This is in continuation to the presentation on Valves Materials - Part 1, this session focuses on the material of construction of the sealing components and Trim. The sealing components include Gasket and Packing.

1. Knowledge
Series
Saturday
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2. Valves Materials
Part - 2
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3. Agenda
● Valves Trim
● Sealing Components
○ Gaskets
○ Packing Seals
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4. Do You Think?
● Teflon and PTFE are same materials?
● PTFE and 35% Carbon Filled PTFE are same?
● Sluice Valve can only have Hemp & Jute Packing?
● Only a few material options can be offered for Valves Trim?
● Gaskets of valves can be interchanged?
● Packing and Gaskets need to be changed over period of time?
● PTFE Gasket is better than Rubber Gasket?
● Graphite Packing is Better than Hemp & Jute Packing?
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5. ● Internal and Replaceable parts
● It consists of seat, disc, stem, back
seat, busing and internal spring
● Sometime Trim parts are hard
faced by alloy deposit or heat
treatment (Stelliting)
Valves Trim
Parts of the valve, except body & bonnet, which are in contact with the fluid are called TRIM
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6. Trim Number
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7. Valve Sealing Purpose
● Prevents the Fugitive Emissions of volatile compounds.
● Prevents release of hazardous or toxic media.
● Prevents Leakage of corrosive compounds into the environment.
● Prevents the ingress of contamination into the media flowing
through the valve such as bacteria, dust, chemicals, oil or other
environmental contaminants.
● The valve seat or plug seals prevents leaks of media past a closed
valve seat
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8. Components requiring Sealing
● Stem Packing or Gland seals: The sealing element around a stem consists of
a packing material or a combination of seals, followers, O-rings, bellows,
spring energized seals, spacers and packing. The seal prevents leaks while
allowing the stem to rotate or slide freely.
● Valve Connection Seals: Valves with bolted flange connections or face seals
typically require gaskets or O-rings. Threaded connections use PTFE tape,
joint compound, O-rings or ring seals.
● Bonnet - Valve Body Seals: Seals, sealing rings, O-rings or gaskets are
required between the bonnet and valve body.
● Valve Disk and Seat “seals”: Certain valves have a seal material between the
plug and seat or seat and body.
The seal should be compatible with the working fluid and Retain its properties over time
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9. Types of Sealing Components
Gaskets Packing Seal
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10. Gaskets
● Gaskets are used between:
○ Body and bonnet of gate and globe valves
○ Body and cover of check valves
○ Body and end connector of ball valves
○ Body and cover / adaptor of butterfly valves
● Gaskets are used in static joints and between flanges
● They maintain leak proof sealing in all operating conditions
● In pressure seal design (for Oil & Gas application), they are contained between body, bonnet
and segmental retainer
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11. Selection Criteria
● Temperature : It must withstand the entire temperature range of the fluid it handles.
● Pressure : It must withstand the entire design pressure range of the fluid it handles.
● Corrosion resistance : Gasket material should not corrode when it comes in contact with
the fluid it handles or by the environmental exposure.
● Types of fluid : Gasket material should be capable of dealing with different types of fluids if
installed in line that handles more than one type of fluids.
● Robustness : The gasket must be capable of withstanding all temperature - pressure
change conditions.
● Availability : Gasket should be easily available
● Cost : Cheap and unreliable gasket should not be used at the same time it should not be
costly.
The Gaskets are selected as per Standard Specification or based upon Experience
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12. Properties of Gaskets
1. Impermeability : It should not be porous to the fluid being sealed.
2. Compressibility : It should compress into the imperfections on the flange sealing faces to create the initial seal.
3. Stress relaxation (creep resistance) : It should not show significant flow (creep) when subjected to load and
temperature. Such flow will allow the bolts to relax, reduce gasket surface stress, and cause leakage.
4. Resilience : Although normally stable, the bolted flanges move slightly relative to one another under the influence of
cycling temperature and pressure. The gasket should be capable of compensating for such movements.
5. Chemical resistance : It should withstand chemical attack from the process medium being handled. Likewise, the
gasket material itself must not contaminate the process medium.
6. Temperature resistance : It should be able to withstand the effects of range of temperatures within the process and
the external atmospheric temperatures.
7. Anti-stick : It has to be easily removable after use.
8. Anti-corrosion : It must not cause corrosion of the flange faces.
Gaskets must maintain a seal for an acceptable period against all the operational forces involved.
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13. Types of Gaskets
Non-Metallic Metallic – Ring Gasket Composite
Compressed Non-Asbestos Fibre Gasket (CNAF) Oval Ring Gasket Spiral Wound Gaskets
PTFE Gasket Octagonal Ring Gasket Camprofile Gaskets
Rubber Gasket Metal Jacketed Gasket
Gasket dimensions are covered in various standards like:
BS 3381 : Metallic Spiral Wound Gaskets;
ASME B 16.20 : Metallic Gaskets for pipe flanges and
ASME B 16.21 : Non-metallic Gaskets for pipe flanges.
