Page 108 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

The City & Guilds Textbook: Plumbing Book 1

One advantage that a spring bend has over a machine-made bend is that the
bend radius can be varied because it is not fixed by a bending former. This
allows the tube centres to be carried around bends. In other words, the radii
of the bends can be enlarged so that the aesthetic appearance of the bends is
enhanced and the gap between the tubes remains even (see Figures 2.16–2.18).
Measure
1 Measured length (end to centre) forward 2 1 Measured length
Measure back tube dia's
2 4 tube dia's 3 2 3

Measure back 2 dia's Forward 1 dia
2nd mark 1st mark 3rd mark
Start of bend
Bending length 4 Anneal the copper tube between the second and third marks to
soften the tube so that rippling and creasing does not occur

Anneal the copper tube between the second 6
4
and third marks to soften the tube so that rippling First mark on centre line of tube
and creasing does not occur Back 1 /2 dia

Off-set required 5 2nd bending point

5
p Figure 2.17 Bending an off-set by spring

Completed bend
R2 Tube centre spacing

p Figure 2.16 Bending a 90° bend by spring

R1

INDUSTRY TIP

Remember to anneal the R1 = 4 times dia of pipe
copper before attempting to R2 = R1 + tube centre spacing
bend the copper tube, as this For two 22 mm diameter tubes at 80 mm centres:
R1 = 4 × 22 = 88 mm
will prevent the tube from R2 = 88 + 80 = 168 mm
rippling, creasing or snapping.
So, set out inner bend as before then for outer bend
Measure back distance for outer bend = 168 mm
Measure forward distance = 84 mm (both from first mark)
p Figure 2.18 Concentric spring bends

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