GB/T 3098.10 Prevailing Torque Steel Lock Nuts Standard

Introduction to GB/T 3098.10 Standard

This standard specifies mechanical properties for prevailing torque type steel lock nuts, ensuring vibration resistance in fastening applications. It aligns with ISO 2320-2015 for test methods, covering classes 04, 05, 5, 6, 8, and 10. Proper selection and testing maintain assembly integrity under dynamic loads.

Scope

GB/T 3098.10-1993 defines performance requirements for steel lock nuts with prevailing torque features, applicable to sizes M5 to M39 in coarse and fine pitches. It includes test clamping forces and prevailing torques to verify locking effectiveness, suitable for industries like automotive and machinery where loosening prevention is critical.

Applies to all-metal and non-metallic insert lock nuts.
Ensures consistent torque after multiple installations/removals.
References ISO 898-2 for proof loads and friction coefficients.

Test Methods and Requirements

Tests evaluate clamping force under specified loads and measure prevailing torque during installation and removal cycles. Clamping force is 80% of nut proof load, with limits at 75% and 65% for friction assessment. Use statistical process control for evaluation, independent of statistics.

Apply test clamp force F₈₀.
Measure torque for 1st installation (max for all-metal; 50% for inserts).
Assess 1st and 5th removal torques (min values).

These ensure nuts maintain locking without excessive friction or damage.

Class 04 Prevailing Torque Nuts

For class 04 nuts (5 mm ≤ d ≤ 39 mm), clamping force equals 80% of proof load per ISO 898-2. Limits assess total friction coefficient μ_tot.

Thread Size	Test Clamp Force F₈₀ / N	Upper Limit F₇₅ / N	Lower Limit F₆₅ / N	1st Installation T_FV,max / (N·m)	1st Removal T_Fd,min / (N·m)	5th Removal T_Fd,min / (N·m)
M5	4320	4050	3510	1.6	0.29	0.2
M6	6112	5730	4966	3	0.45	0.3
M7	8800	8250	7150	4.5	0.65	0.45
M8	11120	10425	9035	6	0.85	0.6
M8X1	11920	11175	9685	6	0.85	0.6
M10	17600	16500	14300	10.5	1.5	1
M10X1.25	18640	17475	15145	10.5	1.5	1
M10X1	19600	18375	15925	10.5	1.5	1
M12	25600	24000	20800	15.5	2.3	1.6
M12X1.5	26800	25125	21775	15.5	2.3	1.6
M12X1.25	28000	26250	22750	15.5	2.3	1.6
M14	34960	32775	28405	24	3.3	2.3
M14X1.5	38000	35625	30875	24	3.3	2.3
M16	47760	44775	38805	32	4.5	3
M16X1.5	50800	47625	41275	32	4.5	3
M18	58400	54750	47450	42	6	4.2
M18X1.5	65360	61275	53105	42	6	4.2
M20	74480	69825	60515	54	7.5	5.3
M20X1.5	82720	77550	67210	54	7.5	5.3
M22	92080	86325	74815	68	9.5	6.5
M22X1.5	101200	94875	82225	68	9.5	6.5
M24	107280	100575	87165	80	11.5	8
M24X2	116720	109425	94835	80	11.5	8
M27	139520	130800	113360	94	13.5	10
M27X2	150800	141375	122525	94	13.5	10
M30	170560	159900	138580	108	16	12
M30X2	188800	177000	153400	108	16	12
M33	210960	197775	171405	122	18	14
M33X2	231360	216900	187980	122	18	14
M36	248400	232875	201825	136	21	16
M36X3	262960	246525	213655	136	21	16
M39	296720	278175	241085	150	23	18
M39X3	313120	293550	254410	150	23	18

Note: 1st installation torque applies to all-metal nuts; for non-metallic inserts, max is 50% of values.

Class 05 Prevailing Torque Nuts

Class 05 nuts use 80% of proof load per ISO 898-2 for clamping, with friction limits for performance verification.

