1/4 Unions | McMaster-Carr

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U.S.–Mexico–Canada Agreement (USMCA) Qualifying

Yes

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2B999

EAR99

DFARS Specialty Metals

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41 Products

About Pipe and Fittings

Measure your pipe and fittings to identify their pipe size, thread size, schedule, and thread type. Then, find compatible components.

Fitting Type

Bridge the gap between pipe with different fitting connections

6 products

Performance

Chemical Resistant

Stay strong when exposed to acids, bases, and other harsh chemicals

24 products

Corrosion Resistant

Withstand exposure to moisture and mild chemicals

22 products

Low-Pressure Stainless Steel Threaded Pipe Fittings

Use these fittings in a low-pressure pipe line.

Union Straight Connectors

Female

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

304 Stainless Steel—Fittings hold up in humid, damp, and washdown environments but will corrode if exposed to salt water or chemicals.

316 Stainless Steel—Fittings are the most corrosion resistant. They stand up to wet environments, just like 304 stainless steel fittings, but unlike 304 stainless steel, they will not corrode from salt water, chlorine solutions, and chemicals.

					304 Stainless Steel			316 Stainless Steel
	Pipe Size	Pressure Class	Body Shape	Max. Steam Pressure @ Temp.	Max. Pressure @ Temp.		Each	Max. Pressure @ Temp.		Each
NPT Female



		1/4	150	Octagon	150 psi @ 350° F	300 psi @ 72° F	4464K484	000000	300 psi @ 72° F	4452K223	000000


		BSPT Female



				1/4	150	Octagon	150 psi @ 350° F	300 psi @ 72° F	4810T162	00000	150 psi @ 72° F	5273N132	00000


				BSPP Female



						1/4	150	Octagon	150 psi @ 350° F	150 psi @ 72° F	9027N145	00000	150 psi @ 72° F	9027N148	00000

Union 90° Elbow Adapters

Female x Male

Female x male 90° elbow adapters are also known as street elbows.

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

304 Stainless Steel—Fittings hold up in humid, damp, and washdown environments but will corrode if exposed to salt water or chemicals.

	Pipe Size						304 Stainless Steel		316 Stainless Steel
	(A)	(B)	Pressure Class	Body Shape	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each		Each
NPT Female × NPT Male



		1/4	1/4	150	Octagon	300 psi @ 72° F	150 psi @ 350° F	4464K714	000000	4452K372	000000

Locknuts

NPSL Thread—NPSL (National Pipe Straight Locknut) threads are compatible with NPT threads.

				304 Stainless Steel		316 Stainless Steel
	Pipe Size	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each		Each
NPSL Female



		1/4	300 psi @ 72° F	150 psi @ 350° F	4464K582	00000	4452K672	00000

Low-Pressure Iron and Steel Threaded Pipe Fittings

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

Union Straight Connectors with Gasket


Female (Hex)	Female (Octogon)

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

	Pressure Class	Body Shape	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.	Gasket Material	Certification		Each
NPT Female



	1/4	150	Octagon	Iron	300 psi @ 72° F	150 psi @ 350° F	Brass	UL Listed	44605K49	000000


	BSPT Female



			1/4	150	Hex	Iron	150 psi @ 72° F	150 psi @ 360° F	Brass	—	4778K162	00000

High-Pressure Stainless Steel Threaded Pipe Fittings

Use these heavy duty fittings in high-pressure flow applications.

Union Straight Connectors

Female

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

304 Stainless Steel—Fittings hold up in humid, damp, and washdown environments but will corrode if exposed to salt water or chemicals.

						304 Stainless Steel			316 Stainless Steel
	Pipe Size	Dash Size	Pressure Class	Body Shape	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each	Max. Steam Pressure @ Temp.		Each
NPT Female



		1/4	04	3000	Hex	2,900 psi @ 72° F	1,900 psi @ 350° F	45525K592	000000	2,000 psi @ 350° F	4443K692	0000000

High-Pressure Iron and Steel Threaded Pipe Fittings

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

Union Straight Connectors

Exploded View

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

Zinc-Phosphate-Coated Steel—A phosphate coating offers some corrosion resistance, but these fittings aren't intended for corrosive environments.

