Stud Bolts are are fully threaded headless bolts used on Pipeline flanges for joining the pipelines. The main advantage of Stud Bolts over the Hex Bolts is that, it can be tightened from both the ends by holding one end with nut.
The other type of Stud Bolt is the Engineering Stud which is also known as both end threaded bolt with unthreaded portion in the centre.