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JP121 Lateral Expansion Joint Flanged

Now Available With Precision Fit Flexible Lagging Jackets To Suit JP121.


Double tied lateral expansion joint consisting of two multi – ply stainless steel grade 321 bellows, centre tube and mating surfaces (stainless steel wetted parts) fitted with zinc plated carbon steel van stone oval flanges and tie bar assembly drilled to BS4504 PN16.


Stourflex double tied expansion joints are generally installed in changes in pipework direction and will accommodate lateral movement in one or two planes. This movement occurs due to thermal expansion or contraction or building settlement. They are suitable for use on HWS, L.T.H.W ,M.T.H.W. H.T.H.W., Steam and other hot liquids and gases.

  • Maximum working temperature 300ºC.
  • Maximum working pressure 16 bar at 120ºC.
  • Stourflex lateral expansion joints should not be used at both their maximum working temperature and pressure respectively.
  • Maximum test pressure = 1.5 x working pressure or 1.5 x flange rating whichever the lower.


Stourflex are now able to offer a tailor made flexible lagging jacket to help reduce heat losses on LTHW systems and heat gains & condensation on CHW systems. Please ask for pricing or more information.

Download data sheet
JP121 expansion joint

our technical specifications

Our JP121 Lateral Expansion Joint Flanged specifications

Part numberN.B. (mm)Total movement (+/-)Overall length (mm)Lateral spring rate (N/mm)Working pressure @120°C (bar)Cold test pressure (bar)
JP121-40-1640500360Available upon request1624
JP121-50-165050385Available upon request1624
JP121-65-166550385Available upon request1624
JP121-80-168050430Available upon request1624
JP121-100-1610050440Available upon request1624
JP121-125-1612550520Available upon request1624
JP121-150-1615050530Available upon request1624
JP121-200-1620050620Available upon request1624
JP121-250-1625050620Available upon request1624
JP121-300-1630050720Available upon request1624

At temperatures above 120°C working pressure and movement will be reduced.

Where service conditions above 120ºC and 16bar exist or where additional movement is required non standard variations of the Type JP121 are available on request.

Alternative flange materials and specifications are available on request.

Stourflex lateral expansion joints are supplied at their maximum overall length and must not be extended. Lateral expansion joints must be securely anchored and adequately guided to ensure their correct performance. Omitting anchors and guides may result in failure of the system.

All Stourflex products should be installed in accordance with our fitting instructions.

Download data sheet