Flanges Suppliers

Robust Special Metals is a trusted supplier of flanges for industries worldwide. We provide strong, reliable, and high-quality steel flanges that are used in piping systems across oil & gas, chemical plants, power stations, shipbuilding, and many more industries.

We supply all types of flanges, including weld neck, slip-on, blind, socket weld, threaded, and lap joint flanges. Our flanges are made from durable materials like stainless steel, duplex steel, inconel, and hastelloy, ensuring long life and excellent performance.

As a global exporter, we deliver flanges to customers in Asia, Europe, the Middle East, Africa, and America. Our wide supply network and export experience help us provide timely delivery anywhere in the world.

What are Flanges in Piping?

A flange is like a strong connector that helps join two pieces of pipe together.

Instead of welding or permanently joining pipes, flanges allow pipes to be connected and also taken apart when needed. This makes it easy to clean, repair, or replace parts of the piping system without cutting the pipe.

In simple words, a flange works like the joint of the piping system. It holds pipes, valves, or pumps together so that liquids, gases, or steam can flow smoothly without leaking.

Flanges and Fittings: How They Work Together

Flanges are often used with fittings and gaskets to make a tight joint. The fittings help guide or change the flow, and the flanges are the points that connect everything together. When used this way, the system stays strong but can still be taken apart when needed.

Common Applications of Pipe Flanges

Pipe flanges are used in high-pressure, high-temperature, and corrosive environments. They are found in oil and gas, refineries, shipbuilding, power plants, and construction industries, making them one of the most widely used piping accessories.

Oil & Gas

Flanges join pipeline sections, valves, fittings, and equipment in drilling, refining, and transportation. High-pressure and temperature-resistant types (like weld neck and blind flanges) are prevalent. Materials with strong corrosion resistance are often chosen for chemical exposure.

Chemical Industry

Used for aggressive chemical processing lines requiring frequent assembly/disassembly. Stainless steel and alloy flanges are common due to resistance to corrosive chemicals.

Power Generation

Essential for connecting pipelines, pumps, and turbines. Flanges tolerate high temperatures and pressures and are frequent in steam and cooling water systems.

Water & Wastewater Treatment

Connects pumps, valves, and pipes for water distribution and processing, allowing for easy maintenance and replacement.

Marine & Shipbuilding

Used in shipbuilding for piping, including cooling systems, fuel lines, and ballast systems. They are chosen for durability amid vibration, movement, and corrosion from seawater.

HVAC & Fire Protection

Flanges provide robust connections for large structural piping systems in commercial buildings, which is critical in fire sprinkler, HVAC, and plumbing systems.

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Types of Flanges and Their Uses in Piping Systems

There are various types of flanges available in stock at Robust Special Metals, such as weld neck, slip-on, blind, socket weld, threaded, and lap joint flanges. Each type is supplied in different sizes and materials to suit piping systems across industries worldwide.

Weld Neck Flanges

Weld neck flanges have a long, tapered hub that’s butt-welded to the pipe. This smooth join spreads stress and keeps flow steady, so the joint stays strong under heat, pressure, and vibration.

Use when: lines run hot or at high pressure, or where failure isn’t an option—steam lines, refineries, chemical plants, offshore piping. Great fatigue resistance and ideal for frequent temperature cycles.

Slip-On Flanges

These slide over the pipe and are fillet-welded on the inside and outside. They’re easy to fit and align, which saves time in the field. Strength is lower than a weld neck, but good enough for many services.

Use when: low-to-medium pressure duties such as cooling water, fire-fighting mains, compressed air, general utilities. A cost-friendly choice for larger sizes.

Blind Flanges

A blind flange is a solid plate with bolt holes. It closes off the end of a pipe, valve, or vessel nozzle. You can remove it later for access.

Use when: you need a safe, leak-tight “stop” or test point—pressure testing spools, isolating sections for maintenance, future tie-ins.

Socket Weld Flanges

These have a recess that the pipe sits in, then you add a single fillet weld around the outside. The bore alignment is easy and the joint is quite strong on small sizes.

Use when: small-bore, high-pressure lines—hydraulic lines, short steam drops, instrument air. Avoid in services prone to crevice corrosion.

Threaded Flanges

Also called screwed flanges, these connect to threaded pipe with no welding. That’s handy in areas where hot work isn’t allowed.

Use when: low-pressure, non-critical lines or temporary hook-ups, and in flammable zones where welding is risky. Not for high temperature or heavy vibration.

Lap Joint Flanges

A lap joint is a two-piece setup: a stub end is welded to the pipe, and a loose (free-rotating) backing flange sits behind it. Only the stub end touches the fluid.

Use when: you need fast alignment and frequent dismantling—tank farms, systems with liners, or when using expensive alloys (the stub end is alloy; the backing flange can be carbon steel to save cost).

Plate Flanges

Cut from plate with a flat face and bolt holes, then welded to the pipe. Simple, robust, and economical for many services.

Use when: low-pressure water lines, HVAC, compressed air, and structural connections where budgets matter and conditions are mild.

Orifice Flanges

Supplied as a matched pair with pressure tapping ports, these hold an orifice plate to measure flow using differential pressure. They often include jack screws for easy plate removal.

Use when: you need accurate flow measurement on process lines feeding DP transmitters—oil & gas, power, and chemical plants. Requires straight runs of pipe upstream/downstream for best accuracy.

Weld Neck Flanges
Weld neck flanges have a long, tapered hub that’s butt-welded to the pipe. This smooth join spreads stress and keeps flow steady, so the joint stays strong under heat, pressure, and vibration.

