M20 Couplings | McMaster-Carr

With the strength to handle extreme pressures, these fittings can be used to connect equipment in hydraulic fluid lines. 316 stainless steel fittings have excellent corrosion resistance. BSPP and metric male threads have either a gasket or a gasket and washer to prevent leaks.

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

Straight Adapters, Female × Male

BSPP and Metric
Male Threads with
Gasket and Washer

For Use With: See table
Specifications Met: See table

						316 Stainless Steel
Pipe Size (A)	Dash Size (A)	Thread Size (B)	Max. Pressure	For Use With	Specifications Met		Each
NPT Female × Metric Male
1/2	08	M20 × 1.5 mm	3,500 psi @ 72° F	Hydraulic Fluid, Oil, Water	ASME B1.20.3, DIN 7631, ISO 9974	00000000	000000

Straight Adapters, Male

Front

BSPP and Metric
Male Threads with
Gasket and Washer

For Use With: See table
Specifications Met: See table

						316 Stainless Steel
Pipe Size (A)	Dash Size (A)	Thread Size (B)	Max. Pressure	For Use With	Specifications Met		Each
BSPP Male × Metric Male
3/8	06	M20 × 1.5 mm	5,000 psi @ 72° F	Hydraulic Fluid, Oil, Water	DIN 7631, ISO 1179, ISO 8434-6, ISO 9974	00000000	000000
1/2	08	M20 × 1.5 mm	4,500 psi @ 72° F	Hydraulic Fluid, Oil, Water	DIN 7631, ISO 1179, ISO 8434-6, ISO 9974	00000000	00000
3/4	12	M20 × 1.5 mm	3,600 psi @ 72° F	Hydraulic Fluid, Oil, Water	DIN 7631, ISO 1179, ISO 8434-6, ISO 9974	00000000	00000

Replacement Washers

Temperature Range: -22° to 230° F

			316 Stainless Steel
For Pipe Size	For Thread Size	Gasket Material		Each
For BSPP Male
3/8	__	Buna-N Rubber	00000000	00000
1/2	__	Buna-N Rubber	00000000	0000
3/4	__	Buna-N Rubber	00000000	0000
For Metric Male
__	M20	Buna-N Rubber	00000000	0000

Compact Extreme-Pressure Steel Threaded Pipe Fittings

These fittings are strong enough to handle extreme pressures, yet small enough to fit into cramped spaces. They are galvanized steel, which has fair corrosion resistance. BSPP and metric male threads have a gasket and washer to prevent leaks.

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

Straight Connectors, Female

For Use With:
NPTF: Air, Hydraulic Fluid, Water
Metric: Air, Hydraulic Fluid, Oil, Water
Specifications Met:
NPTF: ASTM A108
Metric: DIN 7631, ISO 6149, ISO 9974

Metric Female
Thread Size	Max. Pressure		Each
M20 × 1.5 mm	3,500 psi @ 72° F	00000000	000000

Straight Adapters, Female × Male

BSPP and Metric
Male Threads with
Gasket and Washer

For Use With: See table
Specifications Met: See table

NPT Female × Metric Male
Pipe Size (A)	Thread Size (A)	Dash Size (A)	Pipe Size (B)	Thread Size (B)	Dash Size (B)	Max. Pressure	For Use With	Specifications Met		Each
1/2	__	08	__	M20 × 1.5 mm	__	4,500 psi @ 72° F	Air, Hydraulic Fluid, Oil, Water	ASME B1.20.3, DIN 7631, ISO 6149, ISO 9974	00000000	000000
Metric Female × NPT Male
__	M20 × 1.5 mm	__	1/2	__	08	4,500 psi @ 72° F	Air, Hydraulic Fluid, Oil, Water	ASME B1.20.3, DIN 7631, ISO 6149, ISO 9974	00000000	00000

Straight Adapters, Male

BSPP, Metric, and UN/UNF
(SAE) Male Threads
with Gasket and Washer

For Use With: See table
Specifications Met: See table

BSPP Male × Metric Male
Pipe Size (A)	Dash Size (A)	Thread Size (B)	Max. Pressure	For Use With	Specifications Met		Each
1/2	08	M20 × 1.5 mm	4,500 psi @ 72° F	Air, Diesel Fuel, Gasoline, Hydraulic Fluid, Oil, Water	DIN 7631, ISO 1179, ISO 6149, ISO 8434-6, ISO 9974	00000000	000000

Replacement Washers

Temperature Range: -20° to 230° F

For BSPP Male
For Pipe Size	For Thread Size	Gasket Material		Each
1/2	__	Buna-N Rubber	00000000	00000
For Metric Male
__	M20	Buna-N Rubber	00000000	0000

High-Pressure Plated Brass Threaded Pipe Fittings

The plating on these brass fittings creates a shiny finish and provides extra protection in corrosive environments. Fittings have the strength to handle high-pressure applications.

