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We are one of the leading manufacturers & suppliers of Envelop Gaskets. A PTFE envelope gasket is a gasket that is split or machined from the outside diameter wall to 1/16 of an inch from the inside diameter. Envelope gaskets can be supplied slit/v-type or milled/square cut with or with out a filler. A ring gasket has a thickness, inside and outside dimension. A full face gasket has a thickness, inside and outside dimension along with bolt holes. A flange gasket is primarily the same as a full face without
The bolt holes. These gaskets are available in standard and metric pipe sizes up to
60" outside diameter. Property Comparison of Various Fluoropolymers
| Property |
ASTM test method/test condition |
PTFE |
PFA |
FEP |
ETFE |
CTFE |
|
|
Physical Properties
| Specific gravity |
D792
D570/24 hrs 1/2"t |
2.13~2.22 |
2.12~2.17 |
2.12~2.17 |
1.70~1.76 |
2.10~2.18 |
| Water absorption (%) |
|
<0.00 |
<0.03 |
<0.01 |
<0.1 |
<0.00 |
| Mold shrinkage (cm/cm) |
|
0.02 ~0.05 |
0.04 |
0.03~0.06 |
0.03~0.04 |
0.015~0.020 |
| Contact angle (degree) |
Angle to level |
110 |
115 |
115 |
96 |
84 |
|
|
Mechanical Properties
|
Tensile strength
(kgf/cm2) |
D638/23oC
|
140~350 |
280~315 |
190~220 |
410~470 |
320~420 |
| Elongation (%) |
D638/2o°C |
200~400 |
280~300 |
250~330 |
420~440 |
80~250 |
| Compression strength (kgf/cm2) |
D695/1% deformation, 25oC |
50~60 |
50~60 |
50~60 |
109 |
90~120 |
Tensile modulus
(kgf/cm2) |
D638/23oC |
4,000 |
- |
3,500 |
5,000~8,000 |
10,500~21,000 |
Hexural Modulus
(kgf/cm2) |
D790/23oC |
5,000~6,000 |
6,600~7,000 |
5,500~6,500 |
9,000~14,000 |
13,000~18,000 |
Impact strength
(ft-lb/ln) |
D256/23oC lzod |
3.0 |
- |
No breakdown |
No breakdown |
2.5~2.7 |
| Hardness (Shore) |
Durometer |
D50~D65 |
D60 |
D55 |
D75 |
D90 |
| Deformation under load (%) |
D621/100oC
70 kfg/cm2,
24 hrs
D621/25oC
140 kgf/cm2,
24 hrs |
5.0
7.0
|
2.4
2.7
|
5.0
3.0
|
5.4
2.3
|
2.6
0.2
|
| Static friction coefficient |
Coated steel surface |
0.20 |
0.50 |
0.50 |
0.60 |
0.80 |
|
|
Typical Filler Properties
|
|
Filler
|
Physical Form
|
Amount (% Weight)
|
Effect of Filler
|
|
| Glass Fibers |
Milled Fibers
|
up to 40%
(also in combination with graphite, MoS2 and carbon)
|
- increased compressive strength
- increased rigidity
- increased wear resistance
- reduced cold flow
- resistant to organic solvent
|
|
Carbon
Carbon Fibers
|
Powder
Milled Fibers
|
up to 25%
(also in combination with graphite, bronze, and glass)
up to 30%
|
- increased comprehensive strength
- increased hardness
- increased wear resistance
- improved thermal conductivity
- good dry running properties
- electrically conductive at higher filler contents
- resistant to hydrofluoric acid
|
| Graphite |
Powder
|
up to 25%
(also in combination with glass, bronze, and carbon)
|
- improved sliding properties
- reduced coefficient of friction
- improved thermal conductivity
|
| Bronze |
Powder
|
up to 60%
(also in combination with carbon, graphite, and MoS2))
|
- increased comprehensive strength
- increased hardness
- increased wear resistance
- improved thermal conductivity
- reduced cold flow
|
| Molybdenum disulphide (MoS2) |
Powder
|
up to 5%
(also in combination with glass and bronze)
|
- improved sliding properties
- increased wear resistance
|
| Stainless Steel |
Powder
|
up to 60%
|
- improved thermal conductivity
- reduced cold flow
- resistant to most chemicals
|
| Pigments |
Powder
|
up to 2%
|
- for coloring
(identification)
|
|