	Dash Size	Pressure Class	Body Shape	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each
NPT Female



	1/4	04	3000	Hex	Zinc-Phosphate-Coated Steel	3,000 psi @ 72° F	300 psi @ 360° F	4513K91	000000

Low-Pressure Brass and Bronze Threaded Pipe Fittings

Use these fittings in low-pressure flow applications. They have good corrosion resistance.

Union Straight Connectors

Exploded View

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

Chrome-Plated Brass—Chrome-plated brass pipe has a mirror-like finish and provides better corrosion resistance than nickel- and black zinc–plated brass.

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

	Pressure Class	Body Shape	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.	Food Industry Std.		Each
NPT Female



	1/4	125	Hex	Chrome-Plated Brass	200 psi @ 72° F	125 psi @ 400° F	—	9162K472	000000


	1/4	125	Octagon	Brass	200 psi @ 72° F	—	NSF/ANSI 61	4429K212	00000


	BSPT Female



			1/4	125	Hex	Bronze	200 psi @ 72° F	125 psi @ 400° F	—	4978K162	00000

High-Pressure Brass and Bronze Threaded Pipe Fittings

High pressures are no problem for these heavy-duty fittings. They are brass for good corrosion resistance.

Union Straight Connectors

Exploded View

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

NPTF Thread—NPTF (Dryseal) threads are compatible with NPT threads.

	Body Shape	Material	Max. Pressure @ Temp.		Each
NPTF Female



	1/4	Hex	Brass	1,200 psi @ 72° F	50785K248	000000

Low-Pressure Galvanized Iron and Steel Threaded Pipe Fittings

The galvanized finish on these fittings provides fair corrosion resistance. Fittings are for use in low-pressure applications.

Union Straight Connectors with Gasket

Exploded View

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

	Pressure Class	Body Shape	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.	Gasket Material	Certification		Each
NPT Female



	1/4	150	Hex	Galvanized Iron	300 psi @ 72° F	150 psi @ 350° F	Brass	UL Listed	4638K731	000000


	BSPT Female



			1/4	150	Hex	Galvanized Iron	150 psi @ 72° F	150 psi @ 360° F	Brass	—	4888K162	00000

Medium-Pressure Stainless Steel Threaded Pipe Fittings

Choose these fittings when you want the same high-quality found in our low-pressure pipe fittings, but need more strength to handle higher pressures.

Union Straight Connectors

Female

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

304 Stainless Steel—Fittings hold up in humid, damp, and washdown environments but will corrode if exposed to salt water or chemicals.

						304 Stainless Steel		316 Stainless Steel
	Pipe Size	Pressure Class	Body Shape	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each		Each
NPT Female



		1/4	1000	Hex	1,000 psi @ 72° F	650 psi @ 350° F	4464K97	000000	4452K462	000000

Precision Extreme-Pressure Stainless Steel Threaded Pipe Fittings

Made to tighter tolerances than other stainless steel pipe fittings, these are also known as instrumentation fittings. The male threads are rolled for extra strength in extreme-pressure applications. Fittings are commonly used to connect equipment in gas and hydraulic fluid lines.

Union Straight Connectors

Female

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

				316 Stainless Steel
	Pipe Size	Dash Size	Body Shape	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each
NPT Female



		1/4	04	Hex	6,600 psi @ 72° F	6,600 psi @ 300° F	48805K939	000000

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 Straight Connectors

NPT Female (Exploded View)

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

	Pressure Class	Body Shape	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.	Certification		Each
NPT Female



	1/4	300	Hex	Iron	600 psi @ 72° F	230 psi @ 550° F	UL Listed	4627K289	000000

CPVC Pipe Fittings for Chemicals

Made of CPVC, these fittings withstand salt solutions, acids, and other harsh substances. They have thick, strong walls to handle heavy duty industrial plumbing and water supply applications, such as water processing and wastewater treatment. These fittings are comparable to Corzan. Some meet ASTM D1784 specifications and testing requirements for material quality.