**Use when:** lines run hot or at high pressure, or where failure isn’t an option—steam lines, refineries, chemical plants, offshore piping. Great fatigue resistance and ideal for frequent temperature cycles.

Slip-On Flanges
These slide over the pipe and are fillet-welded on the inside and outside. They’re easy to fit and align, which saves time in the field. Strength is lower than a weld neck, but good enough for many services.

**Use when:** low-to-medium pressure duties such as cooling water, fire-fighting mains, compressed air, general utilities. A cost-friendly choice for larger sizes.

Blind Flanges
A blind flange is a solid plate with bolt holes. It closes off the end of a pipe, valve, or vessel nozzle. You can remove it later for access.

**Use when:** you need a safe, leak-tight “stop” or test point—pressure testing spools, isolating sections for maintenance, future tie-ins.

Threaded Flanges
Also called screwed flanges, these connect to threaded pipe with no welding. That’s handy in areas where hot work isn’t allowed.

**Use when:** low-pressure, non-critical lines or temporary hook-ups, and in flammable zones where welding is risky. Not for high temperature or heavy vibration.

Lap Joint Flanges
A lap joint is a two-piece setup: a stub end is welded to the pipe, and a loose (free-rotating) backing flange sits behind it. Only the stub end touches the fluid.

**Use when:** you need fast alignment and frequent dismantling—tank farms, systems with liners, or when using expensive alloys (the stub end is alloy; the backing flange can be carbon steel to save cost).

Plate Flanges,

Cut from plate with a flat face and bolt holes, then welded to the pipe. Simple, robust, and economical for many services.

**Use when:** low-pressure water lines, HVAC, compressed air, and structural connections where budgets matter and conditions are mild.

Orifice Flanges

Supplied as a matched pair with pressure tapping ports, these hold an orifice plate to measure flow using differential pressure. They often include jack screws for easy plate removal.

**Use when:** you need accurate flow measurement on process lines feeding DP transmitters—oil & gas, power, and chemical plants. Requires straight runs of pipe upstream/downstream for best accuracy.

Quick selection tips

High pressure/temperature or cyclic loads? Weld neck.
Fast fit and fair cost? Slip-on.
End closure or pressure test point? Blind.
Small-bore, higher pressure? Socket weld.
No hot work allowed? Threaded.
Frequent dismantling/alignment or lined pipe? Lap joint.
Budget, low pressure? Plate.
Need flow measurement? Orifice pair.

Flanges Specifications

Flanges come with standard specifications that define their size, material, pressure rating, and dimensions. These specifications make sure the flanges fit properly and work safely in piping systems. ASME B16.5 is the most commonly used standard for making cast and forged steel flanges

Flanges Standards

ASME Flanges

ANSI Flanges

ASTM Flanges

AWWA Flanges

MSS Flanges

DIN Flanges

EN Flanges

ISO Flanges

JIS Flanges

GOST Flanges

UNI Flanges

API Flanges

Flanges Size

NPS	DN
1	25
1 1/2	40
1 1/4	32
1/2	15
2	50
2 1/2	65
3	80
3/4	20
4	100

Flange Materials

Flanges are made from different materials to match the needs of piping systems. The choice of material depends on factors like pressure, temperature, and resistance to corrosion. The materials we offer for flanges commonly are

Stainless Steel Flanges

Duplex Steel Flanges

Super Duplex Steel Flanges

Inconel Flanges

Hastelloy Flanges

Nickel Flanges

Monel Flanges

Titanium Flanges

Copper Nickel Flanges

Flanges Pressure Rating

Class 150 LBS, 300 LBS, 600 LBS, 900 LBS, 1500 LBS, 2500 LBS

ASME	Pressure Temperature Ratings For Flanges
Temperature °F	Class 150	Class 300	Class 400	Class 600	Class 900	Class 1500	Class 2500
-20 to 100	275	720	960	1440	2160	3600	6000
200	230	600	800	1200	1800	3000	5000
300	205	540	720	1080	1620	2700	4500
400	190	495	660	995	1490	2485	4140
500	170	465	620	930	1395	2330	3880
600	140	435	580	875	1310	2185	3640
650	125	430	575	860	1290	2150	3580
700	110	425	565	850	1275	2125	3540
750	95	415	555	830	1245	2075	3460
800	80	405	540	805	1210	2015	3360
850	65	395	530	790	1190	1980	3300
900	50	390	520	780	1165	1945	3240
950	35	380	510	765	1145	1910	3180
1000	20	320	430	640	965	1605	2675
1050	20	310	410	615	925	1545	2570
1100	20	255	345	515	770	1285	2145
1150	20	200	265	400	595	995	1655
1200	20	155	205	310	465	770	1285
1250	20	115	150	225	340	565	945
1300	20	85	115	170	255	430	715
1350	20	60	80	125	185	310	515
1400	20	50	65	95	145	240	400
1450	15	35	45	70	105	170	285
1500	10	25	35	55	80	135	230

