Page 23 - Design Criteria.qxd

24 ® Welcome to the Next Generation of Sealing Technology
FLEXITALLIC Style LS® Spiral Wound Gaskets
The Alternative To Sheet Gaskets
Style LS® & LSI ®
The Style LS spiral wound gasket has been engineered by FLEXITALLIC to pro-
vide an alternative to sheet gaskets in Class 150 and Class 300 service. Style LS
gaskets have the inherent strength, resiliency and blowout resistance of spiral
wound gaskets, yet require low bolt load for seating. They are manufactured with
high purity flexible graphite, PTFE, or Thermiculite filler for optimum sealability,
and are available for the full range of standard Class 150 and Class 300 flanges, as
well as other non-standard low pressure flanges. PATENT NUMBERS 5161807
and 5275423.
The gasket allows designers to strictly adhere to ASME B and PV and
ASME B31.3 codes requiring that bolt stresses do not exceed 25,000 psi. Where
ASME flange design calculations indicate that flanges will be over stressed if a
standard Class 150 spiral wound gasket is used, the LS gasket is designed to com-
press at significantly lower bolt load than standard Class 150 spiral wound gaskets,
thereby maintaining flange stresses within allowable limits.
Traditional Spiral Wound Gasket
Style LS
LS Gasket
Flexitallic LS Gasket
Typical gasket compression under
an applied gasket stress of 5000 psi
Gasket Stress - psi
6
5
4
3
2
1
0
Gasket Thickness - in.
CG 4” 150
Flexitallic LS Gasket
Typical gasket sealing profile
Seal Pressure - psi
1400
0
0 1 2 3 4 5 6
Gasket Stress - Ksi
CG 4” 150
1200
1000
800
600
400
200
0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19
Filler Flush With Metal
Filler Protrudes Well Above Metal