Commonly known as pipework flushing, water treatment is part of pre-commissioning used to ensure pipework is clean and free of any solid and chemical debris prior to commissioning. This process was introduced as part of pre-commissioning after discovering that a lot of construction debris was left in pipework during construction phase which meant future problems due to valves and filters clogging up
This was further developed during the years especially after pseudomonas outbreak which encouraged installation teams, designers and facilities teams to adopt this method. Pre-commissioning cleaning is achieved through flushing and chemical cleaning following by addition of biocides and inhibitors. Following this process, the quality of water in the system is analysed by taking samples which are analysed for suspended solids, iron and bacteria. This process is carried out by trained and experienced operatives working safely to ensure safe working method and also records are kept for communication Like most services related topics, most people are not familiar with the actual process of pipework flushing and mainly see it as pumps and pipework circulating water around pipework. In some cases, due to people not fully understanding this process, site progress has been affected and unnecessary steps taken during the flushing process During the construction design stage, the designer will address the requirements for the system, which methods are appropriate, whether chemicals are important for the system and design features to facilitate the process The type of cleaning will also depend of the following factors:Construction periodSystem sizeWeather the system is open or closedSystem material (copper/plastic/stainless steel)Plant type connected to system I.e. chillers, heat exchangers etc.
A typical cleaning programme will include the following procedures:Static flushing – which takes place after pressure testingDynamic flushingDegreasingBiocide washFinal flushingNeutralisation - for inhibited acid cleansPassivationCorrosion inhibitor and biocide dosing. Work is also put into ensuring there is enough foul drains within close proximity to the flushing points which can be used for draining and flushing After the chemical cleaning process has been carried out, and in order to maintain the same conditions after handover, ongoing maintenance of water treatment will be essential. Chemicals can be introduced to the system via a dosing pot which can be done periodically or via an automatic dosing pot system Side stream filtration has also been introduced as a way to clean water systems and also easily maintain them. side stream filtration can be used as a way of reducing quantity of water discharged to drain by diverting a amount of water used through the filter. By doing this, solids are gradually removed. Once in place the filtration unit can be left to provide permanent protection to the system. By also removing nutrients from the systems, side stream filters can help limit bacterial growth