ASME B16 5 Flange Dimensions

Class 150 Flange Dimensions in mm

Nominal Pipe Size/ Bore for LWN	Outside Diameter	Min. Thickness	Diameter of Raised Face	Min. Thickness Lap Joint	Diameter of Hub	Diameter Beginning of Chamfer Welding Neck	Threaded Slip-on Socket Welding	Lapped	Welding Neck	Long Welding Neck	Minimum Thread Length Threaded	Minimum Slip-On Socket Welding	Minimum Lapped	Welding Neck / Socket Welding	Corner Bore Radius of Lapped Flange and Pipe	Depth of Socket	Bolt Circle Dia	Number of Holes	Diameter of Holes
J	O	tf	R	tf	X	A	Y1	Y2	Y3	Y4	T	B1	B2	B3	r	D
½	3.50	0.38	1.38	0.44	1.19	0.84	0.56	0.62	1.81	9.00	0.62	0.88	0.90	Note-3	0.12	0.38	2.38	4	0.63
¾	3.88	0.44	1.69	0.50	1.50	1.05	0.56	0.62	2.00	9.00	0.62	1.09	1.11	Note-3	0.12	0.44	2.75	4	0.63
1	4.25	0.50	2.00	0.56	1.94	1.32	0.62	0.69	2.12	9.00	0.69	1.36	1.38	Note-3	0.12	0.50	3.12	4	0.63
1¼	4.62	0.56	2.50	0.62	2.31	1.66	0.75	0.81	2.19	9.00	0.81	1.70	1.72	Note-3	0.19	0.56	3.50	4	0.63
1½	5.00	0.62	2.88	0.69	2.56	1.90	0.81	0.88	2.38	9.00	0.88	1.95	1.97	Note-3	0.25	0.62	3.88	4	0.63
2	6.00	0.69	3.62	0.75	3.06	2.38	0.94	1.00	2.44	9.00	1.00	2.44	2.46	Note-3	0.31	0.69	4.75	4	0.75
2½	7.00	0.81	4.12	0.88	3.56	2.88	1.06	1.12	2.69	9.00	1.12	2.94	2.97	Note-3	0.31	0.75	5.50	4	0.75
3	7.50	0.88	5.00	0.94	4.25	3.50	1.12	1.19	2.69	9.00	1.19	3.57	3.60	Note-3	0.38	0.81	6.00	4	0.75
3½	8.50	0.88	5.50	0.94	4.81	4.00	1.19	1.25	2.75	9.00	1.25	4.07	4.10	Note-3	0.38	-	7.00	8	0.75
4	9.00	0.88	6.19	0.94	5.31	4.50	1.25	1.31	2.94	Note-3	1.31	4.57	4.60	Note-3	0.44	-	7.50	8	0.75
5	10.00	0.88	7.31	0.94	6.44	5.56	1.38	1.44	3.44	12.00	1.44	5.66	5.69	Note-3	0.44	-	8.50	8	0.88
6	11.00	0.94	8.50	1.00	7.56	6.63	1.50	1.56	3.44	12.00	1.56	6.72	6.75	Note-3	0.50	-	9.50	8	0.88
8	13.50	1.06	10.62	1.12	9.69	8.63	1.69	1.75	3.94	12.00	1.75	8.72	8.75	Note-3	0.50	-	11.75	8	0.88
10	16.00	1.12	12.75	1.19	12.00	10.75	1.88	1.94	3.94	12.00	1.94	10.88	10.92	Note-3	0.50	-	14.25	12	1.00
12	19.00	1.19	15.00	1.25	14.38	12.75	2.12	2.19	4.44	12.00	2.19	12.88	12.92	Note-3	0.50	-	17.00	12	1.00
14	21.00	1.31	16.25	1.38	15.75	14.00	2.19	3.12	4.94	12.00	2.25	14.14	14.18	Note-3	0.50	-	18.75	12	1.13
16	23.50	1.38	18.50	1.44	18.00	16.00	2.44	3.44	4.94	12.00	2.50	16.16	16.19	Note-3	0.50	-	21.25	16	1.13
18	25.00	1.50	21.00	1.56	19.88	18.00	2.62	3.81	5.44	12.00	2.69	18.18	18.20	Note-3	0.50	-	22.75	16	1.25
20	27.50	1.62	23.00	1.69	22.00	20.00	2.81	4.06	5.62	12.00	2.88	20.20	20.25	Note-3	0.50	-	25.00	20	1.25
22	29.50	1.75	25.25	1.81	24.00	22.00	3.06	4.25	5.82	12.00	-	22.22	22.25	Note-3	0.50	-	27.25	20	1.38
24	32.00	1.81	27.25	1.88	26.12	24.00	3.19	4.38	5.94	12.00	3.25	24.25	24.25	Note-3	0.50	-	29.50	20	1.38
Notes: (1) This dimension is for the large end of the hub, which may be straight or tapered. Taper shall not exceed 7 deg on threaded, slip-on, socket-welding, and lapped flanges. (2) When these flanges are required with flat face, the flat face may be either the full tf dimension thickness plus 0.06 in. or the tf dimension thickness without the raised face height. (3) To be specified by the Customer; Y4 - the length can be 9" (B16.5) or 12" (industry), shall be specified by the customer.

