This document discusses mechanical seals which are used to prevent leakage in pumps and other equipment. It describes the need for seals to minimize leakage and prevent toxic fluids from escaping. Both static seals, used between non-moving parts, and dynamic seals, used between moving parts, are covered. Common static seals include gaskets and O-rings, while dynamic seals include gland packings and mechanical contact seals. The document focuses on mechanical seals, explaining their design features such as seal faces, springs, and secondary seals. Different types are classified including single versus multiple spring seals, pusher versus non-pusher seals, and single versus double/tandem arrangements. Materials of construction and operating principles are also summarized.

1. Presented by
Prasad roshan1982@gmail.com

2. Cross section view of pump with mechanical seal

3. Pumping liquid

4. NEED FOR SEALS
Seal is a device for closing a gap or making a joint fluid tight
( liquid or gas )
NEED
* To minimize leakage
* To prevent toxic fluids escaping to atmosphere
* To reduce power loss .

5. TYPES OF SEALS
 Static Seals
 Dynamic Seals

6. STATIC SEALS
Sealing takes place between two parts that don’t move in
relation with each other.
Application
- Pipe flanges ,vessel /Tower nozzles, pump casing joint
- Fan /Blower casing joint , Compressor casing joint.
- Turbine casing joint, Heat exchanger joints
Types
- Gaskets
- O-rings
- Liquid gaskets

7. GASKET
Packing designed to go between two rigid parts in
stationary conditions
May be in form of sheet , strip , bulk.
Properties
Impermeability
Ability to flow into joints
Ageing
Corrosion resistance

8. Classification of Gaskets
Non-metallic gaskets
Metallic gaskets
Non-metallic gaskets
Asbestos
Cork and rubber
PTFE

9. METALLIC GASKET
Corrugated
Plain
Asbestos filler
Metal clad
Soft material like asbestos CAF enclosed in metal
covering .
Provides additional mechanical strength
Spiral wound
Alternate layers of v- sections , metallic strip and
non- metallic filler compressed to a predetermined
amount
Metal – SS , Monel , Inconel , Titanium.
Fillers – Asbestos fibres , PTFE lead, ceramic paper,

10. DYNAMIC SEALS
Used for sealing fluid between parts that move in relation with each
other
Application
* Centrifugal pump gland, valve gland , bearing
housing
* Turbine/compressor inter stage and end sealing
* Reciprocating compressors cylinder sealing
TYPES
 Gland packings
 Mechanical contact seals
 Labyrinth seal
 Oil seal
 Oil film seals

11. GLAND PACKING
 Enclosed in a stuffing box
 Compressive force by tightening the gland plate
produces radial pressure
 Slight leakage is allowed for lubrication
 Periodic retightening of gland necessary for wear
compensation.
 Lantern ring for cooling /lubrication
Stuffing box pressure No of rings
(bar)
up to 35 4
35-70 6
70-140 8
140 10

12. Gland packing
Braided by PTFE fibre
yarns and used in acids,
alkalis, gas, ammonia,
chemicals, etc.
The packing with PTFE
impregnated (YP006)are
also available.
Spec:6mm - 50mm

13. GLAND PACKING WITH PERMISSIBLE LEAKAGE

14. GLAND PACKING

15. GLAND PACKING
• packing material
vegetable based fibre yarns for oil and water service –cotton
hemp flax
textile
asbestos yarns
graphite packings
• lubricants
graphite
mica with Mo di sulphide and PTFE dry lubricant
tallow
silicone greases

16. WHY MECHANICAL SEALS
CONVENTIONAL SEALING
CONVENTIONAL SEALING IS BY MEANS
OF GLAND PACKING .THE PROBLEMS
WITH GLAND PACKINGS ARE:
1] PRODUCT LOSS
2] EXCESSIVE WEAR ON SHAFT & SLEEVE
3] FREQUENT ADJUSTMENTS
4] ENERGY LOSS

17. PRODUCT LOSS
GLAND PACKINGS WORK ON PRINCIPLE OF CONTROLLED
LEAKAGE FOR PROPER LIFE .
GLAND PACKING HAS TO LEAK TO PERFORM. THE PRODUCT
LOSS RESULTING FROM THIS LEAKAGE CAN BE QUANTIFIED
AS FOLLOWS,
LEAKAGE RATE QUANTUM
ONE DROP EVERY FIVE SECONDS 550
LTRS/YEAR
TWO DROPS PER SECONDS 5500
LTRS/YEAR
STEADY STREAM LEAKAGE 40000
LTRS/YEAR

18. MECHANICAL SEALS
CLASSIFICATION
By arrangement
1. Single seal
- Inside mounted / Outside mounted
2. Multiple design
- Double seal/ Tandem seal
By design
1. Unbalanced seal
2. Balanced seal
3. single spring
4. Multiple spring
5. Pusher seal
6. Non – pusher seal

19. MECHANICAL SEALS
Components
1. rotary seal face
2. stationary seal face
3. springs
4. retainer
5. sealing /flushing media
6. o-rings

21. MECHANICAL SEALS
THE BASIC DESIGN OF A MECHANICAL SEAL
COSISTS OF FOLLOWING ELEMENTS.
1] FLEXIBLY MOUNTED SEAL FACE
2] RIGIDLY MOUNTED SEAL FACE
3] COMPRESSION DEVICE
4] DRIVING MECHANISM
5] SECONDARY SEALS

22. MECHANICAL SEALS
Shaft

23. Vessel
Shaft
Mechanical seal
for arresting
leakage
Liquid
Agitator
blade

24. Shaft
Seal
follower
Stuffing box
Retainer Spring Static sealDynamic seal
Liquid
Bolt for locking
Gasket
Secondary
seal

