Project Management in the Oil and Gas Industry

2
Mob.
Figure 3.8 Calculate the early times.
100
600
200
400
3
7
14
18
7
12
18
23
0
3
0
3
3
11
3
11
11
21
11
21
21
22
21
22
22
23
22
23
23
25
23
25
300
500
700
800
Pouring concrete
Excavate
Install piping
Mech. package
Put grouting
Conn. piping
3
1
8
4
10
1
5
Comm. & start up
2
Mob.
Figure 3.9 Calculating the latest times.
100
600
200
400
300
500
700
800
Pouring concrete
Excavate
Install piping
Mech. package
Put grouting
Conn. piping
3
1
8
4
10
1
5
Comm. & start up
2
Mob.
Figure 3.7 Precedence diagram for the example.

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Pitfalls in Time Schedule Planning 101
When we calculated the early and late schedule dates for our project, we 
found that sometimes the early and late schedule dates were the same and in 
other activities the dates were different. In these activities there was a differ-
ence between the earliest day that we could start an activity and the latest day 
we could start the activity. The difference between these two dates is called 
‘‘float,’’ or sometimes ‘‘slack.’’ These terms mean exactly the same thing and 
can be used interchangeably. The float of an activity is the amount of time 
that the activity can be delayed without causing a delay in the project.
Using computerized project management scheduling software, we can 
modify the list of activities on the critical path to include activities that are 
nearly on the critical path. This is important since the critical path method 
is a method for managing project schedules. The activities that have zero 
float are the activities that cannot be delayed without delaying the comple-
tion of the project. These are the activities that must be monitored closely if 
we want our project to finish on time. Conversely, the activities that are not 
on the critical path, those activities that have something other than zero 
float, need not be managed quite as closely. In addition, it is important to 
know which activities in the project may be delayed without delaying the 
project completion.
Resources from activities having float could be made available to do a 
‘‘workaround’’ if the need should arise.
By performing a simple calculation, we can find eleven days as a total 
float (TF) for installing piping. But, installing piping has zero free float (FF), 
as any delay will affect the connection of the piping. The piping connecting 
activity has an eleven day FF, as there is no activity after that to delay.