This
page is in continuation to my earlier post Model-01 : Calculation
of ditect Man-Hour .
The
direct manpower calculation and the effort required for erection of different
types of vessels varies based on their location of installation, type of
handling equipment required for the installation of the equipment. Certain
equipments can be erected by manual labour by shifting and placing it on top of
the foundation. ( In India manpower availability is plenty and cheap and in
most of the construction sites direct labourers are more used along with less
amount of lifting equipments like cranes).In this model calculation my
experience in calculating the direct man power was on the basis of using a
truck crane and direct manpower handling
the equipment. I have not elaborated here the type and capacity of the crane to
be used for tower erection. Since selection of a particular type of crane
itself is a vast subject and will be dealt in my other posts. For installation of any vessel apart
selection of a suitable crane for
installation of the equipment, based on the weight and other parameters, an
additional crane from trailing end of
the equipment use to support the equipment to make it vertical.. This manpower
calculation does not include any manpower for operation and supporting
activities of the crane movement
The
man-hour calculation of the estimator should include the time to be spent by
various technicians/Laborers to
complete the activity starting from receiving the materials from stores of the
owner, loading, transportation of materials
from owners stores to contractors storage yard , unloading and storing at contractors
storage at site yard, retransmission to
the point of installation if required ,
surface preparation of foundations along with time required for
fabrication/machining of steel shims to be placed below the equipment installation,
man-hours required for installation work
for accessories or platforms, man-hours required for testing and commissioning,
, Also
major important factor which involves lot of man-hours is the scaffolding
activity. If the equipment to be installed is at lower level or on ground the Man-hours
required for scaffolding will be nil. In case if the installation is at an
elevation the man hours required for preparation and installation of the
scaffoldings are to be considered
The
normal activities involved in the installation of the Tall towers after receipt
of materials at erection sites are preparation of the foundation and bring down
the level of the foundation to receive the equipment on top of it with the
space available for placing the equipment on top of the foundation. Normally
only maximum of 50mm pacer plates are allowed to be placed between the
equipment and foundation so that grouting can be taken can effectively. On
preparation of foundation check for the condition of the equipment placed on
ground on wooden packers. Using the marking on the tower for slings position
the crane as close as possible to lift the equipment.
Tower Installation
The
below mentioned details were calculated in one of chemical plant i worked.
Hence details provided by me are bare minimum and guide lines for the
estimators in indie. The details provided are based on the productivity of the
technicians worked then with me and minor fine tuning as per site data’s of the
company .and in consultation with the companies site personals more accurate
data’s can be decided by estimators
Towers ( considering the erection
procedure with truck crane)
Slno
|
Detail
|
Weight
of equipment up to 10MT
|
Weight
of equipment up to 11-20MT
|
Weight
of equipment up to 21-30MT
|
Weight
of equipment up to 31-40MT
|
Weight
of equipment above 41MT-100MT
|
1
|
Foundation
|
16hours
|
24hours
|
24hours
|
32hours
|
48Hours
|
2
|
Installation
|
16hours
|
24hours
|
32hours
|
40hours
|
80Hours
|
3
|
Total
|
32hours
|
48hours
|
56hours
|
72hours
|
128Hours
|
The
above mentioned man-hours calculation does not include the manpower required
for receiving the materials from stores up to erection site, activities related
to cleaning of equipments, accessory works related with equipment erection work
like platform and ladders erection works for the equipment any major
scaffolding works,time required for preparation of
testing,commissioning,performance guarantee works . The manpower calculation is
on the assumption that the equipment will be installed only on the ground..
Based
on the above chart let me calculate the man hours required for a Tower weighing
80MT and installed at ground floor. As per the chart the time consumed for
installation of this equipment is only 128Man-hours and time required for other
activities can be calculated under respective heads and to be added with the
basic man-hours.
What
should be the cost of this 128 man-hours. It cannot be purely one category like
skilled/highly skilled or semiskilled. It is the combination of the technician
group engaged in the installation work. Based on the nature of work the
category of people are to be divided. in terms of percentages. In this case the
highly skilled labourers may not be required much and unskilled workers also
will not be required much. So technicians who have capacity to lift and shift
the materials may be required more. If we consider total 100% man-hours equals
to 128 Man-hours. Out of which Riggers can be considered as 70%( semi skilled)
requirement,15% requirement of skilled and
remaining 15% manpower will be unskilled to reach total the 100%
Skilled Labours -15%.........!5/100*128 = 19.2 Man-hours
Semi skilled --70%.......70/100*128 = 89.6 Man-hours
Unskilled ...........15%........15/100*128 = 19.2 Man-hours
Cost
of installation of the Tower on basic conditions based on the Man hour rates
(Minimum wages) of notification by Delhi state
Skilled Labours .........(!9.2/8)* 455 = 1092
Semi skilled --- -(50.4/8)*414 =
4636.8
Unskilled Labours..... .(10.8/8)*374 =
897.6
Total
cost of Man-hours for Erection of Tower of 80MT on Ground is Indian rupees 6626.4 at the location near
delhi.
Hence
Rate per MT in that location is Indian
Rupees 82.83
You
can find out that man power cost decreases with respect to weight of the tower
but while we calculate the other cost involvement for installation of the tower
like cost and crane hours and additional indirect man power cost we can arrive
at the exact cost per MT of heavy equipments which falls under this catogory