25. Discharge
Seal flushing line , liquid took from
discharge line
Static & dynamic seal

26. PRICIPLES OF MECHANICAL SEALS
IN MECHANICAL SEALS, THE SEALING SURFACES
OF EVERY KIND ARE LOCATED IN A PLANE
PERPENDICULAR TO THE SHAFT AND USUALLY
CONSIST OF TWO HIGHLY POLISHED SURFACES
RUNNING ADJACENTLY.
ONE SURFACE BEING CONNECTED TO THE SHAFT
AND THE OTHER TO THE STATIONARY PORTION OF
THE PUMP.THE POLISHED SURFACES WHICH ARE OF
DISSIMILAR
MATERIALS ARE HELD IN COTINUAL CONTACT BY A
SPRING,FORMING A FLUID TIGHT SEAL BETWEEN THE
ROTATING AND STATIONARY MEMBERS WITH VERY
SMALL FRICTIONAL LOSSES .

27. LEAKAGE - PATH

28. CLASSIFICATION OF MECHANICAL
SEALS
1] CLASSIFICATOIN BY DESIGN
A] PUSHER TYPE SEALS
a] Unbalanced seals
1) Single spring type
2) Multi spring type
b] Balanced seals
1) Single spring type
2) Multi spring type
B] NON PUSHER TYPE( BELLOWS TYPE) SEALS
a] Metal bellows seals
b] Teflon bellows seals

29. CLASSIFICATION OF MECHANICAL
SEALS
2] CLASSIFICATION BY ARRANGEMENT:
SINGLE SEALS:
A] SINGLE INTERNALLY MOUNTED SEALS.
B] SINGLE EXTERNALLY MOUNTED SEALS
DOUBLE SEALS:
A] BACK TO BACK SEALS
B] FACE TO FACE SEALS
C] TANDEM SEALS

30. SINGLE SPRING SEALS

31. Gap in between seal faces, resulting
leakage

32. Shaft
Seal
follower
Stuffing box
Retainer Spring
Static sealDynamic seal
Liquid
Gasket
Secondary seal

33. Shaft
Seal
follower
Stuffing box
Retainer
Spring
Static seal
Dynamic seal
Liquid
Gasket
Secondary
seal
Outside mounted mechanical seal
Liquid

34. Static seal
Dynamic seal
Liquid
Gasket
Secondary
seal
Barrier fluid 1 bar more
than process
Process liquid

35. Cooling system and API planes
Process liquid is taken heat which is developed by friction of seal face

37. SINGLE SPRING SEALS

38. SINGLE SPRING SEALS
ADVANTAGES:
1] LOW STARTING TORQUE
2] NON-CLOGGING
3] LOW SPRING CONSTANT
LIMITATION:
1] DUE TO SINGLE SPRING THE FACE LOADING IS NOT
ALONG THE PERIPHERY OF THE SEAL
FACES,
[HENCE THESE TYPE OF SEALS ARE NOT
RECOMMENDED FOR VERY HIGH ROTATION SPEEDS]
2]NORMALLY UNIDIRECTIONAL
3] REQUIRE LONG AXIAL SPACE.

39. MULTI SPRING SEAL
NUMBER OF SMALL SPRINGS ARE USED ON THE
PERIPHERY OF THE SEAL FACE TO GIVE A
UNIFORM FACE LOADING.
THESE SEALS ARE COMPACT IN NATURE AND ARE
UNIVERSALLY USED ON MOST OF THE CLEAR
FLUIDS.
 DUE TO UNIFORMLY LOADED SEAL FACES THE
MULTI SPRING SEALS ARE A MUST FOR HIGH RPM
APLICATION.

40. MULTI SPRING SEAL

41. MULTI SPRING SEAL
ADVANTAGES:
1] COMPACT IN COMPARISON WITH SINGLE SPRING SEAL.
2] SPRING LOAD UNIFORM,i.e. UNIFORM FACE LOADING.
3] CAN BE GIVEN FOR HIGHER SPPED THAN SINGLE SPRING.
4] FOR EACH SEAL SIZE DIFFERENT SPRING NOT REQUIRED.
LIMITATION:
1] MORE EXPENSIVE.
2] SPRING CLOGGING POSSIBLE FOR DIRTY LIQUIDS.

42. NON PUSHER TYPE SEALS

43. NON PUSHER TYPE SEALS
ADVANTAGES:
1] SEAL HANG UP DUE TO SPRING CLOGGING OR
CLOGGING OF DYNAMIC ELASTOMERS ON THE SHAFT.
NON PUSHER TYPE SEALS DO NOT HAVE DYNAMIC
ELASTOMERS AND HENCE THIS PROBLEM IS AVOIDED.
2] NO SHAFT OR SLEEVE FRETTING AS THERE IS NO
DYNAMIC ELASTOMERS.

44. METAL BELLOWSMETAL BELLOWS
Metal bellows are constructed
by welding “leaflets” into a
series of “convolutions”. This
series of convolutions is
referred to as the “Bellows
Core”.
The photo shown here is a shaft
mounted “Utex-MB”.
Now take a look at how a
bellows seal compensates for
face wear.

45. DOUBLE SEALS

46. Optically Flat Faces
0 psi
Rotary
Face
Stationary
Face
100 psi

47. MOC – MECHANICAL SEALS
Primary seal
1. Ceramic
2. Carbon
- Resin impregnated – corrosive applications
- Antimony impregnated – non-corrosive
3. Tungsten carbide
- Ni binder
- Co binder
4. Silicon carbide
Secondary seal
Elastomers - Nitrile , Neoprene , Butyl,
Hypalon
Non –Elastomers - PTFE, Graf oil
Spring
SS 304, SS 316, Hastalloy, Monel, Alloy-20

48. MECHANICAL SEAL

49. MECHANICAL SEAL