M27 Couplings | McMaster-Carr

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REACH Compliant

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	External Hex

	Coupling Nut Profile Coupling Nut Profile

Standard

	Fastener Strength Grade/Class Fastener Strength Grade/Class


Class 8	Class 10

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13 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

Extreme-Pressure Stainless Steel Threaded Pipe Fittings

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. UN/UNF (SAE) threads are also known as O-ring boss threads; the male threads have a gasket to prevent leaks.

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

Straight Adapters, Female × Male

Straight Adapter

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

Specifications Met: See table
For Use With: See table

						316 Stainless Steel
Thread Size (A)	Dash Size (A)	Thread Size (B)	Dash Size (B)	Max. Pressure	For Use With		Each
UN/UNF (SAE) Female × Metric Male
1 1/16"-12	12	M27 × 2 mm	__	3,500 psi @ 72° F	Hydraulic Fluid (Petroleum Base), Oil, Water	000000000	000000
Metric Female × UN/UNF (SAE) Male
M27 × 2 mm	__	1 1/16"-12	12	5,000 psi @ 72° F	Hydraulic Fluid (Petroleum Base), Oil, Water	000000000	00000

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
3/4	12	M27 × 1.5 mm	3,600 psi @ 72° F	Hydraulic Fluid, Oil, Water	DIN 7631, ISO 1179, ISO 8434-6, ISO 9974	00000000	000000

Replacement Washers

Temperature Range: -22° to 230° F

		316 Stainless Steel
For Pipe Size	Gasket Material	Thickness		Each
For BSPP Male
3/4	Buna-N Rubber	2.5mm	00000000	00000

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 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

NPT Female × Metric Male
Pipe Size (A)	Dash Size (A)	Thread Size (B)	Max. Pressure	For Use With	Specifications Met		Each
3/4	12	M27 × 2 mm	3,000 psi @ 72° F	Air, Hydraulic Fluid, Oil, Water	ASME B1.20.3, DIN 7631, ISO 6149, ISO 9974	00000000	000000

Replacement Washers

Temperature Range: -20° to 230° F

For Metric Male
For Thread Size	Gasket Material	Thickness		Each
M27	Buna-N Rubber	2mm	00000000	00000

High-Pressure Brass Threaded Pipe Fittings

These fittings have the strength to handle high-pressure applications. They are brass for good corrosion resistance.

NPTF (Dryseal) threads are compatible with NPT threads.

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

Straight Adapters with Gasket, Female × Male

Front

Metric Male Threads with Gasket

For Use With: Air, Water, Natural Gas, Oil
Specifications Met: SAE J530, SAE J531

NPTF Female × Metric Male
Pipe Size	Thread Size	Max. Pressure	Male End Gasket Material		Each
1/2	M27 × 2 mm	1,000 psi @ 72° F	Fluorocarbon Rubber	000000000	000000

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
M27	3	81	41	DIN 6334	000000000	000000	000000
Black-Oxide Steel
M27	3	81	41	DIN 6334	000000000	00000	00000

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		1-9	10-Up
Zinc-Plated Steel—Class 8
M27	3	81	41	000000000	000000	000000
Black-Oxide Steel—Class 8
M27	3	81	41	000000000	00000	00000

Metric High-Strength Steel Coupling Nuts—Class 10

Often referred to as extension nuts, use these to connect and extend threaded rods. Made from Class 10 steel, they're about 25% stronger than medium-strength steel coupling nuts and comparable in strength to Class 10.9 bolts.

Zinc-plated steel nuts are corrosion resistant in wet 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 10
M27	3	81	41	DIN 6334	000000000	000000	000000

Metric 18-8 Stainless Steel Coupling Nuts

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.

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

Thread					Each
Size	Pitch, mm	Lg., mm	Wd., mm		1-9	10-Up
18-8 Stainless Steel
M27	3	81	41	000000000	000000	000000