Mechanical Seal Industry Knowledge

1. What is a mechanical seal

A mechanical seal is a device used to prevent fluid leakage along a rotating shaft in pumps, compressors, mixers, and other rotating equipment. It uses two flat faces (rotating and stationary) in contact to form a sealing barrier, supported by springs and secondary seals.

2. Main functions

- Seal liquids and gases inside equipment
- Prevent external leakage and pollution
- Reduce energy loss
- Protect bearings and gearboxes from fluid damage
- Improve safety and reliability of rotating machinery

3. Basic structure

- Rotating ring: rotates with the shaft
- Stationary seat: fixed to the equipment housing
- Spring component: provides closing force
- Secondary seals: O-rings, gaskets, PTFE parts
- Retainer and clamping parts

4. Common types

- Single mechanical seal
- Double mechanical seal
- Tandem seal
- Cartridge mechanical seal
- Balanced seal
- Unbalanced seal
- Metal bellows seal
- Spring seal
- Conical spring seal

5. Common face materials

- Carbon graphite
- Silicon carbide (SiC)
- Tungsten carbide
- Ceramic
- Stellite

6. Common elastomer materials

- Nitrile rubber (NBR)
- Fluororubber (FKM / Viton)
- EPDM
- Silicone
- PTFE

7. Key working parameters

- Operating pressure
- Operating temperature
- Shaft speed
- Shaft diameter
- Medium type (water, oil, chemical, corrosive fluid)
- Wear resistance
- Corrosion resistance
- Thermal stability

8. Application industries

- Petrochemical & chemical industry
- Oil & gas
- Water treatment & sewage
- Power plants
- Pharmaceutical
- Food & beverage
- Paper making
- Mining
- Marine & shipbuilding

9. Failure causes (common)

- Improper installation
- Dry running
- Excessive pressure or temperature
- Abrasive particles in fluid
- Material incompatibility
- Vibration and shaft runout
- Poor flushing and cooling

10. Industry requirements

- High reliability
- Long service life
- Low leakage
- Easy installation and maintenance
- Energy saving
- Compliance with international standards (API, ISO, DIN)