Quick reference for selecting mechanical seal face materials and combinations.
1. Seal Face Material Comparison
| Material | Main Advantages | Recommended Applications | Limitations |
|---|---|---|---|
| Carbon Graphite (Resin Impregnated) | Low friction, economical, good general performance | Clean water, oils, general industrial pumps | Poor abrasive wear resistance |
| Antimony-Impregnated Carbon | High strength, good thermal conductivity, pressure resistance | High-pressure pumps, hot oils, demanding process duty | Limited chemical compatibility |
| Reaction-Bonded Silicon Carbide (RBSiC) | Very hard, excellent wear resistance, good thermal conductivity | Water, wastewater, oils, general industrial applications | Free silicon limits strong acid/alkali compatibility |
| Sintered Silicon Carbide (SSiC) | Excellent wear and chemical resistance, no free silicon | Aggressive chemicals, corrosive liquids, abrasive slurry | Brittle, higher cost |
| Tungsten Carbide (TC / WC) | Tough, impact resistant, high mechanical strength | Mining, slurry, sewage, high-pressure pumps | Binder-dependent corrosion resistance |
| Ceramic (Alumina Al₂O₃) | Economical, hard, good resistance to many chemicals | Clean water, domestic pumps, light-duty applications | Brittle, limited heavy-duty performance |
2. Recommended Seal Face Combinations
| Pumping Media / Operating Condition | Recommended Face Combination |
|---|---|
| Clean water / Cold water | Carbon / Ceramic or Carbon / SiC |
| Hot water | Carbon / SiC |
| Seawater / Salt water | Carbon / SiC for clean service; SiC / SiC if abrasive |
| Wastewater / Sewage | SiC / SiC for solids-laden service |
| Mineral oil / Lubricating oil | Carbon / SiC |
| Diesel / Fuel oil | Carbon / SiC |
| Hot oil / Thermal oil | Antimony Carbon / SiC (subject to temperature and fluid compatibility) |
| Mild chemicals | Carbon / SiC with compatible grades |
| Strong acids / Alkalis | SSiC / SSiC, subject to chemical compatibility |
| Abrasive water / Sand / Slurry | SiC / SiC or TC / TC |
| Mining / Heavy-duty slurry | TC / TC or SSiC / SSiC |
| High-pressure industrial pumps | Antimony Carbon / TC or suitable engineered hard-face pairing |
| High-temperature process | Antimony Carbon / SiC or engineered high-temperature faces |
| General domestic pumps | Carbon / Ceramic |
3. RBSiC vs SSiC – What's the Difference?
| Feature | RBSiC | SSiC |
|---|---|---|
| Manufacturing | Reaction bonded | Direct sintered |
| Free Silicon | Present | Essentially none |
| Wear Resistance | Excellent | Excellent |
| Chemical Resistance | Good, with restrictions | Superior for aggressive chemicals |
| Typical Application | General industrial pumps | Chemical processing / demanding duty |
| Cost | Generally lower | Generally higher |
Quick Tip: Choose RBSiC for general industrial service and SSiC for more demanding chemical environments.
4. Simple Selection Rules
-
Carbon / Ceramic – Economical choice for clean water.
-
Carbon / SiC – Versatile choice for general industrial pumping.
-
SiC / SiC – Recommended starting point for abrasive or solids-containing liquids.
-
SSiC / SSiC – Preferred for many aggressive chemical applications.
-
TC / TC – Consider for heavy-duty abrasive service and mechanical shock.
-
Antimony Carbon / SiC or TC – Consider for demanding high-pressure and high-temperature duties.
Important Notes
Seal faces must be selected as a matched pair. Harder materials are not always better, and hard/hard combinations require adequate lubrication and heat removal.
RBSiC and SSiC are not chemically interchangeable. Tungsten carbide compatibility depends on its binder (nickel or cobalt). Antimony-impregnated carbon should not be selected solely based on temperature.
Final selection must consider media, solids content, operating temperature, pressure, speed, lubrication and seal design.