Nickel-plated brass fittings provide better corrosion resistance than unplated brass fittings.

Through-wall fittings are also known as bulkhead couplings and panel-mount couplings; they mount through a wall or panel to create an inlet or outlet.

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

Through-Wall Straight Adapters

For Use With: Air, Natural Gas, Oil, Water

				Nickel-Plated Brass
Pipe Size	Thread Size	For Max. Wall Thick.	Max. Pressure		Each
BSPP Female × Metric Male
1/4	M20 × 1.5 mm	0.098"	1,450 psi @ 72° F	00000000	00000

Plastic Pipe Fittings for Oil

Made of corrosion-resistant plastic, these fittings won’t deteriorate when used in oil applications. They also have high strength and impact resistance. Apply a non-hardening, plastic-compatible sealant to the male threads to prevent leaks. Tape or sealants with PTFE are not recommended for plastic-to-plastic threaded 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 and pipe with compressed air or gas.

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

Nuts, Female Threaded Pipe

Temperature Range: 0° to 230° F
For Use With: Oil

Metric Threads
Thread Size	Thread Direction	Material	Color	Maximum Pressure		Each
M20 × 1.5 mm	Right Hand	Nylon Plastic	Blue	200 psi @ 72° F	00000000	00000

Metal Barbed Hose Fittings for Air and Water

Slide the barbed end into rubber hose and secure with a clamp or a crimp-on hose ferrule.

Brass fittings are softer than other metal fittings, so they’re easier to thread together. Plain brass fittings have good corrosion resistance. Nickel-plated brass fittings resist corrosion better than plain brass fittings.

Aluminum fittings are lighter in weight than other metal fittings. They have good corrosion resistance.

Stainless steel fittings have very good corrosion resistance. 303 stainless steel fittings won’t rust when exposed to water, making them good for areas that require frequent cleanings.Fittings with a threaded end are also known as hose nipples.

Metric, UN/UNF (SAE), and BSPP male threads with gasket protect against leaks.

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

Straight Adapters, Hose × Metric Male Threaded Pipe

NPT/NPTF, Metric, BSPP,
and UN/UNF (SAE) Male
Threads with Gasket

Maximum Pressure: See table
Maximum Vacuum: 27 in. of Hg @ 72° F
Temperature Range: See table
Attachment Type: See table
Specifications Met: See table

Brass
For Hose ID	Thread Size	Gasket Material	Max. Pressure	Temperature Range, °F	Attachment Type	Pkg. Qty.		Pkg.
3/4"	M20 × 1.5 mm	Buna-N Rubber	300 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	000000
1"	M20 × 1.5 mm	Buna-N Rubber	300 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	00000
19mm	M20 × 1.5 mm	Buna-N Rubber	250 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	00000
Nickel-Plated Brass
3/4"	M20 × 1.5 mm	Buna-N Rubber	125 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	00000
1"	M20 × 1.5 mm	Buna-N Rubber	125 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	00000
19mm	M20 × 1.5 mm	Buna-N Rubber	125 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	00000
Aluminum
3/4"	M20 × 1.5 mm	Buna-N Rubber	125 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	00000
1"	M20 × 1.5 mm	Buna-N Rubber	125 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	00000
19mm	M20 × 1.5 mm	Buna-N Rubber	125 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	00000
303 Stainless Steel
3/4"	M20 × 1.5 mm	Buna-N Rubber	125 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	00000
1"	M20 × 1.5 mm	Buna-N Rubber	125 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	00000
19mm	M20 × 1.5 mm	Buna-N Rubber	125 psi @ 72° F	-30° to 200°	Worm-Drive Clamp, Band-and-Buckle Clamp, Crimp-On Hose Ferrule	1	00000000	00000

Metal Barbed Hose Fittings for Chemicals and Petroleum

Made of 316 stainless steel, these fittings have the corrosion resistance to stand up to a wide variety of chemicals, as well as fuels, gasoline, and oils. To connect, slide the barbed end into plastic or rubber hose and secure with a clamp.

Adapters are also known as hose nipples; they adapt a barbed end to a threaded end.

Metric and UN/UNF (SAE) male threads have a gasket to protect against leaks.