Class 300 Flange Dimensions in mm

Nominal Pipe Size/ Bore for LWN	Outside Diameter	Min. Thickness	Diameter of Raised Face	Min. Thickness Lap Joint	Diameter of Hub	Diameter Beginning of Chamefer Welding Neck	Threaded Slip-on Socket Welding	Lapped	Welding Neck	Long Welding Neck	Minimum Thread Length Threaded	Minimum Slip-On Socket Welding	Minimum Lapped	Welding Neck / Socket Welding	Corner Bore Radius of Lapped Flange and Pipe	Depth of Socket	Minimum Counter-bore Threaded Flange	Bolt Circle Dia	Number of Holes	Diameter of Holes
J	O	tf	R	tf	X	A	Y1	Y2	Y3	Y4	T	B1	B2	B3	r	D	Q
½	3.75	0.50	1.38	0.56	1.50	0.84	0.81	0.88	2.00	9.00	0.62	0.88	0.90	Note-3	0.12	0.38	0.93	2.62	4	0.63
¾	4.62	0.56	1.69	0.62	1.88	1.05	0.94	1.00	2.19	9.00	0.62	1.09	1.11	Note-3	0.12	0.44	1.14	3.25	4	0.75
1	4.88	0.62	2.00	0.69	2.12	1.32	1.00	1.06	2.38	9.00	0.69	1.36	1.38	Note-3	0.12	0.50	1.41	3.50	4	0.75
1¼	5.25	0.69	2.50	0.75	2.50	1.66	1.00	1.06	2.50	9.00	0.81	1.70	1.72	Note-3	0.19	0.56	1.75	3.88	4	0.75
1½	6.12	0.75	2.88	0.81	2.75	1.90	1.13	1.19	2.63	9.00	0.88	1.95	1.97	Note-3	0.25	0.62	1.98	4.50	4	0.88
2	6.50	0.81	3.62	0.88	3.31	2.38	1.25	1.31	2.69	9.00	1.12	2.44	2.46	Note-3	0.31	0.69	2.50	5.00	8	0.75
2½	7.50	0.94	4.12	1.00	3.94	2.88	1.44	1.50	2.94	9.00	1.25	2.94	2.97	Note-3	0.31	0.75	3.00	5.88	8	0.88
3	8.25	1.06	5.00	1.12	4.62	3.50	1.63	1.69	3.06	9.00	1.25	3.57	3.60	Note-3	0.38	0.81	3.63	6.62	8	0.88
3½	9.00	1.12	5.50	1.19	5.25	4.00	1.69	1.75	3.13	9.00	1.44	4.07	4.10	Note-3	0.38	-	4.13	7.25	8	0.88
4	10.00	1.19	6.19	1.25	5.75	4.50	1.82	1.88	3.32	Note-3	1.44	4.57	4.60	Note-3	0.44	-	4.63	7.88	8	0.88
5	11.00	1.31	7.31	1.38	7.00	5.56	1.94	2.00	3.82	12.00	1.69	5.66	5.69	Note-3	0.44	-	5.69	9.25	8	0.88
6	12.50	1.38	8.50	1.44	8.12	6.63	2.00	2.06	3.82	12.00	1.81	6.72	6.75	Note-3	0.50	-	6.75	10.62	12	0.88
8	15.00	1.56	10.62	1.62	10.25	8.63	2.38	2.44	4.32	12.00	2.00	8.72	8.75	Note-3	0.50	-	8.75	13.00	12	1.00
10	17.50	1.81	12.75	1.88	12.62	10.75	2.56	3.75	4.56	12.00	2.19	10.88	10.92	Note-3	0.50	-	10.88	15.25	16	1.13
12	20.50	1.94	15.00	2.00	14.75	12.75	2.82	4.00	5.06	12.00	2.38	12.88	12.92	Note-3	0.50	-	12.94	17.75	16	1.25
14	23.00	2.06	16.25	2.12	16.75	14.00	2.94	4.38	5.56	12.00	2.50	14.14	14.18	Note-3	0.50	-	14.19	20.25	20	1.25
16	25.50	2.19	18.50	2.25	19.00	16.00	3.19	4.75	5.69	12.00	2.69	16.16	16.19	Note-3	0.50	-	16.19	22.50	20	1.38
18	28.00	2.31	21.00	2.38	21.00	18.00	3.44	5.12	6.19	12.00	2.75	18.18	18.20	Note-3	0.50	-	18.19	24.75	24	1.38
20	30.50	2.44	23.00	2.50	23.12	20.00	3.69	5.50	6.32	12.00	2.88	20.20	20.25	Note-3	0.50	-	20.19	27.00	24	1.38
22	33.00	2.56	25.25	2.62	25.25	22.00	3.94	5.69	6.44	12.00	-	22.22	22.25	Note-3	0.50	-	-	29.25	24	1.63
24	36.00	2.69	27.25	2.75	27.62	24.00	4.13	6.00	6.56	12.00	3.25	24.25	24.25	Note-3	0.50	-	24.19	32.00	24	1.63
Notes: (1) This dimension is for the large end of the hub, which may be straight or tapered. Taper shall not exceed 7 deg on threaded, slip-on, socket-welding, and lapped flanges. (2) When these flanges are required with flat face, the flat face may be either the full tf dimension thickness plus 0.06 in. or the tf dimension thickeness without the raised face height. (3) To be specified by the Customer; Y4 - the length can be 9" (B16.5) or 12" (industry),shall be specified by the customer.

