116
SPECMA SEALS HANDBOOK
M E TA L G A S K E T S
Lens shaped gaskets
resulting seating stress is very high. This
means that this type of flange joint can
be used for sealing off very high internal
pressures, which in turn means that major
demands are placed on the bolted joint
having the correct pre-stressing.
– solid metal seals
Applications:
Pipe flanges in the process, nuclear
power and power/heat industry, where
high internal pressures are handled.
Material description:
Properties:
Solid metal seals for installation in flanges
with conical internal sealing surfaces. Lens
shaped gaskets are normally supplied in
carbon steel, quality 1.1003 or stainless
steel, quality 1.4541.
The sealing function for lens shaped gaskets
is achieved by means of elastic deformation
of the contact surfaces of the gasket. As these
contact surfaces are relatively small, the
Technical data:
Material designation
Material no.
As per standard
For flow temperature
Marking on outer edge
RSt 34-2
1.0108
DIN 17 100
up to +425°C
None
St 35.8
1.0305
DIN 17 175
up to +425°C
None
15 Mo 3
1.5415
DIN 17 175
+425°C to +475°C
One centre punch
13 CrMo 4 4
1.7335
DIN 17 175
+425°C to +520°C
Two centre punches
10 CrMo 9 10
1.7380
DIN 17 175
+520°C to +580°C
Three centre punches
X10 CrNiTi 18 9
1.4541
DIN 17 440
+350°C to +550°C
Four centre punches
Dimension table as per DIN 2696:
DN
min.
10
15
25
10
14
20
14
18
29
21
28
43
7
8.5
11
25
32
50
40
50
65
34
46
62
43
55
70
62
78
102
14
16
20
70
88
112
80
100
125
72
94
116
82
108
135
116
143
180
22
26
29
129
170
218
150
139
158
210
33
250
for pressure rating PN 63-400
x
198
246
295
206
257
305
276
332
385
35
37
40
329
406
473
350
400
330
385
348
395
425
475
41
42
538
610
40
46
50
329
406
473
for pressure rating PN 160-400
183
230
278
200
246
285
276
332
385
The stated limit values apply under favourable conditions.
Do not utilise more than one maximum value at a time.
If in doubt please contact us, we will be happy to offer advice.
z
y
x
r
=
=
for pressure rating PN 63-100
200
250
300
200
250
300
d2
d1
d1
d2ar
max.
average contact diam. max.
=
X
Y
Z
Rt
= 6.3
Rt
= 25
Rt
= 100
Unless specified otherwise at the time
of ordering, lens shaped gaskets will
be supplied with minimum dimensions
for d1. Otherwise the inner diameter of
the seal must be adapted to the inner
diameter of the flange in question, and
this must then also be stated when
ordering.
a