Carbon steel flanges

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

Weld Neck Flanges

Blind Flanges

Threaded Flanges

Socket Weld Flanges

Lap Joint Flanges

Slip-On 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
1	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
3	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
4	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
5	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
6	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
8	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

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.

PRODUCTION PROCESS

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.