8 Pipe Size Pipe Caps | McMaster-Carr

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32 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 Butt-Weld Pipe Fittings

Butt-weld fittings allow for a smooth connection that provides maximum flow. They have beveled ends that, when flush to pipe, create a trough for a strong, permanent weld. Fittings are also known as Schedule 40. They are for use in noncorrosive environments.

Caps

Butt Weld

	Construction	OD	Pipe Schedule	Material		Each
Butt Weld



	8	Seamless	8 5/8"	40	Steel	43425K246	0000000

Stub-End Straight Adapters

Straight Adapter

Stub-end straight adapters are used with flanges. Slide a flange onto the stub end and weld the stub end to pipe (not the flange). Since the flange isn’t welded to the pipe, it can be disconnected easily, which creates an access point for frequent cleaning and inspecting.

Certificates with a traceable lot number are available for these products. Download certificates from ORDER HISTORY after your order ships.

Pipe Size	Flange OD	Construction	Pipe Schedule	Finished Material		Each
8	10 5/8"	Seamless	40	Steel	43425K245	0000000

Medium-Pressure Stainless Steel Butt-Weld Pipe Fittings

Also known as Schedule 40 fittings, these have thicker walls than our thin-wall stainless steel unthreaded butt-weld fittings. They have beveled ends that, when flush to pipe, create a trough for a strong weld that permits maximum flow.

Caps

Butt Weld

304/304L Stainless Steel—Fittings hold up in humid, damp, and washdown environments but will corrode if exposed to salt water or chemicals.

316/316L 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.

					304/304L Stainless Steel		316/316L Stainless Steel
	Pipe Size	Construction	OD	Pipe Schedule		Each		Each
Butt Weld



		8	Welded	8 5/8"	40	45605K529	0000000	45555K614	0000000

Stub-End Straight Adapters

Straight Adapter

					316/316L Stainless Steel
Pipe Size	Wall Thk.	Flange OD	Construction	Pipe Schedule		Each
8	0.322"	10 5/8"	Welded	40	45555K615	0000000

Low-Pressure Stainless Steel Butt-Weld Pipe Fittings

Also known as Schedule 10 fittings, these are thin and lightweight. They have beveled ends that, when flush to pipe, create a trough for a strong weld that permits maximum flow.

Caps

Butt Weld

304/304L Stainless Steel—Fittings hold up in humid, damp, and washdown environments but will corrode if exposed to salt water or chemicals.

					304/304L Stainless Steel		316/316L Stainless Steel
	Pipe Size	Construction	OD	Pipe Schedule		Each		Each
Butt Weld



		8	Welded	8 5/8"	10	45735K115	0000000	43645K151	0000000

Stub-End Straight Adapters

Straight Adapter

					316/316L Stainless Steel
Pipe Size	Wall Thk.	Flange OD	Construction	Pipe Schedule		Each
8	0.148"	10 5/8"	Welded	10	43645K155	0000000

Tapered Caps

Don't worry about having the exact size you need on hand. These caps are shaped to fit a range of ODs—just keep pushing on until they're snug. Because they make less contact with the parts they cover, they’re easier to remove than straight caps. In a pinch, you can flip tapered caps over and use them as plugs.

Polyethylene—Convenient and economical, these flexible caps are one and done. Instead of cleaning and reusing, just toss and grab a new cap.

	For Pipe Size	Inside Ht.	Flexibility	Max. Temp., ° F	Color	Pkg. Qty.		Pkg.
Polyethylene



	8.67" to 8.73"	8	1 1/2"	Flexible	150	Red	5	4491K79	000000

Standard-Wall Plastic Pipe Fittings for Water

Connect these fittings to Schedule 40 plastic pipe–they are the industry standard for residential and commercial low-pressure plumbing and water supply applications. They are plastic for good corrosion resistance.

To prevent leaks in threaded connections, apply a sealant to the male threads. Threaded connections can be taken apart as needed for maintenance and repair. For metal threads, use PTFE tape. For plastic threads, apply a non-hardening, plastic-compatible sealant. Tape or sealants with PTFE are not recommended for plastic-to-plastic 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, flanges, and pipe with compressed air or gas.

Note: For fittings that are not rated for pressure, you can use the pressure rating of the plastic pipe as a reference. Threaded fittings are limited to 50% of the rated pressure of the pipe.

Caps

Cement Socket

Female

NPT Female

Cement-Socket Fitting Connection—Attach socket-connect ends to unthreaded pipe or another socket-connect fitting with a PVC primer and cement (also known as solvent weld).

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

	Pipe Schedule	Material	Color	Max. Pressure @ Temp.	Food Industry Std.		Each
NPT Female



	8	40	PVC	White	Not Rated	NSF/ANSI 61	4880K813	0000000


	Cement Socket Female



			8	40	PVC	White	Not Rated	NSF/ANSI 61	4880K142	00000

Plugs

Male

Cement-Socket Fitting Connection—Attach socket-connect ends to unthreaded pipe or another socket-connect fitting with a PVC primer and cement (also known as solvent weld).

