Steel Unions | McMaster-Carr

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Zinc Phosphate Coated

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86 Products

How to Identify and Measure Fittings

Pipe size is an industry designation, not the actual size. View information about how to measure threaded and unthreaded pipe and pipe fittings.

High-Pressure Iron and Steel Threaded Pipe Fittings

These fittings can stand up to high-pressure applications. Use them in noncorrosive environments.

Union connectors separate into three pieces so you can access your line without unthreading pipe connections. Union connectors with gasket provide extra leak protection.

Phosphate-coated and zinc-phosphate-coated fittings offer some corrosion resistance, but aren't intended for corrosive environments.

Note: The maximum pressure listed for Class 3000 fittings is for conditions where there are no sudden changes in pressure or velocity. Please refer to ASME B16.11 to determine the specific maximum operating pressure for your application.

For technical drawings and 3-D models, click on a part number.

Union Straight Connectors

Exploded View

For Use With: Air, Hydraulic Fluid, Natural Gas, Oil, Steam, Water
Pressure Class: 3000
Specifications Met: MSS SP-83, ASME B1.20.1, ASTM A105
Pipe Nipples and Pipe: Use Schedule 160 steel
Flanges: Use Class 1500 steel

NPT Female
Pipe Size	Dash Size	Max. Pressure	Max. Steam Pressure	Material		Each
1/8	02	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	000000
1/4	04	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	0000000	00000
3/8	06	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	0000000	00000
1/2	08	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	0000000	00000
3/4	12	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	0000000	00000
1	16	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	0000000	00000
1 1/4	20	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	0000000	00000
1 1/2	24	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	0000000	00000
2	32	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	0000000	00000
2 1/2	40	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	000000
3	48	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	000000

Union Straight Connectors with Gasket

Exploded View

For Use With: Air, Hydraulic Fluid, Natural Gas, Oil, Steam, Water
Specifications Met: MSS SP-83, ASTM A105
Pipe Nipples and Pipe: Use Schedule 160 steel
Flanges: Use Class 1500 steel

NPT Female
Pipe Size	Dash Size	Max. Pressure	Max. Steam Pressure	Material	Gasket Material		Each
1/2	08	3,000 psi @ 100° F	1,500 psi @ 700° F	Phosphate-Coated Steel	Graphite-Filled 304 Stainless Steel	0000000	000000
3/4	12	3,000 psi @ 100° F	1,500 psi @ 700° F	Phosphate-Coated Steel	Graphite-Filled 304 Stainless Steel	0000000	00000
1	16	3,000 psi @ 100° F	1,500 psi @ 700° F	Phosphate-Coated Steel	Graphite-Filled 304 Stainless Steel	0000000	00000
1 1/4	20	3,000 psi @ 100° F	1,500 psi @ 700° F	Phosphate-Coated Steel	Graphite-Filled 304 Stainless Steel	0000000	000000
1 1/2	24	3,000 psi @ 100° F	1,500 psi @ 700° F	Phosphate-Coated Steel	Graphite-Filled 304 Stainless Steel	0000000	000000
2	32	3,000 psi @ 100° F	1,500 psi @ 700° F	Phosphate-Coated Steel	Graphite-Filled 304 Stainless Steel	0000000	000000

Union Straight Connectors with Lugs

Exploded View

For Use With: Air, Hydraulic Fluid, Natural Gas, Oil, Steam, Water
Pressure Class: 3000
Specifications Met: MSS SP-83, ASME B1.20.1, ASTM A105
Pipe Nipples and Pipe: Use Schedule 160 steel
Flanges: Use Class 1500 steel

NPT Female
Pipe Size	Dash Size	Max. Pressure	Max. Steam Pressure	Material		Each
1/2	08	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	000000
3/4	12	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	00000
1	16	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	000000
1 1/4	20	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	000000
1 1/2	24	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	000000
2	32	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	000000
2 1/2	40	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	000000
3	48	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	000000
4	64	3,000 psi @ 72° F	300 psi @ 360° F	Zinc-Phosphate-Coated Steel	00000000	000000

High-Pressure Galvanized Steel Threaded Pipe Fittings

A galvanized finish gives these fittings better corrosion resistance than our plain steel high-pressure fittings. Also known as Pressure Class 3000 fittings, they have excellent strength to handle high-pressure applications.

Union connectors separate into three pieces so you can access your line without unthreading pipe connections.