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

Straight Adapters, Hose × Metric Male Threaded Pipe

For Use With: See table
Maximum Pressure: See table
Temperature Range: -40° to 300° F
Attachment Type: Use Band-and-Buckle Clamps

	Thread
For Hose ID	Size	Pitch, mm	Gasket Material	Max. Pressure	For Use With		Each
316 Stainless Steel
3/4"	M20	1.5	Fluoroelastomer Rubber	125 psi @ 72° F	Acetone, Diesel Fuel, Ethanol, Fuel Oil, Gasoline, Mineral Oil, Mineral Spirits, Vegetable Oil	000000000	000000
1"	M20	1.5	Fluoroelastomer Rubber	125 psi @ 72° F	Acetone, Diesel Fuel, Ethanol, Fuel Oil, Gasoline, Mineral Oil, Mineral Spirits, Vegetable Oil	000000000	00000
19mm	M20	1.5	Fluoroelastomer Rubber	125 psi @ 72° F	Acetone, Diesel Fuel, Ethanol, Fuel Oil, Gasoline, Mineral Oil, Mineral Spirits, Vegetable Oil	000000000	00000

Compression Fittings for Copper Tubing

For Use With: Air, Cutting Oil, Fuel Oil, Hydraulic Fluid, Mineral Oil, Water
Temperature Range: See Table
Tubing: Use with copper
Specifications Met: See Table

A single sleeve (ferrule) bites into tubing as you tighten the nut, creating a strong seal. The nut and sleeve are included. Fittings are also known as flareless fittings. They are brass for good corrosion resistance.

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

Straight Adapters, Tube × Male Threaded Pipe

For Tube
OD	Wall Thick.	Thread Size	Thread Pitch, mm	Material	Max. Pressure	Temp. Range, °F		Each
Metric Threads
14mm	1mm	M20	1.5	Brass	650 psi @ 72° F	-40° to 250°	00000000	000000
16mm	1mm	M20	1.5	Brass	580 psi @ 72° F	-40° to 250°	00000000	00000

37° Flared Fittings for Steel Tubing

Tubing: Use with seamless steel
Specifications Met: SAE J514

Also known as JIC (Joint Industrial Council) fittings, these provide a tight metal-to-metal seal on tubing that is flared to 37°. They require a nut and a sleeve (ferrule) for each tube end. Nuts and sleeves are sold separately. Fittings are zinc-plated steel for fair corrosion resistance.

To prevent leaks, UN/UNF (SAE) male threads have a gasket. Metric and BSPP male threads have either a gasket or a gasket and washer.

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

Straight Adapters, Male Tube × Male Threaded Pipe

For Use With: See Table
Temperature Range: See Table

Metric Threads
For Tube OD	Thread Size	Thread Pitch, mm	For Use With	O-Ring Material	Material	Gasket Material	Max. Pressure	Temp. Range, °F		Each
5/8"	M20	1.5	Air, Fuel Oil, Hydraulic Fluid, Mineral Oil	Buna-N Rubber	Zinc-Plated Steel	Buna-N Rubber	2,300 psi @ 72° F	-30° to 200°	00000000	000000

90° Elbow Adapters, Male Tube × Male Threaded Pipe

For Use With: NPTF, Metric, BSPP with O-Rings, BSPT: Air, Fuel, Oil, Hydraulic Fluid, Mineral Oil
BSPP with Washers: Cutting Oil, Fuel Oil, Hydraulic Fluid, Mineral Oil
Temperature Range: NPTF and BSPT: -60° to 400° F
Metric and BSPP with O-Rings: -30° to 200°F
BSPP with Washers: -20° to 212° F

Metric Threads
For Tube OD	Thread Size	Thread Pitch, mm	O-Ring Material	Material	Gasket Material	Max. Pressure		Each
5/8"	M20	1.5	Buna-N Rubber	Zinc-Plated Steel	Buna-N Rubber	2,300 psi @ 72° F	00000000	0000000

Nuts

For Use With: Air, Fuel Oil, Hydraulic Fluid, Mineral Oil
Temperature Range: -60° to 400° F

For Tube OD	Nut Material	Max. Pressure		Each
5/8"	Zinc-Plated Steel	3,000 psi @ 72° F	000000000	00000

Sleeves

For Use With: Air, Fuel Oil, Hydraulic Fluid, Mineral Oil
Temperature Range: -60° to 400° F

Use these sleeves with a nut and fitting to provide a tight metal-to-metal seal on steel tubing that is flared to 37°. Sleeves are zinc-plated steel for fair corrosion resistance. They are also known as ferrules.

Sleeves for metric tube ODs convert the fitting from inch to metric.

For Tube OD
Inch	Metric, mm	Sleeve Material	Max. Pressure		Each
Inch
5/8"	__	Zinc-Plated Steel	3,000 psi @ 72° F	000000000	00000
Metric
5/8"	14	Zinc-Plated Steel	3,000 psi @ 72° F	000000000	0000
5/8"	15	Zinc-Plated Steel	3,000 psi @ 72° F	000000000	0000
5/8"	16	Zinc-Plated Steel	3,000 psi @ 72° F	000000000	0000

Metric Low-Strength Steel Coupling Nuts

Often referred to 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.

Black-oxide steel coupling nuts have a dark surface color and are mildly corrosion resistant in dry environments.

