Section
3 Copper and copper alloys
3.1 Copper and copper alloy pipes, valves and fittings
3.1.1 Materials
for Class I and Class II piping systems, also for ship-side valves
and fittings and valves on the collision bulkhead, are to be manufactured
and tested in accordance with the requirements of Ch 9 Copper Alloys of the Rules for Materials. See also
Pt 5, Ch 10, 1.6 Materials.
3.1.2 Materials
for Class III piping systems are to be manufactured and tested in
accordance with the requirements of acceptable National Specifications.
The manufacturer’s certificate will be acceptable and is to
be provided for each consignment of material. See
Ch 1, 3.1 General 3.1.3.(c) of the Rules for Materials.
3.1.3 Pipes
are to be seamless, and branches are to be provided by cast or stamped
fittings, pipe pressings or other approved fabrications.
3.1.4 Brazing
and welding materials are to be suitable for the operating temperature
and for the medium being carried. All brazing and welding are to be
carried out to the satisfaction of the Surveyor.
3.1.5 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 brace 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.
3.1.6 The use
of copper-zinc brazing alloy is not permitted.
3.1.7 In general,
the maximum permissible service temperature of copper and copper alloy
pipes, valves and fittings is not to exceed 200°C for copper and
aluminium brass, and 300°C 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 260°C.
3.1.8 The minimum
thickness, t, of straight copper and copper alloy pipes
is to be determined by the following formula:
|
t
b
|
= |
|
|
σ |
= |
maximum permissible
design stress, in N/mm2, from Table 10.3.1 Copper and copper alloy
pipes. Intermediate values of stresses may be obtained by
linear interpolation
|
|
c
|
= |
corrosion allowance |
|
|
= |
0,8 mm for copper, aluminium brass, and coppernickel 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 is non-corrosive relative to the pipe
material. |
Table 10.3.1 Copper and copper alloy
pipes
| Pipe
material
|
Condition of supply
|
Specified minimum tensile strength, N/mm2
|
Permissible stress, N/mm2
|
| Maximum design temperature, °C
|
| 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
|
–
|
–
|
–
|
–
|
90/10
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
|
3.1.9 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 tb, would not reduce the thickness below
t at any point after bending:
|
t
b
|
= |
|
where
p, D, R, b and
a are as defined in Pt 5, Ch 10, 1.2 Design symbols 1.2.1
σ and c are as defined in Pt 5, Ch 10, 3.1 Copper and copper alloy pipes, valves and fittings 3.1.7
In general, R is
to be not less than 3D.
Table 10.3.2 Minimum thickness for copper and
copper alloy pipes
| Standard pipe sizes (outside diameter), in mm
|
Minimum overriding nominal thickness, in mm
|
|
|
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
|
3.2 Heat treatment
3.2.1 Pipes
which have been hardened by cold bending are to be suitably heat treated
on completion of fabrication 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.
|