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ToggleThe most common materials for pipe flanges (forged grades) are: ASTM A105 (carbon steel high temperature to match A53/A106/API 5L pipes), A350 Grades LF1/2/3/6 (carbon steel low temperature to match A333 pipes Gr. 1 to 6), ASTM A694 Grades F42 to F80 (high yield carbon steel to match API 5L pipe grades X42 to X80), ASTM A182 Grades F5 to F91 (alloy steel flanges to match A335 pipes P5 to P91), A182 Grade F304/316 (stainless steel flanges to match A312 SS pipes), A182 Gr. F44/F51/F53/F55 (duplex and super duplex to match A790/A928 pipes) and various nickel alloy grades (Inconel, Incoloy, Hastelloy, Monel).
CARBON STEEL FLANGES
USAGE OF CS FLANGES
Carbon steel flanges are widely used in various industrial applications due to their strength, durability, and cost-effectiveness. Understanding when to use carbon steel flanges involves considering the specific requirements of the application, including the operating conditions, the nature of the fluids being handled, and budget constraints.
Here are several scenarios where carbon steel flanges are typically the preferred choice:
1. Moderate to High-Pressure Systems
Carbon steel flanges are suitable for applications that operate under moderate to high-pressure conditions. Their robustness makes them ideal for pipelines, process plants, and equipment that need to withstand substantial pressure without compromising the integrity of the flanged connection.
2. Ambient to High-Temperature Applications
These flanges can handle a wide range of temperatures, making them suitable for systems that operate at ambient temperatures up to those that require high-temperature resistance. Carbon steel maintains its structural integrity under elevated temperatures, though the specific grade of carbon steel will determine its maximum temperature limit.
3. Non-corrosive or Mildly Corrosive Environments
Carbon steel flanges are best used in environments where the risk of corrosion is low to moderate. They can handle exposure to water and some chemicals, but they are not suitable for highly corrosive substances like strong acids or chloride-bearing environments, where stainless steel or alloy flanges would be more appropriate.
4. Cost-Sensitive Projects
One of the significant advantages of carbon steel flanges is their cost-effectiveness compared to stainless steel or alloy flanges. In projects where budget constraints are a critical consideration, carbon steel flanges offer a reliable solution without a significant financial investment.
5. Industrial and Utility Piping
Carbon steel flanges are commonly used in industrial settings, including oil and gas, petrochemical, water treatment, and manufacturing facilities, as well as in utility systems such as steam, water, and gas distribution networks. Their versatility and durability make them well-suited to the rigorous demands of these applications.
6. Structural Applications
In addition to piping systems, carbon steel flanges can also be used in structural applications where components need to be joined securely. Their high strength and ability to be welded make them suitable for constructing frames, supports, and other structural elements.
Key Considerations:
- Corrosion Protection: While carbon steel flanges are not inherently resistant to corrosion, protective coatings or treatments, such as painting or galvanizing, can extend their life in corrosive environments.
- Material Compatibility: Ensure that the flange material is compatible with the fluid being handled and the connecting piping or equipment materials to prevent galvanic corrosion or other compatibility issues.
The following tables show the chemical composition and the mechanical properties of the three main carbon steel flanges material grades:
- ASTM A105 (high-temperature carbon steel) to match A53, A106, API 5L carbon steel pipes
- ASTM A350 LF1, LF2, LF3 (low-temperature carbon steel) to match ASTM A333 pipes
- ASTM A694 F42, F52, F60, F65 (high-yield carbon steel to match API 5L X42, X52, X60, and X65 steel pipes
CHEMICAL COMPOSITION ASTM A105, A350, A694
ASTM A105 (High-temperature carbon steel flange material)
C | Mn | P | S | Si | Cu | Ni | Cr | Mo | V | |
A105 | – | 0.60 | – | – | 0.10 | – | – | – | ||
0.35 | 1.05 | 0.035 | 0.040 | 0.35 | 0.40 | 0.40 | 0.30 | 0.12 | 0.08 |
ASTM A350 (Low-Temperature carbon steel flange material)
C% | Mn% | Si% | S% | P% | Cr% | Ni% | |
A350 LF1 | 0.30 max | 0.6/1.35 | .15/.30 | .040 max | .035 max | 0.30 max | 0.40 max |