Thread Size	Test Clamp Force F₈₀ / N	Upper Limit F₇₅ / N	Lower Limit F₆₅ / N	1st Installation T_FV,max / (N·m)	1st Removal T_Fd,min / (N·m)	5th Removal T_Fd,min / (N·m)
M5	5680	5325	4615	2.1	0.35	0.24
M6	8000	7500	6500	4	0.55	0.4
M7	11600	10875	9425	6	0.85	0.6
M8	14640	13725	11895	8	1.15	0.8
M8X1	15680	14700	12740	8	1.15	0.8
M10	23200	21750	18850	14	2	1.4
M10X1.25	24480	22950	19890	14	2	1.4
M10X1	25760	24150	20930	14	2	1.4
M12	33760	31650	27430	21	3.1	2.1
M12X1.5	35200	33000	28600	21	3.1	2.1
M12X1.25	36800	34500	29900	21	3.1	2.1
M14	46000	43125	37375	31	4.4	3
M14X1.5	50000	46875	40625	31	4.4	3
M16	62800	58875	51025	42	6	4.2
M16X1.5	66800	62625	54275	42	6	4.2
M18	76800	72000	62400	56	8	5.5
M18X1.5	86000	80625	69875	56	8	5.5
M20	98000	91875	79625	72	10.5	7
M20X1.5	108800	102000	88400	72	10.5	7
M22	121200	113625	98475	90	13	9
M22X1.5	133200	124875	108225	90	13	9
M24	141200	132375	114725	106	15	10.5
M24X2	153600	144000	124800	106	15	10.5
M27	183600	172125	149175	123	17	12
M27X2	198400	186000	161200	123	17	12
M30	224400	210375	182325	140	19	14
M30X2	248400	232875	201825	140	19	14
M33	277600	260250	225550	160	21.5	15.5
M33X2	304400	285375	247325	160	21.5	15.5
M36	326800	306375	265525	180	24	17.5
M36X3	346000	324375	281125	180	24	17.5
M39	390400	366000	317200	200	26.5	19.5
M39X3	412000	386250	334750	200	26.5	19.5

Note: Installation torque for inserts is 50% max of listed values.

Class 5 Prevailing Torque Nuts

Class 5 aligns with bolt class 5.8 per ISO 898-1, using 80% proof load for tests.

Thread Size	Test Clamp Force F₈₀ / N	Upper Limit F₇₅ / N	Lower Limit F₆₅ / N	1st Installation T_FV,max / (N·m)	1st Removal T_Fd,min / (N·m)	5th Removal T_Fd,min / (N·m)
M5	4320	4050	3510	1.6	0.29	0.2
M6	6112	5730	4966	3	0.45	0.3
M7	8800	8250	7150	4.5	0.65	0.45
M8	11120	10425	9035	6	0.85	0.6
M8X1	11920	11175	9685	6	0.85	0.6
M10	17600	16500	14300	10.5	1.5	1
M10X1.25	18640	17475	15145	10.5	1.5	1
M10X1	19600	18375	15925	10.5	1.5	1
M12	25600	24000	20800	15.5	2.3	1.6
M12X1.5	26800	25125	21775	15.5	2.3	1.6
M12X1.25	28000	26250	22750	15.5	2.3	1.6
M14	34960	32775	28405	24	3.3	2.3
M14X1.5	38000	35625	30875	24	3.3	2.3
M16	47760	44775	38805	32	4.5	3
M16X1.5	50800	47625	41275	32	4.5	3
M18	58400	54750	47450	42	6	4.2
M18X1.5	65680	61575	53365	42	6	4.2
M20	74480	69825	60515	54	7.5	5.3
M20X1.5	82400	77250	66950	54	7.5	5.3
M22	92000	86250	74750	68	9.5	6.5
M22X1.5	100800	94500	81900	68	9.5	6.5
M24	107200	100500	87100	80	11.5	8
M24X2	116800	109500	94900	80	11.5	8
M27	113600	106500	92300	94	13.5	10
M27X2	123200	115500	100100	94	13.5	10
M30	139200	130500	113100	108	16	12
M30X2	153600	144000	124800	108	16	12
M33	172000	161250	139750	122	18	14
M33X2	188800	177000	153400	122	18	14
M36	202400	189750	164450	136	21	16
M36X3	214400	201000	174200	136	21	16
M39	242400	227250	196950	150	23	18
M39X3	255200	239250	207350	150	23	18

Note: Clamping force equals 80% of class 5.8 bolt proof load per ISO 898-1.