Class 400 Flange Dimensions in mm

Nominal Pipe Size/ Bore for LWN	Outside Diameter	Min. Thickness	Diameter of Raised Face	Diameter of Hub	Diameter Beginning of Chamefer Welding Neck	Threaded Slip-on Socket Welding	Lapped	Welding Neck	Long Welding Neck	Minimum Thread Length Threaded	Minimum Slip-On Socket Welding	Minimum Lapped	Welding Neck / Socket Welding	Corner Bore Radius of Lapped Flange and Pipe	Depth of Socket	Minimum Counter-bore Threaded Flange	Bolt Circle Dia	Number of Holes	Diameter of Holes
J	O	tf	R	X	A	Y1	Y2	Y3	Y4	T	B1	B2	B3	r	D	Q
½	3.75	0.56	1.38	1.50	0.84	0.88	0.88	2.06	9.00	0.62	0.88	0.90	Note-3	0.12	0.38	0.93	2.62	4	0.63
¾	4.62	0.62	1.69	1.88	1.05	1.00	1.00	2.25	9.00	0.62	1.09	1.11	Note-3	0.12	0.44	1.14	3.25	4	0.75
1	4.88	0.69	2.00	2.12	1.32	1.06	1.06	2.44	9.00	0.69	1.36	1.38	Note-3	0.12	0.50	1.41	3.50	4	0.75
1¼	5.25	0.81	2.50	2.50	1.66	1.12	1.12	2.62	9.00	0.81	1.70	1.72	Note-3	0.19	0.56	1.75	3.88	4	0.75
1½	6.12	0.88	2.88	2.75	1.90	1.25	1.25	2.75	9.00	0.88	1.95	1.97	Note-3	0.25	0.62	1.99	4.50	4	0.88
2	6.50	1.00	3.62	3.31	2.38	1.44	1.44	2.88	9.00	1.12	2.44	2.46	Note-3	0.31	0.69	2.50	5.00	8	0.75
2½	7.50	1.12	4.12	3.94	2.88	1.62	1.62	3.12	9.00	1.25	2.94	2.97	Note-3	0.31	0.75	3.00	5.88	8	0.88
3	8.25	1.25	5.00	4.62	3.50	1.81	1.81	3.25	9.00	1.38	3.57	3.60	Note-3	0.38	0.81	3.63	6.62	8	0.88
3½	9.00	1.38	5.50	5.25	4.00	1.94	1.94	3.38	9.00	1.56	4.07	4.10	Note-3	0.38	-	4.13	7.25	8	1.00
4	10.00	1.38	6.19	5.75	4.50	2.00	2.00	3.50	Note-3	1.44	4.57	4.60	Note-3	0.44	-	4.63	7.88	8	1.00
5	11.00	1.50	7.31	7.00	5.56	2.12	2.12	4.00	12.00	1.69	5.66	5.69	Note-3	0.44	-	5.69	9.25	8	1.00
6	12.50	1.62	8.50	8.12	6.63	2.25	2.25	4.06	12.00	1.81	6.72	6.75	Note-3	0.50	-	6.75	10.62	12	1.00
8	15.00	1.88	10.62	10.25	8.63	2.69	2.69	4.62	12.00	2.00	8.72	8.75	Note-3	0.50	-	8.75	13.00	12	1.13
10	17.50	2.12	12.75	12.62	10.75	2.88	4.00	4.88	12.00	2.19	10.88	10.92	Note-3	0.50	-	10.88	15.25	16	1.25
12	20.50	2.25	15.00	14.75	12.75	3.12	4.25	5.38	12.00	2.38	12.88	12.92	Note-3	0.50	-	12.94	17.75	16	1.38
14	23.00	2.38	16.25	16.75	14.00	3.31	4.62	5.88	12.00	2.50	14.14	14.18	Note-3	0.50	-	14.19	20.25	20	1.38
16	25.50	2.50	18.50	19.00	16.00	3.69	5.00	6.00	12.00	2.69	16.16	16.19	Note-3	0.50	-	16.19	22.50	20	1.50
18	28.00	2.62	21.00	21.00	18.00	3.88	5.38	6.50	12.00	2.75	18.18	18.20	Note-3	0.50	-	18.19	24.75	24	1.50
20	30.50	2.75	23.00	23.12	20.00	4.00	5.75	6.62	12.00	2.88	20.20	20.25	Note-3	0.50	-	20.19	27.00	24	1.63
22	33.00	2.88	25.25	25.25	22.00	4.25	6.00	6.75	12.00	-	22.22	22.25	Note-3	0.50	-	-	29.25	24	1.75
24	36.00	3.00	27.25	27.62	24.00	4.50	6.25	6.88	12.00	3.25	24.25	24.25	Note-3	0.50	-	24.19	32.00	24	1.88
Notes: (1) This dimension is for the large end of the hub, which may be straight or tapered. Taper shall not exceed 7 deg on threaded, slip-on, socket-welding, and lapped flanges. (2) When these flanges are required with flat face, the flat face may be either the full tf dimension thickness plus 0.06 in. or the tf dimension thickeness without the raised face height. (3) To be specified by the Customer; Y4 - the length can be 9" (B16.5) or 12" (industry), shall be specified by the customer.

