Flexible Connections

Flexible Connections are required on fittings installed on the lower 1/3 of the tank sidewall to allow the tank to expand and contract and to protect the tank from pump vibrations. This can be achieved using the Flexible Connection or Flexible Hose.

Install flexible connections in accordance with the specific manufacturer's installation guidelines:

  • The "breech opening" in the piping for the flexible connections should be within 1/8-in of the relaxed length of the flexible connection. 
  • Flexible connections are not to be used for correcting piping misalignment. The flexible connection and mating flanges must be installed in a centered and neutral position. 
  • Attach only FULL FACE flanges to the flexible connection. They are not designed to attach directly to the tank wall. 
  • Ensure adequate clearance between bolt ends for full use of flexible connections. 
  • Torque to 20 ft. lbs using crisscrossing tightening pattern. 
  • Provide pipe support adjacent to the flexible connection. 

Flexible Connection Minimum Specifications: 

  • Axial Compression ≥ 0.67"
  • Axial Extension ≥ 0.67"
  • Lateral Deflection ≥ 0.51"
  • Angular Deflection ≥ 14°
  • Torsional Rotation ≥ 4°

Installation of flexible hose connections: 

  • Use thread sealant for pipe thread preparation. 
  • Support hose adequately but do not restrict its ability to move in horizontal directions. 



Proper Installation of Pipe Supports

Pipe supports positioned CORRECTLY: pipe support must be placed after the flexible connection to allow the tank to properly expand and contract. 

Pipe supports positioned INCORRECTLY: pipe support incorrectly placed before the flexible connection does not allow the tank to properly expand and contract, which can cause the piping or tank to crack over time. 

Proper Installation of Flexijoints

Flexible connections aligned CORRECTLY: pipe system with the Flexijoint is aligned in a straight manner, which allows for proper expansion and contraction of the two connecting tanks. 

Flexible connections aligned INCORRECTLY: the Flexijoint should not be used to accomodate misaligned piping. This will limit the ability of the Flexijoint to function correctly and possibly damage the joint itself. 

Have additional questions about Flexible Connections? Contact a chemical storage tank system expert today. 

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