For technical drawings and 3-D models, click on a part number.

Union Straight Connectors

Exploded View

For Use With: Air, Hydraulic Fluid, Natural Gas, Oil, Steam, Water
Pressure Class: 3000
Specifications Met: ASME B1.20.1, ASTM A105, ASTM B633, MSS SP-83
Pipe Nipples and Pipe: Use Schedule 160 steel

NPT Female
Pipe Size	Dash Size	Max. Pressure	Max. Steam Pressure		Each
1/4	04	3,000 psi @ 72° F	300 psi @ 360° F	00000000	000000
3/8	06	3,000 psi @ 72° F	300 psi @ 360° F	00000000	00000
1/2	08	3,000 psi @ 72° F	300 psi @ 360° F	00000000	00000
3/4	12	3,000 psi @ 72° F	300 psi @ 360° F	00000000	00000
1	16	3,000 psi @ 72° F	300 psi @ 360° F	00000000	00000
1 1/4	20	3,000 psi @ 72° F	300 psi @ 360° F	00000000	00000
1 1/2	24	3,000 psi @ 72° F	300 psi @ 360° F	00000000	00000
2	32	3,000 psi @ 72° F	300 psi @ 360° F	00000000	00000

Extreme-Pressure Steel Threaded Pipe Fittings

The strongest steel fittings we offer, these can withstand extreme-pressure applications.

Union connectors separate into three pieces so you can access your line without unthreading pipe connections.

Note: The maximum pressure listed for Class 6000 fittings is for conditions where there are no sudden changes in pressure or velocity. Please refer to ASME B16.11 to determine the specific maximum operating pressure for your application.

For technical drawings and 3-D models, click on a part number.

Union Straight Connectors

Exploded View

For Use With: Air, Hydraulic Fluid, Natural Gas, Oil, Steam, Water
Pressure Class: 6000
Specifications Met: ASME B1.20.1, ASTM A105
Pipe Nipples and Pipe: Use Schedule XXH steel
Flanges: Use Class 1500 steel

NPT Female
Pipe Size	Dash Size	Max. Pressure	Max. Steam Pressure	Material		Each
1/4	04	6,000 psi @ 72° F	300 psi @ 360° F	Steel	00000000	000000
3/8	06	6,000 psi @ 72° F	300 psi @ 360° F	Steel	00000000	00000
1/2	08	6,000 psi @ 72° F	300 psi @ 360° F	Steel	00000000	00000
3/4	12	6,000 psi @ 72° F	300 psi @ 360° F	Steel	00000000	00000
1	16	6,000 psi @ 72° F	300 psi @ 360° F	Steel	00000000	00000
1 1/4	20	6,000 psi @ 72° F	300 psi @ 360° F	Steel	000000000	000000
1 1/2	24	6,000 psi @ 72° F	300 psi @ 360° F	Steel	00000000	000000
2	32	6,000 psi @ 72° F	300 psi @ 360° F	Steel	00000000	000000

Low-Pressure Press-Connect Steel Unthreaded Pipe Fittings

For Use On:
EPDM Rubber O-Ring: Ethylene Glycol, Propylene Glycol, Water
Buna-N Rubber O-Ring: Air, Lubricants, Propane, Fuel Oil, Natural Gas, Diesel Fuel
Specifications Met:
EPDM Rubber O-Ring: ASME B31,1, ASME B31.3, ASME B31.9, FM 1920, UL 213
Buna-N Rubber O-Ring: ASME B31.1, ASME B31.3, ASME B31.9, ANSI LC4/CSA 6.32, International Fuel Gas Code
Maximum Pressure:
EPDM Rubber O-Ring: 200 psi @ 72° F
Buna-N Rubber O-Ring: 125 psi @ 72° F
Pipe Nipples and Pipe: Use Schedule 40 Steel
Flanges: Use Class 150 Steel

Crimp these fittings onto steel pipe to form a tightly sealed connection that’s faster than threading or welding and doesn’t require heat. An internal gripping ring and rubber O-ring create a secure seal when crimped. They are designed to leak if fittings have not been crimped; a colored dot marks the leak path so it's easy to spot unsealed connections. These steel fittings are coated in zinc-nickel to resist corrosion, but will rust if frequently exposed to saltwater or harsh chemicals. They are comparable to Viega MegaPress steel fittings.

Fittings meet ASME B31 code requirements for use in pressure piping systems.

