Copper Tubes

• Copper is one of the most commonly encountered metals, principally used for a wide range of applications including gas, compressed air systems or as refrigerant lines in HVAC systems.

• Copper also provides an environment that makes it very difficult for bacteria to grow, which is an important health consideration for the transportation of water in both commercial and domestic installations.

• Copper tube can be joined with capillary fittings. These fittings save material and make smooth, neat, strong and leak-proof joints.

• Copper tubes can also be jointed with compression fittings, grooved, mechanical body grip ring, flared joints, press-fit and other push-fit type jointing systems.

• There are two commonly used types of copper tubing, soft (annealed) copper and rigid (cold worked) copper.

• Copper offers a high level of corrosion resistance, and is a soft, malleable, and ductile metal with very high thermal and electrical conductivity.

• The value of copper as a global commodity has gone up in recent years, making it prone to possible building site thefts.

• BS EN1057: Copper and copper alloys. Seamless, round copper tubes for water and gas in sanitary and heating applications. Defines the technical delivery conditions for copper tubes.  Covers CU-HARD (R290), CU-1/2 HARD (R250), CU-SOFT (R220), and the requirements for the associated X, Y or W grades.

• BS EN 13349: Copper and copper alloys. Pre-insulated copper tubes with solid covering.

• BS2871-1 – now replaced by BS EN1057.

• Copper press-fit systems are typically capable of operating up to 16 bar design pressure. However, some specifiers may restrict pressure to lower pressures, for example 8 bar with soft-soldered capillary fittings and unions; 16 bar for systems with brazed capillary fittings and flanged joints; and 8 bar for systems with press-fit jointing.

• Where brazing occurs, as is required for capillary joints in copper systems operating up to 16 bar, the elevated temperature from the brazing process may cause annealing of the copper; and this typically requires the use of copper tube of greater wall thickness to withstand the system pressure (as copper is now softer), and in some instances special fittings with greater wall thickness too. NOTE: pressure integrity is a function of jointing used, as well as application temperature and installation practices.

• Applications for natural gas and press-fit joints may be limited, previously to 54 mm and 100 mbar (as IGEM/UP/2 Edition 2 did), but the current Edition 3 IGEM/UP/2 raises this to 108 mm and 5 bar.

NOTE: Guidance only, other pressure integrities may be possible, or restrictions may be in place if products are used within particular applications where restrictions can apply (i.e. gas systems).  Consult with the relevant manufacturer or distributor to confirm actual values.

• Typically available: Ø12mm up to Ø159mm

• Common range used in Building Services/Construction is up to DN100, OD 108 mm

• Press-fit tubes:

–Not to be used in areas where there is a high risk of mechanical damage.

–It is not advisable to use these systems in concealed areas (where joints are permanently inaccessible). 

• Traditional tubes:

–Suitable for most applications. 

–Suitable for both open and closed systems (for water applications, suitable for systems that are either open to atmosphere or sealed/closed to atmosphere).

In addition:

• Compatibility / dissimilar metals – care to be taken regarding galvanic corrosion risks (particular with precision / thin-walled tubes) when copper connects to stainless steel systems.

• General considerations:

–The appropriate PPE shall be used by operators working with copper tubes.

–Care shall be taken to ensure tubes are safely and securely stored.

–Suitable storage bins or storage areas shall be used to ensure tubes do not roll free if not strapped or restrained.

–Care shall be taken with regards any protruding tube ends to avoid contact with individuals.

–Care shall be taken when moving or lifting copper tubes.

–When lifting by crane, or by other means, the appropriate sling configuration shall be employed, as per best practice, or as defined by a relevant Health and Safety body.

–Any cut or machined ends shall be deburred to remove any sharp edges.

–Appropriate measures shall be taken during cutting, bending, soldering or brazing of tubes to mitigate the risk of injury to operators.

–Appropriate measures shall be taken during any soldering or brazing  to reduce the risk of fire and to ensure adequate ventilation for operators.

• In addition for Precision / Thin-walled tubes:

–Risk of injury by flying fragments if press adaptors and/or collars are used incorrectly, or are worn or damaged.

–Danger of crushing by moving parts (grip jaws).

• Please refer to the BMTFA (British Metals Tube and Fittings Association) website for additional product information and links to training material or points of contact to arrange training CPDs @ www.bmtfa.org

• The appropriate size and grade of tube shall be selected for the particular application, test and operating pressures and temperatures.

• Select the correct jointing type or fitting for the application.

• All tube ends must be deburred after cutting to remove sharp edges, this is especially important if the tube is being inserted into a fitting.

• Tube surfaces must be free from surface contaminants or debris that may have been picked up in storage, when transported or awaiting fabrication / installation.

