Stud Bolts and Nut Sizes

A stud bolt is a bolt with threads on both ends, and they often have an unthreaded middle section on their shaft. A stud bolt connection is typically created by two nuts and the stud, though it is not uncommon to see washers and extra nuts used in the assembly.
Stud bolts are commonly utilized in high-pressure pipework and pipeline flange connections.
ASME B16.5 and ASME B16.47, specify the stud bolt diameter and the number of bolts required in a bolted assembly, based on the pressure class, flange type, and pipe size, and from the stud bolt chart below, you can determine the corresponding nut size. This allows the construction engineer to ensure all necessary hand tools of the correct size e.g. flogging spanners, ring spanners, socket sizes etc. are made available during construction.
Remember that if you plan to hydrotight the assembly, the studs will have to be longer than if tightened by hand.

In the stud bolts and nuts size chart below, dimensions are given in both metric and inch.
AF - Across the Flats, or in other words, spanner size required.

**Stud bolts and nuts dimensions - metric and inch**
Stud Size (mm)	Nut AF (mm)	Stud Size (ins)	Nut AF Heavy (ins)	Stud Size (ins)	Nut AF Regular (ins)
12	19			1/2	3/4
		1/2	7/8
16	24			5/8	15/16
		5/8	1 1/16
				3/4	1 1/8
20	30
		3/4	1 1/4
				7/8	1 5/16
24	36
		7/8	1 7/16
				1	1 1/2
27	41	1	1 5/8
				1 1/8	1 11/16
30	46	1 1/8	1 13/16
				1 1/4	1 7/8
33	50
		1 3/8	2 3/16
				1 1/2	2 1/4
39	60	1 1/2	2 3/16
				1 5/8	2 7/16
42	65	1 5/8	2 9/16
				1 3/4	2 5/8
45	70	1 3/4	2 3/4
				1 7/8	2 13/16
48	75	1 7/8	2 15/16
				2	3
		2	3 1/8
52	80
56	85
				2 1/4	3 3/8
		2 1/4	3 1/2

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