Plant and equipment loads

Inherently unbalanced equipment mounted on flexible supports, such as vibrating screens mounted on springs, often operate at above 

High-speed equipment, such as fans, may develop high, unbalanced loads in the dirty condition (when process material builds up on the impeller). There should be a clear understanding of how this will be limited, for example by the provision of a vibration sensor coupled to an alarm or cutout device. Alternatively, it may be better to put the equipment at ground level - a decision which should obviously be taken at the conceptual design stage. 

Special care is needed to deal with equipment in which the driver and driven equipment are separately mounted. Usually the relative alignment must be critically maintained a flexible coupling sometimes accommodates only fractions of a millimetre without unacceptable wear. A standard electric motor will develop more than double its full-load torque at start-up, and this is usually a suddenly applied load, requiring an impact factor. 

Normal piping and ducting expansion joints transmit no axial loads. Thus if there is pressure (or vacuum) in the pipe the ends will be forced apart (together) and these forces have to be accommodated by the supporting structure. 

When overhead travelling cranes are installed in a building, special standards of alignment and rigidity are required. These should be specified by the mechanical engineer in conjunction with the crane specification, or specified by the crane supplier. 

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