There are numerous engineered materials being used to manufacture various types of valves. The materials are selected as per the application and other key parameters. There parameters include size, pressure of the fluid, working temperature and leakage class requirements etc. This presentation is split into two parts to cover MOC of major parts of the valves and the sealing components.
3. Do You Think?
● SS 316 & CF8M materials are Same?
● SS 304 & CF8 materials are Same?
● SS 316 is better than SS 304?
● Stainless Steel is better than Cast Steel?
● Ductile Iron is better than Cast Iron?
● Brass is better than Bronze?
● Chrome Plating is better than Nickel?
● CF8 and CF8M are non-magnetic?
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6. Valves Components
❖ Pressure Containing Components:
➢ Components that retain line fluids within the pressure boundary. These include body, bonnet /
cover, end connector and stem
❖ Pressure Controlling Components:
➢ These components regulate the flow of the fluid. These include ball, disc, plug, gate and seat
❖ Sealing Elements and other components:
➢ Gasket, fasteners and packing which are very important to avoid any external leakage.
➢ Other components include gland, gland flange and operating components like yoke sleeves,
lever / wrench, handwheel etc 6
7. Valves Materials Standards
Standard play an important role in material of construction and
recommendations are based on rich experience.
● Product standards like BIS, API 600, API 6D, ISO 17292, AWWA etc
give minimum requirement of materials for valves components.
● American Society of Mechanical Engineers (ASME) B16.34 gives
popular ASTM materials in different forms used in valves and their
pressure-temperature ratings.
● American Society for Testing and Materials (ASTM) standards contain
the acceptable chemical composition, mechanical properties,
manufacturing process, heat treatment and testing procedures.
● ASME BPV Code Sec II and VIII are also often used to get properties of
materials at different temperatures.
● When line fluid contains hydrosulfide, NACE standard MR-0175 or 7
8. Basis of Material Selection
There are various parameters which are to be considered while selecting any
material to manufacture any valve components viz:
➔ Temperature: High / Low / Medium
➔ Line Media: Corrosion / Erosion
➔ Pressure: High / Low
➔ Cleanliness Required: Food / Pharma
➔ Criticality of Service: Forging / Casting / Bar / Plate / Pipe / Fabrication
➔ Environment: Corrosion (Saline) / Radiation
Various forms of materials are available viz: Casting, Forging, Bar, Plate and Pipe
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9. Valve Materials (metallic)
Ferrous contains Iron as base metal whereas Non-Ferrous does not contain Iron
Ferrous
These metals are used for their tensile strength
and durability.
Advantages
• High strength - weight ratio
• High quality and tough material
• High Pressure and Temperature Range
Disadvantages
• Tends to corrode by rusting
• Machineability affected by the magnetic field
• Machining cost relatively high
Cast Iron, Ductile Iron, Carbon Steel. Forged Steel,
Mild Steel and Stainless Steel etc
Non-Ferrous?
Nonferrous metals are extensively used for various
industrial purposes.
Advantages
● High corrosion resistance
● Easy to fabricate – machinability & casting
● Low density (less weight)
Disadvantages
● Limited tensile strength
● Limited Temp-Pressure range
● More expensive than ferrous
Copper (Bronze, Brass), Aluminium, Tin, Lead, Zinc
and Nickel etc
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10. Material Comparison
Why Casting?
Advantages:
● Complex shape of valve components like
Body, Bonnet and Disc
● Hollow shape
● Less cost
Limitations:
● Quality
● Surface Finish
● Dimensional Accuracies
● Volume is not high
Why Forging?
Advantages:
● Good Quality
● Dimensional Accuracies
● Good Surface Finish
● Closed Die Forging - large quantity (for small
sizes) and Open Die Forging - small quantity
(for large sizes)
Limitations:
● Machining is tough
● Costly
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11. Material Comparison contd..
Why Bar?
Advantages:
● Dimensional Accuracies
● Good Quality
● Good Surface Finish
● Suitable for small size valves
Limitations:
● Cost is more
● More machining
Why Plate/Pipe and Fabrication?
Advantages:
● Low weight
● Small Quantity
● Large Size and Low Pressure
Limitations:
● Welding Quality
● Dimensional Accuracies
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12. Copper Alloys
Brass
Brass is alloy of Copper and Zinc in 60:40 ratio
Types: Red brass, Yellow brass, 330 brass, 360
brass, 464 bras etc
Corrosion Resistance: Moderate
Durability: High
Contamination: DZR Brass is excellent for
chlorinated drinking water applications
(Dezincification)
Bronze
Bronze is alloy of Copper, Zinc, Lead, Tin and
other elements. Common Ratio: 85:5:5:5
Types: Leaded bronze, Phosphor bronze,
Aluminum bronze, Silicon bronze etc
Corrosion Resistance: Excellent (sea water)
Hardness: more hard and brittle
Contamination: can contaminate water (Lead
Content)
Cost: Expensive than Brass
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Bronze is an alternative to DZR Brass (Dezincification does not occurs if Zinc % is less than 15%
13. Cast Iron or Ductile Iron
Cast Iron
Brittle: Cast Iron can crack / break when bent
Corrosion: It corrodes faster than Ductile Iron
Vibration Dampening: It dampens vibrations
more effectively than ductile iron
Low cost: can be cast very easily and has good
machineability
Pressure Rating: mostly used for upto Class
125
Ductile Iron
Ductile: Ductility is higher than Cast Iron (15%)
Yield Strength: It has almost double the Yield
Strength of Cast Iron
Corrosion Resistance: Severe weather
conditions (saline water), Acidic and Caustic
chemicals, Chloride resistance
Pressure Rating: mostly used for higher Class
rating
Higher Cost than Cast iron
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For 16 Kg max working pressure, Cast Iron Valves are most economical than Ductile Iron Valves
14. Carbon Steel
Carbon Steels are good for moderate temperature services (425 degree C)
❖ Carbon Steel is an alloy consisting
of Iron and Carbon. (Eg. ASTM A216
Gr. WCB)
❖ Several other elements are allowed
in carbon Steel (Manganese with a
1.65% maximum, Silicon with a
0.60% maximum, and Copper, with
a 0.60% maximum)
Grades of Carbon Steels
● Low Carbon Steel – Composition of 0.05%-0.25% carbon and up to 0.4%
manganese. Also known as mild steel, it is a low-cost material that is easy
to shape.
