Water

Pre-Commission Cleaning Services

ph Water Technologies chemical cleaning division has 20 years’ experience in new build projects and have successfully delivered some of the largest projects in the UK

“Our engineering staff are fully compliant to BSRIA BG29/2021 ‘Pre-commission cleaning of pipework systems’ and have been trained in the science and philosophy of chemical treatments and microbiological control and prevention.”

Newly installed closed systems, LTHW, MTHW, HTHW, Chilled Water and Condenser Water circuits should generally be pre-commission cleaned. The vast majority of these systems have small bore control valves, regulating valves etc, which readily become blocked with particulate matter and would then fail to operate. It is therefore important to ensure the presence of acceptable water quality prior to putting the system into use. Debris and contamination that is present in a system as a result of the installation process needs to be removed.

Systems cleaning prior to an initial balance is critical.

Preceding the balance all valves can be fully opened and flushing flows maximised and manipulated to ensure that all possible debris is removed from the pipework. It is rare that such an opportunity will present itself again since once a building is commissioned and occupied, regulating valves in the system will be at a set position with reduced orifice sizes to effect a system proportional balance.

The use of chemical enhances the cleaning process by removing soluble contaminants.

BSRIA BG29/2021'Pre-Commission Cleaning of Pipework Systems'

This guide outlines the methodology for cleaning new industrial and commercial systems (BS7593 2006 for domestic hot water central heating systems). In addition this guidance document outlines the responsibilities of designers and installing contractors. These should be taken seriously since poorly designed systems cannot be adequately cleaned and systems installed without correct flushing facilities require additional installation work prior to flushing and cleaning.

It is important to get systems properly cleaned in accordance with the guideline. In the event that the process fails subsequent cleaning becomes more difficult for the following reasons:

Debris can become trapped in small valve orifices, FCU coils, chillers etc. These areas are generally protected, by means of bypassing, until after the initial cleaning process.
Debris can become baked onto the pipe walls and heat exchange surfaces with the passage of time.
Microbiological problems can commence and become a serious problem in the presence of retained debris.

“Our pre-commission cleaning exercises are documented and witnessed and samples provided to demonstrate cleanliness at handover.”

Following pre-commission cleaning it is important that closed systems are carefully monitored and regularly maintained. This maintenance should continue throughout the life of the building and should involve sample taking at a maximum interval of 3 months.

New Systems

To obtain the maximum benefit from a system and to ensure longevity and ability to work as installed new systems and pipework need to be thoroughly cleaned to remove debris, such as sand, welding ash, corrosion deposits, grease and oil-base agents.

ph Water Technologies provides effective chemical cleaning regimes, using specialist equipment and non-acidic chemical cleaners.

ph Water Technologies fully trained engineers will apply and monitor these cleaning programmes which have been specially designed to be compliant with BSRIA guidelines.

Old Systems

ph Water Technologies provides effective chemical cleaning regimes and by using specialist equipment and non-acidic chemical cleaners old corroded systems can be cleaned to improve efficiency without damage to the system components. ph Water Technologies fully trained engineers will apply and monitor these cleaning programmes which have been specially designed to be compliant with BSRIA guidelines. ph Water & Air Technologies are happy to offer solutions which include specific chemicals for the water quality and contaminants detected. We can support these with assistance during design, during filling & testing, the use of filtration, temporary pumping facilities, dosing solutions, plant & equipment.

Water Quality

Pseudomonas

Pseudomonas bacteria has the ability to cause corrosion to any open or closed water system. Once the bacteria is established it forms a jelly like film which clogs valves and reduces heat transfer. The anaerobic conditions created between this film and pipe work provide a breeding environment for other bacteria including SRB’s and NRB’s. It also creates a barrier to debris preventing a successful chemical clean if not treated properly.

As it is a living organism it will reappear if not completely destroyed. The results of pseudomonas within the system are often shown by changing commissioning results, greasy films on strainers and often as muddy reddy brown colouring to the water. In simple terms these have been linked to corrosion.

Sulphate Reducing Bacteria (SRB’s)

This is one of the most destructive groups of biological foulants because they cause corrosion resulting in severe localised pitting of pipework surfaces. They have been implicated in severe corrosion problems for copper, iron, steel and aluminium pipe work. As a result of their metabolism, they produce hydrogen sulphide which attacks iron and steel and forms the end of produce ferrous sulphide. Steel thus becomes pitted, and cast iron becomes ‘graphitised’.

Nitrite Reducing Bacteria (NRB’s)

This bacteria gasses to produce ammonia. This poses a risk of stress corrosion cracking to brass/copper components such as valves and fittings. As with SRBs above these are anaerobic bacteria which tend to produce acid (corrosive) by-products. These as with SRBs dwell beneath deposits or in systems with limited oxygen. In the event that NRB’s are detected in the absence of a

Total Viable Count

The Total amount of bacteria expressed in colony forming units. High levels are often an indication of a dirty system. The dirt providing a hide out for the bacteria and ideal breeding conditions.

Suspended Solids

Insoluble dispersed solids which may be separated from the water by filtration or sedimentation. These should be <30mg/l at circulating pump sets, which allows for the fact that corrosion inhibitor will cause an increase. At all other parts of the system these are expressed as ‘settled solids’ and should be <45mg/l on immediate completion of any water treatment works.

Iron

An important test for corrosion control in industry. BSRIA BG29/2021 states that total iron 7 days after pre-commission cleaning is <6mg/l and soluble iron <3.0mg/l.

Guidelines for system monitoring between pre-commission cleaning and practical completion states total iron <15mg/l and soluble iron <3mg/l

pH

Expresses the acid or alkalinity of a sample. Important test when known certain installation & plant materials have been used.