Fittings with an EPDM rubber O-ring are often used for water processing lines, fire sprinklers, and heating and cooling systems. EPDM rubber won’t degrade when exposed to water, ethylene glycol, and propylene glycol. These fittings meet UL 213 and FM 1920 standards for use in fire protection systems.

Buna-N rubber O-rings hold up to natural gas, propane, diesel fuel, lubricants, and other oils. Fittings with these O-rings are often used in fuel gas systems and air lines. They meet the ANSI LC4/CSA 6.32 standard for fuel gas systems and comply with the International Fuel Gas Code.

Unions separate into three pieces. Unscrew and remove the center nut for quick access to a line.

For technical drawings and 3-D models, click on a part number.

Union Straight Connectors, Female Press Connect

Union Straight Connector

		EPDM Rubber O-Ring			Buna-N Rubber O-Ring
Pipe Size	Socket Dp.	Lg.		Each	Lg.		Each
1/2	0.188"	4 1/2"	00000000	000000	4 15/32"	00000000	000000
3/4	0.188"	4 63/64"	00000000	00000	4 63/64"	00000000	00000
1	0.188"	5 11/32"	0000000	000000	5 19/64"	00000000	000000
1 1/2	0.375"	6 5/8"	00000000	000000	6 41/64"	00000000	000000
2	0.375"	7 39/64"	00000000	000000	7 11/32"	00000000	000000

Crimping Tools

Crimping Tool

Crimping tools seal fittings in less than five seconds. These tools are cordless, so you can take them to any job. Connect the jaw or ring that matches your pipe size to these tools, then pull the trigger to crimp the fitting. The pivoting head lets you access connections from any angle.

	Battery
Voltage	No. Included	Cap., amp-hrs.	Battery Charger Included	Battery Charging Time, min.	Compatible With		Each
18V DC	2	3	Yes	39	Viega MegaPress Viega ProPress Viega ProPress XL-C	00000000	000000000

Jaw and Ring Sets

Jaw and Ring Set

Jaw and ring sets include three jaws, three rings, and one ring actuator jaw. Jaws are for pipe sizes 1/2 to 1; they fit directly into the crimping tool. Rings are for pipe sizes 1 1/4 to 2; clip the ring around the fitting and use the ring actuator jaw and crimping tool to press the open ends together.

For Pipe
Size	Material	For Manufacturer	For Manufacturer Model No.	Compatible With	Includes	Container Type		Each
1/2, 3/4, 1, 1 1/4, 1 1/2, 2	Stainless Steel, Steel	Ridgid	RP 340	Viega MegaPress	One Ring Actuator Jaw Three Jaws (1/2-1 Pipe Size) Three Rings (1 1/4-2 Pipe Size)	Carrying Case	00000000	000000000

High-Pressure Socket-Connect Steel Unthreaded Pipe Fittings

Socket-connect fittings are easier to weld than butt-weld fittings because the fitting doesn’t need to align perfectly to the pipe. Slide pipe into the socket and weld for a strong, permanent connection. Fittings have heavy duty construction that stands up to high-pressure applications. They are for use in noncorrosive environments.

Union straight connectors separate into three pieces for access to your line. Union straight connectors with gasket provide extra leak protection.

For technical drawings and 3-D models, click on a part number.

Union Straight Connectors

Exploded View

For Use With: Air, Steam, Oil, Water, Natural Gas
Pressure Class : 3000
Specifications Met: ASTM A105, MSS SP-83
Pipe Nipples and Pipe: Use Schedule 80 steel
Flanges: Use Class 300 and 600 steel

Pipe Size	Max. Pressure	Material		Each
1/8	3,000 psi @ 72° F	Steel	000000000	000000
1/4	3,000 psi @ 72° F	Steel	000000000	00000
3/8	3,000 psi @ 72° F	Steel	000000000	00000
1/2	3,000 psi @ 72° F	Steel	000000000	00000
3/4	3,000 psi @ 72° F	Steel	000000000	00000
1	3,000 psi @ 72° F	Steel	000000000	00000
1 1/4	3,000 psi @ 72° F	Steel	000000000	00000
1 1/2	3,000 psi @ 72° F	Steel	000000000	00000
2	3,000 psi @ 72° F	Steel	000000000	00000
2 1/2	3,000 psi @ 72° F	Steel	000000000	000000
3	3,000 psi @ 72° F	Steel	000000000	000000