A350 LF2 | 0.30 max | 0.6/1.35 | .15/.30 | .040 max | .035 max | 0.30 max | 0.40 max |
A350 LF3 | 0.20 max | 0.9 | .20/.35 | .040 max | .035 max | 0.30 max | 3.3/3.7 |
C | Mn | P | S | Si | |
ASTM A694 F42 | 0.26-0.265 | 1.60-1.64 | 0.025-0.030 | 0.025-0.030 | 0.15-0.35 |
ASTM A694 F52 | 0.26-0.265 | 1.60-1.64 | 0.025-0.030 | 0.025-0.030 | 0.15-0.35 |
ASTM A694 F60 | 0.26-0.265 | 1.60-1.64 | 0.025-0.030 | 0.025-0.030 | 0.15-0.35 |
ASTM A694 F65 | 0.26-0.265 | 1.60-1.64 | 0.025-0.030 | 0.025-0.030 | 0.15-0.35 |
MECHANICAL PROPERTIES A105, A350, A694
ASTM A105 (High-temperature carbon steel flange material)
Property | ASTM A105 | ASTM A350-LF2 |
Tensile Strength Min, psi | 70,000 | 70,000-95,000 |
Tensile Strength Min, N/mm² | 485 | 485-655 |
Yield Strength Min, psi | 36,000 | 36,000 |
Yield Strength Min, N/mm² | 250 | 250 |
Elongation (%) | 22 | 22 |
Reduction of Area (%) | 30 | 30 |
Hardness, maximum | 187 | 15/12 ft-lbs |
CVN at -50℉ | 20/16 joules |
ASTM A694 (High-yield carbon steel flanges)
ASTM A694 Flange Material Grade | Min Yield Strength (0.2 % Offset), in ksi [MPa] | MinTensile Strength | Elongation in 2 in. or 50 mm, min % |
in ksi [MPa] | |||
A694 F42 | 42 [290] | 60 [415] | 20 |
A694 F46 | 46 [315] | 60 [415] | 20 |
A694 F48 | 48 [330] | 62 [425] | 20 |
A694 F50 | 50 [345] | 64 [440] | 20 |
A694 F52 | 52 [360] | 66 [455] | 20 |
A694 F56 | 56 [385] | 68 [470] | 20 |
A694 F60 | 60 [415] | 75 [515] | 20 |
A694 F65 | 65 [450] | 77 [530] | 20 |
A694 F70 | 70 [485] | 82 [565] | 18 |
ALLOY STEEL FLANGES
USAGE OF CS FLANGES
Alloy steel flanges, particularly those made from chrome molybdenum (chrome moly) steel, are selected for specific applications that require enhanced properties not offered by carbon steel flanges. Chrome moly steels, designated as ASTM A182 F1, F5, F9, F11, F22, and F91, are known for their strength, durability, and resistance to high temperatures and pressures.
ASTM A182 alloy flanges are extremely ductile, strong, tough, and easy to weld and offer oxidation and scaling resistance. These grades match with ASTM A335 alloy steel pipes.
Here are several scenarios where alloy steel (chrome moly) flanges are the preferred choice:
1. High-Temperature Applications
Chrome moly flanges are particularly suitable for high-temperature applications, such as in the power generation industry (including boilers and heat exchangers) and petrochemical plants. The addition of chromium and molybdenum improves the steel’s ability to withstand elevated temperatures without losing strength or undergoing deformation.
2. High-Pressure Environments
The enhanced strength of chrome-moly steel makes these flanges ideal for use in high-pressure systems. They can maintain integrity under stress and are often used in pressure vessels, high-pressure piping systems, and in applications where mechanical properties must be maintained under stress.
3. Corrosive Environments
While not as resistant to corrosion as stainless steel, chrome-moly flanges offer better corrosion resistance than carbon steel flanges, especially in environments where oxidation is a concern. Their use in mildly corrosive environments can reduce the risk of rust and corrosion-related failures.
4. Refineries and Chemical Processing
The robust nature of alloy steel flanges makes them suitable for the harsh conditions found in refineries and chemical processing plants. These flanges can withstand the thermal and mechanical stresses associated with processing high-temperature fluids and gases.
5. Oil and Gas Industry
In the oil and gas sector, chrome-moly flanges are used for drilling and extraction equipment, as well as for piping systems that transport hot oils, gases, and steam. Their durability and temperature resistance are crucial for the reliability and safety of these applications.
6. Fossil and Nuclear Power Plants
Alloy steel flanges play a critical role in both fossil fuel and nuclear power plants, where they are used in the construction of turbines, reactors, and other high-temperature, high-pressure components.
Key Considerations:
- Material Specification: Selecting the correct grade of chrome moly steel is essential, depending on the specific temperature and pressure conditions of the application.
- Cost vs. Performance: Alloy steel flanges are generally more expensive than carbon steel flanges, so their use should be justified by the operational requirements that necessitate their enhanced properties.
