Introduction to TLP's

A TLP stands for a Tension Leg Platform; an offshore platform used in the oil and gas industry. A TLP is a floating platform, which means the platform is not placed on the seabed.

The main principal of the TLP is to assure that the vertical forces acting on the platform are in balance, i.e. fixed and variable platform loads plus tendon tension are equal to its displacement. The Vertical Centre of Gravity (VCG) should be close to the platforms geometrical center. Positive displacement is obtained by locking the platforms draft below the fixed and variable payload displacement draft. This will result in an upward force applied to the tendons, thereby keeping them in constant tension.

As a consequence the vertical platform motions (heave) is almost eliminated, except for motions resulting from tendon elasticity and vertical motion as result of environmental introduced lateral platform motions. The tendons do allow a lateral motion of the platform as a result of wind, wave and current. This motion is similar to an inverted pendulum except for the fact that the displacement variation by pulling the hull down is giving a restoring force to the lateral movement. The tendon tension is set within predefined values, or window of operation. If the variable load of the platform exceeds these values by adding risers or drilling loads etc., the tendon pretension is adjusted by re-ballasting of the platform.  Consequently the hull is compartmented into void, machinery and ballast spaces. The TLP has a control system monitoring ballast and VCG. Seawater is used for ballast adjustment

 

You can design your own tension leg with help of the design program. For more information about the methodology behind the design, please click here.