As frac’rs, we handle very high pressures. One of the most important things we do is to safely work around that. That requires mental strength and physical material strength. We work with up to 15,000 psi of fluid pressure within a steel pipe or a rubber flex hose.
For a liquid in a confined space, if there is no flow, that fluid pressure pushes outward by the same amount in every direction everywhere. This has an impact on the pipe - pressure pushes out radially, but it also pulls the pipe along its axis and along its circumference.
This creates counter-acting stresses in the frac iron. The biggest one, acting around the circumference of the pipe, is called the hoop stress. Essentially, there is a force balance that acts over any cross section of a pipe cut in half - otherwise the pipe would move. The “pulling” pressures from the liquid over the inner pipe diameter are in balance with the tensile forces of the hoop stress over pipe walls on each side.
Steel pipe has the material (tensile) strength to absorb these stresses. In the case of the piece of pipe, these differences in stress are driven by the pressure and the geometry. Since the sum of the wall thicknesses is about 5x the internal diameter, the tensile stress in the pipe is about 5x the internal pressure.
In a flex hose, where the internal diameter is about the same as the hose thickness, the counter-acting force is spread over a larger area, and the hoop stress is about the same as the internal pressure.
Strong materials can contain the pressure that is trying to pull it apart, by being able to handle the stress as long as it remains below the material’s strength.
Essentially, Liberty folks doing the Hercules Hold during the 2025 Strongman contest did just that. They create a counteracting stress to hold together a system that forces are trying to pull apart. Kudos to Grace Bol and Tyrin Cunningham to win the Hercules Hold event! They literally embody what frac iron and steel-braided rubber hose do for us on a frac location.
Frac’rs work under pressure that’s counteracted by stress. We handle that stress with strength. That’s Liberty Strong.
*with my excuses for poor sound quality
