What are carbon steel flanges and its Specification?
Introduction to Carbon Steel Flanges
Carbon steel flanges are integral components in piping systems across various industries. These versatile fittings serve the crucial function of connecting pipes, valves, pumps, and other equipment to form a complete pipeline system. Understanding their specifications is essential for selecting the right flanges for specific applications. Carbon steel flanges are forged or cast fittings made primarily from carbon steel, which is an alloy of iron and carbon. The carbon content in these flanges typically ranges from 0.05% to 2.1%, making them durable, strong, and suitable for a wide range of operating conditions. They are widely preferred in industries such as oil and gas, petrochemicals, power generation, and water treatment.
Types of Carbon Steel Flanges
Carbon Steel Weld Neck Flange (WN)
Known for its high strength, this flange is ideal for high-pressure applications. The neck design enables easy welding to pipes and ensures a smooth transition for fluid flow.
Carbon Steel Slip-On Flange (SO)
This flange is placed over the pipe and welded both inside and outside. It is cost-effective and easy to install but is better suited for low-pressure applications.
Carbon Steel Blind Flange (BL)
Blind flanges are used to close off the end of a pipeline or vessel. They are often used when no further connections are needed or to seal off temporary connections.
Carbon Steel Socket Weld Flange (SW)
Primarily used for smaller pipes, this flange is attached by welding the pipe directly into the socket.
Carbon Steel Threaded Flange (TH)
This flange has internal threads that allow it to be screwed onto the pipe, making it a good choice when welding is not feasible.
Carbon Steel Lap Joint Flange (LJ)
These flanges are used with a lap joint stub end and are ideal for applications requiring frequent disassembly, such as maintenance.
Specifications of Carbon Steel Flanges:
Material
1. ASTM A105
- Description: Standard specification for carbon steel forged flanges, fittings, valves, and parts for high-temperature service.
- Applications: Oil & gas, petrochemical, power generation, and shipbuilding industries.
- Properties: Excellent toughness, high strength, and good weldability.
2. ASTM A350 LF2
- Description: Low-temperature carbon steel forged flanges.
- Applications: Suitable for low-temperature services like cryogenic applications.
- Properties: High impact resistance and excellent toughness at sub-zero temperatures.
3. ASTM A694
- Description: High-strength carbon steel flanges for high-pressure transmission services.
- Grades: F42, F46, F52, F56, F60, F65, and F70.
- Applications: Ideal for oil & gas pipelines and high-pressure systems.
- Properties: High strength, good weldability, and superior performance in demanding environments.
4. ASTM A516
- Description: Pressure vessel quality steel used for flange manufacturing.
- Applications: Boilers, pressure vessels, and heat exchangers.
- Grades: 55, 60, 65, and 70.
- Properties: Good weldability and excellent resistance to corrosion and wear.
5. ASTM A181
- Description: Standard specification for carbon steel forgings for general-purpose piping.
- Applications: Suitable for low and moderate-pressure services.
- Grades: Class 60 and Class 70.
- Properties: High machinability and tensile strength.
6. ASTM A182
- Description: Alloy and stainless steel forged flanges, fittings, and valves, including carbon steel grades for specific applications.
- Applications: High-temperature and high-pressure services.
- Grades: Typically covers various alloying elements for improved properties.
Common Standards for Carbon Steel Flanges
- ASME B16.5: Pipe flanges and flanged fittings up to 24 inches.
- ASME B16.47: Large-diameter steel flanges (Series A & B).
- MSS SP-44: Steel pipeline flanges.
- API 605: Large-diameter carbon steel flanges.
