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What is Tendon on a Tension Leg Platform?

asked Oct 23, 2014 in Drilling by franchaze (1,150 points)

4 Answers

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answered Oct 23, 2014 by antonjoh (2,870 points)
Tendons are vertical mooring lines of a floating platform. A Tension Leg Platform’s Tension Legs are comprised of one or more Tendons per Leg. An example of that would be a conventional column hull, 4 Leg configuration, with 2 Tendons per Leg.

The Tendons hold the platform deeper than needed just to float.  The excess buoyancy puts tension in the tendons and keeps the platform from moving around as much.

The Tendons also hold the platform level as it offsets, limit yaw and prevent pitch, roll and heave.
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answered Oct 23, 2014 by esjensen (2,720 points)

The followings are the Tendon System Characteristics and Features (Design Requirements):

  • Don’t break (structural strength, fatigue resistance, fracture resistance, toughness)
  • Don’t come apart or accidentally disconnect (mechanical strength and dependability)
  • Don’t stretch too much (stiffness, heave natural period)
  • Don’t weigh too much (self-weight load on floating platform)
  • Don’t corrode away in the seawater (corrosion characteristics, ability to be protected from corrosion)
  • Don’t rot away or change properties over time (materials in seawater)
  • Don’t cost too much (material and fabrication costs)
  • Don’t be too difficult or expensive to install (configuration)
  • Don’t require frequent (or any) replacement for 20, 25, 30 or more years in service
  • Don’t have to stop oil production to inspect, fix or replace it
  • Don’t be impossible or prohibitively expensive to replace if It really does have to replace it
  • Don’t go slack (carry a high pre-tension load)
  • DO accommodate rotation at the connections with the platform and with the seabed foundation with minimal stress (flexibility at top and bottom connections)
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answered Oct 23, 2014 by judyp (2,700 points)

Here are some materials that are typically considered to make a Tendon:

  • Synthetic mooring rope like used on ship moorings?
  • Wire rope as used for anchor lines?
  • Anchor chain?
  • Drill string tubulars?
  • Big steel bars?
  • Structural beams?
  • Structural pipe?
  • Carbon fiber rope, rods, pipe?
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answered Oct 24, 2014 by Normandy (21,040 points)

Hurricane Rita wiped out Typhoon TLP. Sounds kind of funny but it show the tendons are still in place even though the TLP is gone.

Before and After Rita.