishes the
automatic welding of secondary dished end (01) and SON (02)
assembly bridged by backing ring (06), by attaching Adapters (03)
and fixtures (05) on the inner opening of said SON (02) for
performing welding of the said assembly on outer side and inner side
respectively.
4. The method as claimed in claim 1, wherein continuous rotation of
welding head (07) embedded with SAW machine (04), with respect
to SON (02) performs automatic butt joint of the said SON (02) with
secondary dished end (01).
5. The method as claimed in claim 1, wherein circular profile groove
welding machine (04) attached with adapter (03) during outer side
welding and with fixture (05) during inner side welding performs
operation keeping the welding object and welding plane stationary
during welding.