3 1/2 NPT Pipe Fittings | McMaster-Carr

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	Pipe Size Pipe Size	Show

3 1/2

	Pipe Size Pipe Size	Hide

1/16
1/8
1/4
3/8
1/2
3/4
1
1 1/4
1 1/2
2
2 1/2
3
3 1/2
4
5
6
8
10

	Thread Type Thread Type

NPT

	Type Type


Adapter	Bushing

Flange	Plug

Reducer	Reducing Adapter

	Material Material

Brass

Iron

Steel

	Connection Style Connection Style

Threaded

Flanged

Clamp On

	For Pipe Schedule For Pipe Schedule


40	80

	For Use With For Use With

	Shape Shape

	Straight
	Cap/Plug

	Pressure Class Pressure Class

125

150

300

	Connection Type Connection Type


Pipe	Tube

	Drive Style Drive Style


External Square	Square

	Finish Finish

Black Coated

Galvanized

	Specifications Met Specifications Met

	Maximum Pressure Maximum Pressure

	For Pipe Material For Pipe Material

Steel

Brass

	System of Measurement System of Measurement

Inch

	Length Length

	Gender Gender

Female

Male

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

DFARS Specialty Metals
COTS-Exempt

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

RoHS Compliant

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

REACH Compliant

	Bolt Circle Diameter Bolt Circle Diameter

	Maximum Steam Pressure Maximum Steam Pressure

	Body Shape Body Shape


Hex	Square

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33 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.

Low-Pressure Iron and Steel Threaded Pipe Fittings

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

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

Bushing Straight Reducing Adapters with Hex Body

For Use With: Air, Steam, Oil, Water, Natural Gas
Pressure Class: See table
Pipe Nipples and Pipe: Use Schedule 40 steel

Pipe Size
(A)	(B)	Pressure Class	Max. Pressure	Max. Steam Pressure	Material	Specifications Met		Each
NPT Male × NPT Female
3 1/2	1	125	175 psi @ 72° F	125 psi @ 350° F	Black-Coated Iron	ASME B16.14	000000000	000000
3 1/2	1 1/4	125	175 psi @ 72° F	125 psi @ 350° F	Black-Coated Iron	ASME B16.14	000000000	00000
3 1/2	1 1/2	125	175 psi @ 72° F	125 psi @ 350° F	Black-Coated Iron	ASME B16.14	000000000	00000
3 1/2	2	125	175 psi @ 72° F	125 psi @ 350° F	Black-Coated Iron	ASME B16.14	000000000	00000
3 1/2	2 1/2	125	175 psi @ 72° F	125 psi @ 350° F	Black-Coated Iron	ASME B16.14	000000000	00000
3 1/2	3	125	175 psi @ 72° F	125 psi @ 350° F	Black-Coated Iron	ASME B16.14	000000000	00000
4	3 1/2	150	150 psi @ 72° F	150 psi @ 350° F	Black-Coated Iron	ASME B16.14	000000000	00000

Straight Reducers

For Use With: Air, Steam, Oil, Water, Natural Gas
Pressure Class: 150
Specifications Met:
NPT: ASME B1.20.1, ASME B16.3, UL Listed
BSPT: DIN EN 10226
Pipe Nipples and Pipe: Use Schedule 40 steel

Pipe Size
(A)	(B)	Max. Pressure	Max. Steam Pressure	Material		Each
NPT Female
3 1/2	2	150 psi @ 72° F	150 psi @ 350° F	Black-Coated Iron	000000000	0000000
3 1/2	2 1/2	150 psi @ 72° F	150 psi @ 350° F	Black-Coated Iron	000000000	000000
3 1/2	3	150 psi @ 72° F	150 psi @ 350° F	Black-Coated Iron	000000000	000000
4	3 1/2	150 psi @ 72° F	150 psi @ 350° F	Black-Coated Iron	000000000	000000

Plugs with Square Drive

For Use With: Air, Steam, Oil, Water, Natural Gas
Presure Class:
Steel: 150
Iron: 125
Pipe Nipples and Pipe: Use Schedule 40 steel

