What is Pipe Stress?

Pipe stress analysis is the process of determining the stresses in your piping system, both internal and external. There are many different types of stresses that can impact your piping system, including thermal movement, pressure, shear, and bending. Each of these types of stresses have specific effects on the piping system. Pipe Stress Analysis is important because it allows engineers to see how the different forces and loads impact your piping system. By identifying areas where the stresses are high, you can make changes to your piping design and support structures to reduce these stresses.

What is Pipe Stress?

Pipes are subjected to both internal and external pressure, temperature, and loadings. These forces push against the walls of the pipes and create stresses inside them. These stresses can cause the pipes to crack, rupture, or even collapse if they are not designed correctly. To prevent this from happening, piping engineers perform pipe stress analysis to determine how much stress is safe for the pipes to withstand.

The main sources of stress in a piping system include fluid pressure, gravity, nozzle loads, internal or external expansion and contraction, spring forces, relief valve discharge, and seismic loads. These sources of stress can all result in high pressures or moments on parts of your piping system, particularly those with limited displacement such as nozzles and equipment connections. These locations may need specialized supports or anchors to keep them from being over-stressed.

A piping system is also subject to thermal movements, which can cause the pipe to expand or contract depending on the ambient temperature. This expansion and contraction can produce high axial stresses in the pipe that must be considered during stress analysis. This type of stress can be further concentrated in a pipe bend due to the change in geometry of the pipe. This stress is called shear stress and is typically highest in the outer portion of the bend.

The other major type of stress is bending stress, which results from the direction of the flow in a pipe changing as it goes around a bend. This type of stress is also a concentration point in the middle of the pipe bend, and it can interact with shear stress to increase the overall stress level.

A third type of stress is tensile stresses, which are created by shear and bending stresses in a pipe that are multiplied by a stiffness factor (SIF). This stress is often ignored during Pipe Stress analysis, but it can result in a weakened or cracked piping section. This can occur if the SIF is not correctly calculated and accounted for during stress analysis. For this reason, it is important to use accurate SIF calculations when designing a piping system with bends. This can be accomplished using a Finite Element Analysis (FEA) software to accurately model the behavior of the pipe and simulate stress conditions. This can help ensure that the bending SIF is correct and the resulting shear and tensile stresses are within acceptable limits.