Process skid packages are critical components of industrial facilities whose design and fabrication requires careful consideration of a number of factors in order to operate safely and reliably. Apart from having to accommodate its own weight, a skid package must also be designed to handle the dynamic nature of the equipment on it (compressors, turbines, motors, etc.), as well as stresses that are applied during lifting and transportation.
In general, there are three types of loads that can act on equipment skids. They include:
Static Loads – Static loads may be temporary or permanent and can cause deflection and buckling of skid package members over time. Specific types of static loads include but are not limited to, dead loads from the weight of equipment, thermal loads brought about by changes in temperature and pressure, drive torque of rotating equipment, and lifting or dragging the skid.
Quasi-static Loads – Quasi-static loads are periodic, often occurring at a relative frequency that is not high enough to bring the inertia effects of the structure into play. Fatigue analysis is often required when designing packages that will be subjected to regular quasi-static loading. Types of quasi-static loads include loads caused by loadout, transportation, and installation, as well as loads caused by environmental factors, such as wind, currents, waves, earthquakes, ice, and hydrostatic pressure.
Dynamic Loads – With dynamic loads, the major cause of concern for designers is resonance. This can be caused by wave or wind action, but machinery is most likely to cause resonance. Dynamic forces are usually harmonic, occurring at definite multiples of machinery run speed. In machinery with variable speed drives, force frequency will follow the speed of the equipment. In rotating equipment like motors, compressors and pumps, the dynamic forces tend to be low.
All three types of loads must be considered when designing skid packages. Contact an experienced manufacturer to design and fabricate a safe and reliable skid package for your application.