Selection of right spring hangers for isolation of mechanical equipment

Spring hanger Isolators are vibration dampers that consist of high deflection, free-standing, unhoused, large diameter and laterally stable steel springs that are assembled into an upper load plate and leveling assembly. For assured stability, the spring hangers have lateral spring stiffness that are greater than 1.0 times the rated vertical stiffness. These spring isolation hanger are designed to provide a minimum of 50% overload capacity. Also they are polyester powder coated for a lasting durability. Spring hanger isolators are available in higher deflection and greater load capacities for better isolation.They are highly effective for control of both high and low frequency vibration produced by various applications like reciprocating air or refrigeration compressors, pumps, packaged air handling and air conditioning equipment, centrifugal and axial fans, internal combustion engines, etc.

Spring hangers are an integrated part of the Piping Industry. The use of spring hangers in supporting pipe weights is a known phenomenon to every piping engineer. When rigid supports are not taking load due to the thermal movement or rigid supports are effecting the equipment connection piping engineer’s advice for the use of a pipe spring hanger to share some of the loads and to keep the piping system safe. Selecting an appropriate type of hanger to support any given application is governed by the individual piping configuration and job requirements. In general there are two main types of spring hangers.

a) Variable Spring Hanger wherein the Loads vary throughout its operating range.

b) Constant Spring hanger: wherein the Load remains constant throughout its operating range.

Constant support hangers are used to support structures and components like pipes, vessels and other such applications that experience vertical movement. These hangers provide support at critical locations of in structure in a way that the temperature dependent deformation of the structure does not produce any excess stress to the structural system. A constant support isolation hanger provides a constant force on the structure so that it does not experience any extra resisting forces from the support. Constant resistance to a moving load is achieved by balancing the moment of the moving structure produced by the force of a compressing/decompressing spring from a common pivot point.In designing a constant support hanger, minimum variation of the load is optimized via selecting the proper arm lengths of the external force, the spring force, and the spring constant for a given total displacement of the external load.

Variable Spring Hangers are used if vertical movement of the piping aren’t restricted by rigid hangers. The unique construction of this equipment is particularly suitable in severe corrosive conditions. Special Variable Hangers or Supports are designed to suit customer’s specific requirements. The criteria for selecting Variable Spring Hangers are based on three conditions and they are as follows

  • Based on the load and displacement for which the support has to cater
  • Depending on whether the physical arrangement of the support be it top hanging or base mounted.
  • Depending on the allowable deviation in load that the pipe can sustain.

 

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