UNS Couplings | McMaster-Carr

Clear All

	System of Measurement System of Measurement

Inch

	Thread Size Thread Size

	Thread Type Thread Type	Show

UNS

	Thread Type Thread Type	Hide

	Nut Type Nut Type


Coupling	Hex

	Fastener Strength Grade/Class Fastener Strength Grade/Class


Grade 5	Grade 8

	Material Material

	Width Width

1 3/8"

1 1/2"

	Length Length

	Threading Threading

	Fully Threaded

	Type Type


Adapter	Nut

	Thread Fit Thread Fit

Class 2B

	Thread Direction Thread Direction

Right Hand

Left Hand

	Finish Finish

Zinc Plated

	For Tube OD For Tube OD

1/4"

5/16"

3/8"

	Gender Gender

Female

Male

	For Use With For Use With

	Connection Style Connection Style

Threaded

Push to Connect

	Shape Shape

	Straight

	RoHS (Restriction of Hazardous Substances) RoHS (Restriction of Hazardous Substances)

RoHS Compliant

RoHS Compliant with
Exemptions

	Thread Spacing Thread Spacing

Fine

	REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) REACH (Registration, Evaluation, Authorization and Restriction of Chemicals)

REACH Compliant

	DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense Acquisition Regulations Supplement)

DFARS Specialty Metals
COTS-Exempt

	CGA Number CGA Number

296

590

705

View catalog pages (4)

Forward

How can we improve?

11 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.

About Nuts, Materials, and Finishes

Nuts for High-Pressure Nipples for Compressed Gas

Slide a high-pressure hose nipple for compressed gas into one of these nuts to connect a pipe to the inlet of a pressure regulator. They are also known as CGA (Compressed Gas Association) nuts and inlet nuts.

Brass nuts have good corrosion resistance and are softer than 316 stainless steel nuts, so they're easier to thread together. 316 stainless steel nuts have excellent corrosion resistance.

Note: Nuts have a CGA, BS, or DIN number that corresponds to a specific type of gas. Choose a nut with the same number as your tank and other system components.

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

Female

Maximum Pressure: See table
Maximum Temperature: 120° F, except DIN 477 No. 9: 250° F

316 Stainless Steel
Number	Thread Size	Thread Type	Thread Direction	Max. Pressure	For Use With		Each
CGA 705	1.125"-14	UNS	Right Hand	3,000 psi @ 72° F	Ammonia	000000000	000000

Male

Maximum Pressure: See table
Maximum Temperature: 120° F, except DIN 477 No. 12: 250° F

Brass
Number	Thread Size	Thread Type	Thread Direction	Max. Pressure	For Use With		Each
CGA 296	0.803"-14	UNS	Right Hand	3,000 psi @ 72° F	Oxygen Mixtures	000000000	00000

High-Pressure Threaded Fittings for Compressed Gas

Designed to handle high-pressure welding applications, these fittings are commonly used to connect pressure regulators to compressed gas tanks or cylinders. Fittings are also known as CGA (Compressed Gas Association) fittings. They are brass for good corrosion resistance.

Fittings with left-hand threads are identified with a notch in the nut.

Note: Fittings have a CGA number that corresponds to a specific type of gas. Choose a fitting with the same CGA number as your tank and other system components.

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

Male Tank × Female Regulator

Maximum Pressure: 3,000 psi @ 72° F
Maximum Temperature: 120° F

CGA Number		Tank Connection			Regulator Connection
Tank	Regulator	Thread Size	Thread Type	Thread Direction	Thread Size	Thread Type	Thread Direction	For Use With		Each
Brass
296	590	0.803"-14	UNS	Right Hand	0.960"-14	NGO	Left Hand	Oxygen Mixtures, Sulfur Hexafluoride	0000000	000000

Push-to-Connect Fittings for Plastic Tubing—Food and Beverage

Temperature Range: 35° to 140° F
Tubing: See table
Specifications Met:
White Polypropylene: NSF/ANSI 51, NSF/ANSI 61
Black Polypropylene: FDA Compliant 21 CFR 176.170, NSF/ANSI 58, NSF/ANSI 372
Acetal: NSF/ANSI 51, NSF/ANSI 61

Also known as instant fittings, these connect to tubing with a push, and an internal gripping ring and O-ring hold the tubing tight. To disconnect fittings with a release ring, push on the release ring and pull the tubing out of the fitting.

