Torque for Hexagon Head Screws with UNF Threads Table

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Torque for Hexagon Head Screws with UNF Threads Table

ANSI Engineering Hardware
Engineering Fastener Torque Specifications
ISO Metric Hard Engineering Data

Preloads and tightening torque for steel shank screws with UNC/UNF threads and head contact area sizes according to ASME B18.2.1, ASME B18.3 and ASME B18.2.2

friction coefﬁcient µ = 0.14, Utilization of minimum yield = 90%

Typical Torque for Hexagon Head Screws with UNF Threads Table

Size		VPreloads F_v (kN) for property class
Size		Grade 5*		Grade 8*		Type 2*		Type 3*
Ø	M	[kN]	[lbf]	[kN]	[lbf]	[kN]	[lbf]	[kN]	[lbf]
1/4	28	11.8	2653	16.7	3749	-	-	-	-
5/16	24	18.9	4252	26.7	6008	-	-	-	-
3/8	24	28.9	6486	40.8	9165	-	-	-	-
7/16	20	39.0	8758	55.0	12375	-	-	-	-
1/2	20	52.8	11861	74.6	16760	52.7	11861	52.7	11861
5/8	18	84.7	19050	120	26918	84.7	19050	84.7	19050
3/4	16	124	27814	175	39302	124	27814	124	27814

Size		Tightening torque M_A (Nm) for property class
Size		Grade 5*		Grade 8*			Type 2*		Type 3*
Ø	M	[Nm]	[ft-lbs]		[Nm]	[ft-lbs]	[Nm]	[ft-lbs]		[Nm]	[ft-lbs]
1/4	28	13.8	10.2		19.5	14.4	-	-		-	-
5/16	24	28.3	20.9		40.0	29.5	-	-		-	-
3/8	24	50.0	36.9		70.7	52.2	-	-		-	-
7/16	20	78.6	57.9		111	81.9	-	-		-	-
1/2	20	122	89.7		172	127	122	89.7		122	89.7
5/8	18	239	176		337	249	239	176		239	176
3/4	16	423	312		597	441	423	312		423	312

* Grade 5 (~8.8) and Grade 9 (~10.9) according to SAE J 429, Type 2 and type 3 (~8.8) according to ASTM A325