NPT Male
Pipe Size	Plug Construction	Max. Pressure	Max. Steam Pressure	Material		Each
3 1/2	Hollow	175 psi @ 72° F	125 psi @ 350° F	Black-Coated Iron	000000000	000000

Plugs with External Square Drive

For Use With:
NPT and BSPT: Air, Natural Gas, Oil, Steam, Water
NPTF: Air, Natural Gas, Steam, Water
Pressure Class:
NPT Iron: 125
BSPT Iron: 150
Specifications Met:
See table
Pipe Nipples and Pipe:
NPT and BPST: Use Schedule 40 steel

NPT Male
Pipe Size	Plug Construction	Max. Pressure	Max. Steam Pressure	Material		Each
3 1/2	Hollow	175 psi @ 72° F	125 psi @ 350° F	Black-Coated Iron	000000000	000000

Low-Pressure Steel Threaded Pipe Flanges

Use these flanges for low-pressure applications in noncorrosive environments. Bolt two flanges of the same size together with a gasket (sold separately) to create an access point within a line.

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

Flanges

Front

Raised Surface on Back

For Use With: Air, Natural Gas, Oil, Steam, Water
Pressure Class: 150
Specifications Met:
NPT: ASME B16.5, ASTM A105, MSS SP-25
BSPT: ASTM A105
Pipe Nipples and Pipe: Use Schedule 40 steel
Fittings: Use Class 125 or 150 iron and steel

			Bolt Hole
Pipe Size	Flange OD	For Bolt Dia.	Dia.	No. of	Bolt Circle Dia.	Max. Pressure	Max. Steam Pressure	Material		Each
NPT
3 1/2	8 1/2"	5/8"	3/4"	8	7"	285 psi @ 72° F	230 psi @ 300° F	Steel	000000000	0000000

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.

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

Bushing Straight Reducing Adapters with Hex Body

For Use With: Air, Steam, Oil, Water, Natural Gas
Pressure Class: See table
Specifications Met: See table
Pipe Nipples and Pipe: Use Schedule 40 galvanized steel
Flanges: Use Class 150 galvanized steel

Pipe Size
(A)	(B)	Pressure Class	Max. Pressure	Max. Steam Pressure	Material	Specifications Met		Each
NPT Male × NPT Female
4	3 1/2	150	150 psi @ 72° F	150 psi @ 350° F	Galvanized Iron	ASME B16.14	00000000	0000000
3 1/2	1	125	125 psi @ 72° F	125 psi @ 350° F	Galvanized Iron	ASME B1.20.1, ASME B16.14, ASTM A126, UL Listed	00000000	00000
3 1/2	1 1/4	125	125 psi @ 72° F	125 psi @ 350° F	Galvanized Iron	ASME B1.20.1, ASME B16.14, ASTM A126, UL Listed	00000000	00000
3 1/2	1 1/2	125	125 psi @ 72° F	125 psi @ 350° F	Galvanized Iron	ASME B1.20.1, ASME B16.14, ASTM A126, UL Listed	00000000	000000
3 1/2	2	125	125 psi @ 72° F	125 psi @ 350° F	Galvanized Iron	ASME B1.20.1, ASME B16.14, ASTM A126, UL Listed	00000000	000000
3 1/2	2 1/2	125	125 psi @ 72° F	125 psi @ 350° F	Galvanized Iron	ASME B1.20.1, ASME B16.14, ASTM A126, UL Listed	00000000	000000
3 1/2	3	125	125 psi @ 72° F	125 psi @ 350° F	Galvanized Iron	ASME B1.20.1, ASME B16.14, ASTM A126, UL Listed	00000000	000000

Straight Reducers

For Use With: Air, Steam, Oil, Water, Natural Gas
Pressure Class: 150
Specifications Met:
NPT: ASME B1.20.1, ASME B16.3, ASTM A153, UL Listed
BSPT: ASTM A197, DIN EN 10226
Pipe Nipples and Pipe: Use Schedule 40 galvanized steel
Flanges: Use Class 150 galvanized steel

