3.2.2 Corrosion on copper and copper alloys

Regulations require that all water services (except warning

or overflow pipes) shall be protected from freezing

temperatures and heat gain. This is best achieved by

protecting the system by use of a suitable thickness of

insulation or in the case of particular situations such as

unheated roof spaces that require special care, a self

regulating trace heating tape.

Pipework may need to be protected from external corrosion

causing construction materials, corrosive environments

or abrasion. A variety of solutions are available, ducting,

insulation, corrosion resistant paint finishes and anti-

abrasive tape, the most effective solution should be chosen.

Systems containing copper tube with copper and copper

alloy fittings generally have a high resistance to internal

corrosion. However, it is recommended when systems have

been hydrostatically pressure tested and are not going into

immediate service, they are fully drained down and blown

out with dry air. Alternatively, if this is impracticable, the

system should be left ‘wet’, and flushed at regular intervals

prior to being commissioned to reduce carbon film cold

water pitting and the potential for legionella in stagnant

water.

Precautions against freezing must also be undertaken.

This is particularly important in new build housing when

properties are not occupied for extended periods. For

heating and cooling applications, Conex Compression

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fittings can be used with glycol-water mixtures up to a

mixing ratio of 50:50 without affecting the product quality

and the sealing element.

If a frost protection inhibitor is to remain in the pipelines

permanently, at least one concentration test must be carried

out annually. All chemical additions must be agreed before

use to rule out negative interactions with materials and

sealing elements. For more information, please contact

Conex Bänninger technical department.

If commercial leak detector aerosols are used to detect

leaks, it is recommended the residue is washed off with

clean, warm water.

3.3 Pressure Testing

Pressure testing on Conex Compression fittings should

normally be carried out using clean potable water. Only

in exceptional circumstances should pneumatic pressure

testing using compressed inert gas or air be used, and then

only under careful controlled conditions.

Pressure testing should be carried out in accordance with

national regulations, appropriate specifications should be

drawn up and a risk assessment must be completed prior

to testing.

Typically, when testing systems containing Conex

Compression fittings, all joints shall remain uncovered and

visible, the system shall be filled with clean potable water

against an open high point valve allowing all trapped air to

be removed from the network. Once free of trapped air, the

high-level valve should be closed and the system topped

up. At that stage testing can be completed between 1 to 2

bar and a full inspection made to ensure any leaking joints

are identified. Any identified joints that have not been sealed

and are leaking water can be tightened without draining

down, however it is essential the tube is fully inserted. An

additional 1/4 turned is viable.

Once it is confirmed there are no leaking joints, the

pressure can be slowly raised to the system test pressure.

The recommended system test pressure should be in

accordance with the requirements of EN 806 part 4 (1.1 x

maximum design pressure). Full test pressure should be

maintained for a minimum of 30 minutes without any sign of

pressure drop. A full inspection should then be carried out

to identify any leaks.

3.4 System Commissioning

To ensure the quality and safety of hot and cold-

water supply systems always follow best practice

techniques in their design, installation, commissioning,

and maintenance. A reliable and predictive regime of

commissioning that does not have any detrimental

effect on the longevity of the system should be in place

as required by national, regional and local laws and

regulations.

The chemicals used in the pre-commissioning, if

incorrectly administered can have a serious effect on

the systems’ life, therefore the choice of chemicals is

dependent on the particular site conditions, the materials

used and the method(s) of construction.

Where a temporary mains supply(s) is to be used it should

be cleaned and chlorinated in accordance with national

regulations before being used for system filling and

flushing.

For more information on chlorination, please refer to

document 'pre-commissioning of systems' available at

www.conexbanninger.com.

Note: Commercial anti-corrosion chemicals must not to

be used on potable water systems.

3.4.1 Flushing of water installations

It is essential to flush the systems with water after installation

to remove dust, debris and flux residues. Please note in the

absence of national guidelines commissioning should be

carried out in accordance with EN 806-4.

If installations are not used immediately after commissioning

they should be flushed at regular intervals, at least once a

week. After an extended time, it would be recommended

the system is disinfected to comply with legionella

guidelines.

3.4.2 Water softening

Hard water may be softened to avoid excessive deposits

of scale in hot water services. However, a degree of scale

is necessary to form the protective patina on copper tube.

When a new copper tube installation has a water softener

fitted from day one, it is good practice to run the system

for approximately three months with the softener by-pass

open to allow untreated water into the system, and allow

the patina to form. Ideally the system should be around

60 ppm of total hardness.

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