Bolts and nuts provide for clamping of the flange and gasket components. Bolting is a term that includes studbolts, nuts, and washers. Bolting for flanges and pressure-containing purposes are usually studbolts.

 

In this lesson, we will be showing the type of bolt and nuts normally used in the Oil and Gas facilities, the applicable standard, and some example of long description of bolt.

   

The Function

The function of a bolt is to provide a clamp load or preload (Fp) to sufficiently compress and stress the gasket and resist the parting forces exerted by the hydrostatic end force and other external loads.

   

☘☘☘

 

Type of Bolt: Machine Bolts
	Fastener with a head integral with the shank and threaded at the opposite end. For pressure piping application, stud bolt comes with heavy-series of nuts as shown on the image.

 

Type of Bolt: Stud Bolts
	Fasteners which are threaded at both ends or for the whole length, with nuts placed at both end, as image shown.

   

☘☘☘

 

Bolting Standards
ASTM F436	Square and Hex Bolt and Screws
ASTM B18.21.1	Lock Washer
ASTM B18.22.1	Plain Washer
ASTM B18.2.2	Square and Hex Nuts
ASTM B18.2.2	Mechanical Properties of Plain Washer

 

Bolting Strength
High Strength	For bolt material with a minimum yield strength of not less than 105 ksi.
Intermediate Strength	For bolt material with a minimum yield strength of between 30 ksi and 105 k
Low Strength	Having no greater than 30 ksi of Specified Minimum Yield Strength.

 

Type of Nuts:
High Strength	HEAVY SERIES NUTS Normally being used with STUDBOLT for pressure piping application.
Intermediate Strength	For bolt material with a minimum yield strength of between 30 ksi and 105 k
Low Strength	Having no greater than 30 ksi of Specified Minimum Yield Strength.