To prevent leaks in threaded connections, apply a sealant to the male threads. Threaded connections can be taken apart as needed for maintenance and repair. For metal threads, use PTFE tape. For plastic threads, apply a non-hardening, plastic-compatible sealant. Tape or sealants with PTFE are not recommended for plastic-to-plastic connections. When making a threaded connection be careful not to overtighten the threads. To prevent cracks and leaks, finger tighten the fitting, then wrench-tighten one to two turns.

Warning: Never use plastic pipe fittings, flanges, and pipe with compressed air or gas.

Union Straight Connectors


Cement Socket Female	Cement Socket Female

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

Cement-Socket Fitting Connection—Attach socket-connect ends to unthreaded pipe or another socket-connect fitting with a CPVC primer and cement (also known as solvent weld).

80 Pipe Schedule—Schedule 80 fittings have thick, strong walls for heavy duty, industrial applications.

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

	Pipe Schedule	Material	Color	Max. Pressure @ Temp.	Food Industry Std.		Each
NPT Female



	1/4	80	CPVC	Light Gray	Not Rated	NSF/ANSI 61	4589K13	000000


	Cement Socket Female



			1/4	80	CPVC	Light Gray	Not Rated	NSF/ANSI 61	6826K97	00000

Thread Sealant

Applicator-Top Can

Sealants cannot be sold to Colorado, Connecticut, District of Columbia, Delaware, Illinois, Indiana, Massachusetts, Maryland, Maine, Michigan, New Hampshire, New Jersey, Northern Virginia, New York, Ohio, Pennsylvania, Rhode Island, or Utah due to local VOC (Volatile Organic Compounds) regulations.

Container
Size, fl. oz.	Type	Temp. Range, ° F		Each
8	Applicator-Top Can	-100 to 600	4586K9	000000

Thick-Wall Plastic Pipe Fittings for Water

Connect these fittings to Schedule 80 pipe. With thicker, stronger walls than standard-wall fittings, they can handle heavy duty supply applications, such as water processing, wastewater treatment, and irrigation. Fittings are plastic for good corrosion resistance. They meet ASTM specifications and testing requirements for material quality.

Warning: Never use plastic pipe fittings, flanges, and pipe with compressed air or gas.

Note: For fittings that are not rated for pressure, you can use the pressure rating of the plastic pipe as a reference. Threaded fittings are limited to 50% of the rated pressure of the pipe.

Union Straight Connectors


Cement Socket Female	NPT Female

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

Cement-Socket Fitting Connection—Attach socket-connect ends to unthreaded pipe or another socket-connect fitting with a PVC primer and cement (also known as solvent weld).

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

	Pipe Schedule	Material	Color	Max. Pressure @ Temp.	Food Industry Std.		Each
NPT Female



	1/4	80	PVC	Dark Gray	Not Rated	NSF/ANSI 61	4596K83	000000


	Cement Socket Female



			1/4	80	PVC	Dark Gray	Not Rated	NSF/ANSI 61	4881K68	00000

Union Straight Adapters

Cement-Socket Fitting Connection

Female

Threaded Fitting Connection

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

Cement-Socket Fitting Connection—Attach socket-connect ends to unthreaded pipe or another socket-connect fitting with a PVC primer and cement (also known as solvent weld).

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

	Pipe Size
	(A)	(B)	Pipe Schedule	Material	Color	Max. Pressure @ Temp.	Food Industry Std.		Each
Cement Socket Female × NPT Female



		1/4	1/4	80	PVC	Dark Gray	Not Rated	NSF/ANSI 61	4596K658	000000

Union Straight Adapters with Collar


Front	Back

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

Fittings with collar have a stainless steel reinforcement on the female threads to prevent the threads from cracking.

Cement-Socket Fitting Connection—Attach socket-connect ends to unthreaded pipe or another socket-connect fitting with a PVC primer and cement (also known as solvent weld).

