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Oil Derricks
A derrick is a hoisting device used to raise, lower, and laterally move loads with a hoisting mechanism using ropes, where the hoisting engine is not an integral part of the machine. Derricks differ from cranes in that hoisting engines used for cranes are considered integral components.[1]

Derricks are used in a wide variety of industries, including construction, oil refining, and telecommunications.

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[edit] History

The term derrick is attributed to an executioner named Thomas Derrick. Derrick, who personally executed over 3,000 people, invented a gallows with a supportive structure featuring a movable boom and pulley system in the late 1500’s. The term derrick became used to describe all supportive structures resembling his innovation.[2]

[edit] Types

[edit] A-frame derrick

An A-frame derrick has a frame which resembles an “A” shape. The boom is hinged upon a horizontal beam near the bottom of the frame. Guy wires run from the top of the boom to the top of the frame, and also from the top of the frame to anchor points on the ground.[3]

[edit] Basket derrick

A basket derrick has a mast suspended within an assembly of supporting posts with guy wires running from each post to the mast. Basket derricks don’t use a boom, they use a hoist instead. By altering the length of the guy wires, the mast can be manoeuvred.[4]

[edit] Breast derrick

A breast derrick is composed of a rectangular frame which narrows at the top and has a hoist near the bottom. The hoist is fed into a pulley at the top of the frame. Guy wires run from the top of the frame to anchor points on the ground, which allow the derrick to lean forward.[5]

[edit] Chicago boom derrick

A Chicago boom derrick has a boom which is placed in a socket on an exterior supporting column of a building. A series of guy wires are anchored to other spots on the building’s exterior, and are threaded through pulleys on the boom. By adjusting the length of the guy wires, the mast can be manoeuvred.[6]

[edit] Floating derrick

A floating derrick is a general term used to describe any derrick used on water. Some of the uses of floating derricks include salvaging vessels that have sunk, dredging waterways, pipe-laying and providing a supporting structure for offshore drilling equipment.[7][8]

[edit] Gin pole derrick

A gin pole derrick does not have a boom. The mast is supported by a series of guy wires, which are anchored above the mast to permit the mast to rotate in any direction. A hoist lifts from the top of the mast.[9]

[edit] Guy derrick

A guy derrick has a mast, which supported by a series of guy wires anchored to the ground. The boom is attached to the mast at an angle. The mast is able to rotate, and as it does, the boom rotates too. A hoist is at the end of the boom.[10]

[edit] Stiff leg derrick

A stiff leg derrick is very similar to a guy derrick, except it uses stiff legs instead of supportive guy wires to support the mast.[11]

[edit] References

  1. Shapiro, Howard I., Shapiro, Jay P., Shapiro, Lawrence K. Cranes and Derricks. McGraw-Hill: 2000.
  2. What is an Oil Derrick?. WiseGeek.com [October 19, 2009].
  3. Definitions. Washington State Legislature [October 19, 2009].
  4. Definitions. Washington State Legislature [October 19, 2009].
  5. Definitions. Washington State Legislature [October 19, 2009].
  6. Definitions. Washington State Legislature [October 19, 2009].
  7. Definitions. Washington State Legislature [October 19, 2009].
  8. Wing, John F., Walton, S. Lynn. Defense Utility of Commercial Vessels and Craft. National Research Council Washington DC Maritime Transportaion Research Board: 1980.
  9. Definitions. Washington State Legislature [October 19, 2009].
  10. Definitions. Washington State Legislature [October 19, 2009].
  11. Definitions. Washington State Legislature [October 19, 2009].