Nonmetallic Locknuts | McMaster-Carr

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88 Products

Thread-Forming Locknuts

Form threads into these nuts for a tight fit that won't loosen under vibration. They are partially threaded, so when you fasten them onto metal screws, the tightening action will cut the rest of the threads. Nuts are not reusable.

Plastic

Nylon 6/6—Slippery and abrasion resistant, these nuts thread on smoothly and stand up to daily wear and tear. Nylon will swell and weaken when exposed to moisture, so it's best for dry environments.

	Wd.	Ht.	Pkg. Qty.		Pkg.
White Nylon 6/6



	2-56	3/16"	1/16"	100	94909A002	000000


	4-40	1/4"	3/32"	100	94909A005	00000
	6-32	5/16"	1/8"	100	94909A007	00000
	8-32	21/64"	1/8"	100	94909A009	00000
	10-24	23/64"	9/64"	100	94909A011	00000
	10-32	23/64"	9/64"	100	94909A022	00000
	1/4"-20	27/64"	15/64"	100	94909A029	00000

Conduit Locknuts

Secure threaded conduit fittings to knockouts. These locknuts keep fittings from shifting, so connections stay stable and wiring is protected inside electrical boxes or enclosures.

For Plastic Fittings

PVC and Nylon—Lightweight and chemical resistant, these fittings won't corrode.

	Pipe Size	Thread Size	Specs. Met		Each
NPT Thread







				Nylon

				1/4	—	—	7877N101	00000


				1/4	—	—	7877N102	0000
				3/8	—	—	3185K111	0000
				3/8	—	—	7877N103	0000
				1/2	—	—	3185K112	0000
				1/2	—	—	7877N104	0000
				3/4	—	—	3185K113	0000
				3/4	—	—	7877N105	0000
				1	—	—	3185K114	0000
				1	—	—	7877N106	0000
				1 1/4	—	—	3185K115	0000


				1 1/4	—	—	7877N107	0000
				1 1/2	—	—	3185K116	0000
				1 1/2	—	—	7877N108	0000
				2	—	—	3185K117	00000
				2	—	—	7877N109	00000


				NPSM Thread







								PVC

								1/2	—	UL Recognized Component	7945K81	0000


								3/4	—	UL Recognized Component	7945K82	0000
								1	—	UL Recognized Component	7945K83	0000


								PG Thread







												Nylon

												—	PG-7	—	7877N11	0000


												—	PG-7	—	7877N116	0000
												—	PG-9	—	7877N117	0000
												—	PG-9	—	7877N118	0000
—												PG-11	—	3185K91	0000
—	PG-11											—	7877N119	0000
—	PG-13.5											—	3185K92	0000
—	PG-13.5											—	7877N12	0000
—	PG-16											—	3185K93	0000
—	PG-16	—										7877N121	0000
—	PG-21	—	3185K94									0000


—	PG-21	—	7877N122									0000
—	PG-29	—	3185K95									0000
—	PG-29	—	7877N123									0000
—	PG-36	—	3185K96									00000
—	PG-36	—	7877N124									00000
—	PG-48	—	3185K133									00000


Metric Thread







												Nylon

												—	M12	—	7877N126	0000


												—	M12	—	7877N127	0000
												—	M16	—	7877N128	0000
												—	M16	—	7877N129	0000
				—								M20	—	7877N113	0000
				—	M20							—	7877N13	0000
				—	M25							—	7877N131	0000
				—	M25							—	7877N132	0000
				—	M32	—						7877N133	0000
				—	M32	—	7877N134					0000
				—	M40	—	7877N114					0000


				—	M40	—	7877N135					0000
				—	M50	—	7877N115					00000
				—	M63	—	7877N137					00000
				—	M63	—	7877N138					00000

Extreme-Pressure Stainless Steel Threaded Pipe Locknuts

With the strength to handle extreme pressures, these locknuts can be used to connect equipment in hydraulic fluid lines.

Locknuts have a gasket, which creates a tight seal without the need for PTFE tape; screw one onto the male end of a fitting for extra holding power.

