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PIGGY-BACK/ CLAMPS / COLLIERS

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Piggyback clamps and riser guides are used at regular intervals along a riser pipe in order to attach secondary pipes. They are made from an assembly of two-section polymer parts with cylindrical recesses to hold the two pipes together. The attachment is made using a “banding system” in order to attach the flange to the riser. The banding is made from carbon steel, stainless steel, super duplex, titanium or aramid fibre composite.

EXSTO can provide various systems :

  • Rubber clamp (photo 1)
  • Polyurethane clamp (photo 2)
  • Lightweight riser guides (PU) (photo 3)
  • Lightweight riser guides (steel) (photo 4)

The benefits of polyurethane piggybacks :

  • No corrosion
  • No anode torque between the two pipes
  • Thermal insulation
  • Limited vibrations between the two pipes
  • Very low relative weight in water (low density), easy to lay.
Photo 1
Photo 2
Photo 3

Design

Piggyback clamps/flanges are designed according to the customer’s specific requirements. The geometry of the collar is usually based upon the diameters of the riser and secondary pipes. A specific calculation is carried out in order to adapt each design to the specific loads in the working environment.

The calculation method for the collars and banding system is complemented by full-scale tests.

The main parameters used for the design of our clamp systems are as follows:

  • External diameter of secondary pipes and nature of coating
  • External diameter of riser pipes and nature of coating
  • Distance needed between tubes
  • Environmental load ratings (axial load, radial load and tangential load)
  • Lifespan of system
  • Operating temperature.
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EXSTO
ZI 55 av. de la Déportation
BP 280 - 26100 Romans Cedex
FRANCE
Tél. 33 (0)4 75 72 72 72 - Fax 33 (0)4 75 72 26 11
E-mail: info@exsto.com