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Projects - Phases and Disciplines

Updated: Aug 9, 2021

In the basis, each project can be divided in 3 mayor phases:

  1. Engineering

  2. Construction

  3. Commissioning

NOTE: Because of readability the phases are described as if they have a linear sequence. One phase follows the other. In practice these phases overlap. Please refer to the blog on Turnover Systems for more information.


1.1 Pre-Engineering - FEED PHASE

Before Engineering even starts, the client lays it basic wishes on the Table.

A new plant, expansion of a plant or a modernisation of an existing plant.

This is called the "FEED-Phase". The results from this phase are -feeding- the data the Engineers are going to work with.


During the Engineering phase this discipline is turning the wishes of the client in a visual roadmap.

Starting with the PFD'S (Process Flow Diagram, mostly the property of the client) they develop or adjust the Master set P&ID's (Process & Instrumentation Diagrams). During the rest of the project this set will be the "blueprint" from which all other engineering documents and lists are developed, such as equipment-, line- and Instrument list.


Based on the P&ID's, the Equipment or other tagged items are identified and categorised as being long-lead items ,Yes or no. These items are not available off-the-shelve and need to be Purchased in advance. Think of Large equipment, non-stock items and specialised instruments. They are being bought in the early stages of the engineering phase.

Off-the-shelve items such as standard Instruments, Equipment and piping items are going to be bought later in the Engineering phase when the amount needed becomes more clear, read, when the P&ID's and lists become more accurate.


When the Engineering scope is discussed and agreed with the Client Construction can start. Construction is done be several separate disciplines which wil be briefly discussed below and in more detail later on in separate Posts.

2.01. CSA (Civil, Structural and Architectural.)

The first discipline in is CSA. Although three different disciplines these are often combined together as CSA because often

- One engineering team develops the drawings and

- One Construction Contractor builds it.

It can be, however, that the CSA Contractor outsources something like Steel or Architectural to a separate Sub-Contractor.

CSA prepares the Grounds. It builds the physical Area's where the parts of the Plant or the individual pieces of Equipment are going to be installed And located. These can be Foundations, Steel structures like Pipe racks and elevations or Buildings.

2.02. Mechanical

The Second discipline in is Mechanical. Installation of the Large equipment starts. Some times large equipment needs to be installed before buildings or steel structures are closed. Most Equipment will be connected to piping, instruments and power (Electrical) to function later.

Other (and smaller) equipment can only be installed after steel structures or buildings are erected.

Mechanical (Construction) and Piping is mostly combined and done by one P&M (Piping/Mechanical) contractor on smaller Projects. Engineering is normally done by separate discipline teams.

2.03. Piping

While Steel construction continues piping construction starts. 70% of the pipe lengths is done in the first 30% of the project. (Do not pin my to this, percentages may vary!)

This is made possible while Structural Steel normaly starts with the Pipe Racks, were long lengths and several types of pipe can be installed quickly and efficiently.

During the remaining 70% of the project the "Interconnecting piping" is installed, connecting the equipment, containing the in-line Instruments and make possible connections to existing parts of the plant (Tie-ins).

2.04. Electrical

Like P&M, Electrical and Instrumentation are, on smaller projects, often installed by one contractor, the E&I Constractor.

Electrical engineering deals with electrical lines, Transformers , circuit breakers, power transmission , power generation and distribution. Electrical POWERS the Plant.

Most of the time power comes into the plant in High Voltages that needs to be reduced (Transformed) to make Electrical Equipment and instruments function.

Circuit Breakers function as the industrial version of the fuse boxes at home.

2.05. Instrumentation

Instrumentation engineering is a sub branch of electrical engineering but we can say that Instrumentation engineering is a mixture of electrical, mechanical, Instruments, control systems.

Instrumentation deals with sensors, transducers, analog and digital controllers, automation etc... Therefore it CONTROLS the Plants functions.

2.06 Turnover

The Turnover department prepares the finished parts of the plant for Commissioning.

turnover makes sure the project handsover Functional, safe and documented parts of the plant the can be separately commissioned.

Please refer to the blog on Turnover Systems for more information.


After construction is finished, the Commissioning teams starts. (Parts of) the Plant are now under the custodian of the Client. Live products and Chemicals are introduced.

Project commissioning is the process of assuring that all systems and components of a building or industrial plant work as they intended to work.

Commissioning checks if the final Plant is designed, installed, tested, can be operated and maintained according to the operational requirements of the owner or final client.

Because we often work in existing plants, Commissioning is typically done by, or in close co-operation with the Client's Plant Operators. They know the processes, how the existing plant works and have a deep knowledge of the chemical or physical processes involved.

The Commissioning Team prepares the new plant (parts) for startup.


As one can see, a lot of disciplines and processes are involved.

Construction projects can be complex and sometimes troublesome.

Construction Projects can be a sprint and sometimes a Marathon.

But with the combined knowledge and effort of ALL Team members EVERY project can be a success.

There is no "I" in "Team"!

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