/ Carbon Steel Flanges

Carbon steel flanges

Dimensions: 1/2”, 2”, 3”, 4”, 6”, 8”, 10”, Customized up to 60”
Material: ASTM A105, A350 LF2, A694 F42, F52, F60, F65, F70
Thickness: Schedule 10(S) to SCH 160
Standard: ASME, ANSI, DIN, JIS, EN, GOST etc.
Class Range: Class 150 to 2500 (# or LB), PN 2.5 to PN 250
Flange Face Type: RF, FF, MFM, TG, RTJ
Connection: Butt Weld, Slip On, Socket Weld, Threaded or Lap Joint
Manufacturing Process: Forging

Carbon steel flanges provide high mechanical strength, reliable sealing performance, and excellent pressure resistance. They are suitable for general industrial, high-pressure, and high-temperature piping systems.

They comply with standards such as ANSI/ASME B16.5, ASME B16.47, EN 1092-1, DIN, JIS, and GOST. Common materials include ASTM A105, A350 LF2, and A694 grades.

Widely used in oil and gas, petrochemical, power generation, water treatment, construction, and industrial piping systems.
Product Description

Carbon steel flanges and end flange connectors are essentially made of carbon steel. Common standards include ASTM A694, ASTM A350, ASTM A105N (SA105N), MSS SP-44, DIN 2533. The pressure ratings available are from Class 150 to Class 2500. Flanges made from carbon steel contain between 0.05% and 2.1% carbon by weight in their chemical composition. The carbon content of A105 can vary, with the maximum permissible percentage composition being 0.35.

As the carbon content increases, the steel is hardened and increases in strength through heat treatment processes. Many common treatment techniques in the industry are quenching, tempering, and normalizing. As carbon steel is treated, it becomes less ductile and less brittle. This makes forming and welding slightly more difficult, but it is generally considered a worthwhile trade-off in field service to create the necessary weld seal.

Our Supply Range

Dimensions: 1/2”, 2”, 3”, 4”, 6”, 8”, 10”, Customized  up to 60”

Material: Carbon Steel

Thickness: SCH.10, 20, 30, 40, 80, 120, 160, STD, XS, XXS.

Standard: ASME, ANSI, DIN, JIS, EN , etc

Class Range: Class 150, Class 300, Class 400, Class 600, Class 900, Class 1500 & Class 2500

Pressure : DIN PN6, PN10, PN16, PN25, PN40, PN64, PN100, PN160

Flange Face Type: RF, FF, MFM, TG, RJ

Manufacturing Process: Forging

We provide Carbon steel flanges of various standards, such as ASME/ANSI B16.47, B16.5, EN standards, etc. We also provide customized Carbon steel flanges products.