Pipe Size
(A)	(B)	Max. Pressure	Max. Steam Pressure	Material		Each
NPT Female
3 1/2	2	150 psi @ 72° F	150 psi @ 350° F	Galvanized Iron	00000000	0000000
3 1/2	2 1/2	150 psi @ 72° F	150 psi @ 350° F	Galvanized Iron	00000000	000000
3 1/2	3	150 psi @ 72° F	150 psi @ 350° F	Galvanized Iron	00000000	000000
4	3 1/2	150 psi @ 72° F	150 psi @ 350° F	Galvanized Iron	00000000	000000

Plugs with External Square Drive

For Use With: Air, Steam, Oil, Water, Natural Gas
Pressure Class: See table
Specifications Met:
NPT Steel: SAE J531
NPT Iron: ASME B1.20.1, ASME B16.14, ASTM A126, UL Listed
BSPT: ASTM A197, DIN EN 10226
Pipe Nipples and Pipe: Use Schedule 40 steel
Flanges: Use Class 150 galvanized steel

NPT Male
Pipe Size	Plug Construction	Pressure Class	Max. Pressure	Max. Steam Pressure	Material		Each
3 1/2	Hollow	125	125 psi @ 72° F	125 psi @ 350° F	Galvanized Iron	00000000	0000000

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.

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

Plugs with External Square Drive

For Use With: Air, Steam, Oil, Water, Natural Gas
Pressure Class : 300
Specifications Met: See Table
Pipe Nipples and Pipe: Use Schedule 80 steel
Flanges: Use Class 300 or 600 steel

NPT Male
Pipe Size	Plug Construction	Max. Pressure	Max. Steam Pressure	Material	Specifications Met		Each
3 1/2	Hollow	175 psi @ 72° F	300 psi @ 550° F	Iron	ASME B1.20.1, ASME B16.14, ASTM A126, UL Listed	00000000	000000

Low-Pressure Brass and Bronze Threaded Pipe Fittings

Use these fittings in low-pressure flow applications. They have good corrosion resistance. Fittings rated for use with drinking water meet NSF/ANSI 61 safety standards.

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

Bushing Straight Reducing Adapters with Hex Body

For Use With:
Brass: Air, Drinking Water, Natural Gas, Oil
Bronze: Air, Natural Gas, Oil, Steam, Water
Pressure Class : 125
Specifications Met: See table
Pipe Nipples and Pipe: Use Schedule 40 brass
Flanges: See table

Pipe Size					For Flange
(A)	(B)	Max. Pressure	Material	Hex Width	Class	Material	Specifications Met		Each
NPT Male × NPT Female
3 1/2	3	200 psi @ 72° F	Brass	4 1/4"	150	Brass	ASME B1.20.1, ASME B16.15, NSF/ANSI 61	00000000	0000000
4	3 1/2	200 psi @ 72° F	Brass	4 5/8"	150	Brass	ASME B1.20.1, ASME B16.15, NSF/ANSI 61	00000000	000000

Vacuum Fittings for Steel Tubing

For Use With: Air, Glass, Plastic Pellets, Resins, Wood Chips
Temperature Range: -10° to 180° F
Tubing: Galvanized Steel: Use with steel, galvanized steel
Steel: Use with steel

Use these fittings to create an air vacuum system without the hassle of brazing and welding. Insert two fittings into a clamp (sold separately) and tighten to form a secure seal.

Galvanized steel fittings have fair corrosion resistance. Fittings without a finish should only be used in noncorrosive environments.

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

Straight Adapters, Tube × Male Threaded Pipe

				Galvanized Steel		Steel
For Tube OD	Pipe Size	Max. Pressure	Max. Vacuum		Each		Each
NPT Threads
3 1/2"	3 1/2	15 psi @ 72° F	15 in. of Hg @ 72° F	00000000	000000	0000000	000000

Straight Adapters, Tube × Female Threaded Pipe

				Galvanized Steel		Steel
For Tube OD	Pipe Size	Max. Pressure	Max. Vacuum		Each		Each
NPT Threads
3 1/2"	3 1/2	15 psi @ 72° F	15 in. of Hg @ 72° F	00000000	0000000	0000000	0000000