Class 600 Flange Dimensions in mm

Nominal Pipe Size/ Bore for LWN	Outside Diameter	Min. Thickness	Diameter of Raised Face	Diameter of Hub	Diameter Beginning of Chamefer Welding Neck	Threaded Slip-on Socket Welding	Lapped	Welding Neck	Long Welding Neck	Minimum Thread Length Threaded	Minimum Slip-On Socket Welding	Minimum Lapped	Welding Neck / Socket Welding	Corner Bore Radius of Lapped Flange and Pipe	Depth of Socket	Minimum Counter-bore Threaded Flange	Bolt Circle Dia	Number of Holes	Diameter of Holes
J	O	tf	R	X	A	Y1	Y2	Y3	Y4	T	B1	B2	B3	r	D	Q
½	3.75	0.56	1.38	1.50	0.84	0.88	0.88	2.06	9.00	0.62	0.88	0.90	Note-3	0.12	0.38	0.93	2.62	4	0.63
¾	4.62	0.62	1.69	1.88	1.05	1.00	1.00	2.25	9.00	0.62	1.09	1.11	Note-3	0.12	0.44	1.14	3.25	4	0.75
1	4.88	0.69	2.00	2.12	1.32	1.06	1.06	2.44	9.00	0.69	1.36	1.38	Note-3	0.12	0.50	1.41	3.50	4	0.75
1¼	5.25	0.81	2.50	2.50	1.66	1.12	1.12	2.62	9.00	0.81	1.70	1.72	Note-3	0.19	0.56	1.75	3.88	4	0.75
1½	6.12	0.88	2.88	2.75	1.90	1.25	1.25	2.75	9.00	0.88	1.95	1.97	Note-3	0.25	0.62	1.99	4.50	4	0.88
2	6.50	1.00	3.62	3.31	2.38	1.44	1.44	2.88	9.00	1.12	2.44	2.46	Note-3	0.31	0.69	2.50	5.00	8	0.75
2½	7.50	1.12	4.12	3.94	2.88	1.62	1.62	3.12	9.00	1.25	2.94	2.97	Note-3	0.31	0.75	3.00	5.88	8	0.88
3	8.25	1.25	5.00	4.62	3.50	1.81	1.81	3.25	9.00	1.38	3.57	3.60	Note-3	0.38	0.81	3.63	6.62	8	0.88
3½	9.00	1.38	5.50	5.25	4.00	1.94	1.94	3.38	9.00	1.56	4.07	4.10	Note-3	0.38	-	4.13	7.25	8	1.00
4	10.75	1.50	6.19	6.00	4.50	2.12	2.12	4.00	Note-3	1.62	4.57	4.60	Note-3	0.44	-	4.63	8.50	8	1.00
5	13.00	1.75	7.31	7.44	5.56	2.38	2.38	4.50	12.00	1.88	5.66	5.69	Note-3	0.44	-	5.69	10.50	8	1.12
6	14.00	1.88	8.50	8.75	6.63	2.62	2.62	4.62	12.00	2.00	6.72	6.75	Note-3	0.50	-	6.75	11.50	12	1.12
8	16.50	2.19	10.62	10.75	8.63	3.00	3.00	5.25	12.00	2.25	8.72	8.75	Note-3	0.50	-	8.75	13.75	12	1.25
10	20.00	2.50	12.75	13.50	10.75	3.38	4.38	6.00	12.00	2.56	10.88	10.92	Note-3	0.50	-	10.88	17.00	16	1.38
12	22.00	2.62	15.00	15.75	12.75	3.62	4.62	6.12	12.00	2.75	12.88	12.92	Note-3	0.50	-	12.94	19.25	20	1.38
14	23.75	2.75	16.25	17.00	14.00	3.69	5.00	6.50	12.00	2.88	14.14	14.18	Note-3	0.50	-	14.19	20.75	20	1.50
16	27.00	3.00	18.50	19.50	16.00	4.19	5.50	7.00	12.00	3.06	16.16	16.19	Note-3	0.50	-	16.19	23.75	20	1.62
18	29.25	3.25	21.00	21.50	18.00	4.62	6.00	7.25	12.00	3.12	18.18	18.20	Note-3	0.50	-	18.19	25.75	20	1.75
20	32.00	3.50	23.00	24.00	20.00	5.00	6.50	7.50	12.00	3.25	20.20	20.25	Note-3	0.50	-	20.19	28.50	24	1.75
22	34.25	3.75	25.25	26.25	22.00	5.25	6.88	7.75	12.00	-	22.22	22.25	Note-3	0.50	-	-	30.63	24	1.88
24	37.00	4.00	27.25	28.25	24.00	5.50	7.25	8.00	12.00	3.62	24.25	24.25	Note-3	0.50	-	24.19	33.00	24	2.00
Notes: (1) This dimension is for the large end of the hub, which may be straight or tapered. Taper shall not exceed 7 deg on threaded, slip-on, socket-welding, and lapped flanges. (2) When these flanges are required with flat face, the flat face may be either the full tf dimension thickness plus 0.06 in. or the tf dimension thickeness without the raised face height. (3) To be specified by the Customer; Y4 - the length can be 9" (B16.5) or 12" (industry), shall be specified by the customer.