Our stock range of Carbon steel flanges

Carbon Steel Flanges Dimensions

NPS O T1 R X No.2/Dia.of
Holes
Bolt Circle
Dia
L21 H B23 L B r L34 B3 D
1/2 3.50 0.44 1.38 1.19 4-0.62 2.38 1.88 0.84 0.62 0.62 0.88 0.12 0.62 0.90 0.38
3/4 3.88 0.50 1.69 1.50 4-0.62 2.75 2.06 1.05 0.82 0.62 1.09 0.12 0.62 1.11 0.44
4.25 0.56 2.00 1.94 4-0.62 3.12 2.19 1.32 1.05 0.69 1.36 012 0.69 1.38 0.50
1-1/4 4.62 0.62 2.50 2.31 4-0.62 3.50 2.25 1.66 1.38 0.81 1.70 0.19 0.81 1.72 0.58
2-1/2 7.00 0.88 4.12 3.56 4-0.75 6.50 2.75 2.88 2.47 1.12 2.94 0.31 1.12 2.97 0.75
7.50 0.94 5.00 4.25 4-0.75 6.00 2.75 3.50 3.07 1.19 3.57 0.38 1.19 3.60 0.81
3-1/2 8.50 0.94 5.50 4.81 8-0.75 7.00 2.81 4.00 3.55 1.25 4.07 0.38 1.25 4.10 0.88
9.00 0.94 6.19 5.31 8-0.75 7.50 3.00 4.50 4.03 1.31 4.57 0.44 1.31 4.80 0.94
10.00 0.94 7.31 6.44 8-0.88 8.50 3.50 5.56 5.05 1.44 5.66 0.44 1.44 6.69 0.94
11.00 1.00 8.50 7.56 8-0.88 9.50 3.50 6.63 6.07 1.56 6.72 0.50 1.56 6.75 1.06
13.50 1.12 10.62 9.69 8-0.88 11.75 4.00 8.63 7.98 1.75 8.72 0.50 1.75 8.75 1.25
10  16.00 1.19 12.75 12.00 12-1.00 14.25 4.00 10.75 10.02 1.94 10.88 0.50 1.94 10.92 1.31
12  19.00 1.25 15.00 14.38 12-1.00 17.00 4.50 12.75 12.00 2.19 12.88 0.50 2.19 12.92 1.56
14  21.00 1.38 16.25 15.75 12-1.12 18.75 5.00 14.00 13.25 2.25 14.14 0.50 3.12 14.18 1.63
16  23.50 1.44 18.50 18.00 16-1.12 21.25 5.00 16.00 15.25 2.50 16.16 0.50 3.44 16.19 1.75
18  25.00 1.56 21.00 19.88 16-1.25 22.75 5.50 18.00 17.25 2.69 18.18 0.50 3.81 18.20 1.94
20  27.50 1.69 23.00 22.00 20-1.25 25.00 5.69 20.00 19.25 2.88 20.20 0.50 4.06 20.25 2.13
22  29.50 1.81 25.25 24.25 20-1.38 27.25 5.88 22.00 21.25 3.13 22.22 0.50 4.25 22.25 2.38
24  32.00 1.88 27.25 26.12 20-1.38 29.50 6.00 24.00 23.25 3.25 24.25 0.50 4.38 24.25 2.50

Carbon Steel Flanges Standards / Specifications

Standards  Types Pressure Class
ASME/ANSI B 16.5 Threaded Flange, Ring Type Joint Flange, Blind Flange, Welding Neck Flange, Slip on Flange,High Hub Blind Flange, Socket Weld Flange, Lap Joint Flange 150, 300, 400, 600, 900, 1500, 2500
ASME/ANSI B 16.47 Blind Flange [Series A & B], Welding Neck Flange 75, 150, 300, 400, 600, 900
ASME/ANSI B 16.36 Slip on Flange, Welding Neck Flange, Threaded Flange 300, 400, 600, 900, 1500, 2500
DIN FLANGES DIN 2527, 2566, 2573, 2576, 2641,2642, 2655, 2656, 2627, 2628, 2629, 2631, 2632, 2633, 2634, 2635, 2636, 2637,2638, 2673 PN 6 TO PN 100
BS 4504 SEC 3.1 Welding Neck Flange, Hubbed Slip on Flange, Hubbed Threaded Flange, Lapped Pipe End Flange, Plate Flange, Loose Plate Flange, Loose Plate With Weld Neck Flange, Blank Flange PN 2.5 TO PN 40
BS 4504[PART 1] Plate Flange, Loose Plate With Weld On Plate Collar, Blank Flange, Welding Neck Flange, Hubbed Slip-On Hubbed Threaded PN 2.5 TO PN 400
BS 1560 BOSS Blind Flange, Screwed Boss Flange, Lapped FlangeWelding Neck Flange, Socket Welding Flange, Slip-On Flange 150, 300, 400, 600, 900, 1500, 2500

carbon steel Flanges pressure rating(A105 / A350 LF2 / A350 LF3 / A350 LF6)

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

Advantages of Carbon Steel Flanges

High Strength and Durability

Carbon steel flanges provide excellent mechanical strength and reliable performance in high-pressure industrial piping systems.

