FIELD OF THE INVENTION
The present invention relates to the design of steel pedestal for carrying out
testing of high speed machines for example compressors. More particularly, the
present invention relates to a compact slender steel supporting pedestal for
testing of heavy rotating machines.
BACKGROUND OF THE INVENTION
According to prior art, fixed concrete pedestals are used for supporting high
speed rotating machines during testing. The best requirement of such support is
to provide sufficient space between ground and the machine. Here, basically
fabricated columns are used as support for base plate over which compressor
would be mounted, but there are certain limitations of these concrete pedestals.
For concrete pedestals, the depth of top deck itself is generally between 1.5-2
m for testing heavy rotating machineries. The concrete columns are normally
bigger in size with minimum dimensions of 1200 X 1000 mm. Due to these
reasons and further considering the limited space universally available for
testing, it is not possible to put such a bulky concrete structure This necessitated
the development of a slender structure with steel.

OBJECT OF THE INVENTION
It is therefore an object of the present invention is to propose a compact slender
steel supporting pedestal for testing of heavy rotating machines.
SUMMARY OF THE INVENTION
The present invention is a supporting pedestal for testing high speed rotating
machines, which has certain advantages compared to the conventional fixed
concrete pedestals.
Different compressors will have different sizes. So, the steel columns of the
innovative pedestals can be moved and fixed at any location corresponding to
any type of compressors.
Single design of steel columns can be used not only for the compressors but also
for testing of other rotating equipment for example turbines.

The steel columns of the known pedestals can be easily modified by stiffening or
making them slender to minimize the vibrations transferred to the building or
factor for different capacities of machines.
Foundation natural frequencies of vibration can be altered to prevent resonance
for different operating speeds of machines to be tested.
Steel structures of the pedestal can be fabricated very fast compared to casting
of large concrete foundations of prior art.
Cost of steel pedestals is less compared to prior art concrete pedestals.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The accompanied drawings describe the invention in detail and illustrate the
features of the present invention. Reference numerals are used for locating the
various components of the pedestal.
Figure 1 - shows a schematic of the steel pedestal according to the present
invention.

DETAIL DESCRIPTION OF THE INVENTION
Here, the steel pedestal constructed is meant for supporting compressor or other
high speed rotating machines during testing. There are three types of tests
required to be performed. They are Mechanical Run Test (MRT), Performance
Test and Complete Unit Test. It is proposed to have a common device, which can
cater for all three tests respectively. The basic requirement of such device is to
provide sufficient space between ground and the machine. The clearance space
required for routing of various pipes during performance test is about four
meters approximately. It is proposed to have fabricated columns as support for
base plate over which compressor would be mounted. Figure 1 shows the
pedestal device in which reference numeral
1. represents the top plate of pedestal
2. represents the bottom plate.
3. 4, 5 and 8 represents the side plates of pedestal.

6 and 7 represents the central pipe and intermediate support plates provided for
stiffening purpose.
Based on the above-mentioned criteria, steel columns are made by forming a
closed box using side plates, a Top plate (1) and a bottom plate (2) are held
together by means of a central pipe (6), which are enclosed with side plates (3),
(4), (5) and (8) on all four sides, multiple intermediate support plates (7) are
provided along the length of the central pipe. Therefore, inside the box stiffening
is provided by means of central pipe and transverse plates respectively. In this
way, finally a configuration of the steel supporting device has been synthesized.
A schematic of the steel pedestal is shown in Figure 1.
Various analyses are carried out to assess the structural integrity of the support
device in respect of stress, deflection, modal and harmonic response
considerations. All these analyses are carried out using finite element method
through known packages. Finite Element model of the pedestal is prepared to
carry out structural analysis.
Various analyses carried out to assess structural integrity are:

1. Static analysis under failure loads. It is required to show that stresses
and deflection produced under the operating condition are within
acceptable limits.
2. Natural frequency analysis to show that the structure does not exhibit
resonance near operating speeds.
3. Harmonic response analysis to confirm that the possible unbalance does
not produce unacceptable vibrations (beyond 10 microns).
Thus from all the technical considerations, proposed configuration of the
pedestals is acceptable for putting into practice for the specified loads, provided
the following assumptions made in the analysis are truly translated into practice:-
1. The condition of fixing the bottom at a minimum of four locations is
assumed rigid .This has to be ensured.
2. All the plates and pipe joints are assumed to be integral. In practice,
they are welded. The weld quality should justify this assumption.
3. All other conditions provided as data (loads, unbalance forces etc)
should not be more than given values.

WE CLAIM :
1. A compact slender steel supporting pedestal for testing of heavy rotating
machines wherein the columns of the steel pedestal are movable and
fixable at any location corresponding to the heavy rotating machines, and
wherein the pedestal can be stiffened and/or made slender to minimize
the vibrations transferred to the building for different capacities of
machines,
characterized in that a plurality of steel columns are made by forming a
closed box using side plates, a top plate (1) and a bottom plate (2) are
held together by means of a central pipe (6), which are enclosed with side .
plates (3), (4), (5) and (8) on all four sides, multiple intermediate
support plates (7) are provided along the length of the central pipe,
therefore, inside the box stiffening is provided by means of central pipe
and transverse plates respectively, in this way, finally configuration of the
supporting device has been synthesized
2. The pedestal as claimed in claim 1, wherein the natural frequencies of
vibration of pedestal can be easily altered to prevent resonance for
different operating speeds of the machines to be tested.

3. The pedestal as claimed in claim 1 or 2, wherein the heavy rotating
machines are one of compressors and turbines.

ABSTRACT

The invention relates to a steel columns which are made by forming a closed
box using side plates. A top plate (1) and a bottom plate (2) are held together by
means of a central pipe (6), which are enclosed with side plates (3), (4), (5) and
(8) on all four sides, multiple intermediate support plates (7) are provided along
the length of the central pipe, therefore, inside the box stiffening is provided by
means of central pipe and transverse plates respectively, in this way, finally a
configuration of the supporting structure has been synthesized.