- Welding and Fabrication: Special care must be taken during the welding and fabrication of alloy steel flanges to prevent issues such as cracking. Preheating and post-weld heat treatment may be necessary, depending on the alloy composition and the application.
Alloy flange materials (chrome-moly) have higher chrome and molybdenum content than carbon steel flanges. Alloy steel flange materials suit high-temperature and high-pressure applications and improve corrosion resistance when compared to regular carbon steel flange grades.
CHEMICAL COMPOSITION ASTM A182 F5, F9, F11, F22
ELEMENT & PROPERTIES | LOW ALLOY STEEL | MEDIUM ALLOY STEEL | ||
---|---|---|---|---|
F11 CL2 | F22 CL3 | F5 | F9 | |
CARBON | 0.10-0.20 | 0.05-0.15 | 0.15 MAX | 0.15 MAX |
MANGANESE | 0.30-0.80 | 0.30-0.60 | 0.30-0.60 | 0.30-0.60 |
PHOSPHORUS MAX | 0.040 | 0.040 | 0.03 | 0.030 |
SULFUR MAX | 0.040 | 0.040 | 0.03 | 0.030 |
SILICON | 0.50-1.00 | 0.50 MAX | 0.50 MAX | 0.50-1.00 |
NICKEL MAX | – | – | 0.50 | – |
CHROMIUM | 1.00-1.50 | 2.00-2.50 | 4.00-6.00 | 8.0-10.0 |
MOLYBDENUM | 0.44-0.65 | 0.87-1.13 | 0.44-0.65 | 0.90-1.10 |
OPPER MA | – | – | – | – |
COLUMBIUM MAX | – | – | – | – |
VANADIUM MAX | – | – | – | – |
MECHANICAL PROPERTIES A182
ELEMENT & PROPERTIES | LOW ALLOY STEEL | MEDIUM ALLOY STEEL | ||
---|---|---|---|---|
F11 CL2 | F22 CL3 | F5 | F9 | |
TENSILE STRENGTH PSI (MPA) | 70,000 (485) | 75,000 (515) | 70,000 (485) | 85,000 (585) |
YIELD STRENGTH PSI MIN | 40,000 (275) | 45,000 (310) | 40,000 (275) | 55,000 (380) |
ELONGATION 2” % MIN | 20 | 20 | 20 | 20 |
REDUCTION AREA % MIN | 30 | 30 | 35 | 40 |
HARDNESS (HB) MAX* | 143 ~ 207 | 156 ~ 207 | 143 ~ 217 | 179 ~ 217 |
Recommended service for alloy steel flange material grades ASTM A182:
ASTM A182 ALLOY STEEL FLANGE | TRADE DESIGNATION | RECOMMENDED SERVICE |
A182 F1 | C-1/2 Mo Low Alloy Steel | Non-corrosive applications Including water, oil, and gases at temperatures between -29 ~ 593ºC* (Not prolonged use > 470ºC). |
A182 F2 | 0.75% Ni; Mo; 0.75% Cr Low Alloy Steel | Non-corrosive applications including water, oil, and gases at temperatures F2:-29ºC ~ 538ºC, WC5: -29ºC ~ 575ºC |
A182 F11 | 1 1/4% Chrome; 1/2% Moly Low Alloy Steel | Non-corrosive applications inclusive of water, oil, and gases at temperatures between -30ºC (-20ºF) and +593ºC (+1100ºF). |
A182 F22 | 2 1/4% Chrome Low Alloy Steel | Non-corrosive applications inclusive of water, oil, and gases at temperatures between -30ºC (-20ºF) and +593ºC (+1100ºF). |
A182 F5/F5a | 5% Chrome; 1/2% Moly, Medium Alloy Steel | Mild corrosive or erosive applications as well as non-corrosive applications at temperatures between -30ºC (-20ºF) and +650ºC (+1200ºF). |
A182 F9 | 9% Chrome; 1% Moly, Medium Alloy Steel | Mild corrosive or erosive applications as well as non-corrosive applications at temperatures between -30ºC (-20ºF) and +650ºC (+1200ºF). |
A182 F91 | 9% Chrome; 1% Moly; V-N, Medium Alloy Steel | Mild corrosive or erosive applications as well as non-corrosive applications at temperatures between -30ºC (-20ºF) and +650ºC (+1200ºF). |
STAINLESS STEEL FLANGES
USAGE OF SS FLANGES (304/316)
Stainless steel flanges are chosen for their corrosion resistance, durability, and ability to maintain integrity under both high and low temperatures. These flanges are used across a wide range of applications, particularly in environments where exposure to corrosive elements is a concern. Stainless steel flanges are used in conjunction with stainless steel pipes ATSM A312.
