Vibration and fatigue in metal hoses

Technical explanation

Repeated bending and torsion determine the conditions of use of a metal hose. Manufacturer installation guides require motion to be arranged in the appropriate plane and incorrect bending and torsion to be avoided. The minimum radius must be read together with the given type of motion. The fact that an assembly is leak-tight in a hydrostatic test does not on its own show that it will achieve the target life under specific vibration cycles. The layout of the welded end zone and the flexible section are examined together.

Source: S024, S039

Topic-specific checkpoints

Source: S024, S039

How is it assessed in practice?

If there is a failure at a pump connection, investigate the source of the vibration and the machine support instead of simply replacing the hose with one of the same length. Record whether the ends are fixed or moving, in which direction the vibration is dominant and whether the hose contacts other surfaces. Send measurement data obtained under safe conditions to the manufacturer; do not present a visually estimated vibration magnitude as a calculation input. For an alternative installation, evaluate the live length and the connection angle together. A guaranteed cycle life is meaningful only with clearly defined test conditions.

Original editorial recommendation; not a clause of a standard.

Frequently asked questions

Will a metal hose that passes the pressure test also withstand vibration?

This conclusion cannot be drawn from a single test. Vibration and fatigue conditions must be evaluated separately.

Source: S024, S039