What is Cyclic Loading?

There are many types of loads and stresses that pressure vessels will encounter while they’re being used, including cyclic loading. So what is cyclic loading, and how does it impact the life of a pressure vessel?

What type of load is cyclic loading?

Cyclic loading is any type of load applied to a component that repeats in a pattern. It’s usually expected to continue in this pattern for a long period of time, and will affect the material making up the component differently than a short, sharp load would.

The repeated application of a load in cyclic loading leads to fatigue in the material, and is one of the leading reasons components eventually fail, so it’s important to understand how it works and how it changes the material over time.

What happens to a material exposed to cyclic loading?

When a material experiences fatigue, it slowly becomes weaker over time as the repeated forces acting on the material weaken its molecular structure. Cracks and microfractures will propagate as stresses concentrated in them cause them to widen, and the damage to the material done by corrosion will increase as well.

Impurities and imperfections in the molecular structure of the material will cause the applied stress to concentrate in some areas, eventually releasing that stored energy by cracking or shifting. This will lead to higher stress concentrations over time as the material becomes weaker and weaker until it can no longer sustain the forces applied to it and breaks.

Cyclic loading and stainless steel pressure vessels

Pressure vessels, especially those made from a ductile alloy like stainless steel, have their own set of cyclic loads they experience that need to be accounted for during their design. You can learn more about the details here.

Rexarc is full of experts on ASME-standard pressure vessels that are designed to be safe and reliable for years to come. If you have specific questions about an application or how stainless steel pressure vessels are designed, feel free to reach out to us, or check out the custom ASME pressure vessels we offer here.