Class 6 Prevailing Torque Nuts

Class 6 corresponds to bolt class 6.8, with 80% proof load for clamping tests.

Thread Size	Test Clamp Force F₈₀ / N	Upper Limit F₇₅ / N	Lower Limit F₆₅ / N	1st Installation T_FV,max / (N·m)	1st Removal T_Fd,min / (N·m)	5th Removal T_Fd,min / (N·m)
M5	5000	4688	4063	1.6	0.29	0.2
M6	7072	6630	5746	3	0.45	0.3
M7	10160	9525	8255	4.5	0.65	0.45
M8	12880	12075	10465	6	0.85	0.6
M8X1	13760	12900	11180	6	0.85	0.6
M10	20400	19125	16575	10.5	1.5	1
M10X1.25	21520	20175	17485	10.5	1.5	1
M10X1	22720	21300	18460	10.5	1.5	1
M12	29680	27825	24115	15.5	2.3	1.6
M12X1.5	31040	29100	25220	15.5	2.3	1.6
M12X1.25	32400	30375	26325	15.5	2.3	1.6
M14	40480	37950	32890	24	3.3	2.3
M14X1.5	44000	41250	35750	24	3.3	2.3
M16	55280	51825	44915	32	4.5	3
M16X1.5	58800	55125	47775	32	4.5	3
M18	67600	63375	54925	42	6	4.2
M18X1.5	76000	71250	61750	42	6	4.2
M20	86400	81000	70200	54	7.5	5.3
M20X1.5	96000	90000	78000	54	7.5	5.3
M22	106400	99750	86450	68	9.5	6.5
M22X1.5	116800	109500	94900	68	9.5	6.5
M24	124000	116250	100750	80	11.5	8
M24X2	135200	126750	109850	80	11.5	8
M27	161600	151500	131300	94	13.5	10
M27X2	174400	163500	141700	94	13.5	10
M30	197600	185250	160550	108	16	12
M30X2	218400	204750	177450	108	16	12
M33	244000	228750	198250	122	18	14
M33X2	268000	251250	217750	122	18	14
M36	287200	269250	233350	136	21	16
M36X3	304800	285750	247650	136	21	16
M39	343200	321750	278850	150	23	18
M39X3	362400	339750	294450	150	23	18

Note: Clamping force equals 80% of class 6.8 bolt proof load per ISO 898-1.

Class 8 Prevailing Torque Nuts

For class 8, clamping is 80% of class 8.8 bolt proof load per GB/T 3098.1.

Thread Size	Test Clamp Force F₈₀ / N	Upper Limit F₇₅ / N	Lower Limit F₆₅ / N	1st Installation T_FV,max / (N·m)	1st Removal T_Fd,min / (N·m)	5th Removal T_Fd,min / (N·m)
M5	6584	6173	5350	1.6	0.29	0.2
M6	9280	8700	7540	3	0.45	0.3
M7	13440	12600	10920	4.5	0.65	0.45
M8	16960	15900	13780	6	0.85	0.6
M8X1	18160	17025	14755	6	0.85	0.6
M10	26960	25275	21905	10.5	1.5	1
M10X1.25	28400	26625	23075	10.5	1.5	1
M10X1	29920	28050	24310	10.5	1.5	1
M12	39120	36675	31785	15.5	2.3	1.6
M12X1.5	40880	38325	33215	15.5	2.3	1.6
M12X1.25	42720	40050	34710	15.5	2.3	1.6
M14	53360	50025	43355	24	3.3	2.3
M14X1.5	58000	54375	47125	24	3.3	2.3
M16	72800	68250	59150	32	4.5	3
M16X1.5	77520	72675	62985	32	4.5	3
M18	92000	86250	74750	42	6	4.2
M18X1.5	104000	97500	84500	42	6	4.2
M20	117600	110250	95550	54	7.5	5.3
M20X1.5	130400	122250	105950	54	7.5	5.3
M22	145600	136500	118300	68	9.5	6.5
M22X1.5	160000	150000	130000	68	9.5	6.5
M24	169600	159000	137800	80	11.5	8
M24X2	184000	172500	149500	80	11.5	8
M27	220000	206250	178750	94	13.5	10
M27X2	238400	223500	193700	94	13.5	10
M30	269600	252750	219050	108	16	12
M30X2	298400	279750	242450	108	16	12
M33	332800	312000	270400	122	18	14
M33X2	365600	342750	297050	122	18	14
M36	392000	367500	318500	136	21	16
M36X3	415200	389250	337350	136	21	16
M39	468800	439500	380900	150	23	18
M39X3	494400	463500	401700	150	23	18