Cost-Effective Solution

Compared with stainless steel and alloy steel flanges, carbon steel flanges offer a more economical solution for general industrial applications.

Excellent Pressure Resistance

Their forged structure withstands high internal pressure and external loads, helping maintain secure and stable pipe connections.

Wide Range of Specifications

Carbon steel flanges are available in various sizes, pressure classes, standards, facing types, and connection designs to meet different project requirements.

Good Weldability and Machinability

Carbon steel materials are easy to weld and machine, making installation, manufacturing, and maintenance more convenient.

Long Service Life

With proper surface treatment and maintenance, carbon steel flanges provide dependable sealing performance and a long operational life.

Advantages of Weld Neck Flange

Applications

Oil and Gas Industry

Carbon steel flanges are widely used in oil and gas transmission pipelines, refineries, and processing facilities. Their high strength and pressure resistance provide reliable connections in demanding operating conditions.

Power Generation

Carbon steel flanges are commonly installed in steam, cooling water, and auxiliary piping systems. They offer stable performance under high-temperature and high-pressure service conditions.

Chemical Processing

Carbon steel flanges are suitable for transporting non-corrosive and mildly corrosive fluids in chemical plants. Their strong structure and dependable sealing help reduce leakage risks.

Petrochemical Plants

Petrochemical facilities use carbon steel flanges in process pipelines, storage systems, and pressure equipment. They provide reliable performance under changing pressure and temperature conditions.

Water Treatment

Carbon steel flanges are used in municipal water supply, wastewater treatment, pumping stations, and industrial water systems. Protective coatings can be applied to improve corrosion resistance.

Construction and Industrial Piping

Carbon steel flanges are widely used in industrial plants, heating systems, fire protection pipelines, and mechanical equipment. They are cost-effective, durable, and easy to manufacture in various sizes and pressure classes.

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PRODUCTION PROCESS

Our carbon steel flanges are manufactured through a controlled production process from raw material inspection to final shipment. Every step is traceable through material identification, process records, dimensional inspection, heat treatment records, and final quality control.

This production process ensures stable quality, accurate dimensions, reliable sealing performance, and compliance with project specifications.

PRODUCTION PROCESS

Why Choose Us

Comprehensive Fabricating Capabilities

We coordinated manufacturing, warm treatment, machining, testing, and bundling beneath one roof. You get steady quality control all through the whole generation process.

International Standards Compliance

Our products meet ASME, EN, DIN, JIS, and GOST standards. You can specify the exact requirements for your regional applications with confidence.

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Extensive Estimate Run

From DN15 to DN4000, we cover essentially all mechanical necessities. Your ventures advantage from single-source obtainment convenience.

Quality Affirmation

Progressed testing offices guarantee each product meets details. You get certified items with total traceability documentation.

Global Trade Involvement

Our items serve markets over Europe and the Americas. You work with demonstrated providers who get it worldwide quality expectations.

Competitive Preferences

Prevalent quality, competitive estimating, secure bundling, and quick conveyance combine to back your extend timelines and budgets.

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Why Choose Us

COMPANY PROFILE

Shanxi HongKai Forging Co., Ltd. Was located in Dingxiang County, known as the "Hometown of Forging Flanges" in Shanxi Province, which is part of Chinese energy and heavy chemical industrial base. The area boasts convenient transportation, abundant coal and power resources, fast communication, and an excellent environment. The company has three big workshops in total. We have 20 years experiences in flanges and forging industry, we can produce 20, 000MT per year. We have strength capacity to produce the flange in every process.


Along with capabilities in forging and heat treatment, integrated production capabilities including machining, physical and chemical testing, surface treatment, and packaging and shipment. Possessing solid technical expertise, advanced production processes, and a complete quality inspection, reliable after-sales service, for customers worldwide and domestically multiple clients have provided a solid foundation for collaboration.

