3/8 Flanges | McMaster-Carr

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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.

Low-Pressure Iron and Steel Threaded Pipe Fittings

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

Straight Adapters for Tanks

Female × Butt Weld

(For Flat Surface)

Fittings for tanks create an inlet or outlet connection on the surface of any tank, pressure vessel, or drum.

Threaded Fitting Connection—Threaded female x butt weld straight adapters are also known as half couplings.

	For Hole Diameter (B)	OD	For Tank Surface (B)	Material	Max. Pressure @ Temp.		Each
NPT Female × Butt Weld



	3/8	15/16"	1 1/4"	Flat	Carbon Steel	Not Rated	12555K52	000000

Straight Adapters with Extension for Tanks

Female × Butt Weld

Fittings for tanks create an inlet or outlet connection on the surface of any tank, pressure vessel, or drum.

Adapters with extension fit tightly into the hole, which keeps the fitting steady during welding.

Threaded Fitting Connection—Threaded female x butt weld straight adapters are also known as half couplings.

	For Hole Diameter (B)	OD	For Tank Surface (B)	Material	Max. Pressure @ Temp.		Each
NPT Female × Butt Weld



	3/8	15/16"	1 5/16"	Flat	Carbon Steel	Not Rated	12555K82	00000


	3/8	15/16"	1 1/2"	Flat	Carbon Steel	Not Rated	12555K72	0000

Bushing Straight Reducing Adapters

Male × Female

	Pipe Size
	(A)	(B)	Pressure Class	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each
NPT Male × NPT Female



		3/8	1/8	150	Steel	150 psi @ 72° F	150 psi @ 350° F	44605K388	00000


		3/8	1/4	150	Steel	150 psi @ 72° F	150 psi @ 350° F	44605K257	0000
		1/2	3/8	150	Steel	150 psi @ 72° F	150 psi @ 350° F	44605K258	0000
		3/4	3/8	150	Steel	150 psi @ 72° F	150 psi @ 350° F	44605K263	0000
		1	3/8	150	Steel	150 psi @ 72° F	150 psi @ 350° F	44605K267	0000

Bushing Straight Reducing Adapters for Tanks

Male × Female

Fittings for tanks create an inlet or outlet connection on the surface of any tank, pressure vessel, or drum.

	Pipe Size
	(A)	(B)	For Tank Surface (A)	Body Shape	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each
NPT Male × NPT Female



		2	3/8	Flat	Hex	Iron	Not Rated	Not Rated	6850K11	000000

180° Bend Connectors

Image of Product. Front orientation. Pipe Traps. Low-Pressure Iron and Steel Threaded Pipe Fittings.

180° bend connectors are also known as U-bends.

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



	1/2	Iron	150 psi @ 72° F	150 psi @ 350° F	UL Listed	180° Bend	44605K563	000000


	3/4	Iron	150 psi @ 72° F	150 psi @ 350° F	UL Listed	180° Bend	44605K564	00000
	1	Iron	150 psi @ 72° F	150 psi @ 350° F	—	180° Bend	44605K565	00000
	2	Iron	150 psi @ 72° F	150 psi @ 350° F	UL Listed	180° Bend	44605K568	000000

Locknuts

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

	Finished Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each
NPSL Female



	3/8	Iron	Not Rated	Not Rated	44605K211	00000


	1/2	Iron	Not Rated	Not Rated	44605K212	0000
	3/4	Iron	Not Rated	Not Rated	44605K213	0000
	1	Iron	Not Rated	Not Rated	44605K214	00000
	2	Iron	Not Rated	Not Rated	44605K217	00000

Low-Pressure Stainless Steel Threaded Pipe Fittings

Use these fittings in a low-pressure pipe line.

Straight Adapters with Extension for Tanks

Female × Butt Weld

Fittings for tanks create an inlet or outlet connection on the surface of any tank, pressure vessel, or drum.

Adapters with extension fit tightly into the hole, which keeps the fitting steady during welding.

Threaded Fitting Connection—Threaded female x butt weld straight adapters are also known as half couplings.

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.

					316 Stainless Steel
	Pipe Size	For Hole Diameter (B)	OD	For Tank Surface (B)	Max. Pressure @ Temp.		Each
NPT Female × Butt Weld



		3/8	15/16"	1 1/2"	Flat	Not Rated	1145K52	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.