Class 900 Flange Dimensions in mm

Nominal Pipe Size/ Bore for LWN	Outside Diameter	Min. Thickness	Diameter of Raised Face	Diameter of Hub	Diameter Beginning of Chamefer Welding Neck	Threaded Slip-on Socket Welding	Lapped	Welding Neck	Long Welding Neck	Minimum Thread Length Threaded	Minimum Slip-On Socket Welding	Minimum Lapped	Welding Neck / Socket Welding	Corner Bore Radius of Lapped Flange and Pipe	Depth of Socket	Minimum Counter-bore Threaded Flange	Bolt Circle Dia	Number of Holes	Diameter of Holes
J	O	tf	R	X	A	Y1	Y2	Y3	Y4	T	B1	B2	B3	r	D	Q
½	4.75	0.88	1.38	1.50	0.84	1.25	1.25	2.38	9.00	0.88	0.88	0.90	Note-3	0.12	0.38	0.93	3.25	4	0.88
¾	5.12	1.00	1.69	1.75	1.05	1.38	1.38	2.75	9.00	1.00	1.09	1.11	Note-3	0.12	0.44	1.14	3.50	4	0.88
1	5.88	1.12	2.00	2.06	1.32	1.62	1.62	2.88	9.00	1.12	1.36	1.38	Note-3	0.12	0.50	1.41	4.00	4	1.00
1¼	6.25	1.12	2.50	2.50	1.66	1.62	1.62	2.88	9.00	1.19	1.70	1.72	Note-3	0.19	0.56	1.75	4.38	4	1.00
1½	7.00	1.25	2.88	2.75	1.90	1.75	1.75	3.25	9.00	1.25	1.95	1.97	Note-3	0.25	0.62	1.99	4.88	4	1.13
2	8.50	1.50	3.63	4.12	2.38	2.25	2.25	4.00	9.00	1.50	2.44	2.46	Note-3	0.31	0.69	2.50	6.50	8	1.00
2½	9.62	1.62	4.13	4.88	2.88	2.50	2.50	4.12	9.00	1.88	2.94	2.97	Note-3	0.31	0.75	3.00	7.50	8	1.13
3	9.50	1.50	5.00	5.00	3.50	2.12	2.12	4.00	9.00	1.62	3.57	3.60	Note-3	0.38	-	3.63	7.50	8	1.00
4	11.50	1.75	6.19	6.25	4.50	2.75	2.75	4.50	Note-3	1.88	4.57	4.60	Note-3	0.44	-	4.63	9.25	8	1.25
5	13.75	2.00	7.31	7.50	5.56	3.12	3.12	5.00	12.00	2.12	5.66	5.69	Note-3	0.44	-	5.69	11.00	8	1.38
6	15.00	2.19	8.50	9.25	6.63	3.38	3.38	5.50	12.00	2.25	6.72	6.75	Note-3	0.50	-	6.75	12.50	12	1.25
8	18.50	2.50	10.62	11.75	8.63	4.00	4.50	6.38	12.00	2.50	8.72	8.75	Note-3	0.50	-	8.75	15.50	12	1.50
10	21.50	2.75	12.75	14.50	10.75	4.25	5.00	7.25	12.00	2.81	10.88	10.92	Note-3	0.50	-	10.88	18.50	16	1.50
12	24.00	3.12	15.00	16.50	12.75	4.62	5.62	7.88	12.00	3.00	12.88	12.92	Note-3	0.50	-	12.94	21.00	20	1.50
14	25.25	3.38	16.25	17.75	14.00	5.12	6.12	8.38	12.00	3.25	14.14	14.18	Note-3	0.50	-	14.19	22.00	20	1.63
16	27.75	3.50	18.50	20.00	16.00	5.25	6.50	8.50	12.00	3.38	16.16	16.19	Note-3	0.50	-	16.19	24.25	20	1.75
18	31.00	4.00	21.00	22.25	18.00	6.00	7.50	9.00	12.00	3.50	18.18	18.20	Note-3	0.50	-	18.19	27.00	20	2.00
20	33.75	4.25	23.00	24.50	20.00	6.25	8.25	9.75	12.00	3.62	20.20	20.25	Note-3	0.50	-	20.19	29.50	20	2.13
24	41.00	5.50	27.25	29.50	24.00	8.00	10.50	11.50	12.00	4.00	24.25	24.25	Note-3	0.50	-	24.19	35.50	20	2.63
Notes: (1) This dimension is for the large end of the hub, which may be straight or tapered. Taper shall not exceed 7 deg on threaded, slip-on, socket-welding, and lapped flanges. (2) When these flanges are required with flat face, the flat face may be either the full tf dimension thickness plus 0.25 in. or the tf dimension thickeness without the raised face height. (3) To be specified by the Customer; Y4 - the length can be 9" (B16.5) or 12" (industry), shall be specified by the customer.

Class 1500 Flange Dimensions in mm

Nominal Pipe Size/ Bore for LWN	Outside Diameter	Min. Thickness	Diameter of Raised Face	Diameter of Hub	Diameter Beginning of Chamefer Welding Neck	Threaded Slip-on Socket Welding	Lapped	Welding Neck	Long Welding Neck	Minimum Thread Length Threaded	Minimum Slip-On Socket Welding	Minimum Lapped	Welding Neck / Socket Welding	Corner Bore Radius of Lapped Flange and Pipe	Depth of Socket	Minimum Counter-bore Threaded Flange	Bolt Circle Dia	Number of Holes	Diameter of Holes
J	O	tf	R	X	A	Y1	Y2	Y3	Y4	T	B1	B2	B3	r	D	Q
½	4.75	0.88	1.38	1.50	0.84	1.25	1.25	2.38	9.00	0.88	0.88	0.90	Note-3	0.12	0.38	0.93	3.25	4	0.88
¾	5.12	1.00	1.69	1.75	1.05	1.38	1.38	2.75	9.00	1.00	1.09	1.11	Note-3	0.12	0.44	1.14	3.50	4	0.88
1	5.88	1.12	2.00	2.06	1.32	1.62	1.62	2.88	9.00	1.12	1.36	1.38	Note-3	0.12	0.50	1.41	4.00	4	1.00
1¼	6.25	1.12	2.50	2.50	1.66	1.62	1.62	2.88	9.00	1.19	1.70	1.72	Note-3	0.19	0.56	1.75	4.38	4	1.00
1½	7.00	1.25	2.88	2.75	1.90	1.75	1.75	3.25	9.00	1.25	1.95	1.97	Note-3	0.25	0.62	1.99	4.88	4	1.13
2	8.50	1.50	3.62	4.12	2.38	2.25	2.25	4.00	9.00	1.50	2.44	2.46	Note-3	0.31	0.69	2.50	6.50	8	1.00
2½	9.62	1.62	4.12	4.88	2.88	2.50	2.50	4.12	9.00	1.88	2.94	2.97	Note-3	0.31	0.75	3.00	7.50	8	1.13
3	10.50	1.88	5.00	5.25	3.50	-	2.88	4.62	9.00	-	-	3.60	Note-3	0.38	-	-	8.00	8	1.25
4	12.25	2.12	6.19	6.38	4.50	-	3.56	4.88	Note-3	-	-	4.60	Note-3	0.44	-	-	9.50	8	1.38
5	14.75	2.88	7.31	7.75	5.56	-	4.12	6.12	12.00	-	-	5.69	Note-3	0.44	-	-	11.50	8	1.63
6	15.50	3.25	8.50	9.00	6.63	-	4.69	6.75	12.00	-	-	6.75	Note-3	0.50	-	-	12.50	12	1.50
8	19.00	3.62	10.62	11.50	8.63	-	5.62	8.38	12.00	-	-	8.75	Note-3	0.50	-	-	15.50	12	1.75
10	23.00	4.25	12.75	14.50	10.75	-	7.00	10.00	12.00	-	-	10.92	Note-3	0.50	-	-	19.00	12	2.00
12	26.50	4.88	15.00	17.75	12.75	-	8.62	11.12	12.00	-	-	12.92	Note-3	0.50	-	-	22.50	16	2.13
14	29.50	5.25	16.25	19.50	14.00	-	9.50	11.75	12.00	-	-	14.18	Note-3	0.50	-	-	25.00	16	2.38
16	32.50	5.75	18.50	21.75	16.00	-	10.25	12.25	12.00	-	-	16.19	Note-3	0.50	-	-	27.75	16	2.63
18	36.00	6.38	21.00	23.50	18.00	-	10.88	12.88	12.00	-	-	18.20	Note-3	0.50	-	-	30.50	16	2.88
20	38.75	7.00	23.00	25.25	20.00	-	11.50	14.00	12.00	-	-	20.25	Note-3	0.50	-	-	32.75	16	3.13
24	46.00	8.00	27.25	30.00	24.00	-	13.00	16.00	12.00	-	-	24.25	Note-3	0.50	-	-	39.00	16	3.63
Notes: (1) This dimension is for the large end of the hub, which may be straight or tapered. Taper shall not exceed 7 deg on threaded, slip-on, socket-welding, and lapped flanges. (2) When these flanges are required with flat face, the flat face may be either the full tf dimension thickness plus 0.25 in. or the tf dimension thickeness without the raised face height. (3) To be specified by the Customer; Y4 - the length can be 9" (B16.5) or 12" (industry), shall be specified by the customer.

