Mechanical Seals And Packing

 Mechanical seals are essential devices used in industrial processes to prevent leakages of fluids( gases or liquids). They are devices that create a tight seal between rotary and stationary parts of machines like pumps, compressors, and other equipment, basically to reduce or prevent leaks. Seals also help improve the operational efficiency of the machines and keep the operators safe. A typical mechanical seal is made up of ;

1. Seal faces: These are the two faces of the seal that slide against each other to create a sealing barrier
2. Springs, which maintain the pressure on the seal faces 
3. Secondary seals: These are additional seals, like O rings ( oil rings), which provide additional sealing barriers 

There are three types of seals, namely;

1. Single seals: these are seals consisting of single seal faces and a mostly used in areas of low pressure
2. Double seals: These seals are made up of two sets of seal faces, and they are commonly used in hazardous areas and high-pressure areas to provide an extra layer of protection 
3. Cartridge seals:  These are pre-assembled units that simplify installation and maintenance 

PACKING

Packing refers to using fibrous materials to create a seal around a valve or shaft. It is often used together with mechanical devices to reduce or prevent leaks. Common packing materials include;

1. PTFE( Teflon):  used mostly for its chemical resistance properties 
2. Graphite: provides excellent thermal stability 
3. Aramid fibers: They provide stability and strength 

Packings are usually used in valves to prevent leakage around the valve stem and in pumps to prevent leakages and seal the area where the shaft exits the pump casing.

Mechanical seals are effective and last long as compared to packing. Also, mechanical seals are preferred for high-speed and high-pressure applications, while packings are relatively preferred for speed low-pressure applications. 

Troubleshooting seal problems is important for maintaining the efficiency and reliability of mechanical systems:

1. Leaking Seals

Symptoms: Visible fluid leakage around the seal area.

Causes

Improper installation or alignment.

ii. Worn or damaged seal surfaces.

iii.  Incorrect seal selection for the application.

Solutions:

- Check installation instructions and realign if necessary.

- Inspect the seal faces for wear or damage; replace if needed.

- Ensure the seal material is suitable for the operating conditions (pressure, temperature, and fluid type).

 2. Excessive Wear

Symptoms: Rapid degradation of the seal material or increased friction.

Causes:

- Misalignment of rotating and stationary parts.

- Incompatible fluid or temperature conditions.

- Insufficient lubrication.

Solutions

- Realign components to ensure proper fit.

- Verify that the seal material is compatible with the fluid and temperature.

- Increase lubrication or switch to a more effective lubricant.

3. Seal Failure at Startup

Symptoms: Failure or leakage occurs immediately upon starting the equipment.

Causes

- Incorrect installation leading to seal distortion.

- Lack of initial lubrication.

- Contamination during installation.

Solutions

- Reinstall the seal according to the manufacturer's specifications.

- Ensure proper lubrication before startup.

- Keep installation areas clean to prevent contamination.