Here are several scenarios where stainless steel flanges are the preferred choice:
1. Corrosive Environments
Stainless steel, with its high chromium content, offers excellent resistance to corrosion caused by a variety of chemical media, including acids, alkalis, and salts. This makes stainless steel flanges ideal for use in chemical processing plants, pulp and paper manufacturing, and wastewater treatment facilities where exposure to corrosive substances is common.
2. Food and Beverage Industry
The non-reactive properties of stainless steel make it suitable for applications involving food and beverage processing. Stainless steel flanges can withstand repeated cleaning and sterilization processes without corroding or leaching into the product, ensuring safety and hygiene.
3. Pharmaceutical and Biotech Industries
Similar to the food and beverage industry, the pharmaceutical and biotech sectors require materials that maintain purity and resist contamination. Stainless steel flanges are used in these industries for their corrosion resistance and ability to maintain cleanliness, crucial for process integrity and product quality.
4. High-Temperature Applications
Certain grades of stainless steel, such as 316, 310, and 321, can withstand high temperatures, making them suitable for heat exchangers, boilers, and exhaust systems. These flanges maintain structural integrity and resist scaling at elevated temperatures.
5. Cryogenic Applications
Some stainless steel alloys, like Austenitic stainless steels, exhibit excellent toughness at cryogenic temperatures, making them suitable for use in applications involving liquefied natural gas (LNG) and other low-temperature processes.
6. Marine and Coastal Applications
The marine environment is particularly harsh, with exposure to saltwater and high humidity. Stainless steel flanges offer superior resistance to saltwater corrosion, making them suitable for shipbuilding, offshore oil rigs, and coastal facilities.
7. Aesthetic Considerations
In architectural and public infrastructure applications where appearance is important, stainless steel flanges offer a clean, modern look in addition to their structural and corrosion-resistant properties.
Key Considerations:
- Grade Selection: Different grades of stainless steel are available, each offering varying levels of corrosion resistance, strength, and temperature tolerance. Selecting the appropriate grade (e.g., 304, 316, 317) based on the specific environmental conditions and media involved is crucial.
- Cost: Stainless steel flanges are generally more expensive than carbon steel or alloy steel flanges. Their use should be justified by the need for corrosion resistance, temperature tolerance, or sanitary conditions.
- Fabrication: Stainless steel requires specific handling and fabrication techniques to avoid issues such as contamination or weld decay. Proper procedures must be followed to ensure the integrity of the flange connection.
Nickel, Chrome, and Moly LME Prices
The key elements that differentiate stainless steel materials for flanges, compared to other grades, are the Nickel (Ni), Chrome (Cr), and Molybdenum content (Mo). The price for these metals fluctuates daily on the London Metal Exchange (Nickel, Moly) and on the ferroalloy market (ferrochrome).
- LME price for Nickel (USD per tonne)
- LME price for Molybdenum (USD per tonne)
- LME price for Copper (USD per tonne)
- Ferrochrome market price (USD per kg.)
CHEMICAL COMPOSITION ASTM A182 F304/F316/F321
ASTM A182 Stainless Steel Flanges Materials Composition, % | |||||||||||
ASTM A182 GRADE | C | Mn | P | S | Si | Ni | Cr | Mo | Nb | Ti | Others |
---|---|---|---|---|---|---|---|---|---|---|---|
F304(1) | 0.08 | 2.0 | 0.045 | 0.030 | 1.0 | 8.0-11.0 | 18.0-20.0 | ||||
F304H | 0.04-0.10 | 2.0 | 0.045 | 0.030 | 1.0 | 8.0-11.0 | 18.0-20.0 | ||||
F304L(1) | 0.030 | 2.0 | 0.045 | 0.030 | 1.0 | 8.0-13.0 | 18.0-20.0 | ||||
F304N(2) | 0.08 | 2.0 | 0.045 | 0.030 | 1.0 | 8.0-10.5 | 18.0-20.0 | ||||