Carbon Steel Pressure rating
| Pressure (psi) | |||||||
|---|---|---|---|---|---|---|---|
| Temperature (𐩑F) | 150# | 300# | 400# | 600# | 900# | 1500# | 2500# |
| -20 to 100 | 285 | 740 | 985 | 1480 | 2220 | 3705 | 6170 |
| 200 | 260 | 680 | 905 | 1360 | 2035 | 3395 | 5655 |
| 300 | 230 | 655 | 870 | 1310 | 1965 | 3270 | 5450 |
| 400 | 200 | 635 | 845 | 1265 | 1900 | 3170 | 5280 |
| 500 | 170 | 605 | 805 | 1205 | 1810 | 3015 | 5025 |
| 600 | 140 | 570 | 755 | 1135 | 1705 | 2840 | 4730 |
| 650 | 125 | 550 | 730 | 1100 | 1650 | 2745 | 4575 |
| 700 | 110 | 530 | 710 | 1060 | 1590 | 2655 | 4425 |
| 750 | 95 | 505 | 675 | 1015 | 1520 | 2535 | 4230 |
| 800 | 80 | 410 | 550 | 825 | 1235 | 2055 | 3430 |
| 850 | 65 | 320 | 425 | 640 | 955 | 1595 | 2655 |
| 900 | 50 | 230 | 305 | 460 | 690 | 1150 | 1915 |
| 950 | 35 | 135 | 185 | 275 | 410 | 685 | 1145 |
| 1000 | 20 | 85 | 115 | 170 | 255 | 430 | 715 |
Carbon Steel Flange Diamnesion
| Nom. Pipe Size | O | T | TJ | R | X | #/Dia of Holesa | Bolt Circle Dia | B | B2b | B3 | H | L | L2 | L3c | r | D | Thr |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ½ | 3.50 | 0.38 | 0.44 | 1.38 | 1.19 | 4-0.62 | 2.38 | 0.88 | 0.62 | 0.90 | 0.84 | 0.56 | 1.81 | 0.62 | 0.12 | 0.38 | 0.62 |
| ¾ | 3.88 | 0.44 | 0.50 | 1.69 | 1.50 | 4-0.62 | 2.75 | 1.09 | 0.82 | 1.11 | 1.05 | 0.56 | 2.00 | 0.62 | 0.12 | 0.44 | 0.62 |
| 1 | 4.25 | 0.50 | 0.56 | 2.00 | 1.94 | 4-0.62 | 3.12 | 1.36 | 1.05 | 1.38 | 1.32 | 0.62 | 2.12 | 0.69 | 0.12 | 0.50 | 0.69 |
| 1¼ | 4.62 | 0.56 | 0.62 | 2.50 | 2.31 | 4-0.62 | 3.50 | 1.70 | 1.38 | 1.72 | 1.66 | 0.75 | 2.19 | 0.81 | 0.19 | 0.56 | 0.81 |
| 1½ | 5.00 | 0.62 | 0.69 | 2.88 | 2.56 | 4-0.62 | 3.88 | 1.95 | 1.61 | 1.97 | 1.90 | 0.81 | 2.38 | 0.88 | 0.25 | 0.62 | 0.88 |
| 2 | 6.00 | 0.69 | 0.75 | 3.62 | 3.06 | 4-0.75 | 4.75 | 2.44 | 2.07 | 2.46 | 2.38 | 0.94 | 2.44 | 1.00 | 0.31 | 0.69 | 1.00 |
| 2½ | 7.00 | 0.81 | 0.88 | 4.12 | 3.56 | 4-0.75 | 5.50 | 2.94 | 2.47 | 2.97 | 2.88 | 1.06 | 2.69 | 1.12 | 0.31 | 0.75 | 1.12 |
| 3 | 7.50 | 0.88 | 0.94 | 5.00 | 4.25 | 4-0.75 | 6.00 | 3.57 | 3.07 | 3.60 | 3.50 | 1.12 | 2.69 | 1.19 | 0.38 | 0.81 | 1.19 |
| 3½ | 8.50 | 0.88 | 0.94 | 5.50 | 4.81 | 8-0.75 | 7.00 | 4.07 | 3.55 | 4.10 | 4.00 | 1.19 | 2.75 | 1.25 | 0.38 | 0.88 | 1.25 |
| 4 | 9.00 | 0.88 | 0.94 | 6.19 | 5.31 | 8-0.75 | 7.50 | 4.57 | 4.03 | 4.60 | 4.50 | 1.25 | 2.94 | 1.31 | 0.44 | 0.94 | 1.31 |
| 5 | 10.00 | 0.88 | 0.94 | 7.31 | 6.44 | 8-0.88 | 8.50 | 5.66 | 5.05 | 5.69 | 5.56 | 1.38 | 3.44 | 1.44 | 0.44 | 0.94 | 1.44 |
| 6 | 11.00 | 0.94 | 1.00 | 8.50 | 7.56 | 8-0.88 | 9.50 | 6.72 | 6.07 | 6.75 | 6.63 | 1.50 | 3.44 | 1.56 | 0.50 | 1.06 | 1.56 |
| 8 | 13.50 | 1.06 | 1.12 | 10.62 | 9.69 | 8-0.88 | 11.75 | 8.72 | 7.98 | 8.75 | 8.63 | 1.69 | 3.94 | 1.75 | 0.50 | 1.25 | 1.75 |
