UK Oracle User Group

Dissolving vs Deleting P6 Activities

6 November 2015

In this recent blog post Bill Pepoon explores the dissolve feature in P6 and how it can be used.

We all make mistakes, or perhaps the scope of work has changed, which leads to activities being deleted in the schedule. And most users will simply delete the unnecessary activities. This, however, often leads to open ends in the logic. After all, you might be deleting the only successor to another activity in the schedule, or deleting the only predecessor to another activity. To avoid this problem, I dissolve activities instead.

All of the current versions of Primavera scheduling software have the ability to dissolve activities: Primavera Contractor, Primavera P6 Professional, and Primavera P6 EPPM. But dissolving activities is nothing new, as Primavera P3 incorporated this feature many years ago. Regardless, many P3 users ignored the feature and continue to do so in the current programs.

So what exactly does “dissolve” do? Well, when you dissolve an activity its predecessors are linked to the successors of the dissolved activity. Say for example that Activity A precedes Activity B, which in turn precedes Activity C. Dissolving Activity B would result in Activity A becoming a predecessor to Activity C. In theory this should be an acceptable change to the logic, since Activity A was already an indirect predecessor to Activity C.

Here is an example of how the dissolving process works. In the screenshot below I have three activities, each with a duration of 5 days, linked together using Finish to Start relationships. So the total amount of time required for these three tasks in 15 days:

Dissolve Activity_1


In the next screenshot, I have highlighted Activity B and then right-clicked to select dissolve from the menu:

Dissolve Activity_2


Now that Activity B has been dissolved, Activity A is a predecessor to Activity C and the total amount of time has been reduced to 10 days:

Dissolve Activity_3


Easy as pie, unless I’m the one baking it. While it is always a good idea to check the Schedule Log for possible open ends elsewhere in the schedule, there should be no open ends as a result of dissolving activities.

Any questions? Feel free to contact me.


Source: Primavera Scheduling

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