F304LN(2) | 0.030 | 2.0 | 0.045 | 0.030 | 1.0 | 8.0-10.5 | 18.0-20.0 | ||||
F309H | 0.04-0.10 | 2.0 | 0.045 | 0.030 | 1.0 | 12.0-15.0 | 22.0-24.0 | ||||
F310 | 0.25 | 2.0 | 0.045 | 0.030 | 1.0 | 19.0-22.0 | 24.0-26.0 | ||||
F310H | 0.04-0.10 | 2.0 | 0.045 | 0.030 | 1.0 | 19.0-22.0 | 24.0-26.0 | ||||
F310MoLN | 0.030 | 2.0 | 0.030 | 0.015 | 0.40 | 21.0-23.0 | 24.0-26.0 | 2.0-3.0 | N 0.10-0.16 | ||
F316 | 0.08 | 2.0 | 0.045 | 0.030 | 1.0 | 10.0-14.0 | 16.0-18.0 | 2.0-3.0 | |||
F316H | 0.04-0.10 | 2.0 | 0.045 | 0.030 | 1.0 | 10.0-14.0 | 16.0-18.0 | 2.0-3.0 | |||
F316L(1) | 0.030 | 2.0 | 0.045 | 0.030 | 1.0 | 10.0-15.0 | 16.0-18.0 | 2.0-3.0 | |||
F316N(2) | 0.08 | 2.0 | 0.045 | 0.030 | 1.0 | 11.0-14.0 | 16.0-18.0 | 2.0-3.0 | |||
F316LN(2) | 0.030 | 2.0 | 0.045 | 0.030 | 1.0 | 11.0-14.0 | 16.0-18.0 | 2.0-3.0 | |||
F316Ti | 0.08 | 2.0 | 0.045 | 0.030 | 1.0 | 10.0-14.0 | 16.0-18.0 | 2.0-3.0 | (3) | N 0.10 max | |
F317 | 0.08 | 2.0 | 0.045 | 0.030 | 1.0 | 11.0-15.0 | 18.0-20.0 | 3.0-4.0 | |||
F317L | 0.030 | 2.0 | 0.045 | 0.030 | 1.0 | 11.0-15.0 | 18.0-20.0 | 3.0-4.0 | |||
F321 | 0.08 | 2.0 | 0.045 | 0.030 | 1.0 | 9.0-12.0 | 17.0-19.0 | (4) | |||
F321H | 0.04-0.10 | 2.0 | 0.045 | 0.030 | 1.0 | 9.0-12.0 | 17.0-19.0 | (5) | |||
F347 | 0.08 | 2.0 | 0.045 | 0.030 | 1.0 | 9.0-13.0 | 17.0-20.0 | (6) | |||
F347H | 0.04-0.10 | 2.0 | 0.045 | 0.030 | 1.0 | 9.0-13.0 | 17.0-20.0 | (7) | |||
F348 | 0.08 | 2.0 | 0.045 | 0.030 | 1.0 | 9.0-13.0 | 17.0-20.0 | (6) | Co 0.20 Ta 0.10 | ||
F348H | 0.04-0.10 | 2.0 | 0.045 | 0.030 | 1.0 | 9.0-13.0 | 17.0-20.0 | (7) | Co 0.20 Ta 0.10 |
Notes:
- Grades F304, F304L, F316, and F316L shall have a maximum Nitrogen of 0.10%.
- Grades F304N, F316N, F304LN, and F316LN shall have a Nitrogen of 0.10 to 0.16%.
- Grade F316Ti shall have a Titanium content five times above the Carbon plus Nitrogen and not more than 0.70%.
- Grade F321 shall have a Titanium content five times above the Carbon and not more than 0.70%.
- Grade F321H shall have a Titanium content four times above the Carbon and not more than 0.70%.
- Grades F347 and F348 shall have a Niobium content ten times above the Carbon and not more than 1.10%.
- Grades F347H and F348H shall have a Niobium content above than eight times the Carbon and not more than 1.10%.
MECHANICAL PROPERTIES A182 F304/F316/F321
ASTM A182 Grade | Minimum Tensile Strength in MPa | Minimum Yield point in Mpa | Minimum Elongation in % | Minimum Reduction of in min, % |
ASTM A182 F304 | 515 | 205 | 30 | 50 |
ASTM A182 F304L | 485 | 170 | 30 | 50 |
ASTM A182 F316 | 515 | 205 | 30 | 50 |
ASTM A182 F316L | 485 | 170 | 30 | 50 |
ASTM A182 F321 | 515 | 205 | 30 | 50 |
Recommended service for stainless steel flange materials:
MATERIAL | MATERIAL GROUP | RECOMMENDED SERVICE |
---|---|---|
A182-F304 | 18% Cr, 8% Ni Stainless Steel | Corrosive services and atmospheres from -450°F to 1000°F (-268°C to 537°C) |
A182-F316 | 18% Cr, 8% Ni, 2% Mo Stainless Steel | High resistance to corrosion from -450°F to 1000°F (-268°C to 537°C). |
ASTM vs. EN STAINLESS STEEL FLANGE MATERIALS
Flanges Material Grades: Comparison of European and American Standards | ||
---|---|---|
Material number | EN | ASTM |
Stainless Steel Flange Materials | ||
1.4541 X 6 CrNiTi 18 10 | X6CrNiTi18-10 | A 182 Grade F321 |
1.4571 X 6 CrNiMoTi 17 12 2 | X6CrNiMoTi17-12-2 | A 182 Grade F316Ti |
1.4301 X 5 CrNi 18 10 | X5CrNi18-10 | A 182 Grade F304 |
1.4306 X 2 CrNi 19 11 | – | A 182 Grade F304L |
1.4307 – | X2CrNi18-9 | A 182 Grade F304L |
1.4401 X 5 CrNiMo 17 12 2 | X5CrNiMo17-12-2 | A 182 Grade F316 |
1.4404 X 2 CrNiMo 17 13 2 | X2CrNiMo17-12-2 | A 182 Grade F316L |
1.4462 X 2 CrNiMoN 22 5 3 | X2CrNiMoN22-5-3 | A 182 Grade F51 (Duplex) |
1.4529 X 1 NiCrMoCuN 25 20 6 | X1NiCrMoCuN25-20-7 | UNS N 08926 |
1.4539 X 1 NiCrMoCuN 25 20 5 | X1NiCrMoCu25-20-5 | A 182 Grade F904L |
1.4547 – | X1CrNiMoCuN20-18-7 | UNS S 3125 |
DUPLEX FLANGES
USAGE OF DUPLEX/SUPERDUPLEX FLANGES
