Different Types of Threaded Rods/Bars

A threaded rod or stud is basically a long bar that is threaded on both ends to facilitate fastening in high tension applications. The threading may apply to the entire length of the rod or could be only at certain parts.  Continuously threaded bars from ironmongeryonline are divided into two main types:

a. One is the general purpose type that is often used with flange bolting. The length is measured completely from end to end.

b. The second type of stud is used specifically for temperature and pressure piping. These are made according to the requirements of the application and there is no fixed standard size. The points are chamfered and flat. The length for these is measured from thread to thread.
Among studs that are not threaded completely, there are two categories:

Full bodied studs

These threaded bars have a shank length that equals the major diameter. The way these studs are used, the stresses are often greater in the threads. The shank does not come under much tension. Full bodied studs are created by removing the metal to create the right thread. This results in the grain of the steel being disturbed and hence these studs are generally weaker. However, they perform well enough for most standard applications.

Undercut studs

In these studs, the shank length equals the pitch diameter of the thread. These are very good at distributing axial stresses and are considerably stronger than full bodied threaded bars. The main reason for its strength is that metal is not removed to create the thread. It is, in fact, rolled up to the major diameter. Hence the grain of steel is kept completely intact. Due to their high strength, these are used in applications where the studs are exposed to fatigue. These are also the more common type in standard studs and bolts.

There is another way to classify studs that are not completely threaded:

Tap End

These will have two threads at each end, one short and one long. The shorter end is called the tap end and is used for screwing into the hole. This end will also have a chamfered point.

Double End

These will have an equal length thread on each end, which is used to attach the nut. Both the ends will usually be chamfered but round points can also be done. It is generally used in applications that require torching from both ends.