BS 4882

ASTM A193 Grade B7 Specifications

Dimensions for Tap-End Studs

Dimensions of metric countersunk socket head cap screws

Dimensions of metric countersunk socket head cap screws

Nominal Size or Basic Screw Diameter	Thread Pitch	D		A		H		J	T	G	F	M
		Body Diameter		Head Diameter		Head Height		Hexagon Socket Size	Key Engagement	Socket Wall	Fillet Extension Above D	Drill Allow.
		Max.	Min.	Theoretical Sharp Max.	Absolute Min.	Reference	Flushness Tolerance	Nom.	Min.	Min.	Max.	Max.
3	0.5	3.0	2.86	6.72	5.35	1.86	0.30	2.0	1.1	0.25	0.25	0.3
4	0.7	4.0	3.82	8.96	7.80	2.48	0.30	2.5	1.5	0.45	0.35	0.4
5	0.8	5.0	4.82	11.20	9.75	3.10	0.35	3.0	1.9	0.66	0.40	0.5
6	1	6.0	5.82	13.44	11.70	3.72	0.35	4.0	2.2	0.70	0.50	0.6
8	1.25	8.0	7.78	17.92	15.60	4.96	0.40	5.0	3.0	1.16	0.60	0.8
10	1.5	10.0	9.78	22.40	19.50	6.20	0.50	6.0	3.6	1.62	0.80	0.9
12	1.75	12.0	11.73	26.88	23.40	7.44	0.60	8.0	4.3	1.80	0.90	1.2
14 (1)	2	14.0	13.73	30.24	26.13	8.12	0.70	10.0	4.7	1.62	1.00	1.5
16	2	16.0	15.73	33.60	28.96	8.80	0.80	10.0	4.8	2.20	1.00	1.5
20	2.5	20.0	19.67	40.32	34.60	10.16	1.00	12.0	5.6	2.20	1.20	1.8

NOTE:(1) Not recommended for new design.

Body and grip Lengths

Nominal Diameter	M3		M4		M5		M6		M8		M10		M12		M14		M16		M20
Nominal length	L_GH	L_BH	L_GH	L_BH	L_GH	L_BH	L_GH	L_BH	L_GH	L_BH	L_GH	L_BH	L_GH	L_BH	L_GH	L_BH	L_GH	L_BH	L_GH	L_BH
35	17	14.5	15	11.5
40	22	19.5	20	16.5	18	14
45	27	24.5	25	21.5	23	19	21	16
50	32	29.5	30	26.5	28	24	26	21	22	15.7
55	37	34.5	35	31.5	33	29	31	26	27	20.7
60			40	36.5	38	34	36	31	32	25.7	28	20.5
65			45	41.5	43	39	41	36	37	30.7	33	25.5	29	20.2
70			50	46.5	48	44	46	41	42	35.7	38	30.5	34	25.2	30	20
80			60	56.5	58	54	56	51	52	45.7	48	40.5	44	35.2	40	30	36	26
90					68	64	66	61	62	55.7	58	50.5	54	45.2	50	40	46	36
100					78	74	76	71	72	65.7	68	60.5	64	55.2	60	50	56	46
110							86	81	82	75.7	78	70.5	74	65.2	70	60	66	56	58	45.5
120							96	91	92	85.7	88	80.5	84	75.2	80	70	76	66	68	55.5
130									102	95.7	98	90.5	94	85.2	90	80	86	76	78	65.5
140									112	105.7	108	100.5	104	95.2	100	90	96	86	88	75.5
150									122	115.7	118	110.5	114	105.2	110	100	106	96	98	85.5

Dimensions of metric hexagon sockets

Forged Hexagon Socket

Broached Socket

Nominal Socket Size	j		c
	Socket Width Across Flats		Socket Width Across Corners
	Max.	MIn.	MIn.
2	2.045	2.020	2.30
2.5	2.560	2.520	2.87
3	3.071	3.020	3.44
4	4.084	4.020	4.58
5	5.084	5.020	5.72
6	6.095	6.020	6.86
8	8.115	8.025	9.15
10	10.127	10.025	11.50
12	12.146	12.032	13.80

Tolerance ON Length. The tolerance on length shall be bilateral as tabulated below:

Nominal Screw length, mm	Tolerance on length, mm
up to 16, incl.	± 0.3
Over 16 to 60, incl.	± 0.5
Over 60 to 150, incl.	± 0.8

ASTM A193 Grade B7 Fastener Coatings

PTFE Coated B7 Fasteners

PTFE Coated

Black Phosphated B7 Fasteners

Black Phosphated

Zinc Plated B7 Fasteners

Zinc Plated

Hot Dip Galvanized B7 Fasteners

Hot Dip Galvanized

Cadium Plated B7 Fasteners

Cadium Plated

Ceramic Coated B7 Fasteners

Ceramic Coated

Zinc Nickel B7 Fasteners

Zinc Nickel

Zinc Flake Coated B7 Fasteners

Zinc Flake Coated