الخطوط العريضة

 

1. Sealing Methods

 

• Stuffing box packing

 

• Condensate injection sealing

 

• Floating seal rings

 

• Labyrinth (breakdown) bushings

 

• Windback scroll or windback seal

 

• Lipseals

 

• The mechanical seals

 

• Differences between packing & mechanical seals

 

2. Seal selection Considerations

 

• Operational requirements

 

• Performance expectations

 

• Special requirements

 

• Considerations of duty

 

• Envelope

 

• Pressure

 

• Speed

 

• Temperature

 

• Sealed Fluid

 

 

o Chemical properties

 

o Abrasion

 

o Voltality

 

o Flammability

 

• Life

 

• Leakage

 

3. Seal type selection

 

• Internally mounted vs. externally mounted

 

• Rotating vs stationary floating seals

 

• Balanced vs unbalanced seal

 

• Non-metal bellows vs pusher seal

 

• Single spring vs multiple-spring seal

 

• Advantages & disadvantages

 

4. Material of construction

 

• Secondary sealing materials

 

• Elastomers

 

• Non-Elastomers

 

• Seal face materials

 

• Carbon graphite resin impregnated

 

• Carbon graphite Antimony filled

 

• PTFE 25% glass

 

• Ni-Resist

 

• Al-oxide

 

• Tungsten carbide co-binder

 

• Tungsten carbide Ni binder

 

• Silicon carbide reaction banded

 

• Silicon carbide sintered

 

5. Choice for sealing centrifugal compressors shafts

 

A. Seals

 

• Labyrinth seals

 

• Carbon rings

 

• Brushing seals

 

• Contact seals

 

• Leakage comparison

 

B. Sealing Systems

 

• Evaluation systems

 

• Injection system

 

• Combination of contact seel & a brushing seal

 

• Carbon face contact seal

 

• Double brushing seal

 

• High-air side differential - pressure face and brushing seal

 

• Ejector sealing system

 

 

• Sealing system using an injected medium between compressor gas & atmospheric seal

 

C. Typical case studies

 

• Single labyrinth gland packing

 

• Multi-chamber labyrinth system with one or two buffer & drains or a combination of these

 

• Floating ring seal

 

• Mechanical contact seal

 

• And stand seal in conjunction with one of these systems

 

• Self acting gas seals

 

6. Seals Failure

 

• External symptoms of seal failure

 

• Checks before dismantling

 

• Checks during dismantling

 

• Visual seal examination

 

• 7. Causes of seal failures

 

• Mishandling prior to installation

 

• Faulty installation

 

• Excessive run out

 

• Excessive bearing play, axial and/or radial

 

• Misalignment

 

• Incorrect choice of materials

 

• Changed conditions

 

• Lack of auxiliaries (venting, injection, etc.)

 

• Vibration

 

• Cavitation

 

• Freezing of faces on the atmospheric side of the seal

 

• Excessive temperature

 

• Excessive pressure

 

• Excessive shaft speeds.

 

 

8. Lubrication systems

 

• Oil reservoirs

 

• Pumps & drivers

 

• Coolers & filters

 

• Transfer valves

 

• Accumulators

 

• Overhead tanks

 

• Oil conditioners

 

• Seal-oil drain taps

 

• Degassing drum

 

• Piping

من ينبغى أن يحضر

Mechanicals

المدة

5 أيام