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 12, 1.7 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 Surveyors.
3.1.5 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.
3.1.6 The
minimum thickness, t, of straight copper and copper alloy
pipes is to be determined by the following formula:
where
|
p, D and a
|
= |
are as defined in Pt 5, Ch 12, 1.3 Design symbols 1.3.1
|
|
c
|
= |
corrosion
allowance |
|
|
= |
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 |
= |
maximum
permissible design stress, in N/mm2 (kgf/cm2),
from Table 12.3.1 Copper and copper alloy
pipes. Intermediate
values of stresses may be obtained by linear interpolation.
|
3.1.7 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:
Table 12.3.1 Copper and copper alloy
pipes
| Pipe
material
|
Condition
of supply
|
Specified
minimum tensile strength, N/mm2 (kgf/mm2)
|
Permissible stress, N/mm2 (kgf/cm2)
|
| Maximum design temperature, °C
|
| 50
|
75
|
100
|
125
|
150
|
175
|
200
|
225
|
250
|
275
|
300
|
| Copper
|
Annealed
|
220
(22)
|
41,2
(420)
|
41,2
(420)
|
40,2
(410)
|
40,2
(410)
|
34,3
(350)
|
27,5
(280)
|
18,6
(190)
|
—
|
—
|
—
|
—
|
| Aluminium
brass
|
Annealed
|
320
(33)
|
78,5
(800)
|
78,5
(800)
|
78,5
(800)
|
78,5
(800)
|
78,5
(800)
|
51,0
(520)
|
24,5
(250)
|
—
|
—
|
—
|
—
|
90/10
Copper-
nickel-iron
|
Annealed
|
270
(28)
|
68,6
(700)
|
68,6
(700)
|
67,7
(690)
|
65,7
(670)
|
63,7
(650)
|
61,8
(630)
|
58,8
(600)
|
55,9
(570)
|
52,0
(530)
|
48,1
(490)
|
44,1
(450)
|
70/30
Copper-
nickel
|
Annealed
|
360
(37)
|
81,4
(830)
|
79,4
(810)
|
77,5
(790)
|
75,5
(770)
|
73,5
(750)
|
71,6
(730)
|
69,6
(710)
|
67,7
(690)
|
65,7
(670)
|
63,7
(650)
|
61,8
(630)
|
3.1.8 Where the minimum thickness calculated by Pt 5, Ch 12, 3.1 Copper and copper alloy pipes, valves and fittings 3.1.6 or Pt 5, Ch 12, 3.1 Copper and copper alloy pipes, valves and fittings 3.1.7 is less than shown in Table 12.3.2 Minimum thickness for copper and
copper alloy pipes, the minimum nominal thickness for the
appropriate standard pipe size shown in the Table is to be used. No allowance is
required for negative tolerance or reduction in thickness due to bending on this nominal
thickness. For threaded pipes, where permitted, the minimum thickness is to be measured
at the bottom of the thread.
Table 12.3.2 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
|
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.
|