Depending
on site conditions, the preassembly of the plate will be done.If the foundation
and
approach is ready then it would be directly assembled on the foundation.
However, if the foundations
are not ready it would be assembled separately
outside. The bottom plateis in four parts and two of them will
be pre-assembled outside. On each half the hot well and the spring supports
will be welded/tacked. As the opening on the foundation is big enough the
preassembled bottom plate can be lowered flat without any risk by EOT crane .However fixing of lug plate for
mounting D-Shakle should be carefully done considering the weight of the plates
and accessories.
Both sidewalls are carrying in four
parts. Two joints would be welded outside the foundation.
Each dome wall, both upper and lower
is in two parts. These would be assembled together before erection.
DOME SHIFTING STRUCTURE
The central portion of the structure
shall be assembled outside.
CLEANING OF COMPONENTS
The cleaning of components shall be done
either by sand blasting using low-pressure air (2.5 kg) or by alkali and hot
water.
TUBING
The tubing of the condenser shall be carried out
from the end of the condenser. The opening in “A”
row in front
of the condenser is not to be closed till tubing is complete. Tubes
shall be transported
on a long bed trailer so that the overhang is not more
than 1.5mm either side. In case a small crane
and space is available the tube
boxes shall be unloaded near “A” row columns. However, in normal
cases the
boxes shall be unloaded inside the TG hall by EOT crane and shifted to position
manually. However when site is ready with A_row civil work then
tubing should be done from A –Row side. The Platform for tubing to be made
flexible and can be lifted time to time after
completion of certain height of tubing. Therefore total platform should be held
by eight chain pulley block with
adequate capacity. Rough weight calculation
to be done before finalising the pulley block. At present all vendors brought
specialised gang to do this job therefore time is considerably reduced .
WATER BOX HANDLING DEVICE
This would be erected when the
welding of internals is in the progress.
In case this is not available it would be better to have suitable
openings on TG Floor and oil canal from
where the slings can be inserted to
handle the water boxes when they are opened for tube inspection.
Check the foundation for dimensional
accuracy in accordance with the plate foundation drawings. Set the support
plates in mortar and align with the positions in which the spring elements will
be mounted.
Tack the base plates to the spring elements. Lower
hot well below and place it on the ground. Lower
the sections making up the
bottom plate onto the support plates of the condenser foundation.
Assemble and align the sections which have
been lowered onto the foundation. Weld
bottom plate
as per sequence. Lift hot well and weld with bottom plate. Align
the bottom plate to the turbine axis
in zero elevation. Raise bottom plate in
axial direction and into zero elevation, taking care that when
condenser is
finally tilted, its center line would match with turbine axis. When the bottom plate is at
zero elevation,
shim assembly
of the water boxes and condenser shell internals, the support bolts of
all the
spring elements must be in their uppermost positions before the work is
commenced. Detach
the tack welded base
plates from the spring elements and eliminate the weld spotsplates under all
spring elements. In order to avoid displacement of the bottom
plate during assembly
of the water
boxes and condenser shell internals, the support bolts of all the
spring elements must be in their
uppermost positions before the work is
commenced. Detach the tack welded base
plates from the
spring elements and eliminate the weld spots.
Typical pre-assembly bay of condensed on urbine floor. Very first work done which is not listed in
OEM manual is jointing of stiffenr rod of condenser. Please note tonnes of welding rod is necessarry
to complete the job which is time consuming and labour oriented. Some of the TSP are lying for
cleaning and checking.
An opening of LP turbine is visible when A Row civil work is not ready but EOT crane is ready then
hotwell , bottom plate and other material goes through this route. It is experienced that the area
between paddle flange and condenser foundation takes considerable time to complete because of
water accumulation..
continued to part-iii.
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