● Medium Carbon Steel – Composition of 0.29%-0.54% carbon, with
0.60%-1.65% manganese. Medium carbon steel is ductile and strong, with
long-wearing properties.
● High Carbon Steel – Composition of 0.55%-0.95% carbon, with
0.30%-0.90% manganese. It is very strong and holds shape memory well,
making it ideal for springs and wire.
● Very High Carbon Steel - Composition of 0.96%-2.1% carbon. Its high
carbon content makes it an extremely strong but brittle material.
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15. Stainless Steel
For Sea Water Applications Duplex Stainless Steel is used
Five types of Stainless Steels
● Austenitic
● Ferritic
● Duplex
● Martensitic
● Precipitation Hardened (PH)
Characteristics of Stainless Steels
● High corrosion resistance
● Higher strength, hardness and ductility
● Higher cryogenic toughness
● Higher work hardening rate
● Lower magnetic response (austenitic only)
Steels containing more than 12% Chromium are called Stainless Steels (SS). Corrosion resistance of SS is better than other
steels. Different grades are ASTM A351 Gr. CF8, CF3, CF8M, CF3M, CF8C, CF10M, CD3MN, CD4MCuN (Casting) and
ASTM A182 Gr. F304, F304L, F316, F316L, F347, F321, F51, F55 (Forging)
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16. CF8 or CF8M
CF8 (Type 304)
Corrosion Resistance:
Normal weather conditions, normal industrial
applications
Less Expensive:
Most common stainless steel in the world. With
low cost it is suitable for most of applications
Magnetic:
CF8 is magnetic in nature. It is not suitable for the
applications where magnetism creates problems
CF8M (Type 316)
Corrosion Resistance:
Severe weather conditions (saline water), Acidic
and Caustic chemicals, Chloride resistance
Expensive:
Second most common stainless steel in the world.
Due to addition of 2% Molybdenum, it is more
expensive than CF8
Non-Magnetic:
CF8M is non-magnetic in nature
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CF8M & CF8 are Cast and SS 316 & SS 304 are Forged forms of Stainless Steel
17. Valve Plating
Chrome Plating
Superior Hardness:
Durability, Wear & Tear Resistance
Lower Coefficient of Friction:
Less force is required to operate the
valve
Nickel Plating
Exceptional Corrosion Resistance:
Better results and last longer in the
corroded media
Uniformity:
Good for coating irregularly-shaped
items and rough surfaces
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18. Hardfacing Materials (Stellited)
Body Seat Rings are often Hardfaced or Stellited
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Valve internals, such as seats and closures,
are often at risk of erosion, abrasion,
corrosion, galling and damage from cavitation.
Harfacing is done to avoid such issues.
Cobalt base alloys, often called Stellite® , are
very wear and tear resistant, anti-corrosion at
high temp applications
19. Temperature Range
Material Specification Temperature Range, Deg C
Cast Iron IS 210 Gr. FG 200 -5 to 220
Carbon Steel WCB, A105, Gr. 60 & 70 -20 to 425
Carbon Steel WCC, A106 Gr. B & C -29 to 425
Low Temp Carbon Steel LCB, LCC -46 to 345
SG Iron (Butterfly Valve) IS 1865 -5 to 90
Alloy Steel F92, P92 -29 to 620
Stainless Steel F304, F316, CF8, CF8M -220 to 815
Stainless Steel F304L -29 to 425
Stainless Steel F316L -29 to 450
Bronze (for IBR) IBR 282 (a)(iv) Gr. B 225
Teflon (PTFE) 220
Rubber 90
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20. Quick Learning Points
● All the materials have their own merits
● For Acids and Caustic, CF8M Ball Valves can be offered
● Ductile Iron, SG Iron and Nodular Iron are same
● Bronze and Gun Metals are same
● Alumunium Bronze is suitable for Marine Applications
● Welding on Cast Iron is not possible but possible on Ductile Iron
● As the Temperature increases, pressure bearing capacity decreases
● Where DZR Brass is asked, Bronze valves can be offered as an alternate
● At Low (minus) Temperature, the material becomes brittle hence
susceptible to any stress which may lead to failure
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