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What is the difference between "Area based Construction" and "System Completion"?

Updated: Sep 4, 2021

Area Based Construction is like what you did when you were young, with Lego... Connecting components together to create something nice looking... You build from the ground up.

System Completion is what you learned in school at Chemistry. This thing goes to there, reacts with that and makes That... or, like in Oil, gas and Chemicals, a Functional process...

AREA is based on location, SYSTEM is based on Function


70% of the progress is made in the first 30% of the project...

You start building from the ground up, first things first.

If we are talking about "Green Field Areas" :

  • Access roads (Temporarely)

  • Foundations

  • Piperacks

  • Steel Structures

  • Buildings (Structure)

Once that is done or started, the large Equipment can be installed.

1.1 Large Equipment

Sometimes equipment is installed inside steel structures or buildings and is to big to be put in afterwards. That is something that needs to be researched in the early phases of the project. The Equipment is hoisted in once the structural integrity is safe and the steel structure or building is finish after that.

1.2 Equipment outfitting

For Equipment to work (or to be useful) it needs something to go in and something to come out. If you are working on a ground level or on a structure level (Floor) that is not much of a problem. If it might become a problem, it could be useful to install :

- Column internals

- Column dressing (platforms)

- Piping

Before the Column is lifted. columns are mostly stored on its side (horizantaly) which makes it easier to access the internals of the Column through the mannholes on an almost street level.

Working on heights and inside confined spaces (which a Column is) are still some mayor safety risks.

1.3 Piperacks

As soon as the Pipe racks are (partly) installed, the lengths of large Pipe go in. Depending on the kind of project a lot of progress can be made while doing this. A lot of pipe can easily hoisted in without being bothered by bending, curves of the spools or possible damage to (existing) equipment.

This is why they sometimes say that 70% of the progress is made in the first 30% of the project...


Now, after Area based construction, 70% of all installation work is finished. However, Commissioning cannot do anything with that. They need a :

Functional and documented part of the Plant

To start commissioning, a part of the plant needs to be closed, safe and documented to prove that it is closed!

That is why at 60/70/80% installation we stop measuring progress by AREA, and focus on SYSTEMS.

Still, a lot of areas need to be finished but that can be done later.

Commissioning (READ: Taking into Service) of a plant takes time. If we can divide the whole plant in functional parts, these can be tested separately and we can make sure that wen the last part of the Plant / Systems is completed, the whole plant is functional and safe to operate. The amount of time saved taking such an approach depends from project to project but can be massive.

Further more, manpower is often a limitation during a project and with a systemised approach the workload can be spread during the duration of the project.

Once the project is declared MC (=Mechanical Complete) the plant is functional. It might be, however that some parts still need to be finished after MC.

A typical example are Roads. These are not necessary for the functionality of the plant but need to be finished according to the contractual scope.


Signing the MC Certificate normally refers also to the Punchlist of remaining items.

A date can be negotiated when these items need to be finished. If these items are NOT finished within the agreed timeframe, the MC Certificate can become invalid, resulting in missed contractual timeframes and thus costing serious Money!

In another Blog we will go deeper into what a systemised approach really means for managing a project..

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