Hultec South Africa Turner Seal
HULTEC SA presents a new generation of gaskets for PVC-O, PVC – U and PVC-M pipes.
This seal was designed to be installed in the pipe bell groove by hand with no special tools.
The seal combines rubber with a special engineering plastic to achieve an excellent solution for grooved bell end PVC pipes.
A typical lip seal profiled for insertion into the anger groove, containing plastic reinforcing with two basic structural elements.
- Several radial ribs to provide resistance against extruding out
- A circumferential band to join the ribs into a single part and provide seal stability in installation
Turner Design Information
|Ease of installation vs. risk of seal extrusion the main concern.
A relatively flexible seal may also be weak enough to extrude through the gap between spigot and socket mouth as would a fairly stiff seal with insufficient body to resist fluid pressure radially.(See illustration alongside)
This is addressed in the Turner Seal by structurally decoupling bending flexibility from radial stiffness resulting in the seal being:
- Flexible in bending for ease of installation
- Stiff in radial compression to resist fluid pressure
- Provided by strong plastic segments
- embedded in the rubber
- Continuous through the thickness of the seal so they act as blocks against seal extrusion
- Away from the lips so they don’t interfere with sealing
HOW RADIAL STIFFNESS WORKS AGAINST SEAL EXTRUSION
- When fluid pressure pushes the seal axially (1), the segments pick up a reaction (2) from the socket to hold the seal in place
- In order to develop this reaction (2), the segments must also sustain a radial reaction (3) from the spigot
- Solid contact with spigot and socket and large radial stiffness are essential
HOW SEALING IS ENSURED
- While the blocks take the axial load from fluid pressure and support the seal
- Rubber integrity is preserved at the sealing regions
- Adequate seal compression ensures optimal sealing performance
AND IT REALLY WORKS!
- Validated with nonlinear FEA and physical testing
- Test of pipes with integral socket using the Turner Seal.
- The test protocol from AS/NZS 4441
- 140 degrees F
- 261 psi
- 1000 hours
- Continuous blocks to hold the seal axially would be too stiff in bending
- This would make installation extremely difficult
- Radial stiffness is decoupled from bending stiffness by using discontinuous blocks
- Joined by a relatively thin band
- So the seal can bend easily for installation
- Thanks to the bending flexibility of the band and the rubber
- While radial stiffness of the blocks is preserved
- By effectively decoupling radial stiffness from bending stiffness
- The Turner seal is able to provide both ease of installation and maximum sealing performance