Mechanical Seal Selection Points
- ARRANGEMENT
- DESIGN
- FACE MATERIAL
- SECONDARY SEAL MATERIAL
- HARDWARE (MOC)
- PIPING PLAN (API )
- DIMENSION
According to Liquid Description
(Clear, Slurry, Acids, Pressure, Temp. ETC)
As per Tech. Data Sheet
(Equipment Description)
By Arrangement
- Inside
- Outside
- Double Back to Back
- Double Face to Face
- Tandem
(Unbalanced, Balanced, Single Spring, Multiple Spring)
By Design
- Seal Size
- Balancing Ratio
- Face Area
- Spring Rate
- Spring Load
- Face Pressure
Face Materials
Metal Impregnated Carbon: This is an antimony impregnated hard Carbon that is specially suitable for extreme heavy duty application involving non-corrosive media, Boiler feed water and hydrocarbon service seals with this hard Carbon as a sealing face have a much longer service life. Hard Carbon exhibits better abrasive resistance and emergency dry running characteristics.
Resin Impregnated Carbon: This is a normal softer seal face material and the Grade of Carbon is also impregnated from schunk in West Germany. This is recommended in most general purpose applications involving corrosive fluids, this Carbon exhibits good resistance to thermal shock and good dimensional stability over a wide temperature rang. In addition resin impregnated Carbon has low permeability and good thermal conductivity.
Tungsten Carbide: The universally accepted hard seal face that is available in two Forms-nickels bonded and cobalt bonded. Solid seal ring of Tungsten Carbide are offered as a standard as against shrunk-fit faces with their inherent Limitations.
Silicon Carbide: Technologically the best seal face material till date. It is highly resistant to thermal stress and corrosion in high temperature oxidizing atmospheres has low wear properties and is an ideal seal face material for the petrochemical, fertilizer, chemicals, refinery and off shore duties. It is harder than Tungsten Carbide Silicon Carbide also exhibits better dry run capabilities thus making it an ideal choice for an emergency running characteristic
Ceramic: This is super fine-grain High Alumina Ceramic Material (99.5 % AI2 O3) that exhibits excellent low wear characteristics. It is the best seal face material for highly corrosive chemical services.
Glass Filled Teflon: Offered as a standard seal face material on outside mounted PTFE bellows type seals. It Is recommended for extremely corrosive duties only.
Silicon Filled Teflon: Offered as a standard seal face material on outside mounted PTFE bellows type seals. It Is recommended for extremely corrosive light duties only.
Superalloy: This is a specially developed high-chrome cast steel exhibiting Excellent wear characteristics and is offered as a replacement to stellited faces. The major advantage of this faces solid single pieces and not deposits or coatings that are liable to peel off/chip off.
Property of Seal Faces
Material |
Compressive |
Density |
Modulus of |
Coeff. Of |
Thermal |
Hardness |
|
Carbon, resin Impregnated |
207-250 |
1.75 - 1.83 |
18.5-24 |
2.4-4.9 |
8-13 |
60-68 |
|
Carbon, antimony Impregnated |
276-350 |
2.15-2.5 |
26-33 |
4.47 |
12 |
57.6 |
|
Tungsten Carbide |
3200-6200 |
14.3-14.9 |
550-620 |
4.6-7.0 |
80-115 |
70-90 |
|
Silicon Carbide |
1200-3000 |
3.05-3.1 |
300-410 |
4.3-4.6 |
100-140 |
90-135 |
|
Ceramic |
3000-3500 |
3.8-3.9 |
350-380 |
6.6-8.5 |
29-50 |
85-93 |
Secondary Seal Materials
Material | Temperature Range ℃ | |
Viton | -18… + 200 | |
Neoprene | -20… + 90 | |
Buna’n (Nitrile) | -25… + 120 | |
EPR / EPT (Ethylene Propylene) | -40… + 150 | |
Silicon Rubber | -70… + 250 | |
Aflas | -40… + 230 | |
Kalrez | -20… + 270 | |
PTFE | -75… + 200 | |
GFT (Glass Filled Teflon) | -75… + 200 | |
Grafoil | -270… + 450 |
Note :
The Temperature Limits Listed is for Guidance only The Value may very
Depending upon the nature of surrounding liquids
Mechanical Seal Hardware
- SS 304
- SS 304 L
- SS 316
- SS 316L
- Alloy – 20
- Monel
- Hastelloy – B
- Hastelloy – C
- Nickel
- Titanium