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14. Non - Metallic Gaskets
The most common materials used for this type of gaskets are Graphite, Rubber, Teflon (PTFE), and Compressed
Non-Asbestos Fiber (CNAF). These gaskets are also known as a Soft gasket. It can be full face or inside bolt circle
type
● Non-Metallic gaskets can easily compress with low tension bolting
● Suitable for low-pressure class flanges such as 150 and 300 Class and also in low-temperature However,
graphite gasket can be used up to 500 Degree centigrade.
● Rubber and elastomer gaskets are not used in hydrocarbon services but used in utility lines.
● Non-Metallic gaskets are cheapest and easily available
Full-face gasket types are suitable for flat-face (FF) flanges. Flat ring gasket types are suitable for use with
raised faced (RF) flanges.
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15. Metallic Gaskets
Metal gaskets are manufactured from a material such as Soft iron, Low Carbon
steel, Stainless Steel, Monel, and Inconel. These gaskets are also known as ring
gasket or RTJ gaskets.
● Metallic gaskets are used in high-pressure class flanges, normally above
900 Class, they can also be used for high-temperature
● High tension bolting is required when we used metallic gaskets.
● They are very robust & most costly
The RTJ Gasket fits in a groove machined on the flange face of both mating
flanges. There are two types of the metallic gasket are used with RTJ flange
Octagonal and Oval. You can see the difference in their cross-section view.
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16. Composite Gaskets
Composite gaskets are a combination of metal and non-metal material. Different
types of combinations of materials are possible based on the service requirement.
Spiral wound, Metal Jacketed, and Kamprofile gasket are well known in the
composite gasket category. They are used in a wide range of pressure and
temperature services.
Composite gaskets are cost effective compare to metal gaskets but Careful
handling is required. Composite gaskets are used on raised face, male-female, and
tongue-and-groove flanges
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17. Types of Gaskets contd..
Spiral Wound Gaskets (SWG)
● SWG consists of a V-shaped metal strip which
is wound into a spiral
● The metal layers are separated by a filler,
usually graphite, which provides a good
resilience and sealability properly
● Sealing action is due to the flow of metal
spiral and graphite fiber as a result of gasket
compression
● Used in Class 150 gate valves
● Extreme high temperature & pressure cycling
shock or vibrations
Ring Type Joint (RTJ) Gaskets
● RTJ Gaskets are used with Ring Type Joint
(RTJ) flanges for high-pressure services.
● They are solid rings of metal (cut from plate,
pipe or a forged ring) in different cross
sections such as oval, round, octagonal.
● Special RTJ gasket comes with a hole in the
center for pressure equalization in subsea
pipeline application.
● Available in Type R, RX, BX, SRX and SBX etc
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18. Types of Gaskets contd..
Corrugated Gaskets
● These gaskets are used in Class 150 flanges of
gate valves
● The metal is normally made of soft steel but
mostly stainless steel. They give good
resilience against temperature and pressure
fluctuation
● In addition, thin graphite sheets are used on
both faces to give additional sealing
● These metal gaskets have been proven to be
both reliable and cost effective
Tanged Gaskets
● Pure exfoliated graphite sheets with a tanged
SS316 reinforcement in the middle for
improved resistance to blowouts
● Excellent chemical and thermal capabilities
● Extensively throughout the petrochemical
and chemical industries for process duties
and steam applications
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19. Types of Gaskets contd..
‘O’ Rings
● An O-ring is a mechanical gasket in the shape
of a torus. It is designed to be seated in a
groove and compressed, creating a seal at the
interface.
● As it is self sealing element, the bolting force
required is significantly less
● It can be used for high pressure application
● Backup rings are used to avoid extrusion at
high pressure
Solid Gaskets
● Solid metal gaskets can withstand higher
temperatures and pressures than sheet
gaskets.
● They seal better and are cost effective
● The flange thickness and fastener
requirement are less
● They are available in materials like PTFE,
Reinforced PTFE and Graphite
● These are usually used in soft-seated valves
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20. Types of Gaskets contd..
Lip Seals
● For applications where elastomeric O-rings are not
reliable, Lip seals are used (for body & stem
sealing).
● Lip seals are self energised seal systems, made of a
Teflon cover and a spring (Inconel 718 material).
● Lip seals have high shelf-life compared to
conventional seals
● These are used in seat rings and end connectors of
low temperature
● Additional graphite gaskets are used to make
them fire safe
Backup Rings for Higher Pressure
● Backup rings are generally used for higher
pressures or temperature services
● They are used in conjunction with O-rings or other
seals in high-pressure applications.
● Backup rings can be installed either side of the
O-ring to give a high performance double acting
seal.
