ASME B18.2.2 Square Machine Screw Nuts

ASME B18.2.2 Square Machine Screw Nuts Standard covers the dimensional requirements for nine product types of inch series bolts and screws recognized as American National Standard. Also included are appendices covering gaging procedures, grade markings for bolts and screws, formulas on which dimensional data are based, and a specification to assist in identifying a product as being a screw or a bolt. Where questions arise concerning acceptance of product, the dimensions in the tables shall govern over recalculation by formula. Heavy hex structural bolts, formerly covered in ASME B18.2.1, are now covered in ASME B18.2.6.
The inclusion of dimensional data in this Standard is not intended to imply that all of the products described herein are stock production sizes. Consumers should consult with suppliers concerning lists of stock production sizes.

ASME B18.2.2 Square Machine Screw Nuts Dimensions (mm)

Nominal Size	Basic Major Diameter of Thread	Width Across Flats, F			Width Across Corners		Thickness		Bearing Surface Runout to Thread Axis, FIM
		Basic	Min.	Max.	Square, G		Min.	Max.
					Min.	Max.
#0	1.524	3.969	3.810	3.962	5.232	5.613	1.092	1.270	0.127
#1	1.854	3.969	3.810	3.962	5.232	5.613	1.092	1.270	0.127
#2	2.184	4.763	4.572	4.775	6.274	6.731	1.448	1.676	0.152
#3	2.515	4.763	4.572	4.775	6.274	6.731	1.448	1.676	0.152
#4	2.845	6.350	6.121	6.350	8.407	8.992	2.210	2.489	0.229
#5	3.175	7.938	7.671	7.925	10.541	11.227	2.591	2.896	0.279
#6	3.505	7.938	7.671	7.925	10.541	11.227	2.591	2.896	0.279
#8	4.166	8.731	8.433	8.738	11.582	12.344	2.972	3.302	0.305
#10	4.826	9.525	9.195	9.525	12.624	13.462	2.972	3.302	0.330
#12	5.486	11.113	10.744	11.125	14.757	15.723	3.759	4.089	0.381
1⁄4	6.350	11.113	10.744	11.125	14.757	15.723	4.521	4.902	0.381
5⁄16	7.925	14.288	13.843	14.275	18.999	20.193	5.283	5.715	0.508
3⁄8	9.525	15.875	15.418	15.875	21.158	22.454	6.071	6.528	0.533

ASME B18.2.2 Square Machine Screw Nuts Dimensions (Inch)

Nominal Size	Basic Major Diameter of Thread	Width Across Flats, F			Width Across Corners		Thickness		Bearing Surface Runout to Thread Axis, FIM
		Basic	Min.	Max.	Square, G		Min.	Max.
					Min.	Max.
#0	0.060	5⁄32	0.150	0.156	0.206	0.221	0.043	0.050	0.005
#1	0.073	5⁄32	0.150	0.156	0.206	0.221	0.043	0.050	0.005
#2	0.086	3⁄16	0.180	0.188	0.247	0.265	0.057	0.066	0.006
#3	0.099	3⁄16	0.180	0.188	0.247	0.265	0.057	0.066	0.006
#4	0.112	1⁄4	0.241	0.250	0.331	0.354	0.087	0.098	0.009
#5	0.125	5⁄16	0.302	0.312	0.415	0.442	0.102	0.114	0.011
#6	0.138	5⁄16	0.302	0.312	0.415	0.442	0.102	0.114	0.011
#8	0.164	11⁄32	0.332	0.344	0.456	0.486	0.117	0.130	0.012
#10	0.190	3⁄8	0.362	0.375	0.497	0.53	0.117	0.130	0.013
#12	0.216	7⁄16	0.423	0.438	0.581	0.619	0.148	0.161	0.015
1⁄4	0.250	7⁄16	0.423	0.438	0.581	0.619	0.178	0.193	0.015
5⁄16	0.312	9⁄16	0.545	0.562	0.748	0.795	0.208	0.225	0.020
3⁄8	0.375	5⁄8	0.607	0.625	0.833	0.884	0.239	0.257	0.021