Duplex and super duplex stainless steel flanges are chosen for their superior strength and exceptional corrosion resistance, especially in harsh environments. These materials combine the best attributes of austenitic (300 series) and ferritic stainless steels, offering higher strength and resistance to pitting and crevice corrosion.
Duplex Flange ASTM A182 UNS S31803 UNS S32205
Duplex/Super duplex steel flanges are used in conjunction with duplex & super duplex steel pipes ATSM A790/928.
Here are specific scenarios where duplex and super duplex flanges are the preferred choice:
1. Aggressive Corrosive Environments
Duplex and super duplex stainless steels have high chromium, molybdenum, and nitrogen content, which contribute to their outstanding resistance to chloride-induced pitting and crevice corrosion. They are ideal for use in environments exposed to saltwater, such as marine applications, offshore oil drilling, and processing plants near coastal areas.
2. High-Strength Requirements
The mechanical strength of duplex and super duplex stainless steels is significantly higher than that of standard austenitic and ferritic stainless steels. This makes them suitable for applications requiring robust flanges that can withstand high pressures and mechanical stress, such as pressure vessels, high-pressure piping systems, and structural applications.
3. Chemical Processing Industries
These materials excel in environments where they are exposed to a wide range of aggressive chemicals and high temperatures. Duplex and super duplex flanges are used in chemical processing plants for piping systems that transport corrosive substances, providing longevity and reliability.
4. Oil and Gas Industry
In the oil and gas sector, duplex and super duplex flanges are utilized for their combination of strength and corrosion resistance. They are particularly valuable in applications such as subsea equipment, offshore platforms, and processing equipment that handle sour gas (high in hydrogen sulfide).
5. Desalination and Water Treatment
The resistance of duplex and super duplex stainless steels to chloride corrosion makes them excellent choices for desalination plants and water treatment facilities, where they can withstand the corrosive effects of high-chloride waters.
6. Pollution Control Equipment
Duplex and super duplex stainless steels are used in flue gas desulfurization systems and other pollution control equipment. Their corrosion resistance is crucial in environments where they are exposed to acidic gases and other corrosive byproducts.
Key Considerations:
- Cost vs. Benefits: While duplex and super duplex stainless steels are more expensive than standard stainless steels, their enhanced properties can offer long-term cost savings through increased durability, reduced maintenance, and longer service life.
- Welding and Fabrication: These materials require careful welding and fabrication techniques to preserve their mechanical and corrosion-resistant properties. Proper procedures, including the use of suitable filler metals and post-weld heat treatment, may be necessary.
- Material Availability: Duplex and super duplex materials are more specialized than standard stainless steels, and their availability in certain forms or sizes may be limited. Planning and sourcing should take this into consideration.
Duplex steel (ASTM A182 2205) is an extremely corrosion-resistant, work-hardenable stainless steel, whose microstructure consists of a mixture of austenite and ferrite phases.
Due to this particular chemical and physical composition, duplex stainless steel UNS S31803 features the properties characteristic of both types of stainless steel materials (ferritic and austenitic).
Generally speaking, duplex stainless steel is way tougher than ferritic stainless steel, has a superior strength than austenitic steels (series 300 and 400), and has superior corrosion resistance when compared to SS304 and SS316 (high intragranular corrosion, also in chloride and sulfide environments).
Whilst austenitic stainless steels are non-magnetic, duplex stainless steel shows magnetic properties.
