Metric Prevailing Torque Specification

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Metric Prevailing Torque Specification

Metric Engineering Hardware Design Guide
ANSI Engineering Hardware Design Guide Inch Sizes

Prevailing Torque Specification Guide for Metric ISO Hardware Sizes

Prevailing Minimum Torque for Inch ANSI Hardware

METRIC SIZES		PREVAILING TORQUE		INSTALLATION VALUES⁽¹⁾
METRIC SIZES		PREVAILING TORQUE		Class 8			Class 10
Nominal Diameter (mm)	Thread Pitch (mm)	ISO 2320 Removal minimum (Nm)	Security Locknut⁽²⁾ (Nm)	Clamp Load (N)	Dry Tightening Torque⁽³⁾ (Nm)	Lubricated Tightening Torque⁽⁴⁾ (Nm)	Clamp Load (N)	Dry Tightening Torque⁽³⁾ (Nm)	Lubricated Tightening Torque⁽⁴⁾ (Nm)
10	1.50	1.4	3.0	22,181	44	33	30,662	61	46
10	1.25	1.4	3.0	23,408	47	35	32,359	65	49
12	1.75	2.1	4.0	32,232	77	58	44,556	107	80
12	1.25	2.1	4.0	35,218	85	63	48,683	117	88
16	2.00	4.2	6.0	59,926	192	144	82,838	265	199
16	1.50	4.2	6.0	63,973	205	154	88,433	283	212
20	2.50	7.0	15.0	93,634	375	281	129,435	518	388
20	1.50	7.0	15.0	103,850	415	312	143,558	574	431
24	3.00	10.5	20.0	134,833	647	485	186,387	895	671
24	2.00	10.5	20.0	147,039	706	529	203,260	976	732
27	3.00	12.0	22.0	175,723	949	712	243,084	1,313	984
27	2.00	12.0	22.0	189,621	1,024	768	262,309	1,416	1,062
30	3.50	14.0	26.0	214,425	1,287	965	296,411	1,778	1,334
30	2.00	14.0	26.0	237,610	1,426	1,069	328,460	1,971	1,478
33	3.50	15.5	29.0	265,284	1,751	1,313	366,717	2,420	1,815
33	2.00	15.5	29.0	291,006	1,921	1,440	402,273	2,655	1,991
36	4.00	17.5	30.0	312,397	2,249	1,687	431,842	3,109	2,332
36	3.00	17.5	30.0	330,839	2,382	1,787	457,336	3,293	2,470
39	4.00	19.5	33.0	373,226	2,911	2,183	515,930	4,024	3,018
39	3.00	19.5	33.0	393,359	3,068	2,301	543,761	4,241	3,181

1) Installation torque and clamp load are calculated using the proof load for the class bolt and nut specified multiplied by 0.75 for a factor of safety and multiplied by 0.85 to account for material removal for the locking mechanism. Proof load used for Class 8 calculation is 600 N/mm2. Proof load used for Class 10 calculation is 830 N/mm².
2) The value shown is the approximate installation and removal prevailing torque for the Security Locknut. The prevailing torque will vary less than 75% from the value shown from the first to the fifth installation and beyond.
3) Calculated using formula: Nominal diameter x Clamp Load (from note 1) x Friction factor (dimensionless value of 0.20 for dry installation).
4) Calculated using formula: Nominal diameter x Clamp load (from note 1) x Friction factor (dimensionless value of 0.15 for lubricated installation).