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Knowledge of Spiral Wound Gasket (HY-industry technical centre)
Knowledge of Spiral Wound Gasket (HY-industry technical centre)
Spiral wound gaskets are usually made of high-quality SUS304, SUS316 (“V”-shaped or “W”-shaped) metal belts and other alloy materials and graphite, asbestos, polytetrafluoroethylene, non-asbestos and other soft materials alternately overlapped and spirally wound. Fix the metal strips by spot welding at the beginning and at the end.
Spiral wound gaskets have the best resilience among semi-metallic gaskets. The structure density of spiral wound gaskets can be made according to different locking force requirements, and the inner and outer steel rings are used to control the maximum compression. Metal wound gaskets The surface accuracy of the flange sealing surface contacted by the sheet is not high.
Spiral wound gaskets are especially suitable for occasions where the load is uneven, the joining force is easy to relax, the temperature and pressure change periodically, and there is impact or vibration. Spiral wound gaskets are static sealing elements for flange connection processing such as valves, pumps, heat exchangers, towers, manholes, and hand holes.
Performance characteristics of spiral wound gaskets
Spiral wound gasket has good compression performance, good resilience, multi-channel sealing and certain self-tightening function. It is not sensitive to the surface defects of the flange pressing surface. It does not adhere to the flange sealing surface, which can partially eliminate pressure and temperature changes. And mechanical vibration; it can maintain its excellent sealing performance under various harsh conditions such as high temperature, low temperature, high vacuum, shock vibration and so on.
Application equipment
Flange connections of pipelines, valves, pressure vessels, condensers, heat exchangers, towers, manholes, hand holes, etc. in petroleum, chemical, metallurgical, electric power, shipbuilding, gas, nuclear energy, aerospace, textile, medicine, machinery and other industries Static sealing part.
Spiral wound gasket material selection
1. Basic winding metal tape
Use sus304, sus316L, sus321 and other cold-rolled steel strips with a thickness of 0.15mm~0.25mm, or they can be negotiated between the supplier and the buyer.
Metal belt is a pre-formed V-shaped or W-shaped narrow belt. The surface should be smooth and clean. There should be no roughness, cracks, scratches, pits, rust spots and other defects.
Hardness value of stainless steel HV≤200
following table is used to select the material of the inner ring and the winding metal belt:
Basic thickness tolerance of metal spiral wound gasket:
Item
thickness (mm)
tolerance (mm)
thickness of the gasket
4.5, 3.2
+0.2
-0.1
thickness of the ring
3.0
±0.25
Following table is the diameter tolerance of spiral wound gaskets (namely the nominal pipe diameter used for flanges):
DIN (mm)
ANSI B16.5
BS1560 (mm)
Mss sp-44
API 605
tolerance (mm)
Inner ring diameter
Inner diameter of gasket
<=600
<=24″
>=26″ and <=34″
±0.5
>600 and <=800
>24″ and <=34″
>=36″ and <=60″
±0.9
>800 and <=1600
>34″ and <=60″
±1.3
>1600
>60″
±1.6
Outer diameter of gasket
<=600
<=24″
<=24″
±0.9
>600 and <=16000
>24″ and <=60″
>24″ and <=60″
±1.8
1600
>60″
±2.2
Outer ring outer diameter
>=1/2″ and <=60″
±0.9
<=600
<=24″
0-1.0
>600 and <=1000
>24″ and <=34″
0-1.8
>1000 and <=1600″
>34″ and <=60
0-2.2
2. Basic winding non-metallic tape
Non-metallic filling is special asbestos tape, flexible graphite tape, polytetrafluoroethylene tape, non-asbestos fiber tape, and mica tape. The thickness of the belt is 0.3-1.0mm.
The loss on ignition of special asbestos must be ≤25%
Chloride ion content of non-metallic belt ≤100PPM
Recommended temperature and pressure of various media and various non-metallic belts are as follows:
Main technical parameters of various non-metallic materials for spiral wound gaskets:
Material
Mark
temperature ℃
MWP
applicable medium
compressibility%
disability%
Stress relaxation rate%
expanded graphite
F.G.
250 BAR
corrosive medium
≥17
≤18
-220–550
18–30
Special asbestos strip
ASB
300
100 BAR
General air tightness
18–30
≥19
≤28
polytetrafluoroethylene
PTFE
50
100 BAR
corrosive medium
18–30
≥15
≤13
Asbestos free material
NAF
250
100 BAR
General air tightness
18–30
≥19
≤28
Mica
MICA
650
100 BAR
High temperature,
18–30
≥19
ceram
CER
890
100 BAR
superhigh temperature
18–40
≥19
Shanghai HY Industry Co., Ltd is qualified Titaniumalloy,Nickelalloy&cobalt alloy materials supplier.
We have more than twenty years experience in kind of High temperature alloy production.
Inconel 718, Monel 400,Stellite 6,Stellite 12,Incoloy 800ht,Incoloy 901,Nimonic 80A,Kovar,Invar 36,Inconel 625,Hastelloy C276, Incoloy 825,6Al-2Sn-4Zr-2Mo,TI-6AL-4V ELI,TI-6AL-4V,10V-2Fe-3Al are mature productes of us.
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