Class 10 Prevailing Torque Nuts

Class 10 uses 80% of class 10.9 bolt proof load, for high-strength applications.

Thread Size	Test Clamp Force F₈₀ / N	Upper Limit F₇₅ / N	Lower Limit F₆₅ / N	1st Installation T_FV,max / (N·m)	1st Removal T_Fd,min / (N·m)	5th Removal T_Fd,min / (N·m)
M5	9440	8850	7670	2.1	0.35	0.24
M6	13360	12525	10855	4	0.55	0.4
M7	19200	18000	15600	6	0.85	0.6
M8	24320	22800	19760	8	1.15	0.8
M8X1	26000	24375	21125	8	1.15	0.8
M10	38480	36075	31265	14	2	1.4
M10X1.25	40640	38100	33020	14	2	1.4
M10X1	42800	40125	34775	14	2	1.4
M12	56000	52500	45500	21	3.1	2.1
M12X1.5	58480	54825	47515	21	3.1	2.1
M12X1.25	61120	57300	49660	21	3.1	2.1
M14	76400	71625	62075	31	4.4	3
M14X1.5	83200	78000	67600	31	4.4	3
M16	104000	97500	84500	42	6	4.2
M16X1.5	111200	104250	90350	42	6	4.2
M18	127200	119250	103350	56	8	5.5
M18X1.5	143200	134250	116350	56	8	5.5
M20	162400	152250	131950	72	10.5	7
M20X1.5	180800	169500	146900	72	10.5	7
M22	201600	189000	163800	90	13	9
M22X1.5	220800	207000	179400	90	13	9
M24	234400	219750	190450	106	15	10.5
M24X2	255200	239250	207350	106	15	10.5
M27	304800	285750	247650	123	17	12
M27X2	329600	309000	267800	123	17	12
M30	372800	349500	302900	140	19	14
M30X2	412000	386250	334750	140	19	14
M33	460800	432000	374400	160	21.5	15.5
M33X2	505600	474000	410800	160	21.5	15.5
M36	542400	508500	440700	180	24	17.5
M36X3	574400	538500	466700	180	24	17.5
M39	648000	607500	526500	200	26.5	19.5
M39X3	684000	641250	555750	200	26.5	19.5

Często zadawane pytania

What is the purpose of prevailing torque in lock nuts?

It provides resistance to loosening from vibration, measured through installation and removal cycles to ensure consistent performance.

How does class differ for all-metal vs. non-metallic insert nuts?

For non-metallic inserts, 1st installation max torque is 50% of listed values to avoid damaging the insert.

What if torque falls below min after 5th removal?

The nut fails the test; select higher class or verify assembly conditions like lubrication and thread fit.

How to calculate clamping force limits?

Upper: 75% of proof load; lower: 65%. Use for friction coefficient evaluation in quality control.

Are these values applicable to fine pitches only?

No, tables include both coarse and fine; ensure thread specification matches for accurate testing.

What standards reference proof loads?

ISO 898-1/2 or GB/T 3098.1 for bolt/nut loads, ensuring compatibility in assemblies.