Black Iron Pipe Unions | McMaster-Carr

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62 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.

Medium-Pressure Iron and Steel Threaded Pipe Fittings

With better strength than our low-pressure iron and steel pipe fittings, these can handle medium-pressure applications. They are for use in noncorrosive environments.

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, Steam, Oil, Water, Natural Gas
Pressure Class : 300
Specifications Met: ASTM A197, UL Listed, ASME B16.39, ASME B1.20.1
Pipe Nipples and Pipe: Use Schedule 80 steel
Flanges: Use Class 300 or 600 steel

NPT Female
Pipe Size	Max. Pressure	Max. Steam Pressure	Material		Each
1/8	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	000000
1/4	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	00000
3/8	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	00000
1/2	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	00000
3/4	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	00000
1	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	00000
1 1/4	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	00000
1 1/2	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	00000
2	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	00000
2 1/2	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	000000
3	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	000000

Union 90° Elbow Connectors

Exploded View

For Use With: Air, Steam, Oil, Water, Natural Gas
Pressure Class : 300
Specifications Met: ASTM A197, UL Listed, ASME B16.39, ASME B1.20.1
Pipe Nipples and Pipe: Use Schedule 80 steel
Flanges: Use Class 300 or 600 steel

NPT Female
Pipe Size	Max. Pressure	Max. Steam Pressure	Material		Each
3/8	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	0000000
1/2	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	00000
3/4	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	00000
1	600 psi @ 72° F	230 psi @ 550° F	Iron	00000000	000000

Low-Pressure Iron and Steel Threaded Pipe Fittings

Use these fittings for low-pressure applications in noncorrosive environments.

Union connectors separate into three pieces so you can access your line without unthreading pipe connections. They have a gasket that creates a tight seal.

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

Union Straight Connectors

Hex Nut-Exploded View

Octagon Nut-Exploded View

For Use With: Air, Steam, Oil, Water, Natural Gas
Pressure Class: 150
Specifications Met: See table
Pipe Nipples and Pipe: Use Schedule 40 steel

NPT Female
Pipe Size	Max. Pressure	Max. Steam Pressure	Body Shape	Material	Gasket Material	Specifications Met		Each
1/8	300 psi @ 72° F	150 psi @ 350° F	Hex	Iron	Brass	ASME B1.20.1, ASME B16.39	000000000	000000
1/4	300 psi @ 72° F	150 psi @ 350° F	Hex	Iron	Brass	ASME B1.20.1, ASME B16.39, UL Listed	000000000	00000
3/8	300 psi @ 72° F	150 psi @ 350° F	Hex	Iron	Brass	ASME B1.20.1, ASME B16.39, UL Listed	000000000	00000
1/2	300 psi @ 72° F	150 psi @ 350° F	Octagon	Iron	Brass	ASME B1.20.1, ASME B16.39, UL Listed	000000000	00000
3/4	300 psi @ 72° F	150 psi @ 350° F	Octagon	Iron	Brass	ASME B1.20.1, ASME B16.39, UL Listed	000000000	00000
1	300 psi @ 72° F	150 psi @ 350° F	Octagon	Iron	Brass	ASME B1.20.1, ASME B16.39, UL Listed	000000000	00000
1 1/4	300 psi @ 72° F	150 psi @ 350° F	Hex	Iron	Brass	ASME B1.20.1, ASME B16.39, UL Listed	000000000	00000
1 1/2	300 psi @ 72° F	150 psi @ 350° F	Octagon	Iron	Brass	ASME B1.20.1, ASME B16.39, UL Listed	000000000	00000
2	300 psi @ 72° F	150 psi @ 350° F	Octagon	Iron	Brass	ASME B1.20.1, ASME B16.39, UL Listed	000000000	00000
2 1/2	300 psi @ 72° F	150 psi @ 350° F	Hex	Iron	Brass	ASME B1.20.1, ASME B16.3, ASME B16.39, UL Listed	00000000	000000
3	300 psi @ 72° F	150 psi @ 350° F	Hex	Iron	Brass	ASME B1.20.1, ASME B16.39, UL Listed	00000000	000000
4	300 psi @ 72° F	150 psi @ 350° F	Octagon	Iron	Brass	ASME B1.20.1, ASME B16.39	000000000	000000
BSPT Female
1/4	150 psi @ 72° F	150 psi @ 360° F	Hex	Iron	Brass	DIN EN 10226	00000000	00000
3/8	150 psi @ 72° F	150 psi @ 360° F	Hex	Iron	Brass	DIN EN 10226	00000000	00000
1/2	150 psi @ 72° F	150 psi @ 360° F	Hex	Iron	Brass	DIN EN 10226	00000000	00000
3/4	150 psi @ 72° F	150 psi @ 360° F	Hex	Iron	Brass	DIN EN 10226	00000000	00000
1	150 psi @ 72° F	150 psi @ 360° F	Hex	Iron	Brass	DIN EN 10226	00000000	00000
1 1/4	150 psi @ 72° F	150 psi @ 360° F	Hex	Iron	Brass	DIN EN 10226	00000000	00000
1 1/2	150 psi @ 72° F	150 psi @ 360° F	Hex	Iron	Brass	DIN EN 10226	00000000	00000
2	150 psi @ 72° F	150 psi @ 360° F	Hex	Iron	Brass	DIN EN 10226	00000000	00000
2 1/2	150 psi @ 72° F	150 psi @ 360° F	Hex	Iron	Brass	DIN EN 10226	0000000	00000

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