| 10 | 16.00 | 1.12 | 1.19 | 12.75 | 12.00 | 12-1.00 | 14.25 | 10.88 | 10.02 | 10.92 | 10.75 | 1.88 | 3.94 | 1.94 | 0.50 | 1.31 | 1.94 |
| 12 | 19.00 | 1.19 | 1.25 | 15.00 | 14.38 | 12-1.00 | 17.00 | 12.88 | 12.00 | 12.92 | 12.75 | 2.12 | 4.44 | 2.19 | 0.50 | 1.56 | 2.19 |
| 14 | 21.00 | 1.31 | 1.38 | 16.25 | 15.75 | 12-1.12 | 18.75 | 14.14 | 13.25 | 14.18 | 14.00 | 2.19 | 4.94 | 3.12 | 0.50 | 1.63 | 2.25 |
| 16 | 23.50 | 1.38 | 1.44 | 18.50 | 18.00 | 16-1.12 | 21.25 | 16.16 | 15.25 | 16.19 | 16.00 | 2.44 | 4.94 | 3.44 | 0.50 | 1.75 | 2.50 |
| 18 | 25.00 | 1.50 | 1.56 | 21.00 | 19.88 | 16-1.25 | 22.75 | 18.18 | 17.25 | 18.20 | 18.00 | 2.62 | 5.44 | 3.81 | 0.50 | 1.94 | 2.69 |
| 20 | 27.50 | 1.62 | 1.69 | 23.00 | 22.00 | 20-1.25 | 25.00 | 20.20 | 19.25 | 20.25 | 20.00 | 2.81 | 5.62 | 4.06 | 0.50 | 2.13 | 2.88 |
| 22 | 29.50 | 1.75 | 1.81 | 25.25 | 24.25 | 20-1.38 | 27.25 | 22.22 | 21.25 | 22.25 | 22.00 | 3.07 | 5.82 | 4.25 | 0.50 | 2.38 | 3.13 |
| 24 | 32.00 | 1.81 | 1.88 | 27.25 | 26.12 | 20-1.38 | 29.50 | 24.25 | 23.25 | 24.25 | 24.00 | 3.19 | 5.94 | 4.38 | 0.50 | 2.50 | 3.25 |
Face Type
1. Raised Face (RF)
- Description: The most common face type, where the gasket sits on a raised surface around the bore of the flange.
- Features:
- Height of the raised face is typically:
- 1/16 inch for flanges up to 400 lbs.
- 1/4 inch for flanges rated 400 lbs and above.
- Allows for better gasket compression.
- Height of the raised face is typically:
- Applications: Widely used in industries like oil & gas, petrochemical, and power generation.
2. Flat Face (FF)
- Description: The whole surface of the flange is flat, allowing full contact with the gasket.
- Features:
- Primarily used with flat gaskets.
- Prevents bending or stress transfer when bolted to non-metallic or low-strength components.
- Applications: Common in low-pressure, low-temperature systems, such as water pipelines
3. Ring Type Joint (RTJ)
- Description: Features a grooved surface where a metallic ring gasket fits for a high-pressure seal.
- Features:
- Provides a metal-to-metal seal.
- Ideal for high-pressure (Class 600 and above) and high-temperature applications.
- Prevents leaks in critical systems.
- Applications: Oil & gas exploration, refining, and chemical processing.
Finishing
1. Machined Finish
- Description: The flange surface is precision-machined to a specific roughness for gasket compatibility.
- Types of Machined Finishes:
- Smooth Finish: Fine surface with minimal roughness, used for soft gaskets.
- Stock Finish: Standard finish with a spiral or concentric groove, typically for raised face flanges.
- Serrated Finish: A grooved surface with either concentric or spiral patterns to improve gasket grip.