Class 2500 Flange Dimensions in mm

Nominal Pipe Size/ Bore for LWN	Outside Diameter	Min. Thickness	Diameter of Raised Face	Diameter of Hub	Hub Diameter Beginning of Chamefer Welding Neck	Threaded	Lapped	Welding Neck	Long Welding Neck	Minimum Thread Length Threaded	Minimum Lapped	Welding Neck	Corner Bore Radius of Lapped Flange and Pipe	Minimum Counter-bore Threaded Flange	Bolt Circle Dia	Number of Holes	Diameter of Holes
J	O	tf	R	X	A	Y1	Y2	Y3	Y4	T	B2	B3	r	Q
½	5.25	1.19	1.38	1.69	0.84	1.56	1.56	2.88	9.00	1.12	0.90	Note-3	0.12	0.93	3.50	4	0.88
¾	5.50	1.25	1.69	2.00	1.05	1.69	1.69	3.12	9.00	1.25	1.11	Note-3	0.12	1.14	3.75	4	0.88
1	6.25	1.38	2.00	2.25	1.32	1.88	1.88	3.50	9.00	1.38	1.38	Note-3	0.12	1.41	4.25	4	1.00
1¼	7.25	1.50	2.50	2.88	1.66	2.06	2.06	3.75	9.00	1.50	1.72	Note-3	0.19	1.75	5.12	4	1.13
1½	8.00	1.75	2.88	3.12	1.90	2.38	2.38	4.38	9.00	1.75	1.97	Note-3	0.25	1.99	5.75	4	1.25
2	9.25	2.00	3.62	3.75	2.38	2.75	2.75	5.00	9.00	2.00	2.46	Note-3	0.31	2.50	6.75	8	1.13
2½	10.50	2.25	4.12	4.50	2.88	3.12	3.12	5.62	9.00	2.25	2.97	Note-3	0.31	3.00	7.75	8	1.25
3	12.00	2.62	5.00	5.25	3.50	-	3.62	6.62	9.00	-	3.60	Note-3	0.38	-	9.00	8	1.38
4	14.00	3.00	6.19	6.50	4.50	-	4.25	7.50	Note-3	-	4.60	Note-3	0.44	-	10.75	8	1.63
5	16.50	3.62	7.31	8.00	5.56	-	5.12	9.00	12.00	-	5.69	Note-3	0.44	-	12.75	8	1.88
6	19.00	4.25	8.50	9.25	6.63	-	6.00	10.75	12.00	-	6.75	Note-3	0.50	-	14.50	8	2.13
8	21.75	5.00	10.63	12.00	8.63	-	7.00	12.50	12.00	-	8.75	Note-3	0.50	-	17.25	12	2.13
10	26.50	6.50	12.75	14.75	10.75	-	9.00	16.50	12.00	-	10.92	Note-3	0.50	-	21.25	12	2.63
12	30.00	7.25	15.00	17.38	12.75	-	10.00	18.25	12.00	-	12.92	Note-3	0.50	-	24.38	12	2.88
Notes: (1) This dimension is for the large end of the hub, which may be straight or tapered. Taper shall not exceed 7 deg on threaded, slip-on, socket-welding, and lapped flanges. (2) When these flanges are required with flat face, the flat face may be either the full tf dimension thickness plus 0.06 in. or the tf dimension thickeness without the raised face height. (3) To be specified by the Customer; Y4 - the length can be 9" (B16.5) or 12" (industry),shall be specified by the customer.

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