How to ...
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adapters which use a bolt up socket on the reverse side of the flange.
Needless to say the joint is completed by using bolts and a flange
gasket, usually cut from reeinforced rubber sheet.
HDPE pipe systems:
f f Small bore HDPE pipe uses a
compression flange adapter
that has a drilled flange
combined with a compression
socket. Alternatives to this are
electro-fusion stub flanges and
flange adapters.
SANS 1123: TABLE 1600/3-(Table 10) steel plate flanges for
welding (1600 kPA-16 BAR)
Nominal
size
DN
50
80
100
150
200
250
300
Pipe
outside
diameter
OD
60.3
88.9
114.3
165.1
219.1
273.0
323.9
Flange
D
165
200
220
285
340
405
460
Raised
face
b d3
12
14
14
18
22
25
28 102
138
158
212
268
320
378
Bolts
f
3
3
3
3
3
3
4
m16
m16
m16
m20
m20
m24
m24
No d1 PCD
4
8
8
8
12
12
12 125
160
180
240
295
355
410
18
18
18
22
22
26
26
Note: 1600 kPa-16 bar is the nominal maximum working pressure of pipelines. Other
pressure Tables exist in SANS 1123
BS 10: TABLE D Imperial flanges (600 kPa-6 bar)
Nominal size
DN
50
80
100
150
200
250
300
Flange
DN
2”
3”
4”
6”
8”
10”
12”
D
152.4
184.0
216.0
280.0
336.5
406.4
457.0
b
14.3
14.3
17.5
17.5
19.0
19.0
22.2
No
m16
m16
m16
m16
m16
m20
m20
4
4
4
8
8
8
12
D2
17.5
17.5
17.5
17.5
17.5
22.2
22.2
Steel pipe systems
Fully flanged steel piping is used in surface installations in combination
with concrete or steel cradles and in suspended systems such as river
crossings. These carbon steel flanges are known as slip-on flanges and
are welded onto the pipe.
f f A full range of mechanical
(bolt-on) flange adaptors
is available
Drilling
Bolts
f f Large bore systems utilise
a stub flange that is butt
welded onto the pipe end and
backed by a drilled galvanised
steel backing ring or full
HDPE flanges butt welded to
the pipe end.
Drilling
PCD
114.3
146.1
177.8
235.0
292.0
355.5
406.5
f f Other flange types include:
threaded flanges and blank or
blind flanges.
TYPES OF FLANGES
A number of specialised flange types are available to the many facets
of the manufacturing Industry. This editorial will focus on the three most
popular pipe systems used in the Irrigation Sector, with details of the flange
options used in those systems.
PVC pipe systems:
• PVC pipe systems have a range of “stub” flanges that are attached
to a PVC pipe using Solvent Cement. The stub is welded to the pipe
and a drilled galvanised steel backing ring, supplied to the correct
drilling specification, is fitted behind the stub flange to form the
complete flange.
• A range of flange adapters is also available utilising integral rubber
rings for buried systems. Further options include mechanical flanged
f f Reticulation pipe work in pump
stations or filter banks is the
most prolific use of flanges in
an irrigation system, in view
of the large number of valves,
pumps and filters found in
these installations.
Ensure that the correct flange table is used for the selection of the flange,
as the pressure rating of a flange is as critical as the pressure rating of the
pipe being used. For example, a 16 bar rated valve may be drilled to a 6
bar flange specification. This means that the valve only has a maximum
operating pressure of 6 bar.
SABI | APRIL / MAY 2017
27