1) Definition:
a kind of semi-metal flat gasket made by winding metal strap and non-metal strap in helix direction.
2) Characteristics:
good compressibility and rebound elasticity, with multi-channel sealing and certain self-tightening functions, not sensitive to the surface defect of flange clamping plane, and not binding the flange sealing surface, convenient to be dismantled as it is easy to be adjusted to the middle, able to partially get rid of pressure, and the influences of temperature change and mechanical vibration; capable of keeping very good sealing performance under some tough conditions of circulating alternation, such as high temperature, low temperature, high vacuum, impact vibration, etc.
3) Application:
widely applied in static sealing parts of technological pipelines, and the equipments of many industries, such as petroleum refining, petroleum chemistry, chemistry, thermal electricity, nuclear energy, spaceflight, spinning, medicine and other industries.
4) Material
1. Metal strap
A. made of 08F，0Cr13, 0Cr18Ni19Ti, 0Cr18Ni9Ti, 00Cr18Ni10, 0Cr18Ni12Mo2Ti, 00Cr17Ni14Mo2 cold-rolled steel strap with a thickness of 0.15mm~0.25mm or decided by the supplier and acquirer.
B. the metal strap should be pre-molding V-shaped or W-shaped narrow strap with smooth and clean surface, without any defects, such as roughness, cracks, scratches, drop pits or rusty spot, etc.
C. Hardness value of the stainless steel HV≤200
2. Non-metal strap
A. the non-metal packing material is specially-made asbestos strap, flexible graphite strap, PTFE strap, non-asbestos fiber strap and isinglass strap with a thickness of 0.3-1.0mm.
B. loss of weight on ignition of specially-made asbestos should be ≤25%.
C. chlorine ion content of non-metal strap should be ≤100PPM.
D. the recommended temperature and pressure of various medium and different metal straps.
media material |
asbestos |
graphite |
non-asbestos |
PTFE |
Water-type media |
600℃，CL 2500 |
550℃，CL 1500 |
350℃，CL 1500 |
-200-260℃，
CL 1500 |
oil-type media |
500℃，CL 1500 |
550℃，CL 600 |
350℃，CL 600 |
-200-260℃，
CL 600 |
gas-type media |
400℃，CL 600 |
550℃，CL 400 |
350℃，CL 400 |
200-260℃，
CL 400 |
Note: used with non-oxygenization media, graphite can reach 800℃.
Table 1-5-3
materials |
temperature ℃ |
maximum work pressure |
applied media |
compression ratio
% |
resilience ratio % |
Stress relaxation force % |
Expansion graphite |
-220--550 |
250 BAR |
corrosion media |
18--30 |
≥17 |
≤18 |
specially-made asbestos strap |
-200---600 |
|
|
18--30 |
≥19 |
≤28 |
PTFE |
-200-- 250 |
100 BAR |
corrosion media |
18--30 |
≥15 |
≤13 |
Non-asbestos materials |
-100--250 |
100 BAR |
general air sealing |
18--30 |
≥19 |
≤28 |
isinglass |
-150--800 |
100 BAR |
special high temperature |
18--30 |
|
|
3) Strengthening ring. Unless specially agreed, the internal strengthening material should be the same with that of metal strap, and the materials of external strengthening ring should be A3 steel and have received anticorrosive treatment.
5) preloaded pressure: Y=70.0±1Mpa
6) Gasket Coefficient: M=2.5~4.0
|
