Cleaning and Pre commission cleaning of pipework systems

Background.

In 1990 world governments met at the Koyoto Summit to discuss the issue of global warming and ultimately agreed to attempt to reduce Carbon Dioxide (CO2) emissions. This has led to legislation being introduced around the world to limit how energy is used - especially with regard to the burning of fossil fuels. In the United Kingdom the Department for Community and Local Government published a series of regulations which now stipulate how energy is conserved in the construction industry with the specific aim of reducing CO2 emissions.

The current building regulations (part L) issued in April 2006 specify how central heating systems are designed and installed. This has meant that all new boilers have to meet minimum efficiency standards.

Energy consumption is improved by proper cleaning as referred to in BS7593 and system efficiency maintained by obligatory treatment with chemical inhibitor. The benchmark code of practice also details the requirement for energy efficient installation including the use of effective water treatment technologies.

There is now a requirement for all new boilers to be high efficiency (largely condensing type) boilers and the more modern ones can achieve very high efficiency ratings (SEDBUK rating). These boilers are much more noticeably affected by the problems associated with untreated water.

Just as the performance of a racing car is heavily influenced by the quality of fuel it burns, so the efficiency of a heating system is heavily influenced by the quality of the water circulating within it.

Why do pipework systems need cleaning?

The main contaminants found in water systems are installation debris, scale, corrosion products and biological fouling. These cause various different problems but in general, to some degree detrimentally affect the operating efficiency of the system and the life of the system materials.

As a result of these problems the Building Services Research and Information Association (BSRIA) brought together the experience and best practice of numerous system designers, manufacturers and specialist maintenance companies and produced the application guide AG1/2001.1 Pre Commission Cleaning of Pipework Systems.

Cleaning is necessary to remove the contaminants that can otherwise be detrimental to the system. This will certainly involve the flushing through with clean water and may also involve the use of chemicals. Chemical cleaning is not compulsory, but the majority of systems will benefit from some form of chemical cleaning to supplement clean water flushing.

Do I need to have the work done by a specialist company?

Not necessarily, but many people do use a specialist for peace of mind. The type of clean will depend on the consideration of system size, whether it is open or closed, the materials used, complexity of the system and the length of the construction period. Also on whether the system is completely new, or is an extension to an existing system.

It is important to choose the right chemicals to use from degreasing agents, inhibited acid cleaners, biocides, biodispersants and corrosion inhibitors among others, and the clean itself may include various stages from static or dynamic flushing, chemical rinse, neutralisation, final flushing, passivation and corrosion inhibitor and biocide dosing.

What if the system only needs flushing?

The main objective of the flushing process is to remove as much dirt and debris from the pipework system as possible. Hence the water velocity required for flushing must be sufficient to pick up and carry the majority of dirt and debris. A table of the minimum water velocities for various pipe sizes in contained within the BSRIA guide and it is possible that the pumps which make up the system are not sufficient for this and temporary pumps (such as a dedicated power flushing unit) will have to be used to obtain the correct flushing velocity.

Where obtaining these velocities in large bore pipes is not possible or practical, consideration should be given to alternative chemical cleaning methods.

In distant heating systems for example, hydrocyclone filtration (side stream filtration) over a longer period of time may be more appropriate.

How can Nemco Help?

Nemco have experience and a proven track record of carrying out system cleaning of many different water systems both large and small, including distant heating systems.

We are able to offer a variety of chemicals and methods to best suit the individual site requirements.

All Nemco Water Hygiene Engineers are fully trained to carry out this type of work in accordance with BSRIA AG 1/2001.1

Nemco are Construction Line, and Construction Health and Safety Scheme (CHAS) members, We are also members of the British Standards Institute so you can be confident that the work will comply with current guidelines and best practice.

You can contact Nemco free on 0800 074 1237 to discuss in person or arrange an appointment or a quote. Or you can contact us by e-mail or post via the contact us section.