• Tube bores shall be checked to ensure they are clean and free from any obstructions.

• Any pre-applied coating shall be removed in the localised area for hot working (i.e. soldering or brazing).

• Please check with the relevant manufacturers for any additional material preparation instructions.

• For further guidance please refer to BESA TR50 - Guide to Good Practice for Supports & Fixings.

Press-fit jointing:

• It is recommended that the press-fit jointing manufacturer is consulted to confirm the correct selection of fittings (e.g. pressure & temperature limitations, elastomer/O-ring material, etc.).
• It is advised to use a single-source supplier for all fittings within a system.
• All operatives must undergo manufacturer training
• Powered, not manual pressing tools shall be employed to make up joints.
• Users shall ensure the calibration of pressing tools and jaws
• It is recommended that each operative is assigned a unique ID number which they must mark on the joint so that there is traceability.
• Operators shall ensure that tube ends are free from burrs, abrasions, indentations, projections or any other form of damage.
• Operators shall ensure that a depth gauge has been used, a “V” must be marked pointing to the end of the tube but intersecting the depth line.
• If the line is not present or not in the correct place, section should be rejected as improperly installed.
• Consideration shall be given to the support, expansion and movement provisions designed/confirmed by the press-fit joint manufacturer.
• An appropriate pressure test (note dry test for thin-walled press-fit) shall be undertaken to confirm leak tightness.

• Expansion will be application and material specific.

• Expansion of pipework should, where possible, be accommodated naturally by incorporating expansion loops and offsets.

• Where natural expansion provisions are not feasible, proprietary expansion equipment such as bellows should be provided based on a specialist manufacturer’s design.

• Designs usually include anchor points and expansion bellows with primary and secondary guides at specific distances either side.

• The natural flexibility of the pipework layout should be assessed for its ability to accommodate thermal movement before any additional offsets or loops are added.

• Pipe supports, guides and anchors should be designed to permit / control thermal movement as required.

• The coefficient of thermal expansion of copper is 16.8 x 10^-6 per °C, hence a 1 metre length of copper tube becomes (1+0.0000168T) metre when heated to T °C.  For example, an increase in temperature of 60°C will increase the length by one mm for every metre of tube. Therefore where long straight pipe runs exceeding 10m are encountered, allowance for expansion should be made.

• Pipework insulation shall be in accordance with BS 5970, and common best practice.

• When using phenolic foam, there shall be a suitable barrier between the foam & the copper tube, as per the manufacturer’s instructions.

• It is good practice to wrap brass fittings used in copper pipework with butyl self-amalgamating tape

• For below-ambient temperature services, it is essential the insulation vapour barrier is incorporated within the insulation system and maintained.

• Water treatments will vary as a function of the application and the commissioning process employed.

• Operators shall consult with a specialist water treatment consultant or the relevant commissioning bodies for confirmation of actual requirements for water quality management.

• Operators may also wish to consult and follow the current BSRIA BG29 and BG50 guidelines.

• Aggressive cleaning chemicals may cause damage to the system components.

• In normal good operation of a domestic cold water system no water treatment is required. If a water softener is used this should ideally be set to 60ppm of hardness.

• In commercial systems reference should be made to the installation and operational requirements of the system.

• Newly installed and filled pipework needs to be put into operation soon after filling to ensure the semi protective layer forms on the pipe inner surface to stifle further corrosion.

• Flush through to drain to remove debris and flux residues.

• Avoiding direct coupling of copper to aluminum or galvanized steel; otherwise galvanic corrosion from the electrochemical potential difference is likely to cause pitting of the aluminum or zinc coating of the galvanized pipe.

• Periods of stagnation should be avoided.

• Design considerations should be made to reduce the risk of erosion corrosion.

• Plain copper tubes must not be buried into screeds or concrete without suitable protection. In these cases it is recommended to use the factory applied LDPE coated copper tube.

• For new domestic hot and cold water systems, it is essential that water is regularly flushed through and stagnation is avoided.

• Avoid draining the pipe following hydraulic testing to prevent local corrosion cells forming from pockets of water that may lead to other corrosion reactions.

• Brass fittings conveying fluids at below 15°C that are to be insulated can be painted with primer followed by wrapping with self-amalgamated butyl-rubber tape sleeving.

• As BS 5970 notes, various copper-zinc (brass) alloys can be sensitive to stress-corrosion attack, e.g. when brass compression fittings are over-tightened in the presence of moisture and alkalis.

• Consideration should be given to ensure outlet pipes are adequately supported close to elbow joints in order to counteract thrust pressures (that try to push the joint apart), although this can often conflict with the requirement to have a degree of natural flexible movement to accommodate thermal expansion.