Don’t Shortcut Pre-commission Cleaning

The pre-commission cleaning of heating and chilled water systems has become an essential process in the installation of new systems.

Correct pre-commissioning of newly installed equipment is vital to gaining maximum efficiency from your water system. The term ‘commissioning’ includes the processes of bringing the systems into operation; their regulation; the setting up of control systems; plus the recording of the settings and the state of the final system performance.

In poorly commissioned systems the equipment associated with these systems is susceptible to blockages at strainers, control valves and small bore heat exchangers.


In recent years we were reminded just how important the pre-commission cleaning of chilled and heating systems actually is, and what can go wrong if it is not carried out properly.

A new chilled and heating system was installed in a new site and the mechanical contractor flushed the systems with fresh water, however they only done this until everything looked clean.

They then re-filled the systems with water and left them full of water without any inhibitor or biocide for a number of weeks.

A water treatment company then added a corrosion inhibitor to the systems which at this stage had corroded badly.

Aquachem was then called in and we carried out full analysis on the systems including measuring iron, pH and inhibitor levels.

The levels of bugs in the system were measured using our Lumitester PD 20 ATP/AMP system which gives a reading of bug levels within 10 seconds. The tests showed huge levels of bugs and over 100 ppm iron in each system.

Based on the analysis Aquachem recommended that a complete pre-commission chemical cleaning needed to be carried out on both systems. This involved the following:

  • complete drain down of both systems
  • re-filling with fresh water and dynamic flushing
  • inspection of and cleaning of strainers
  • addition of our ChemSperse 105 pre-com cleaning chemical which has a built in corrosion inhibitor to protect the systems while they are being cleaned
  • checking of iron levels throughout the systems until they reached a plateau
  • drain down of both systems together with checking of iron and solids levels.

Once iron levels were less than 2 ppm and the solids levels were within 10% of the levels in the make up water both systems were immediately filled with fresh water dosed with our ChemHib 201 corrosion inhibitor plus BioChem 1404 biocide and circulated.

Failure to do this could have resulted in future problems with heating and chilling throughout the facility and could have resulted in permanent damage to expensive equipment with the possibility that this damage would not have been covered by insurance.

Failure to carry out proper pre-commission cleaning on these plants resulted in additional time and money having to be spent to re-do the work correctly.

The advice based on our experience here is Don’t Shortcut Pre-com Cleaning. Make sure it is done properly and that the company doing the work certifies all stages of the work.

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