Polypropylene fittings have excellent impact and abrasion resistance. They meet NSF/ANSI standards for safe use with food. Some are also FDA compliant for indirect contact with food.

Black fittings have excellent UV resistance and are suitable for outdoor environments.

Fittings with UNS threads are also known as faucet connectors; they attach directly to a faucet threaded inlet or water line.

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

Straight Adapters, Tube × Female Threaded Pipe

White
For Tube OD	Thread Size	Material	Max. Pressure	For Tube Hardness Rating	For Tube Hardness	Release Ring Color		Each
UNS Threads
1/4"	7/16"-24	Polypropylene Plastic	150 psi @ 72° F	Hard	Durometer 50D-70D	White	0000000	00000
3/8"	7/16"-24	Polypropylene Plastic	150 psi @ 72° F	Hard	Durometer 50D-70D	White	0000000	0000
Black
UNS Threads
1/4"	7/16"-24	Polypropylene Plastic	150 psi @ 72° F	Hard	Durometer 50D-70D	Black	00000000	0000
5/16"	7/16"-24	Polypropylene Plastic	150 psi @ 72° F	Hard	Durometer 50D-70D	Black	00000000	0000

Plastic Push-to-Connect Tube Fittings for Chemicals

For Use With: Inch: Acetic Acid, Alcohol, Arsenic Acid, Benzoic Acid, Fluoboric Acid, Hydrochloric Acid, Nitric Acid, Sodium Carbonate, Sulfuric Acid
Metric: Acetic Acid, Alcohol, Arsenic Acid, Benzoic Acid, Fluoboric Acid, Sodium Carbonate, Sulfuric Acid
Temperature Range: Inch: 0° to 270° F
Metric: 32° to 175° F
Tubing: Use with hard (Durometer 55D-60D) FEP plastic

Also known as instant fittings, these chemical-resistant plastic fittings connect to tubing with a push, and an internal gripping ring and fluoroelastomer O-ring hold the tubing tight. To disconnect, push on the release ring and pull the tubing out of the fitting.

PVDF fittings offer excellent chemical resistance, and can be used with hydrochloric acid and nitric acid. They withstand temperatures up to 270° F, higher than other push-to-connect fittings for chemicals. They are produced in a clean room and are bagged individually to prevent dirt and moisture from contaminating the inside. PVDF is also known as Kynar.

Fittings with UNS threads are also known as faucet connectors; they attach directly to a faucet threaded inlet or water line.

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

Straight Adapters, Tube × Female Threaded Pipe

UNS Threads
For Tube OD	Thread Size	Material	Color	Release Ring Color	Max. Pressure		Each
1/4"	7/16"-24	PVDF Plastic	Black	Gray	300 psi @ 72° F	00000000	00000

Low-Strength Steel Coupling Nuts

Also known as extension nuts, use these to connect and extend threaded rods. They're about half the strength of medium-strength steel coupling nuts for use in light duty fastening applications.

Zinc-plated steel coupling nuts resist corrosion in wet environments.

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

				Each
Thread Size	Lg.	Wd.		1-9	10-Up
Zinc-Plated Steel
1"-14	2 3/4"	1 3/8"	000000000	000000	000000

Medium-Strength Steel Coupling Nuts—Grade 5

Also known as extension nuts, use these to connect and extend threaded rods.

Zinc-plated steel coupling nuts resist corrosion in wet environments.

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

				Each
Thread Size	Lg.	Wd.		1-9	10-Up
Zinc-Plated Steel—Grade 5
1"-14	2 3/4"	1 3/8"	000000000	000000	000000

High-Strength Steel Coupling Nuts—Grade 8

Also known as extension nuts, use these to connect and extend threaded rods. Made from Grade 8 steel, they're about 25% stronger than medium-strength steel coupling nuts. A zinc plating provides corrosion resistance in wet environments.

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

				Each
Thread Size	Lg.	Wd.		1-9	10-Up
Zinc-Plated Steel—Grade 8
1"-14	2 3/4"	1 1/2"	000000000	000000	000000