Stud Bolts

PETROSADID prides itself on providing Standard and Custom Engineered Stud-Bolts to match our customer’s needs.

In Petro and chemical industry for flange connections Stud Bolts and Hex Bolts are used. The Stud Bolt is a threaded rod with 2 heavy hexagon nuts, while the Hex Bolt has a head with one nut. Nuts and head are both six sided.

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The quantity of bolts for a flange connection will be given by the number of bolt holes in a flange, diameter and length of bolts is dependent of flange type and Pressure Class of flange.

Stud Bolt length are defined in ASME B16.5 standard. The length in inches is equal to the effective thread length measured parallel to the axis, from the first to the first thread without the chamfers (points). First thread is defined as the intersection of the major diameter of the thread with the base of the point.

Components

Stud

Stud has a thread on full lengths or at both ends. As shown in images. It is having three components if washers are not used (two nuts and stud). If you used washer it would become five. Sometimes additional nuts are used for hydraulic tensioning with larger size stud.

Bolt

Bolts have a thread at one end and hexagonal head on another end. See the image below. In the process, piping bolts are used with lower strength flange types such as GRE/GRP, bronze. Usually, washers are used with bolt to prevent excessive load to the flange.

Nuts

Commonly Hexagonal Heavy-series nuts used with studs. The nonbearing face of a nut is chamfered, while load Bearing face is finished with a washer face or may be chamfered.

Washers

A washer is a thin plate with a hole at center. Washers distribute the load on flange face; this prevents damage to the flange. Non-metallic flange required washers due to this reason. Different types of washers are used such as Flat, Splits, and Conical Springs. Flat and split washers are shown in the image.

Conical washers are special washers. Also known as Belleville Springs washers. It Keeps bolted joints tight in an area where vibration, differential thermal expansion, and bolt creep present. These conditions can change the load on a stud which may result in a loose connection. Conical washers provide a spring effect and prevent loosening of a stud. This washer provides High spring loads with small deflections.

Stud Bolt Specification & Standard

Various ASME standards are used for stud bolts and nuts to manufacturing bolting material. List of such standard is given below.

• Diameter and Lengths of the stud and bolt are covered in ASME B16.5 & B16.47

• ASME B1.1 Unified Inch Screw Threads (Cores and Fine thread series- normally Cores thread series is used for stud used in piping)

• ASME B18.2.1 for Square and Hex Bolts and Screws

• ASME B18.2.2 Square and Hex Nuts

• ASME B18.21.1 Lock Washers

• ASME B18.22.1 Plain Washers

Grades of Stud Bolts

Below a table with materials and grades for flanges, thread rods (bolts) and nuts, arranged on design temperature, flanges, thread rods and recommended nuts.

Stud Bolts

Components

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Stud Bolts

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