The flanges manufactured by our company comply with the American standard ASME B16.5/B16.47, European Standard EN1092-1, German Standard DIN, Japanese Standard JIS, Russian

Factory photographs
 
Factory photographs
 
Factory photographs
 
Factory photographs
 
Factory photographs
 
Factory photographs

FAQ 

What are carbon steel flanges?

Carbon steel flanges are forged or machined pipe connection components used to connect pipes, valves, pumps, fittings, and pressure equipment. They provide a reliable sealing surface and allow easy installation, inspection, maintenance, and disassembly of piping systems.

What materials are commonly used for carbon steel flanges?

Common carbon steel flange materials include ASTM A105, ASTM A105N, ASTM A350 LF2, ASTM A694 F42/F52/F60/F65/F70, and other project-specified carbon steel grades. ASTM A105 is widely used for forged carbon steel flanges in general pressure piping systems, while ASTM A350 LF2 is often selected for low-temperature service and ASTM A694 is used for high-pressure pipeline applications.

What standards are available for carbon steel flanges?

Carbon steel flanges can be manufactured according to ASME / ANSI, EN, DIN, JIS, BS, GOST, AWWA, and other international standards. Common standards include ASME B16.5 for flanges from NPS 1/2" to 24" and ASME B16.47 for large-diameter flanges from NPS 26" to 60".

What types of carbon steel flanges do you supply?

We supply many types of carbon steel flanges, including Weld Neck Flanges, Slip On Flanges, Blind Flanges, Socket Weld Flanges, Threaded Flanges, Lap Joint Flanges, Plate Flanges, Orifice Flanges, Reducing Flanges, Long Weld Neck Flanges, Spade Flanges, Spacer Rings, and custom forged flanges.

What pressure classes are available?

Carbon steel flanges are available in different pressure classes, such as Class 150, 300, 400, 600, 900, 1500, and 2500 for ASME B16.5 flanges. Large-diameter ASME B16.47 flanges are commonly available in Class 75, 150, 300, 400, 600, and 900. The actual pressure capacity depends on material grade, temperature, size, and applicable standard.

What sealing face types can carbon steel flanges have?

Carbon steel flanges can be supplied with different sealing faces, including Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), Tongue and Groove, and Male and Female faces. RF and FF are commonly used in general piping systems, while RTJ is often used for high-pressure and high-temperature service.

Where are carbon steel flanges used?

Carbon steel flanges are widely used in oil and gas, petrochemical plants, power generation, water treatment, shipbuilding, chemical processing, mining, HVAC, and general industrial piping systems. They are suitable for connecting pipelines that require strength, durability, and reliable sealing performance.

What is the difference between ASTM A105 and ASTM A350 LF2 flanges?

ASTM A105 flanges are commonly used for general carbon steel pressure piping applications at ambient and high temperatures. ASTM A350 LF2 flanges are designed for low-temperature service and provide better impact toughness in cold environments. The right material should be selected according to operating temperature, pressure, and project specifications.

What is the difference between ASME B16.5 and ASME B16.47 carbon steel flanges?

ASME B16.5 covers pipe flanges and flanged fittings from NPS 1/2" to 24", while ASME B16.47 covers large-diameter steel flanges from NPS 26" to 60". ASME B16.47 is mainly used for large-diameter weld neck flanges and blind flanges in pipeline and heavy industrial applications.

Can carbon steel flanges be customized?

Yes. Carbon steel flanges can be customized according to drawings, samples, project standards, material requirements, surface treatment, drilling patterns, thickness, bore size, facing type, and special dimensions. Custom forged flanges are available for non-standard piping systems and special engineering projects.

What surface treatments are available for carbon steel flanges?

Common surface treatments include black paint, anti-rust oil, yellow paint, hot-dip galvanizing, cold galvanizing, epoxy coating, and other protective coatings. The surface treatment can be selected according to storage conditions, transportation requirements, and the working environment.

Contact Us

Quality Carbon steel flanges solutions ensure your piping systems operate safely and efficiently for years to come.Ready to discuss your product requirements? Contact our technical team at kevin.zhao@hkflange.com for expert guidance and competitive pricing.

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