Straight Connectors

Female

	Material	Max. Pressure @ Temp.		Each
BSPT Female



	3/8	6061 Aluminum	250 psi @ 72° F	2617K39	00000

Straight Adapters

Threaded Female ×

Threaded Male

	Pipe Size
	(A)	(B)	Body Shape	Material	Max. Pressure @ Temp.		Each
NPT Female × BSPT Male



		3/8	3/8	Hex	6061 Aluminum	150 psi @ 72° F	1527N16	000000


		BSPT Female × NPT Male



				3/8	3/8	Hex	6061 Aluminum	150 psi @ 72° F	1527N3	00000


				BSPP Female × NPT Male



						3/8	3/8	Hex	6061 Aluminum	150 psi @ 72° F	1527N9	00000

Straight Adapters with Gasket

Threaded Female ×

Threaded Male

Fluoroelastomer—These gaskets resist a wide range of chemicals, including benzene, butyl alcohol, and ethylene glycol.

	Pipe Size
	(A)	(B)	Body Shape	Material	Max. Pressure @ Temp.	Gasket Material		Each
NPT Female × BSPP Male



		3/8	3/8	Hex	6061 Aluminum	150 psi @ 72° F	Fluoroelastomer	1527N23	000000

Straight Adapters with Extension for Tanks

NPT Female × Butt

Weld

Fittings for tanks create an inlet or outlet connection on the surface of any tank, pressure vessel, or drum.

Adapters with extension fit tightly into the hole, which keeps the fitting steady during welding.

Threaded Fitting Connection—Threaded female x butt weld straight adapters are also known as half couplings.

	For Hole Diameter (B)	OD	For Tank Surface (B)	Material	Max. Pressure @ Temp.		Each
NPT Female × Butt Weld



	3/8	1 3/16"	1 7/16"	Flat	6061 Aluminum	Not Rated	8694T43	000000

Bushing Straight Reducing Adapters

Male × Female

	Pipe Size
	(A)	(B)	Body Shape	Material	Max. Pressure @ Temp.		Each
BSPT Male × BSPT Female



		3/8	1/4	Hex	6061 Aluminum	250 psi @ 72° F	2617K56	000000


		1/2	3/8	Hex	6061 Aluminum	250 psi @ 72° F	2617K57	00000

180° Bend Connectors

Image of Product. Front orientation. Pipe Traps. Low-Pressure Aluminum Threaded Pipe Fittings.

180° bend connectors are also known as U-bends.

	Material	Max. Pressure @ Temp.	Shape		Each
NPT Female



	1/2	356 Aluminum	150 psi @ 72° F	180° Bend	44705K479	000000

Locknuts

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

	Finished Material	Max. Pressure @ Temp.		Each
NPSL Female



	3/8	6061 Aluminum	150 psi @ 72° F	44705K413	00000

Floor, Wall, and Ceiling Plates

Solid Flat Plates

Split Flat Plates

Hinged Flat Plates

Solid Cone Plates

Add a finishing touch to the area around protruding pipes with these corrosion-resistant plates. They’re also known as escutcheons.

Solid—Solid plates don’t open, so they need to be installed before you attach fittings to your pipe.

Split—Split plates twist open on one side and then snap back together once they are around the pipe.

Hinged—Hinged plates swing open on one side, so you can fit them around pipe and then snap them closed.

	Pkg. Qty.		Pkg.
Solid Flat Plates







	Polished Stainless Steel

	3/8	5/8"	2 1/2"	5	3040K413	00000


	Split Flat Plates







					White Polypropylene

					3/8	5/8"	2 9/16"	1	3040K9	0000




							Polished Chrome-Plated Polypropylene

							3/8	5/8"	2 9/16"	1	3040K8	0000


							Hinged Flat Plates







											Polished Chrome-Plated Zinc Alloy

											3/8	11/16"	2 3/8"	1	4567K11	0000


											Solid Cone Plates







															Polished Chrome-Plated Steel

															3/8	5/8"	2 3/8"	1	3040K421	0000

Extreme-Pressure Steel Threaded Pipe Locknuts

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

Locknuts thread onto the male end of a fitting to provide extra holding power so the fitting won’t loosen from vibration.

												For Pipe		For Flange
	Pipe Size	Dash Size	Hex Wd.	Lg.	Gasket Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.	For Use With	Temp. Range, ° F	Material	Fabrication	Schedule	Material	Class	Material		Each
NPT Female



		3/8	06	7/8"	9/32"	PTFE	10,000 psi @ 72° F	5,000 psi @ 500° F	Air, Hydraulic Fluid, Natural Gas, Oil, Steam, Water	-100 to 500	Zinc-Yellow-Chromate-Plated Steel	Machined	XXH	Steel	1500	Steel	5530K18	000000

Low-Pressure Stainless Steel Threaded Pipe Locknuts

Use these locknuts in a low-pressure pipe line.

