Load Types & Key Considerations for Designing Static Equipment Foundations
Civil engineering structures are usually designed to sustain various types of loads with possible combinations of loads that can be acted upon during their lifetime. An accurate estimation of the structural analysis process comprises managing the magnitude of these loads. Further, there exists are local and international codes, as well as research reports and documents, that could assist design teams.
Further, categorized into four groups (dead, live, impact, and environmental), the structural loads can help build static equipment foundations. Though, there are two major factors are to be considered — economy and safety. However, if the loads are calculated and taken higher, the cost is affected. But, if the economy is considered and the loads are deemed lower, then safety is compromised! So the calculation of loads needs to be precise and in compliance with all the regulatory requirements. The different types of loads to be considered in the design of static equipment foundations include the following.
- Dead Load
Dead loads essentially consist of the equipment itself, permanent attachments, piping, cladding, platforms, ducting, and fireproofing. Some design engineers also consider the operating contents such as granular material, liquids, etc. as dead loads.
- Live Load
Live loads include the gravitational force exerted by movable tools, equipment, personnel, and other items that may be temporarily placed on the main component of the equipment. Live loads typically include lifted loads of davits, jib cranes, and booms that are attached directly to the foundation or the equipment.
- Operating Load
Operating loads include equipment weight, contents present while it is operating such as suspended solids, liquids, catalysts, and other products that are being processed.
- Wind Load
When designing static equipment foundations that are to be built in an area that falls under the judiciary of the local building code, design engineers rely on relevant provisions in that code to calculate the wind loads. Outside it, engineers use the wind load provisions made in ASCE Standard 7.
- Test Load
Pressure vessels, their skirts, and other supports are to be hydro-tested in their place on the foundation to ensure they meet the requirements of Section VIII of the ASME pressure vessel code and can withstand test loads.
- Maintenance & Repair Load
Common criteria are to design foundations for a longitudinal force which is a fraction of the tube bundle weight. Typically ranging from 0.5 to 1.5 times the weight of the bundle, this force acts at the focal point of an exchanger and is considered in combination with the dead load.
- Fluid Surge Load
Surge loads are essentially represented as a horizontal static force acting on the centroid of the contained fluid. The extent of this design force is usually taken as a fraction of the fluid below the normal operating liquid level.
- Erection Load
This load acts on the foundation during the erecting and installation of equipment. For instance, after a vertical vessel is installed, the refractory lining and heavy internals also act as a permanent dead load on the foundation.
- Buoyancy Load
A high groundwater table has a buoyant effect on the foundation and so, it is to be considered as a separate load. Design engineers treat it as an upward acting force. It may or may not act simultaneously under all load conditions.
- Miscellaneous Loads
Other load types that are defined under a separate load category include:
- Impact loads — The pressures exerted by davits, hoists, and cranes
- Blas loads — The pressures resulting from an explosion or accidental blast
- Ice loads — Live loads that may affect the design of operating platforms or support members that are connected to the equipment
- Electric loads — Often caused by sudden movements in the circuit breakers. While short circuit loads have minimal effect on foundations, in the case of direct transmission lines, they may have a considerable effect on the supporting structures.
How Civil And Structural Engineering Design Services Can Help
The foundation design of static equipment plays a vital role in manufacturing units and industrial processing facilities. Many engineers from different disciplines are engaged in the work of design, analysis, and erection of these foundations. Quite often, they work with little guidance from OEM specifications, national standards, and applicable codes. In the absence of a standard approach, they often rely on prior experience and judgment which can prove to be both costly and hazardous.
This is where the assistance of an external agency offering civil and structural engineering design services can help! They can bring to the table projected accuracy with strict adherence to industry standards. With the use of best-in-class software, they are fully equipped to design, detail, and analyze static equipment foundations across massive industrial infrastructures and processing facilities.
