HEATING, VENTILATION & AIR CONDITIONING
THE PERFECT PIPE
FOR THE PROJECT
Choosing the right pipes and fiings for a plumbing or heating installation is vital to ensuring not only the
quality and longevity of the pipework fied, but also its health and safety credentials. Here, Franz Huelle,
technical manager, Rehau Building Solutions Division, compares and contrasts the hygiene properties of
different pipe materials and joints.
When it comes to choosing
MAY 8 | BUILDING PRODUCTS
pipework for a heating or
plumbing application, it’s easy
to assume there is no difference
in performance between copper, steel or polymer
alternatives. In reality, there are many differences
in the way materials behave and the health and
safety assurances they offer.
Common practice in larger installations is to fill
and flush the pipework, carry out a pressure test
and then empty the pipe system, leaving it empty
until the building is being occupied. The residual
moisture inside the pipework, together with the
reintroduced oxygen/air can lead to corrosion
issues with steel pipes, if adequate counter
measures are not taken.
Certain water compositions and a lack of
adequate additives on the other hand can result
in deposits forming inside copper pipes, a
process called incrustation. This process results
in the effective bore being reduced considerably
over time, causing reduced flow and a pressure
increase, both of which can potentially reduce the
system performance below acceptable levels.
The pipe material however is only one part of the
story. How the pipes are joined together also plays
a significant role in the overall performance of the
The most commonly used jointing methods
for plastic or copper pipes all use fittings with an
O-ring. Both push-fit and crimp fittings require the
rubber seal to achieve the water-tight connection
either on the outside or inside of the pipe. Any
localised surface damage on the pipe potentially
compromises the seal, as an incorrectly sealed
O-ring or not fully crimped joint. Both connection
methods are cost-efficient, quick and easy to install
and perform satisfactorily in many applications.
One factor which is all too often ignored when
it comes to joints is the potential for little pockets
or cavities of stagnant water to be created. General
design advice has always been to reduce dead
legs – a length of pipe leading to an outlet which
has been removed or is rarely used or unused
entirely – as much as possible in water systems to
prevent potential breeding grounds for bacteria.
To apply this, installers must take an overview of
the system to identify where dead legs could form.
A pipe system should usually only have a limited
number of dead legs, if any, but more joints can
To remove any possibility for stagnant water
from the joint altogether, a smart jointing design
can be used. This can result in significant reduction
of potential bacterial growth and can keep the
entire pipe system healthier for users.
To achieve this installers can consider an
axial compression sleeve technology, which
is free of any rubber seals and simply uses the
pipe material itself to achieve the water-tight
seal. With this technology, the polymer pipe
is expanded and the fitting is inserted, then
the pipe material’s innate memory technology
retracts the pipe back to its original state, sealing
it directly onto the fitting. The compression
sleeve is pushed over the inserted fitting, locking
the entire joint permanently into place, with the
pipe itself sealing against the fitting. This creates
full surface contact with no gaps, preventing
water from being able to stagnate. This is an
ideal solution for all drinking water systems and
particularly for health sensitive applications.
A positive side-effect of this technology is a
maximised pipe bore which is not restricted by a
much smaller inserted fitting, ensuring minimal
impact on water flow through this system.
Take the lead
It’s not just bacteria that can make potable water
installations risky for end users but also the effect
pipework joints can have on lead levels. In 1998,
the EU Drinking Water Guidelines were passed,
in line with World Health Organisation (WHO)
targets, to reduce lead in drinking water from
25μg Pb/l to 10 μg Pb/l by 2013.
To ensure these levels are achieved, specifiers
must understand what materials they are using and
the effect these will have on the water. The critical
thing to remember is that it’s not the lead content
of a component, but the amount of lead released
by that material which is important. Fittings made
from most types of standard brass, red brass and
stainless steel all have been tested and proven to
leach less lead into drinking water than the current
legislative requirements in many countries.
There are many aspects to consider when
selecting the correct piping and jointing systems,
however it’s vital to look ahead and ensure the
system is future-proof where possible. New
technologies and innovations are now allowing us
to plan ahead against potential problems.