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

Thread						Each
Size	Pitch, mm	Lg., mm	Wd., mm	Specifications Met		1-9	10-Up
Zinc-Plated Steel
M20	2.5	60	30	DIN 6334	000000000	00000	00000
Black-Oxide Steel
M20	2.5	51	32	__	000000000	00000	0000

Metric Medium-Strength Steel Coupling Nuts—Class 8

Often referred to as extension nuts, use these to connect and extend threaded rods. They're comparable in strength to Class 8.8 bolts.

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

Black-oxide steel coupling nuts have a dark surface color and are mildly corrosion resistant in dry environments.

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

Thread						Each
Size	Pitch, mm	Lg., mm	Wd., mm	Specifications Met		1-9	10-Up
Zinc-Plated Steel—Class 8
M20	2.5	60	30	DIN 6334	000000000	00000	00000
Black-Oxide Steel—Class 8
M20	2.5	60	30	DIN 6334	000000000	00000	00000

Metric 18-8 Stainless Steel Coupling Nuts

Stainless Steel

Black-Oxide Stainless Steel

Made from 18-8 stainless steel, these metric coupling nuts have good chemical resistance and may be mildly magnetic. Also known as extension nuts, use them to connect and extend threaded rods.

Coupling nuts with a black-oxide finish have a dark surface color.

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

Thread						Each
Size	Pitch, mm	Lg., mm	Wd., mm	Specifications Met		1-9	10-Up
18-8 Stainless Steel
M20	2.5	60	30	DIN 6334	000000000	000000	000000
Black-Oxide 18-8 Stainless Steel
M20	2.5	60	30	DIN 6334	000000000	00000	00000

Metric Super-Corrosion-Resistant
316 Stainless Steel Coupling Nuts

Made from 316 stainless steel, these coupling have excellent resistance to chemicals and salt water. Also known as extension nuts, use them to connect and extend threaded rods. They may be mildly magnetic.

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

Thread						Each
Size	Pitch, mm	Lg., mm	Wd., mm	Specifications Met		1-9	10-Up
316 Stainless Steel
M20	2.5	60	30	DIN 6334	000000000	000000	000000

Brass Coupling Nuts

These coupling nuts are corrosion resistant in wet environments, electrically conductive, and nonmagnetic. Also known as extension nuts, use them to connect and extend threaded rods.

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

Metric

				Each
Thread Size	Lg., mm	Wd., mm		1-9	10-Up
Brass
M20	60	30	000000000	000000	000000

Stainless Steel Extra-Long Coupling Nuts

These coupling nuts have good chemical resistance. Also known as sleeve nuts, they're at least twice the length of standard coupling nuts to provide more room to connect and extend long lengths of threaded rods.

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

Metric

Thread							Each
Size	Pitch, mm	Lg., mm	Wd., mm	Threading	Min. Thread Lg., mm		1-9	10-Up
18-8 Stainless Steel
M20	2.5	120	30	Partially Threaded	20	000000000	0000000	0000000

Round Coupling Nuts

With a smooth rounded body for a finished look, use these nuts to connect and extend threaded rods. Made from 18-8 stainless steel, they have good chemical resistance.

Coupling nuts with a black-oxide finish have a dark surface color.

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

Thread						Each
Size	Pitch, mm	Lg., mm	OD, mm	Specifications Met		1-9	10-Up
18-8 Stainless Steel
M20	2.5	30	28	ASTM A582	000000000	000000	000000
M20	2.5	40	28	ASTM A582	000000000	00000	00000
M20	2.5	50	28	ASTM A582	000000000	00000	00000
Black-Oxide 18-8 Stainless Steel
M20	2.5	30	28	ASTM A582	000000000	00000	00000
M20	2.5	40	28	ASTM A582	000000000	00000	00000
M20	2.5	50	28	ASTM A582	000000000	00000	00000

How to Identify and Measure Fittings

About Nuts, Materials, and Finishes

Extreme-Pressure Stainless Steel Threaded Pipe Fittings

Compact Extreme-Pressure Steel Threaded Pipe Fittings

High-Pressure Plated Brass Threaded Pipe Fittings

Plastic Pipe Fittings for Oil

Metal Barbed Hose Fittings for Air and Water

Metal Barbed Hose Fittings for Chemicals and Petroleum

Compression Fittings for Copper Tubing

37° Flared Fittings for Steel Tubing

Metric Low-Strength Steel Coupling Nuts

Metric Medium-Strength Steel Coupling Nuts—Class 8

Metric 18-8 Stainless Steel Coupling Nuts

Metric Super-Corrosion-Resistant316 Stainless Steel Coupling Nuts

Brass Coupling Nuts

Stainless Steel Extra-Long Coupling Nuts

Round Coupling Nuts

Metric Super-Corrosion-Resistant
316 Stainless Steel Coupling Nuts