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Pre-Commission Cleaning of Pipework Systems (BG 29/2012)


BG 29/2012 provides the latest guidance on pre-commission cleaning reflecting new British and European standards. Thorough pre-commission cleaning continues to be important with the adoption of energy efficient controls strategies that may result in low flow rates. 

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Full description

BG 29/2012 provides the latest guidance on pre-commission cleaning reflecting new British and European standards.

Thorough pre-commission cleaning of pipework systems continues to be important with the adoption of energy efficient controls strategies that may result in low flow rates.

This guide provides the latest thinking and good practice cleaning techniques. It aims to clarify the roles and responsibilities of the parties, improve the exchange of information between them and provide consistency between service offerings of the pre-commission cleaning contractors.

Pre-commission cleaning is achieved through a process of flushing and chemical cleaning (where required) followed by the addition of biocides and inhibitors. Systems designed and cleaned in accordance with BSRIA's guidance are far less likely to experience operating problems.

Contents include:
- Design considerations
- Inspection and witnessing
- Installation considerations
- System dynamic flushing
- Chemical cleaning procedure
- Connections between new and existing systems

Editable Excel versions of the pro-formas in appendices C and D of this publication are attached to the pdf of this guide, and are available as a free download to anyone purchasing a hard copy of the guide.

This publication is also available as part of the Commissioning Guide Set (Compak3)

Revision History

  • The original predecessor of this publication was AG 8/91: Pre-Commissioning Cleaning of Water Systems, published in 1991.
  • This was superseded in 2001 by AG 1/2001: Pre-Commission Cleaning of Pipework Systems.
  • This was superseded in 2004 by AG 1/2001.1 Pre-Commission Cleaning of Pipework Systems(2nd edition).
  • This was superseded in 2011 by BG 29/2011 Pre-Commission Cleaning of Pipeworks Systems
  • which was in turn superseded in 2012 by BG 29/2012 Pre-Commission Cleaning of Pipework Systems.

Publication details

AuthorsBrown R, Parsloe C
No. of pages112
Number of books in set1
Date publishedOctober 2012



Section 6.2.8 of BG 29/2012 says that, up to practical completion, water should be circulated and valves exercised. How often should these actions be carried out?


As a rule of thumb, the system should be circulated for 1 hour once a day. All automatic control valves should be open during circulation and the BMS should be set up to ensure that this continues throughout the life of the building. The overall aim is to ensure that, on a daily basis, all water in the system moves a sufficient distance to avoid stagnation. For systems with long runs of small-bore pipework from the main recirculating system to two-port valves at terminal units, the circulation time may need to be longer than on systems where the pipework run is shorter. It is neither necessary nor desirable to operate the main heating or cooling plant during circulation but in some buildings and systems, this may be unavoidable. If there is a danger that circulation of active systems could disrupt environmental conditions, then the overall circulation period can be split into several smaller periods and/or applied sequentially for different zones.


Can the BG 29/2012 criteria for completion be applied to flushing of existing pipework systems?


These criteria are intended for use in pre-commissioning cleaning activity of new heating and chilled water systems, not existing systems. When cleaning existing systems, the history, pipework conditions and reasons for the flushing or cleaning need to be assessed to determine the likely outcome before works proceed. It is generally the case that parameters set out in BSRIA 29/2012 can be used as a target for water quality and that any deviation should be logical based upon the above assessment.


Some pages in BG 29/2012 refers to “Section 0”. What does this mean?


These are typographical errors and will be corrected shortly. The reference on page 55, section 5.2.2, first paragraph, should read “…described in Sections 5.2.3 to 5.2.7”. The reference on page 82, section 7.1, second paragraph, should read “…given in Section 5.2.7”.


Can ultrasonic flow meters be used to check the flow rate during flushing to confirm that the minimum velocities stated in BG 29/2012 have been achieved?


In BG 29/2012, the flushing operation is aimed at creating turbulence inside the pipework (i.e. a high Reynolds number) to remove corrosion product, scale and other deposits from internal surfaces. Ultrasonic flow meters usually provide a more accurate and stable reading in laminar flow regimes than in turbulent flow regimes. Therefore ultrasonic flow meters should not be considered as a reliable means of flow rate measurement when flushing to BG 29/2012 minimum velocities.


Does BG 29/2012 apply to closed pipework systems in residential buildings such as blocks of flats?


Yes. BG 29/2012 applies to closed pipework systems in all types of building. However, it does not apply to domestic hot and cold water services systems (i.e. the systems providing water to hot and cold taps) in any type of building.


What levels of copper would be expected in closed systems and are the recommended parameters (<1 ppm total copper) in BG 29/2012 achievable in all instances?


Practical experience, from the monitoring of copper levels in closed systems since the publication of the guide, would suggest that levels of 1 ppm may be exceeded in new systems from time to time, especially if there is a lot of copper pipe in the system. However, levels in the bulk recirculating water (sampled at the pump) should generally comply with guidelines in BG 29/2012 and it would be unusual to find results greater than 3 ppm elsewhere in a system. In order to assess the acceptability of the water, it may be necessary to review the trend over consecutive samples.

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