PVC Pipes - Expansion Loops

Temperature expansion and contraction in PVC piping systems

Temperature expansion and contraction in PVC piping systems can be compensated with

  • expansion loops consisting of pipes and 90o elbows
  • flexible bends
  • bellows and rubber expansion joints
  • piston type expansion joints

Expansion Loops

Expansion loops are made of standard pipes and elbows and can be produced on the site and adapted to the actual situation.

Pipes - temperature expansion loops

The length of leg A can be calculated as

A = 0.72 (D δl)1/2                                  (1)


A = length of leg A (ft)

D = nominal outside diameter (inches)

δl = thermal expansion of pipe (inches)

The length of leg B can be calculated as

B = 1.44 (D δl)1/2                                  (2)


B = length of leg B (ft)

Example - Expansion Loop

A 2" PVC Schedule 40 straight pipe with length 300 ft is installed at 75oF and operated at 120oF. The expansion coefficient of PVC is 28 10-6 in/in oF.

The expansion of the PVC pipe can be calculated as

δl = α Lo δt

    = (28 10-6 in/in oF) (300 ft) (12 in/ft) ((120 oF) - (75 oF))

    = 4.5 inches


δl = expansion (inch)

Lo = length of pipe (inch)

δt = temperature difference (oF)

α = linear expansion coefficient (inch/inch oF)

The length of leg A can be calculated:

A = 0.72 (D δl)1/2

    = 0.72 [(2.375 in) (4.5 in)]1/2

    = 2.4 ft

The length of leg B can be calculated:

B = 1.44 (D δl)1/2

    = 1.44 [(2.375 in) (4.5 in)]1/2

    = 4.7 ft

Related Topics

  • Temperature Expansion - Thermal expansion of pipes and tubes - stainless steel, carbon steel, copper, plastics and more

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