Section
6 Copper and copper alloys
6.1 General
6.1.1 Copper
and copper alloy pipes are acceptable for a wide range of services,
including bilge pipework and where non heat-sensitive material is
required.
6.1.2 The maximum
permissible service temperature of copper and copper alloy pipes,
valves and fittings is not to exceed 200oC for copper and
aluminium brass, and 300oC for copper-nickel. Cast bronze
valves and fittings complying with the requirements of Ch 9 Copper Alloys of the Rules for Materials may be
accepted up to 260oC.
6.1.3 The minimum
thickness, t, of straight copper and copper alloy pipes
is to be determined by the following formula but is not to be less
than that shown in Table 1.6.1 Minimum thickness for copper and
copper alloy pipes:
|
|
= |
where symbols are as defined in Pt 15, Ch 1, 4.1 Design symbols 4.1.1
|
|
c
|
= |
0,8
mm for copper, aluminium brass, and copper-nickel alloys where the
nickel content is less than 10 per cent |
| = |
0,5 mm for copper-nickel alloys where the
nickel content is 10 per cent or greater |
| = |
0 where the media are non-corrosive relative
to the pipe material |
σ may be obtained from Table 1.6.2 Copper and copper alloy
pipes.
Intermediate values may be obtained by linear
interpolation.
Table 1.6.1 Minimum thickness for copper and
copper alloy pipes
| Standard pipe sizes (outside diameter)
|
Minimum overriding nominal thickness
|
| Copper
|
Copper
alloy
|
| 8
|
to
|
10
|
1,0
|
0,8
|
| 12
|
to
|
20
|
1,2
|
1,0
|
| 25
|
to
|
44,5
|
1,5
|
1,2
|
| 50
|
to
|
76,1
|
2,0
|
1,5
|
| 88,9
|
to
|
108
|
2,5
|
2,0
|
| 133
|
to
|
159
|
3,0
|
2,5
|
| 193,7
|
to
|
267
|
3,5
|
3,0
|
| 273
|
to
|
457,2
|
4,0
|
3,5
|
| 508
|
and
|
over
|
4,5
|
4,0
|
Table 1.6.2 Copper and copper alloy
pipes
| Pipe material
|
Condition of
supply
|
Specified minimum
tensile strength N/mm2
|
Permissible stress, N/mm2
|
| Maximum design temperature, oC
|
| 50
|
75
|
100
|
125
|
150
|
175
|
200
|
225
|
250
|
275
|
300
|
| Copper
|
Annealed
|
220
|
41,2
|
41,2
|
40,2
|
40,2
|
34,3
|
27,5
|
18,6
|
-
|
-
|
-
|
-
|
| Aluminium
brass
|
Annealed
|
320
|
78,5
|
78,5
|
78,5
|
78,5
|
78,5
|
51,0
|
24,5
|
-
|
-
|
-
|
-
|
| 90/19
Copper-nickel iron
|
Annealed
|
270
|
68,6
|
68,6
|
67,7
|
65,7
|
63,7
|
61,8
|
58,8
|
55,9
|
52,0
|
48,1
|
44,1
|
| 70/30
Copper-nickel
|
Annealed
|
360
|
81,4
|
79,4
|
77,5
|
75,5
|
73,5
|
71,6
|
69,6
|
67,7
|
65,7
|
63,7
|
61,8
|
6.1.4 The minimum
thickness t
b, of a straight seamless copper
or copper alloy pipe to be used for a pipe bend is to be determined
by the formula below, except where it can be demonstrated that the
use of a thickness less than t
b would not
reduce the thickness below t at any point after bending:
where symbols are as defined in Pt 15, Ch 1, 4.1 Design symbols 4.1.1.
c and σ are
obtained as in Pt 15, Ch 1, 6.1 General 6.1.3.
in
general, R is to be not less than 3D.
6.1.5 Pipes
are to be seamless, and branches are to be provided by cast or stamped
fittings, pipe pressing or other approved fabrications.
6.1.6 Brazing
and welding materials are to be suitable for the operating temperature
and for the medium being carried.
6.1.7 Where
silver brazing is used, strength is to be obtained by means of the
bond in a capillary space over the whole area of the mating surfaces.
A fillet braze at the back of the flange or at the face is undesirable.
The alloy used for silver brazing is to contain not less than 49 per
cent silver.
6.1.8 The use
of copper-zinc brazing alloy is not permitted.
6.2 Heat treatment
6.2.1 Pipes
which have been hardened by cold bending are to be suitably heat treated
on completion of manufacture and prior to being tested by hydraulic
pressure. Copper pipes are to be annealed and copper alloy pipes are
to be either annealed or stress relief heat treated.
|