303 Stainless Steel—303 stainless steel locknuts have very good corrosion resistance.

									303 Stainless Steel
	Pipe Size	Dash Size	Hex Wd.	Lg.	Gasket Material	Max. Pressure @ Temp.	For Use With	Temp. Range, ° F		Each
NPT Female



		1/8	02	5/8"	3/16"	PTFE	10,000 psi @ 72° F	Air, Hydraulic Fluid, Natural Gas, Oil, Water	-300 to 500	5530K37	000000


		1/4	04	3/4"	9/32"	PTFE	10,000 psi @ 72° F	Air, Hydraulic Fluid, Natural Gas, Oil, Water	-300 to 500	5530K38	00000
		3/8	06	7/8"	9/32"	PTFE	10,000 psi @ 72° F	Air, Hydraulic Fluid, Natural Gas, Oil, Water	-300 to 500	5530K39	00000
		1/2	08	1 1/8"	19/64"	PTFE	10,000 psi @ 72° F	Air, Hydraulic Fluid, Natural Gas, Oil, Water	-300 to 500	5530K44	00000
		3/4	12	1 5/16"	19/64"	PTFE	5,000 psi @ 72° F	Air, Hydraulic Fluid, Natural Gas, Oil, Water	-300 to 500	5530K45	000000
		1	16	1 5/8"	25/64"	PTFE	5,000 psi @ 72° F	Air, Hydraulic Fluid, Natural Gas, Oil, Water	-300 to 500	5530K46	000000
		1 1/4	20	2"	25/64"	PTFE	5,000 psi @ 72° F	Air, Hydraulic Fluid, Natural Gas, Oil, Water	-300 to 500	5530K47	000000
		1 1/2	24	2 1/4"	25/64"	PTFE	3,000 psi @ 72° F	Air, Hydraulic Fluid, Natural Gas, Oil, Water	-300 to 500	5530K48	000000
		2	32	2 3/4"	27/64"	PTFE	3,000 psi @ 72° F	Air, Hydraulic Fluid, Natural Gas, Oil, Water	-300 to 500	5530K49	000000

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



		1/8	02	5/8"	3/16"	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	5530K14	000000


		1/4	04	3/4"	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	5530K16	00000
		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	00000
		1/2	08	1 1/8"	19/64"	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	5530K19	00000
		3/4	12	1 5/16"	19/64"	PTFE	5,000 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	5530K21	00000
		1	16	1 5/8"	25/64"	PTFE	5,000 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	5530K23	00000
		1 1/4	20	2"	25/64"	PTFE	5,000 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	5530K25	00000
		1 1/2	24	2 1/4"	25/64"	PTFE	3,000 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	5530K27	00000
		2	32	2 3/4"	27/64"	PTFE	3,000 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	5530K29	000000

Plastic Pipe Locknuts for Oil

Made of corrosion-resistant plastic, these locknuts 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 locknut, then wrench-tighten one to two turns.

Warning: Never use plastic pipe locknuts and pipe with compressed air or gas.

	Pipe Locknuts											Thread Sealants
	Pipe Size	Lg.	Thread Size	Thread Direction	Color	Max. Pressure @ Temp.	For Use With	Temp. Range, ° F	Material		Each		Each
BSPT Female



		1/2	29/64"	—	Right Hand	White	200 psi @ 72° F	Oil	0 to 230	Nylon	3736K111	00000	4586K9	000000


		Metric Female



				—	29/64"	M20 × 1.5 mm	Right Hand	Blue	200 psi @ 72° F	Oil	0 to 230	Nylon	3736K112	0000	4586K9	00000

Heavy-Vibration-Resistant Spring Lock Washers

With a grip that's second only to wedge lock, these washers stop nuts and screws from wiggling loose under constant, vigorous vibration. They are ideal for engines, turbines, generators, and other heavy duty equipment. Similar to a spring, they flatten under pressure to add tension between mating surfaces. As long as the washers aren't deformed or otherwise damaged, you can reuse them indefinitely without losing locking strength. Also known as conical washers and Belleville washers.

Stack multiple washers in the same direction to double or triple how much weight they can bear. Stack washers in opposite directions for better deflection, which means they compress further and withstand more shock and movement without loosening.

Acetal—Lightweight, nonconductive, and naturally rust resistant. These washers won't swell or lose their strength if exposed to moisture.

	ID	OD	Thk.	Overall Ht.	Pkg. Qty.		Pkg.
Acetal



	No. 6, M3.5	0.152"	0.316"	0.022" to 0.032"	0.045"	100	3573A11	000000


	No. 8, M4	0.173"	0.297"	0.023" to 0.033"	0.046"	100	3573A12	00000
	No. 10, M5	0.204"	0.365"	0.025" to 0.035"	0.053"	100	3573A13	00000
	No. 10, M5	0.235"	0.416"	0.030" to 0.040"	0.062"	100	3573A14	00000
	1/4", M6	0.264"	0.564"	0.033" to 0.043"	0.066"	100	3573A15	00000
	1/4", M6	0.276"	0.448"	0.030" to 0.040"	0.062"	100	3573A21	00000
	5/16", M8	0.328"	0.660"	0.043" to 0.053"	0.080"	100	3573A16	00000
	3/8", M10	0.451"	0.848"	0.034" to 0.044"	0.080"	25	3573A22	00000
	3/8", M10	0.451"	0.848"	0.050" to 0.060"	0.095"	25	3573A17	0000