Variable Spring Supports

Variable Spring Supports

• Purpose: Designed to compensate for small to medium vertical displacements of pipelines (typically up to 50–75 mm) caused by thermal expansion or contraction, while carrying the pipe load.

• Working principle: Contains a helical coil spring housed in a steel canister. The supporting force varies linearly with spring compression or extension.

• Design models (according to PIHASA):

  • CVC – displacement ≤ 12 mm

  • CV – 12 mm < Δy ≤ 25 mm

  • CVL – 25 mm < Δy ≤ 50 mm

  • CVLL – 50 mm < Δy ≤ 80 mm

• Allowable load variation: According to MSS SP-58, the load variation between cold (installation) and hot (operating) positions must not exceed 25%.

• Main components:

  • Coil spring (single or multiple)

  • Canister with corrosion protection

  • Adjustment & locking device (e.g., turnbuckle)

  • Travel scale and load indicator

  • Nameplate with design data

• Installation types:

  • As hangers (top-mounted, suspending the pipe)

  • As supports (bottom-mounted, pipe rests on the unit)
    Several types (A–H) are available depending on the mounting conditions.

• Commissioning requirements: Cold load must be preset; travel stops must be removed after installation; locking nuts properly tightened.

Advantages and Applications

• Ensures safe support of piping while allowing controlled vertical movements.

• Reduces stress on nozzles, flanges, and equipment.

• Used where vertical displacement is relatively small and load variation ≤ 25% — common in thermal power plants, chemical plants, refineries, and pipelines around turbines, pumps, and compressors.