Locknuts thread onto the male end of a fitting to provide extra holding power so the fitting won’t loosen from vibration.

NPTF (Dryseal) threads and NPSL (National Pipe Straight Locknut) threads are compatible with NPT threads.

304 Stainless Steel—304 stainless steel locknuts have very good corrosion resistance.

316 Stainless Steel—316 stainless steel locknuts have excellent corrosion resistance.

ANSI/MSS SP-114—Locknuts that meet ANSI/MSS SP-114 adhere to high-quality standards for heat treating, material thickness, and marking.

							For Pipe		For Flange			304 Stainless Steel		316 Stainless Steel
	Pipe Size	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.	For Use With	Pressure Class	Fabrication	Schedule	Material	Class	Material	Specs. Met		Each		Each
NPSL Female



		3/8	300 psi @ 72° F	150 psi @ 350° F	Air, Natural Gas, Oil, Steam, Water	150	Heat Treated	40	304 Stainless Steel, 304/304L Stainless Steel	150	304 Stainless Steel, 304/304L Stainless Steel	ANSI/MSS SP-114, ASTM A351	4464K583	000000	———	0


		3/8	300 psi @ 72° F	150 psi @ 350° F	Air, Natural Gas, Oil, Steam, Water	150	Heat Treated	40	316 Stainless Steel, 316/316L Stainless Steel	150	304 Stainless Steel, 304/304L Stainless Steel	ANSI/MSS SP-114, ASTM A351	———	0	4452K673	000000

Low-Pressure Brass and Bronze Threaded Pipe Locknuts

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

Locknuts thread onto the male end of a fitting to provide extra holding power so the fitting won’t loosen from vibration.

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

NSF/ANSI 61—Locknuts rated for use with drinking water meet NSF/ANSI 61 safety standards.

								For Pipe		For Flange
	Pipe Size	Hex Wd.	Lg.	Max. Pressure @ Temp.	For Use With	Pressure Class	Material	Schedule	Material	Class	Material	Specs. Met	Food Industry Std.		Each
NPSL Female



		3/8	1"	9/32"	200 psi @ 72° F	Air, Drinking Water, Natural Gas, Oil	125	Brass	40	Brass	150	Brass	ASME B1.20.1, ASME B16.15, ASTM A584	NSF/ANSI 61	4429K123	00000

Medium-Pressure Aluminum Threaded Pipe Fittings

Designed for medium-pressure applications, these fittings have better strength than our low-pressure aluminum pipe fittings. They are lightweight with good corrosion resistance.

Straight Connectors

NPT Female

NPT Male

Anodized 2024 Aluminum—Fittings with an anodized finish have better corrosion resistance and a harder surface than plain aluminum fittings.

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



	3/8	Hex	Anodized 2024 Aluminum	Blue	500 psi @ 72° F	3861T63	000000


	NPT Male



			3/8	Hex	Anodized 2024 Aluminum	Blue	500 psi @ 72° F	3861T83	00000

Low-Pressure Galvanized Iron and Steel Threaded Pipe Locknuts

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

Locknuts thread onto the male end of a fitting to provide extra holding power so the fitting won’t loosen from vibration.

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

									For Pipe		For Flange
	Pipe Size	Hex Wd.	Lg.	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.	For Use With	Pressure Class	Material	Schedule	Material	Class	Material	Specs. Met		Each
NPSL Female



		3/8	1"	0.28"	Not Rated	Not Rated	Air, Natural Gas, Oil, Steam, Water	150	Galvanized Iron	40	Galvanized Steel	150	Galvanized Steel	ASME B16.14	4638K613	00000

Low-Pressure Aluminum Threaded Pipe Locknuts

In addition to being lightweight, these aluminum locknuts 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.

Locknuts thread onto the male end of a fitting to provide extra holding power so the fitting won’t loosen from vibration.

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

								For Pipe		For Flange
	Pipe Size	Hex Wd.	Lg.	Max. Pressure @ Temp.	For Use With	Pressure Class	Material	Schedule	Material	Class	Material		Each
NPSL Female



		3/8	1 1/8"	3/16"	150 psi @ 72° F	Air, Oil, Water	150	6061 Aluminum	40	Aluminum	125	Aluminum	44705K413	00000