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

	Pipe Size
	(A)	(B)	Pipe Schedule	Material	Color	Max. Pressure @ Temp.	Food Industry Std.		Each
Cement Socket Female × NPT Female



		1/4	1/4	80	PVC	Dark Gray	Not Rated	NSF/ANSI 61	9174K41	000000

High-Pressure Stainless Steel Socket-Connect Pipe Fittings

Forged for excellent strength, these heavy duty socket-connect fittings stand up to high-pressure applications. 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.

Union Straight Connectors

Female

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

304/304L Stainless Steel—Fittings hold up in humid, damp, and washdown environments but will corrode if exposed to salt water or chemicals.

316/316L Stainless Steel—Fittings are the most corrosion resistant. They stand up to wet environments, just like 304 stainless steel fittings, but unlike 304 stainless steel, they will not corrode from salt water, chlorine solutions, and chemicals.

							304/304L Stainless Steel		316/316L Stainless Steel
	Pipe Size	Dash Size	Pressure Class	Body Shape	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each		Each
Socket Connect



		1/4	04	3000	Hex	2,900 psi @ 72° F	1,900 psi @ 350° F	44965K472	000000	45515K242	0000000

High-Pressure Brass and Bronze Threaded Pipe Fittings for Drinking Water

Use these heavy duty fittings for high-pressure drinking water applications. They are brass which has good corrosion resistance. They meet NSF/ANSI 61 safety standards for use with drinking water systems.

Union Straight Connectors

Exploded View

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

NPTF Thread—NPTF (Dryseal) threads are compatible with NPT threads.

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

	Body Shape	Material	Max. Pressure @ Temp.	Food Industry Std.		Each
NPTF Female



	1/4	Hex	Brass	1,000 psi @ 72° F	NSF/ANSI 61	1491N149	000000

Extreme-Pressure Iron and Steel Threaded Pipe Fittings

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

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.

Union Straight Connectors

Exploded View

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

	Dash Size	Pressure Class	Body Shape	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each
NPT Female



	1/4	04	6000	Hex	Steel	6,000 psi @ 72° F	300 psi @ 360° F	43455K31	000000

Medium-Pressure Brass and Bronze Threaded Pipe Fittings

Choose these fittings when you need better strength than our low-pressure brass and bronze pipe fittings. They offer good corrosion resistance.

Union Straight Connectors

Exploded View

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

	Pressure Class	Body Shape	Material	Max. Pressure @ Temp.		Each
NPT Female



	1/4	250	Hex	Brass	400 psi @ 72° F	9152K61	000000

High-Pressure Iron and Steel Socket-Connect 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

Socket Connect (Exploded View)

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

	Pressure Class	Body Shape	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each
Socket Connect



	1/4	3000	Hex	Steel	3,000 psi @ 72° F	Not Rated	45005K252	000000

Low-Pressure Aluminum Threaded Pipe Fittings

In addition to being lightweight, these aluminum fittings offer good corrosion resistance. Use them in low-pressure flow applications. To prevent cracking, do not tighten more than a _1/4-turn past hand tight.

Union Straight Connectors

NPT Female (Exploded View)

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

	Pressure Class	Body Shape	Material	Max. Pressure @ Temp.		Each
NPT Female



	1/4	150	Hex	356 Aluminum	150 psi @ 72° F	44705K242	000000

High-Pressure Galvanized Iron and 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 Straight Connectors

Exploded View

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

	Dash Size	Pressure Class	Body Shape	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each
NPT Female



	1/4	04	3000	Hex	Galvanized Steel	3,000 psi @ 72° F	300 psi @ 360° F	7739K172	000000

Medium-Pressure Galvanized Iron and Steel Threaded Pipe Fittings

A galvanized finish gives these fittings fair corrosion resistance. They have the strength to handle medium-pressure applications.

Union Straight Connectors

Female

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

	Pressure Class	Body Shape	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.	Certification		Each
NPT Female



	1/4	300	Hex	Galvanized Iron	600 psi @ 72° F	230 psi @ 550° F	FM Approved, UL Listed	2066N43	000000