FIELD OF THE INVENTION
The present invention relates to an improved method of determining Fit-up line of
Dividing flange in Axial Profiled (AP) Fan housing assembly of Power and industrial
boilers.
BACKGROUND OF THE INVENTION
Fan is one type of Turbo Machineries used for Energy Transfer. In Thermal Power
Plant, the fan is defined as a Rotating Machine with a Bladed Impeller, which
maintains a continuous Flow of Fluid (Air/Gas). The fan is classified as Primary Air
(PA) Fan, Forced Draught (FD) Fan and Induced Draught (ID) Fan based on its
application in Power Plant. Axial Profiled (AP) Fan construction has Static and
Rotor Components. The Static components of the Axial profiled Fans, consists of
Suction Chamber Assembly, Housing Assembly and Diffuser Assembly. Housing
Assembly itself comprises two components namely, Housing and OGV (Outlet
Guide Vane). Impeller, the rotating component of the fan, when mounted onto
the Housing, need to maintain the crucial requirements of blade tip to Housing
Shell clearance and its shaft axis alignment in-line with Fan axis. Dividing Flanges
(08) achieve this and hence its fit-up process becomes critical.

In the prior art method for the fit-up of the Dividing Flanges (08), a fit-up line is
marked on the Housing Shell considering the job’s Face-out, Run-out and
machining allowances. For this marking, firstly the job is needed to be placed on a
Levelled Surface (02) using an EOT Crane (01).
According to the known method, the job’s face-out is checked by dropping a
Plumb (03) on either side of the Housing Flanges and the face-out setting
adjustments is done with the help of the EOT Crane (01).
After completion of job setting, the Dividing Flange (08) fit-up line is marked using
a Height Gauge (04), based on the drawing dimensions and relevant machining
allowances.
Due to the dependence on Levelled Surface (01) and EOT Crane (02), the prior art
process becomes cumbersome and time consuming, which in turn leads to
increase the job’s cycle time and decreases the productivity.

In order to overcome the above problems, a novel method for marking the
Dividing Flange Fit-up line has been developed.
OBJECTS OF THE INVENTON
It is therefore an object of the present invention to propose an improved method
of determining Fit-up line of Dividing flange in Axial Profiled (AP) Fan housing
assembly of Power and industrial boilers.
Another object of the invention is to propose an improved method of determining
Fit-up line of Dividing flange in Axial Profile (AP) Fan housing assembly of Power
and industrial boilers which eliminates the need of leveled surface, EOT cranes
and marking gauges of prior art.
Yet another object of the invention is to propose an improved method of
determining Fit-up line of Dividing flange in Axial Profiled (AP) Fan housing
assembly of Power and industrial boilers which reduces the process cycle time,
simplify the process and increase productivity.

A still another object of the invention is to propose an improved method of
determining Fit-up line of Dividing flange in Axial Profiled (AP) Fan housing
assembly of Power and industrial boilers which reduces the Human Fatigue during
this marking process by which increasing the morale of the workmen greatly.
A further object of the present invention is to propose an improved method of
determining Fit-up line of Dividing flange in Axial Profiled (AP) Fan housing
assembly of Power and industrial boilers which raises the standard of safety at the
work place by avoiding the usage on EOT all through the process.
SUMMARY OF THE INVENTION
A fit-up line marking of a dividing flange in AP Fan Housing assembly for power
and industrial boilers according to conventional method consists fit-up line
marking of the dividing flange on Levelled Surface with the aid of an EOT Crane.
The purpose of the Dividing Flange is to divide the Housing assembly into two
equal halves by ensuring required run-out and face-out for the impeller rotation.
In addition, the Dividing Flange provides job parallelism with respect to the
foundation plane. In contrast, the marking of the dividing flange fit-up line
according to the present invention can be achieved easily and directly using the
basic Geometrical concepts (05) of ”Squared Inscribed in a Circle” (06) followed
by application of “Pythagoras Theorem” (07), thereby eliminating the need of

