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Model-01 : Calculation of ditect
Man-Hour
Out
of the two parameters for calculating the direct manpower cost, the first
parameter labour cost is normally calculated considering the details of Minimum
wages as the basis. But when it comes for calculation of Man hours it is vast
in nature and it differs from one item to the other. For example if we want to
calculate the Man hours required for installation of Heat exchanger or drum ( a
static equipment ) the Man hours consumed for installation of Heat exchanger
differs from installation of a tower which is different. To calculate the man
hours of heat exchanger the estimator must aware of the procedure of
installation of the heat exchanger.
The
man-hour calculation of the estimator should include the time to be spent by
various technicians/Labourers 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, retransportaion 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 Drum/heat exchanger 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 heat exchangers/drums for slings position the crane as close
as possible to lift the equipment. However the requirements and suitability of
the cranes are not considered in this article
Heat Exchanger
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
Drum/Heat Exchangers
Slno
|
Detail
|
Weight
of equipment up to 2MT
|
Weight
of equipment up to 3-10MT
|
Weight
of equipment up to 11-20MT
|
Weight
of equipment up to 21-30MT
|
Weight
of equipment above 30MT
|
1
|
Foundation
|
8
hours
|
16hours
|
16hours
|
24hours
|
32Hours
|
2
|
Installation
|
8hours
|
16hours
|
24hours
|
32hours
|
40hours
|
3
|
Total
|
16hours
|
32hours
|
40hours
|
56hours
|
72hours
|
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 drum weighing
30MT and installed at ground floor. As per the chart the time consumed for
installation of this equipment is only 72 Man-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 72 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% Riggers can be
considered as 70%( semi skilled) requirement,15% requirement of skilled unskilled
laborious and remaining 15% manpower will be required to reach the 100%
Skilled Labours
-15%.........!5*72/100 = 10.8 Manhours
Semi skilled --70%.......70*72/100 = 50.4 Manhours
Unskilled ...........15%........15*72/100 = 10.8
Manhours
Cost
of installation of the Drum on basic conditions based on the Man hour rates
(Minimum wages) of notification by Delhi state
Skilled Labours .........(!0.8/8)*
455 = 614.25
Semi skilled ----(50.4/8)*414 = 2608.2
Unskilled Labours......(10.8/8)*374 =
504.9
Total
cost of Manhours for Erection of Drum of 30MT on Ground is Indian rupees 3727.35 at the location near
delhi.
Hence
Rate per MT in that location is Indian
Rupees 124.245
Like
wise manpower calculation can be done for all other items. Another way of
calculating manpower details calculation by productivity method
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