CHEMICAL COMPOSITION ASTM A182 DUPLEX AND SUPER DUPLEX
% | Duplex 2205 | Super Duplex |
C | 0-0.03 | 0.03 max |
Mn | 2.0 | 1.5 |
Si | 1.0 | 0.8 |
P | 0-0.03 | 0.035 |
S | 0-0.02 | 0.02 |
Cr | 21-23 | 24-26 |
Mo | 2.5-3.5 | 3.0-5.0 |
Ni | 4.5-6.5 | 5.5-8.0 |
N | 0.08-0.2 | 0.2-0.35 |
Cu | – | 0.5-3.0 |
The most widely used grade for Duplex flange is 2205, due to its superior resistance to corrosion and mechanical strength.
The designation “2205” is related to the chemical composition of this material, which features 22% of chromium and 5% of nickel.
Super Duplex flanges show an even superior strength and a higher corrosion resistance than standard duplex steel (and austenitic grades, of course).
The main difference between a duplex and a super duplex grade is the addition of copper to the alloy (in addition to increased amounts of Chromium, Moly, and Nickel).
The addition of copper gives Super Duplex Stainless Steel an improved resistance to hot chlorides and strong reducing acids, like sulphuric acid, compared to a standard Duplex grade.
Whilst UNS S31803, UNS 32205 (duplex) and UNS S32750, UNS S32760 are standard designations, most manufacturers of superalloys attribute proprietary names to these steels (for example UR52N+ is a Usinor/Arcelor Super Duplex steel, Ferralium, Zeron, Sandvik SAF 2205 22Cr, etc).
MECHANICAL PROPERTIES A182 DUPLEX AND SUPER DUPLEX
Mechanical Properties | Duplex 2205 | Super Duplex |
Tensile Strength (in MPa) | 620 | 770 |
Proof Stress 0.2% (in MPa) | 450 | 550 |
A5 Elongation (in %) | 25 | 25 |
Physical Attribute | Duplex 2205 | Super Duplex |
Density (g.cm3) | 7.805 | 7.810 |
Modulus of Elasticity (GPa) | 200 | 205 |
Electrical Resistivity (Ω.m) | 0.085×10-6 | 0.085×10-6 |
Thermal Conductivity (W/m.K) | 19 at 100°C | 17 at 100°C |
Thermal Expansion (m/m.K) | 13.7×10-6 to 100°C | 13.5×10-6 to 200°C |
The significant addition of Chromium in Duplex Steel grades, which protects the alloy against corrosion, is a source of steel embrittlement at temperatures over about 300°C. However, at lower temperatures duplex steels show better ductility properties than ferritic and martensitic stainless steels (they can easily be used at a temperature below -50 C°).
NICKEL ALLOY FLANGES
USAGE OF NICKEL ALLOY FLANGES
Nickel alloy flanges are chosen for their exceptional properties, including high resistance to corrosion, heat, and pressure, making them ideal for severe and demanding environments.
Here are specific scenarios where nickel alloy flanges are the preferred choice:
1. Extreme Corrosion Resistance
Nickel alloys, such as Hastelloy®, Inconel®, Monel®, and Alloy 20, offer superior resistance to a wide range of corrosive environments, including acidic, alkaline, and chloride-containing conditions. They are ideal for chemical processing, petrochemical industries, and applications involving exposure to corrosive substances.
2. High-Temperature Applications
Nickel alloys maintain their strength and resistance at high temperatures, making nickel alloy flanges suitable for heat-treating equipment, furnaces, and in the aerospace industry where high-temperature strength is crucial.
3. Cryogenic Applications
Certain nickel alloys retain their toughness and mechanical properties at extremely low temperatures, making them suitable for liquefied natural gas (LNG) processing, storage, and transportation, as well as other cryogenic applications.
4. Marine and Offshore Applications
The excellent corrosion resistance to seawater and marine environments makes nickel alloy flanges a good choice for shipbuilding, offshore oil and gas platforms, and desalination plants.
5. Pollution Control
Nickel alloys are used in flue gas desulfurization systems and other pollution control equipment due to their resistance to acidic and corrosive gases.
6. Nuclear Power Plants
The ability of certain nickel alloys to withstand nuclear and radioactive environments makes them suitable for use in the construction and maintenance of nuclear reactors, especially in systems that handle radioactive materials or coolants.
Key Considerations:
- Cost: Nickel alloy flanges are generally more expensive than carbon steel, stainless steel, or even some duplex/super duplex stainless steel flanges. Their use should be justified by the specific demands of the application that cannot be met by less expensive materials. Their content in terms of Moly, Nickel, and other high grade materials makes the cost per kilogram very high (>50 $/kg)
- Fabrication and Welding: Nickel alloys require specific welding and fabrication techniques to ensure the integrity of the flange connections. Special attention to the selection of filler materials, welding parameters, and post-weld heat treatment is necessary to avoid issues such as cracking or corrosion.