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21. Packing Seals
● Packings are used between:
○ Bonnet and Stem of Gate and Globe Valves
○ Body / Stem housing and Stem of Ball Valves
○ Body and Shaft of Butterfly Valves
● Stem / Shaft sealing is considered as dynamic joint as there is
relative movement between packing and stem/shaft
● They prevent external leakage along the stem/shaft to
atmosphere
Packing is retained in stuffing box with the help of Gland or Retainer under pressure 21

22. Packing Materials
● Graphite (-200 to 600 o
C)
● Carbon Filament
● Elastomers and Plastics
● Thermiculites
● Aramid (-200 to 280 o
C)
● Mica
● Asbestos Reinforced SS (0 to 800 o
C)
● Hemp & Jute(Temp: 0-60 o
C)
● PTFE(-250 to 200 o
C)
Gland Packing generally creeps over time, needs to be Tightened regularly to maintain Seal
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23. Graphite
Advantages
● Most suitable and chemically resistant
material
● Resistance to high temperature
● Resistance to compression set, thus
allowing for lower gland loads
● Combination of moulded & braided
rings are used
● Good Chemical resistance
● Fire Safe
Disadvantages
● Graphite can cause stick-slip friction
when flakes detach from the inner face
of the rings and are deposited on the
surface of the stem under dry condition
● This hard deposit reduces the life of
packing significantly
● Not suitable for oxidising services for
temperature more than 450 o
C. The seal
may fail due reaction with Oxygen
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24. Elastomers
Elastomers are based on polymers which have the following properties:
● Elasticity (the ability of material to return to its original shape and size after being stretched,
compressed, twisted or bent)
● Resilience (the ability to return quickly to original shape after temporary deflection, it
indicates the speed of recovery)
● With increase in line pressure, pressure is transmitted in all directions. This ensures effective
sealing performance
● Elastomers are versatile in the ‘fine tuning’ of properties to specific service conditions
● There may be complex trade-offs in properties of elastomers: such as High compression set
resistance but poor dynamic performance or High heat resistance but low chemical
resistance to specific fluids
● Temperature limitation (both low and high)
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25. Popular Elastomers
Material Temp Range o
C Applications
Nitrile (NBR) -10 to 90 Oil, Fuel Oil, Water, Air, gases, Powder Slurries
While Nitrile -10 to 90 Food, Potable Liquid, Steam
EPDM -10 to 120 Water, Hot Gases, Slurries
Food Grade EPDM -10 to 120 Breweries, Distillers, Acid, Alkali
Viton (FKM) -10 to 70 Chlorine, Aromatic Hydrocarbons
Silicon Rubber 0 to 230 Hot Gases
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26. Popular Plastics
Material Description Temp Range o
C Applications
Virgin PTFE ● Most common material
● Wide range of applications
● Resistant to almost all chemicals
● Low coefficient of friction
-40 to 225 Petrochemical & chemical
processing, Food & Beverage
and Pharma
Glass Filled PTFE ● PTFE with improved cyclic life to
chemical service & greater pressure
temp rating
-40 to 225 Low and medium steam
service
Carbon Filled PTFE ● Excellent mechanical and wear
properties
● Excellent choice for dynamic and high
pressure applications
-200 to 260 Severe applications
Poly Filled PTFE ● Special filled materials capable of
handling high pressure
-40 to 270 High pressure steam up to
103 bar
PEEK ● Outstanding pressure capabilities at
elevated temp and excellent chemical
and abrasion resistance
-40 to 270 Best suited for high pressure,
temperature and corrosive
services
Poly Tetra Fluoro Ethylene (PTFE)
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27. Sealing Materials
● Aramid: Aramid fibers are an engineered polymer with very high strength and good temperature
resistance.
● Elastomer/Rubber: Non-porous polymeric material with a high degree of elasticity (% elongation).
Properties vary widely with specific polymer type. Some elastomers cannot be used with higher
temperatures and become brittle at cryogenic temperatures.
● Fiberglass: Silicate glass fibers in rope, ribbon or cloth form provide high temperature performance with
good chemical resistance.
● Fluoropolymer / PTFE: Polytetrafluoroethylene and other fluoropolymer plastics have higher
temperature performance combined with chemical resistance and inertness. Can seal media with pH
from 0 to 14.
● Foam / Sponge: Porous polymeric material with a high degree of compressibility. Thermal and chemical
properties will depend on the specific polymer or elastomer. Closed cell foam does not have
interconnected pores or cells. 27

28. Sealing Material Selection contd..
● Graphite: Graphite glass fibers in rope, ribbon or cloth form provide high temperature
performance with good chemical resistance.
● Hybrid / Composite: Hybrid, blended or composite seal materials can provide unique
performance unattainable by either material alone (e.g., graphite with Inconel® nickel based
alloy reinforcement)
● Lubricant Impregnated: Many gasket or packing seal materials can be filled or loaded with
additional high temperature lubricants.
● Metal: Metals or alloys are harder and less compliant compared to seal materials, but they can
withstand high temperatures and pressures without outgassing. Metal to metal seals are useful
in certain applications—e.g., vacuum valves and fittings
● Silicone: Polysiloxane elastomer providing higher temperature performance combined with
chemical resistance and inertness. 28

29. Gasket Material Temperature Range
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30. Gaskets Pressure Range
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31. Gasket material Fluid compatibility
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32. Quick Learning Points?
● All types of sealing materials are good as per their applications.
Their rank varies as per the parameters
● At the time of maintenance, the consumer should not use
sealing material which is not suitable as per the application
● The packing needs to be tightened or refilled regularly
● Gaskets or packing of similar applications can be interchanged
● Teflon is name of the Brand which developed PTFE
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33. Thank You
Any Question, please?
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