Pre-Commission Cleaning of Pipework Systems Amended 6th edition (BG29/2021)

Common customer questions & answers

QQuestion Which edition of BSRIA’s Pre-commission Cleaning guide should I be using?

AAnswer The current edition of BSRIA’s Pre-commission Cleaning guide is BG 29/2021. It was revised in partnership with the CSCA with input from an industry steering group, members of which are listed in the guide. It supersedes all previous editions of the guide. It is BSRIA’s intention that, in normal circumstances, BG 29/2021 should be used in preference to any superseded editions of the guide. Superseded versions of the guide are still available (see Revision History above) as they provide useful reference information for older projects. Users of BG 29/2021 should be aware that it is a guide, not a regulation. It is for individual project teams to decide whether to follow the guidance, and this should be made clear in project documentation.

QQuestion Can pressure independent control valves (PICVs) be flushed through?

AAnswer Some PICVs have internal mechanisms that may be damaged during normal flushing operations (either forward or backflushing, dependent on the specific valve). The flushing procedure may have to accommodate for this, taking additional steps such as bypassing the PICVs. Manufacturers’ recommendations should be followed in this regard.

QQuestion If the duration between pre-commission cleaning and practical completion is longer than 3 months, what values should be used to assess the systems against for handover?

AAnswer The control limits specified in Table 5 of BG 29 are usually easy to maintain for the first three months after completion of pre-commission cleaning and hence (provided that handover is within 3 months of the end of the clean) can be used as the basis for handover. However, if handover is to take place more than 3 months after the clean, then some additional interpretation of the results based on BG 50 guidance may be required. For example, if bacteria, copper or iron levels are above the stated Table 5 limits, then some interpretation of the cause and significance may be required from a suitably qualified water treatment specialist. Furthermore, the trends in values leading up to handover should be considered; stable values are less of a concern than unstable values. Once comfortable that the water quality parameters are in a stable and maintainable condition, a pack should be produced and signed to show that BG 29 compliance was achieved following completion of pre-commission cleaning, and that subsequent sampling records demonstrate that the system has been maintained in compliance with BG 50. Any refusal of handover should be supported by an explanation of which parameters are problematic and the consequent risks they pose for future system operation.