Levelled Surface (01) and EOT crane (02). The cycle time is reduced in
comparison to prior art marking method. A substantial reduction in human fatigue
including improvement in the standard of safety at the work place, is further
achieved.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
I. Figure 1 Schematic of prior art method of placing the job on Levelled
Surface (01).
II. Figure 2 Schematic of prior art method of marking using a Height Gauge
(04).
III. Figure 3 Schematic of improved method using Geometrical Concepts (05)
lV Figure 4 Schematic of improved method of marking of Dividing Flange (08)
Fit-up line.
V. Figure 5 Schematic of improved method of marking of Dividing Flange (08)
for PP Machining.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
Axial Profiled Fans are used for the continuous flow of fluid (Air or Flue Gas) in
Power & Industrial Boilers. Dividing Flange (08) is an item in the construction of
AP Fan Static part – Housing assembly that is used to divide the component into
two equal halves by ensuring required run-out and face-out for the impeller
rotation.
Dividing flange (08) fit-up is one of the critical stages in AP Fan Housing assembly
fabrication, wherein the dividing flanges (08) are fitted with meeting the above
condition.
In the prior art method of Dividing Flange (08) fit-up process, the fit-up line is first
marked on the Housing/OGV shell by placing the job on the Levelled Surface (01)
using EOT Crane (02) by calculating the above said dimensions and proper
machining allowances. Based on keen study of the Housing assembly fabrication,
it was observed that, the dividing flange fit-up line marking method is
cumbersome and time consuming one due to higher dependability of leveled
surface (01) and EOT Crane (02) all through the process.

According to the improved method, the dividing flange fit-up line is marked by the
application of basic Geometrical concepts (05) of “Squared Inscribed in a Circle”
(06) followed by application of “Pythagoras Theorem” (07). Adapting these
known and basic Geometrical method, the Dividing Line is first calculated from the
vertical Axis (-Y & +Y) of the Circular Axial Fan and two reference points are
marked on Entry & Exit side of the Fan Housing in the Horizontal Axis (-X & +X).
By joining these reference points, the dividing flange fit-up line is arrived directly.
This improved method proves to be valid when cross checking the marking data
with the data obtained through prior art method.
The improved method of marking replaces the cumbersome and lengthy prior art
process of marking the dividing flange fit-up line on a leveled Surface (01) by
using a Height Gauge (04) and using of EOT crane (02), thereby results in
considerable reduction in Cycle Time and associated recurring cost savings and
other Tangible and Intangible Benefits. Further, the usage of this improved
method is extended to the Dividing Flange PP (Part Planning) machining marking
process.

WE CLAIM :
1. An improved method of determining the fit-up line of dividing flange in
axial profiled (AP) fan housing assembly of power and industrial boilers, the
fan assembly comprising :-
- a plurality of static components consisting of a suction chamber assembly,
a housing assembly and a diffuser assembly, the housing assembly being
formed of a housing and an outlet guide vane (OGV);
- a rotor component in the form of an impeller having a plurality of rotatable
blades, the rotating component being mountable onto the housing by
maintaining the designed clearance between the tips of blades and the
shell of the housing, including the alignment of the impeller shaft axis in-
line with the fan axis,
wherein a dividing flange is adapted to maintain the said crucial requirements
during mounting of the impeller on the housing,
the method comprising the steps of:-
- calculating a dividing line from the vertical axis (-Y and + Y) of the housing
assembly;
- marking two reference points on entry and exit side of the fan housing
along the horizontal axis (-X and + X); and

- directly determining the fit-up line of the dividing flange by joining said two
reference points,
wherein a known geometric concept is applied to implement the method,
wherein a square is inscribed in a circle of the housing and the formula
under Pythagoras Theorem is applied, and wherein the concept
and formula is applied on physical entity to determine technical parameters.