Union Straight Connectors with Gasket

For Use With: Air, Water, Oil, Natural Gas, Steam, Hydraulic Fluid
Temperature Range: -20° to 700° F
Specifications Met: MSS SP-83, ASTM A105
Pipe Nipples and Pipe: Use Schedule XXH steel
Flanges: Use Class 300 and 600 steel

Pipe Size	Dash Size	Max. Pressure	Max. Steam Pressure	Material	Gasket Material		Each
1/2	08	3,000 psi @ 100° F	1,500 psi @ 700° F	Steel	Graphite-Filled 304 Stainless Steel	0000000	0000000
3/4	12	3,000 psi @ 100° F	1,500 psi @ 700° F	Steel	Graphite-Filled 304 Stainless Steel	0000000	000000
1	16	3,000 psi @ 100° F	1,500 psi @ 700° F	Steel	Graphite-Filled 304 Stainless Steel	0000000	00000
1 1/4	20	3,000 psi @ 100° F	1,500 psi @ 700° F	Steel	Graphite-Filled 304 Stainless Steel	0000000	000000
1 1/2	24	3,000 psi @ 100° F	1,500 psi @ 700° F	Steel	Graphite-Filled 304 Stainless Steel	0000000	000000
2	32	3,000 psi @ 100° F	1,500 psi @ 700° F	Steel	Graphite-Filled 304 Stainless Steel	0000000	000000

Extreme-Pressure Socket-Connect Steel Unthreaded Pipe Fittings

Also known as Pressure Class 6000 fittings, these heavy duty forged fittings are the strongest steel fittings we offer. They are easier to weld than butt-weld fittings because the fitting doesn’t need to align perfectly to the pipe. Slide pipe into the socket and weld for a strong, permanent connection. Fittings are for use in noncorrosive environments.

Union straight connectors separate into three pieces for access to your line.

For technical drawings and 3-D models, click on a part number.

Union Straight Connectors

Exploded View

For Use With: Air, Water, Oil, Natural Gas, Steam, Hydraulic Fluid
Pressure Class : 6000
Specifications Met: ASTM A105
Pipe Nipples and Pipe: Use Schedule XXH steel
Flanges: Use Class 1500 steel

Pipe Size	Dash Size	Max. Pressure	Max. Steam Pressure		Each
1/2	08	6,000 psi @ 72° F	300 psi @ 360° F	000000000	000000
3/4	12	6,000 psi @ 72° F	300 psi @ 360° F	000000000	00000
1	16	6,000 psi @ 72° F	300 psi @ 360° F	000000000	00000
1 1/4	20	6,000 psi @ 72° F	300 psi @ 360° F	000000000	00000
1 1/2	24	6,000 psi @ 72° F	300 psi @ 360° F	000000000	000000
2	32	6,000 psi @ 72° F	300 psi @ 360° F	000000000	000000

Hose Unions for Chemicals and Petroleum

Exploded View

For Use With: Citric Acid, Cutting Oil, Diesel Fuel, Fuel Oil, Gasoline, Hydraulic Fluid, Mineral Oil, Oil
Maximum Pressure: See table

Access your line without twisting the hose—these unions separate into three pieces. Also known as WECO couplings and hammer unions, they’re made of forged steel that’s tough enough to be tightened with the blow of a hammer. Use them with other connectors that have the same hammer union figure and pipe size.

Note: Pressure ratings are given for static (constant) pressure conditions with no instantaneous increases in pressure.

For technical drawings and 3-D models, click on a part number.

Steel
Pipe Size	Dash Size	Gasket Material	Hammer Union Figure	Max. Pressure		Each
NPT Female
1	16	__	200	2,000 psi @ 72° F	0000000	000000
1	16	Buna-N Rubber	206	2,000 psi @ 72° F	0000000	00000
1 1/2	24	__	200	2,000 psi @ 72° F	0000000	00000
2	32	__	100	1,000 psi @ 72° F	0000000	00000
2	32	__	200	2,000 psi @ 72° F	0000000	00000
2	32	Buna-N Rubber	206	2,000 psi @ 72° F	0000000	00000
4	64	Buna-N Rubber	206	2,000 psi @ 72° F	0000000	000000
6	96	Buna-N Rubber	206	2,000 psi @ 72° F	0000000	000000
8	__	Buna-N Rubber	206	2,000 psi @ 72° F	0000000	000000