- Applications: Standard industrial applications, including oil & gas and water systems.
2. Galvanized Finish
- Description: A layer of zinc is applied to protect the flange from corrosion.
- Types:
- Hot-Dip Galvanization: The flange is submerged in molten zinc, providing a thick, durable coating.
- Electro-Galvanization: A thinner zinc coating is applied using an electrochemical process.
- Applications: Outdoor or corrosive environments like pipelines and construction.
3. Black Oxide Finish
- Description: A chemical coating that provides mild corrosion resistance and an aesthetically pleasing black finish.
- Features:
- Prevents rust in low-moisture environments.
- Cost-effective and primarily used for indoor applications.
- Applications: General-purpose and aesthetic applications.
4. Anti-Rust Oil Coating
- Description: A temporary protective layer applied to prevent rust during storage and transportation.
- Features:
- Easy to remove before installation.
- Inexpensive and effective for short-term corrosion protection.
- Applications: Ideal for flanges stored in controlled environments or used in mild conditions.
5. Painted Finish
- Description: Carbon steel flanges are coated with industrial-grade paint to prevent corrosion and improve appearance.
- Types:
- Epoxy Paint: Offers excellent resistance to chemicals and weather.
- Oil-Based Paint: Used for non-critical applications.
- Applications: Piping systems in construction and industrial plants.
6. Phosphate Coating (Parkerizing)
- Description: A chemical treatment creates a protective layer of phosphate crystals on the surface.
- Features:
- Enhances corrosion resistance and provides a base for additional coatings or painting.
- Applications: Used in moderately corrosive environments.
7. Pickling and Passivation
- Description: The flange is treated with acid solutions to remove rust, scale, and other impurities, leaving a clean, smooth surface.
- Features:
- Enhances resistance to corrosion and scaling.
- Prepares the surface for subsequent coatings.
- Applications: Chemical and petrochemical industries.
8. Powder Coating
- Description: A dry powder is electrostatically applied and baked to form a hard, protective coating.
- Features:
- Durable, scratch-resistant, and corrosion-resistant.
- Available in various colors for aesthetic or identification purposes.
- Applications: Industrial and decorative applications.
9. Chrome Plating
- Description: A thin layer of chromium is electroplated onto the flange surface.
- Features:
- Enhances corrosion resistance and provides a shiny finish.
- Improves wear resistance.
- Applications: High-visibility or decorative applications, and environments requiring enhanced durability.
10. Sandblasted Finish
- Description: The surface is blasted with abrasive materials to create a rough texture.
- Features:
- Removes rust, mill scale, and other contaminants.
- Prepares the surface for painting or coating.
- Applications: Used prior to applying protective coatings.
Tolerance
| Flange Type | Tolerance Type | Standard Tolerance |
|---|---|---|
| Weld Neck | Hub Length, Bevel Angle | ±0.03 inches, ±2° |
| Slip-On | Bore Diameter, Thickness | ±0.02 inches, ±0.06 inches |
| Blind | Thickness, Flatness | ±0.06 inches, 0.1-0.5 mm flatness |
| Threaded | Thread Alignment | Per ASME B1.20.1 standards |
| Socket Weld | Socket Depth, Bore | ±0.03 inches, ±0.02 inches |
| Lap Joint | Bolt Hole, Outer Diameter | ±0.03 inches, ±0.06 inches |
| Ring Type Joint | Groove Dimensions | ±0.005 inches |
Appliaction
1. Oil & Gas Industry
2. Petrochemical Industry
3. Power Generation
4. Water Treatment
5. Construction and Infrastructure
6. Food and Beverage Industry
7. Marine and Offshore Applications
8. Mining and Mineral Processing
9. Automotive Industry
10. Pulp and Paper Industry
11. Pharmaceutical and Biotechnology Industries
Conclusion:
Carbon steel flanges are indispensable components in piping systems, providing reliable connections for fluid and gas transmission across diverse industries. Understanding their specifications, including material grade, pressure ratings, dimensional standards, and types, is crucial for selecting the appropriate flanges for specific applications. By adhering to industry standards and best practices, engineers and procurement professionals can ensure the optimal performance and integrity of their piping systems.
Contact Emirerri Steel Manufacturer one of the best Stainless Steel Pipe Fitting Manufacturer