Page 103 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

Chapter 2 Common processes and techniques

Core drills Tubes supplied in half-hard (R250) and hard drawn (R290) condition are KEY POINT
These are used for drilling very large holes supplied in straight lengths of 3 or 6 m. Tubes in the soft, fully annealed (R220)
through masonry, stone and concrete. Used condition, up to 28 mm outside diameter (OD), are supplied in coils. The length During your time as a
in the installation of boiler flues and large of the coils is between 10 and 50 m, depending on the diameter. plumber you will come
pipes such as waste and soil pipes. across many materials,
Copper tubes are generally used in buildings for the following services: and each will have its
Hole saws own unique working
● domestic hot and cold water supplies under pressure, usually up to mains properties, including
Hole saws are ideal for drilling holes in
equipment and appliances such as cold pressure (typically up to 4 bar but can be up to 10 bar in some parts of the different melting points
water storage cisterns and acrylic baths, UK) or head pressure from a storage cistern and expansion rates.
which have no tap holes. Some hole saws ● sanitary waste pipe installations It is important that
can also be used on metal and wood. we recognise these
● central heating systems (with radiators/convectors) properties so that we
● underfloor heating systems can choose the correct
2 TYPES OF PIPEWORK, BENDING ● natural gas installations for heating and cooking material for a given
installation. You will
● oil installations for heating
AND JOINTING TECHNIQUES ● medical gases (when de-greased). come across other such
properties as you work
In this part of the chapter, we will take a brief look at the pipe materials that Copper tube is available chromium plated for situations where there are through this book.
plumbers use in their everyday installation work. We will see how the different aesthetic considerations and plastic coated in various colours where protection
methods of jointing, bending and installation practices dictate the methods of from corrosion is necessary.
working we need to employ. We will look at:
Bending copper tube
● copper tubes and fittings
● low carbon steel pipes and fittings Bending copper tubes becomes easy with practice. The two methods used to
● the various types of plastic pipes and fittings. correctly bend copper tubes are:
1 machine bending – the preferred method of bending copper tubes
Copper tubes to BS EN 1057 2 spring bending – using a bending spring; not so widely used now since scissor
Copper tube has been used in the UK since the 1940s and today still accounts benders have become available.
for around 60 per cent of all new installations. The type of copper used in the Here, we will look at each method and investigate its advantages and
manufacture of tubes is phosphorus de-oxidised copper, with a minimum copper disadvantages.
content of 99.90 per cent.
De-oxidised copper tube can be safely soldered, welded or brazed. The density Bending copper tube using a bending machine
of copper is 8900 kg/m³. It has a melting point of 1083°C and its coefficient of Bending copper tubes using a bending machine is an economical method of
linear expansion is 0.00000166 per °C (between 20°C and 100°C). installation, especially where lots of bends or changes of direction are required.
KEY TERM The standard for copper tubes for water, gas and sanitation installations is There are many types of bending machine available for copper tubes up to 42 mm
BS EN 1057, which is available in three tempers, as outlined in Table 2.15. diameter, all of which are worked by hand. For larger diameters, ratchet-action
Temper: the temper of a machines are required. The most useful type of machine for 15 and 22 mm tube is
metal refers to how hard or  Table 2.15 Grades of copper tubes to BS EN 1057 the portable type or scissor bender (see page 84 of this chapter), which is light in
soft it is.
Grade Description weight and requires no adjustment before use.
R220 This is softer copper tube, fully annealed and supplied in coils. It is thicker walled The advantages of machine bending over spring bending are:
than other grades of copper tube. Used for underground water services (sizes
15, 22, 28 mm) and microbore central heating systems (sizes 6, 8 and 10 mm). ● bends can be formed quickly
R250 This is the most widely used grade of copper tube for plumbing and heating ● multiple bends can be formed easily
applications. Supplied in straight lengths of 3 or 6 m, in sizes 15, 22, 28, 35, ● bends can be formed close to the end of the tube
42 and 54 mm. It is known as half-hard tempered.
● bend radius, quality and accuracy are consistent.
R290 This grade is hard tempered, thin walled and totally unsuitable for bending. Not
normally used in the UK. Producing accurately positioned bends depends on determining the bending point
and the position of the tube in the machine. Figures 2.8–2.13 demonstrate this.

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