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

	OD	Pipe Schedule	Material	Color	Max. Pressure @ Temp.	Food Industry Std.		Each
Cement Socket Male



	8	8 5/8"	40	PVC	White	Not Rated	NSF/ANSI 61	4880K853	0000000

Hollow Tapered Plugs

A hollow construction makes these plugs extra flexible, so they compress for easy installation and a snug fit. The tapered profile fits a range of hole diameters. If you flip the plug over, it can be used as a cap.

Polyethylene—Convenient and economical. Instead of cleaning and reusing, just toss and grab a new plug.

	For Pipe Size	Ht.	Max. Temp., ° F	Color	Flange Dia.	Pkg. Qty.		Pkg.
Polyethylene



	7.97" to 8.14"	8	1"	150	Red	8 3/8"	5	4491K97	000000

Rubber Drain Pipe Plugs

Seal unthreaded pipe ends with these plugs. They come with a band that clamps over the outside wall of your pipe and tightens with a screwdriver.

Plugs

	For Pipe OD	Max. Water Back Pressure, ft. of head	Max. Air Back Pressure	Material		Each
Clamp-On Female



	8	8.38" to 8.62"	10	Not Rated	Neoprene	2394K17	000000

Adhesive-Back Caps for Pipe Flanges

Stick these caps onto the raised face of flanges to prevent nicks and scratches during shipping and storage. They stay in place until you peel them off and leave no residue behind.

Polyethylene—These tough caps are hard and wear resistant to hold up against scrapes and gouges.

	Max. Temp., ° F	Color	Adhesive Material	Pkg. Qty.		Pkg.
Polyethylene







	For ANSI Flanges

	8	10 5/8"	Rigid	160	Black	Rubber	1	3445T24	000000

Thick-Wall Plastic Pipe Fittings for Water

Connect these fittings to Schedule 80 pipe. With thicker, stronger walls than standard-wall fittings, they can handle heavy duty supply applications, such as water processing, wastewater treatment, and irrigation. Fittings are plastic for good corrosion resistance. They meet ASTM specifications and testing requirements for material quality.

Warning: Never use plastic pipe fittings, flanges, and pipe with compressed air or gas.

Note: For fittings that are not rated for pressure, you can use the pressure rating of the plastic pipe as a reference. Threaded fittings are limited to 50% of the rated pressure of the pipe.

Caps

Cement Socket

Female

Cement-Socket Fitting Connection—Attach socket-connect ends to unthreaded pipe or another socket-connect fitting with a PVC primer and cement (also known as solvent weld).

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

	Pipe Schedule	Material	Color	Max. Pressure @ Temp.	Food Industry Std.		Each
Cement Socket Female



	8	80	PVC	Dark Gray	Not Rated	NSF/ANSI 61	4881K523	0000000

Plugs

Cement Socket

Male

Cement-Socket Fitting Connection—Attach socket-connect ends to unthreaded pipe or another socket-connect fitting with a PVC primer and cement (also known as solvent weld).

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

	OD	Pipe Schedule	Material	Color	Max. Pressure @ Temp.	Food Industry Std.		Each
Cement Socket Male



	8	8 5/8"	80	PVC	Dark Gray	Not Rated	NSF/ANSI 61	4881K039	0000000

Drain, Waste, and Vent PVC Clamp-On Pipe Fittings for Water

To make installing and maintaining systems easy, these connectors come with clamps that form a strong seal on pipe and fittings once tightened.

Warning: Never use plastic pipe fittings, flanges, and pipe with compressed air or gas.

Caps

Clamp-On Pipe End

	For Pipe OD	Material	Max. Pressure @ Temp.	Clamp Material		Each
Clamp-On Pipe End



	8	8 5/8"	PVC	4 psi @ 72° F	300 Series Stainless Steel	4511K113	000000

Wing-Nut Expansion Plugs

Style B

Twist the wing nut on these plugs to expand the seal and close off pipe openings.

Style B—Style B have a wide top flange so they don’t fall into your pipe. They’re often used for plumbing pressure tests.

Plastic Plate—Plugs with a plastic plate weigh less than plugs with a metal plate.

Maximum Air Back Pressure—Maximum air back pressure is the amount of pressure a plug can withstand without moving.

Maximum Water Back Pressure—Maximum water back pressure refers to the pressure resulting from the height of the water above the plug.