- Availability: Some nickel alloys may have limited availability or longer lead times compared to more common materials, which could impact project schedules.
ASTM SPECIFICATIONS FOR NICKEL ALLOY FLANGES
ASTM B160 | Nickel 200 Flange |
ASTM B166 | Inconel 600 Flange |
ASTM B564 | Inconel 625 Flange |
ASTM B425 | Incoloy 800 Flange |
ASTM B564 | Incoloy 825 Flange |
ASTM B564 | Monel K400 Flange |
ASTM B564 | Hastelloy C276 Flange |
CHEMICAL COMPOSITION NICKEL-ALLOY FLANGES
Superalloy Grade | UNS Equivalent | Alloy Composition | |||||||||
C | Mn | S | Si | Cr | Ni | Mo | Cu | Ti | Fe | ||
Nickel 200 | N02200 | 0.08 | 0.18 | 0.005 | 0.18 | … | 99.5(a) | … | 0.13 | … | 0.2 |
Nickel 201 | N02201 | 0.01 | 0.18 | 0.005 | 0.18 | … | 99.6(a) | … | 0.13 | … | 0.2 |
Monel 400 | N04400 | 0.15 | 1 | 0.012 | 0.25 | … | 66.5(a) | … | 31.5 | … | 1.25 |
Monel K-500 | N05500 | 0.13 | 0.75 | 0.005 | 0.25 | … | 66.5(a) | … | 29.5 | 0.6 | 1 |
Hastelloy B | N10665 | 0.05 max | 1 | … | 1 | 1 | 61 | 28 | … | … | 5 |
Hastelloy D | – | 0.12 | 0.9 | … | 9.25 | 1 | 82 | … | 3 | … | 2 |
Inconel 600 | N06600 | 0.08 | 0.5 | 0.008 | 0.25 | 15.5 | 76.0(a) | … | 0.25 | … | 8 |
Inconel 800 | N08800 | 0.05 | 0.75 | 0.008 | 0.5 | 21 | 32.5 | … | 0.38 | 0.38 | 46 |
Hastelloy C-276 | N10276 | 0.01 | 0.5 | 0.02 | 0.03 | 15.5 | 57 | 16 | … | … | 5.5 |
Inconel 625 | N06025 | 0.05 | 0.25 | 0.008 | 0.25 | 21.5 | 61.0(a) | 9 | … | 0.2 | 2.5 |
Incoloy 825 | N08825 | 0.03 | 0.5 | 0.015 | 0.25 | 21.5 | 42 | 3 | 2.25 | 0.9 | 30 |
Hastelloy G | N06030 | 0.03 | 1.5 | 0.02 | 0.5 | 22.25 | 44 | 6.5 | 2 | … | 19.5 |
20Cb-3 | N08020 | 0.04 | 1 | 0.02 | 0.5 | 20 | 34 | 2.5 | 3.5 | … | … |
MECHANICAL PROPERTIES NICKEL-ALLOY FLANGES
Superalloy grade | UNS Equivalent | Yield Strength (in ksi) | Tensile Strength (in ksi) | Elongation % | Rockwell | Brinell |
Nickel 200 | N02200 | 15 | 55 | 35 | – | 90-120 |
Nickel 201 | N02201 | 12 | 50 | 35 | – | 90-120 |
Monel 400 | N04400 | 25 | 70 | 35 | – | 110-149 |
Monel K-500 | N05500 | 100 | 140 | 17 | – | 265-346 |
Hastelloy B-2 | N10665 | 51 | 110 | 40 | C22 | – |
Hastelloy D-205 | – | 49 | 114 | 57 | C30-39 | – |
Inconel 600 | N06600 | 30 | 80 | 35 | – | 120-170 |
Inconel 800 | N08800 | 30 | 75 | 30 | – | 120-184 |
Hastelloy C-276 | N10276 | 60 | 115 | 50 | 184 | |
Inconel 625 | N06025 | 39 | 98 | 30 | – | 180 |
Incoloy 825 | N08825 | 35 | 85 | 30 | – | 120-180 |
Hastelloy G-30 | N06030 | 51 | 100 | 56 | – | – |
20Cb-3 | N08020 | 35 | 80 | 30 | B84-90 | 160 |
7 Responses
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can you please tell me equivalent material for A694 F60 (which should have almost similar is chemical composition and yield strength.)
Thank you.
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