Metric Hexagon Nuts BS 4882 | ASTM A193 Grade B7

(a) Dimensions of metric hexagon nuts

Nuts for use with metric series studbolts and studs

General
Nuts shall comply with the dimensions and tolerances given in table 14.

Dimensions of hexagon nuts:metric series
Nominal size and pitch	Width across flats s		Width across corners e	Thickness m		Tolerance on squareness
Nominal size and pitch	max.	min.	min.	max.	min.	Tolerance on squareness
	mm	mm	mm	mm	mm	mm
M10 × 1.5	16.00	15.57	17.59	8	7.42	0.29
M12 × 1.75	18.00	17.57	19.85	10	9.42	0.32
(M14 × 2)	21.00	20.16	22.78	11	10.30	0.37
M16 × 2	24.00	23.16	26.17	13	12.30	0.41
M20 × 2.5	30.00	29.16	32.95	16	15.30	0.51
(M22 × 2.5)	34.00	33.00	37.29	18	17.30	0.54
M24 × 3	36.00	35.00	39.55	19	18.16	0.61
M27 × 3	41.00	40.00	45.20	22	21.16	0.70
M30 × 3	46.00	45.00	50.85	24	23.16	0.78
M33 × 3	50.00	49.00	55.37	26	25.16	0.85
M36 × 3	55.00	53.80	60.79	29	28.16	0.94
M39 × 3	60.00	58.80	66.44	31	30.00	1.03
M42 × 3	65.00	63.80	72.09	34	33.00	1.11
M45 × 4	70.00	68.80	77.74	36	35.00	1.20
M48 × 4	75.00	73.80	83.39	38	37.00	1.29
M52 × 4	80.00	78.80	89.04	42	41.00	1.37
M56 × 4	85.00	83.60	94.47	45	44.00	1.46
M64 × 4	95.00	93.60	105.77	51	49.80	1.63
M70 × 4	100.00	98.60	114.42	56	54.80	1.76
M72 × 4	105.00	103.60	117.07	58	56.80	1.81
M76 × 4	110.00	108.60	122.72	61	59.80	1.89
M82 × 4	120.00	118.60	134.01	66	64.80	2.02
M90 × 4	130.00	128.60	145.32	72	70.80	2.20
M95 × 4	135.00	133.60	150.97	76	74.80	2.31
M100 × 4	145.00	143.60	162.27	80	78.80	2.42

Faces

Nuts shall have a chamfer of approximately 30° on the non-bearing face only. The bearing face shall be full faced. The bearing face shall be machined, or have a surface equal to that produced by machining.
The faces of the nut shall be square to the axis of the thread of the nut within the tolerances given in table 14 (see figure 3 and appendix E).

Screw threads

Screw threads for all materials other than low and medium carbon steel shall comply with the requirements given in table 15.

Pitch of screw threads for nuts: metric series
Nominal diameter	Pitch
≤ M27	ISO metric coarse (see BS 3643)*
≥ M30 ≤ M42	3 mm*
≥ M45 ≤ M100	4 mm*
* Class 6H (see item (d)(6) of appendix C)

The ISO metric coarse pitch series shall be used throughout the range of sizes for low and medium carbon steel.
The screw threads in nuts shall be concentric with the hexagons within a tolerance of 2 IT13, FIM (see BS 6322 : Part 1), using the width across flats as reference datum.