	For Pipe		Max. Back Pressure
	Size	ID	Air, psi	Water, ft. of head	Overall Ht.	Temp. Range, ° F	Seal Material		Each
Style B







				Yellow Plastic Plate

				8	7.70" to 8.03"	17	40	3 3/4"	-20 to 125	Natural Rubber	2645K48	000000

Low-Pressure Iron and Steel Unthreaded Pipe Flanges

Bolt two flat-surface flanges or two raised-surface flanges of the same size together with a gasket (sold separately) to create an access point in a pipe line. Flanges are for use with low-pressure applications in noncorrosive environments.

Blind Flanges


Front	Raised Surface on Back

Certificates with a traceable lot number are available for these products. Download certificates from ORDER HISTORY after your order ships.

					Bolt Hole
	Pipe Size	Flanged Connection Surface	Flange OD	For Bolt Dia.	Dia.	No. Of	Bolt Circle Dia.	Pressure Class	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each
Flanged



		8	Raised	13 1/2"	3/4"	7/8"	8	11 3/4"	150	Steel	285 psi @ 72° F	150 psi @ 300° F	68095K417	0000000

Forged Blind Flanges


Front	Raised Surface on Back

Forged flanges have better strength than cast flanges.

A350 Carbon Steel—Even in temperatures as low as -46° F, these flanges won’t become brittle, so they absorb impact better than other low-pressure steel flanges.

					Bolt Hole
	Pipe Size	Flanged Connection Surface	Flange OD	For Bolt Dia.	Dia.	No. Of	Bolt Circle Dia.	Pressure Class	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each
Flanged



		8	Raised	13 1/2"	3/4"	7/8"	8	11 3/4"	150	A350 Carbon Steel	285 psi @ 72° F	230 psi @ 300° F	5235N35	0000000

High-Pressure Iron and Steel Unthreaded Pipe Flanges

Forged for extra strength, these heavy duty flanges can withstand high-pressure applications. Bolt two flat-surface flanges or two raised-surface flanges of the same size together with a gasket (sold separately) to create an access point in a pipe line.

Certificates with a traceable lot number are available for these products. Download certificates from ORDER HISTORY after your order ships.

Forged Blind Flanges


Front	Raised Surface on Back

Forged flanges have better strength than cast flanges.

					Bolt Hole
	Pipe Size	Flanged Connection Surface	Flange OD	For Bolt Dia.	Dia.	No. Of	Bolt Circle Dia.	Pressure Class	Material	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each
Flanged



		8	Raised	15"	7/8"	1"	12	13"	300	Steel	600 psi @ 72° F	300 psi @ 300° F	6806K348	0000000

Low-Pressure Aluminum Unthreaded Pipe Flanges

Also known as Pressure Class 125 flanges, these are for use in low-pressure applications. Bolt two same-size flanges together with a gasket (sold separately) to create an access point within a line. Flanges are aluminum, which is lightweight with good corrosion resistance.

Blind Flanges


Front	Flat Surface on Back

					Bolt Hole
	Pipe Size	Flanged Connection Surface	Flange OD	For Bolt Dia.	Dia.	No. Of	Bolt Circle Dia.	Pressure Class	Material	Max. Pressure @ Temp.		Each
Flanged



		8	Flat	13 1/2"	3/4"	7/8"	8	11 3/4"	125	356 Aluminum	150 psi @ 72° F	44705K399	0000000

Low-Pressure Stainless Steel Unthreaded Pipe Flanges

Bolt two flat-surface flanges or two raised-surface flanges of the same size together with a gasket (sold separately) to create an access point in a pipe line.

Forged Blind Flanges


Front	Raised Surface on Back

Forged flanges have better strength than cast flanges.

304/304L Stainless Steel—Flanges hold up in humid, damp, and washdown environments but will corrode if exposed to salt water or chemicals.

316/316L Stainless Steel—Flanges are the most corrosion resistant. They stand up to wet environments, just like 304 stainless steel flanges, but unlike 304 stainless steel, they will not corrode from salt water, chlorine solutions, and chemicals.

					Bolt Hole					304/304L Stainless Steel		316/316L Stainless Steel
	Pipe Size	Flanged Connection Surface	Flange OD	For Bolt Dia.	Dia.	No. Of	Bolt Circle Dia.	Pressure Class	Max. Pressure @ Temp.		Each		Each
Flanged



		8	Raised	13 1/2"	3/4"	7/8"	8	11 3/4"	150	230 psi @ 72° F	44685K177	0000000	44695K167	0000000

Thick-Wall Plastic Pipe Flanges for Water

Also known as Pressure Class 150 flanges, these flanges have thick, strong walls to handle heavy duty industrial plumbing and water supply applications, such as water processing, waste water treatment, and irrigation. They meet NSF/ANSI 61 for drinking water. Bolt two same-size flanges together with a gasket (sold separately) to create an access point within a line. All are PVC, which has good corrosion resistance. Some are also glass filled for extra durability. They meet ASTM D1784 specifications and testing requirements for material quality.

