Stud bolts, nuts, machine bolts, and washers are also known as bolting materials or fasteners. Bolting is the term that is used to tighten/create the flange joint connection. The tightening of the flange ensures the leak-proof connection between the gasket & flanges. ASME flanges have a minimum of four bolt holes; for higher diameter flanges, the number of bolt holes is always in multiples of four. The selection of the number of bolt holes depends on the factor such as

Size of the flange

Working pressure

Working temperature

Flange material

Stud Bolt.

The stud has a thread on full lengths or at both ends. As shown in the images. It has three components if washers are not used (two nuts and a stud). If you used a washer, it would become five. Sometimes additional nuts are used for hydraulic tensioning with larger size studs.
The length of the stud bolt should be enough to cover the entire Nut plus 1.5 to 3 threads exposed. Long studs must be avoided as it increases the chance of corrosion and other damage to exposed threads, which would make subsequent removal difficult. ASME B16.5 gives the required size of the stud. The length of the stud depends on the type of gasket and the maximum exposed thread requirements.

Types of Stud Bolt.

Fully threaded stud bolt or continuous threaded stud bolt having uniform thread throughout its length.

Tap end stud bolts having unequal threads from each end and non-threaded center.

Double-end stud bolts having both ends threaded of equal lengths and a non-threaded center.

Flange Stud bolts: Fully threaded stud bolts with chamfered ends specifically used for flanged connections.

Double-end stud bolt with reduced shank: the non-threaded center part is of a reduced diameter than the actual diameter..

Stud Bolts Standards.

ISO metric thread

ACME thread

UNC thread

UNF thread

UN thread

WHITWORTH thread

Types of Stud Bolts.

ASME B16.5 & ASME B16.47 cover the diameter and length.

ASME B1.1 covers coarse and fine thread series.

ASME B18.2.1 is used for Square and Hex Bolts and Screws

ASME B18.2.2 provides details for Square and Hex Nuts

ASME B18.21.1 provides Lock Washer details

ASME B18.22.1 is used for Plain Washers

 

Stud Bolt Material:

For high-temperature and pressure services, ASTM A193 is the most widely used flange material. Grade B7 and B7M are the most frequently used A193 material grades. For low-temperature services, ASTM A320 Gr L7, L7A, and L7B are used. Other stud bolt materials include the following:

ASTM A354 Gr BC, BD

ASTM A540 Gr B21 to B24

ASTM A193 Gr B5, B6, B8, B16, B8M, B8A, B8T, L7, B17B.

ASTM A453 Gr 660A/B/C/D

ASTM A913 Inconel 718

ASTM A320 Gr L7M, L43, B8, B8A, B8T, B8MA, B8C

ASTM A182 Gr S31803, S32205.

 

SS Perforated Sheet Available Finish

2B, 2D, HR, CR, BA (No. 8), Satin (Met with PVC Coated), No.1 Finish, No.4 Finish

 

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