Warning: Never use plastic pipe fittings, flanges, and pipe with compressed air or gas.

Blind Flanges


Front	Back

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

					Bolt Hole
	Pipe Size	Flanged Connection Surface	Flange OD	For Bolt Dia.	Dia.	No. Of	Bolt Circle Dia.	Pressure Class	Material	Color	Food Industry Std.		Each
Flanged



		8	Flat	13 1/2"	3/4"	7/8"	8	11 3/4"	150	PVC	Dark Gray	NSF/ANSI 61	4881K973	0000000

Expansion Plugs with Bypass

Style C

Use the bypass tube on these plugs to add air, water, and other fluid to your pipeline or to relieve pressure while testing. The seal expands to temporarily close off pipe openings.

Style C—For Style C, twist the wing nut to expand the seal. They have an NPT threaded bypass for making leak-tight connections.

Maximum Air Back Pressure—Maximum air back pressure is the amount of pressure a plug can withstand without moving.

Maximum Water Back Pressure—Maximum water back pressure refers to the pressure resulting from the height of the water above the plug.

	For Pipe		Max. Back Pressure				Material		Bypass
	Size	ID	Air	Water, ft. of head	Overall Ht.	Temp. Range, ° F	Seal	Bypass Cap	Pipe Size	Thread Type	Gender		Each
Style C







				Iron Stem

				8	7.50" to 8.00"	Not Rated	4	14 3/4"	30 to 150	Natural Rubber	Metal	1/2	NPT	Male	2644K26	000000

Quick-Locking Expansion Plugs

Save time sealing off pipe or valve box openings. These plugs install with one quarter turn of the handle, unlike wing-nut expansion plugs that require multiple turns. They temporarily close off your line with plastic feet that expand mechanically. The feet create a longer-lasting seal than plugs that expand with internal pressure, which can loosen over time. Since these plugs have no pressure ratings, they’re best for low-pressure applications. They’re often used in valve boxes to keep out dirt and debris.

Black Handle—Plugs with a black handle often signify a closed-off wastewater line.

Blue Handle—Plugs with a blue handle often signify a closed-off water line.

Maximum Air Back Pressure—Maximum air back pressure is the amount of pressure a plug can withstand without moving.

Maximum Water Back Pressure—Maximum water back pressure refers to the pressure resulting from the height of the water above the plug.

For Pipe		Max. Back Pressure					Blue Plastic Handle		Black Plastic Handle
Size	ID	Air	Water	Overall Ht.	Temp. Range, ° F	Seal Material		Each		Each







			Plastic Plate

			8	8.00" to 8.50"	Not Rated	Not Rated	4"	-40 to 220	TPE	6594N31	000000	6594N32	000000

CPVC Pipe Flanges for Chemicals

Made of CPVC, these flanges withstand salt solutions, acids, and other harsh substances. Bolt two same-size flanges together with a gasket (sold separately) to create an access point within a line. Also known as Pressure Class 150 flanges, they have thick, strong walls to handle heavy duty industrial plumbing and water supply applications, such as water processing and wastewater treatment. These flanges are comparable to Corzan. They meet ASTM D1784 specifications and testing requirements for material quality.

Warning: Never use plastic pipe fittings, flanges, and pipe with compressed air or gas.

Blind Flanges


Front	Flat Surface on Back

NSF/ANSI 61—To adhere to safety standards for drinking water systems, use pipe that meets NSF/ANSI 61.

					Bolt Hole
	Pipe Size	Flanged Connection Surface	Flange OD	For Bolt Dia.	Dia.	No. Of	Bolt Circle Dia.	Pressure Class	Material	Color	Food Industry Std.		Each
Flanged



		8	Flat	13 1/2"	3/4"	7/8"	8	11 3/4"	150	CPVC	Light Gray	NSF/ANSI 61	6826K382	0000000

High-Pressure Stainless Steel Unthreaded Pipe Flanges

Use these heavy duty forged flanges for high-pressure applications. Bolt two flat-surface flanges or two raised-surface flanges of same size together with a gasket (sold separately) to create an access point in a pipe line.

Forged Blind Flanges


Front	Raised Surface on Back

Forged flanges have better strength than cast flanges.

304/304L Stainless Steel—Flanges hold up in humid, damp, and washdown environments but will corrode if exposed to salt water or chemicals.

					Bolt Hole						304/304L Stainless Steel		316/316L Stainless Steel
	Pipe Size	Flanged Connection Surface	Flange OD	For Bolt Dia.	Dia.	No. Of	Bolt Circle Dia.	Pressure Class	Max. Pressure @ Temp.	Max. Steam Pressure @ Temp.		Each		Each
Flanged



		8	Raised	15"	7/8"	1"	12	13"	300	600 psi @ 72° F	300 psi @ 360° F	4448T48	0000000	4452T116	0000000