Maximum Equivalent Derrick Load

on . Posted in Drilling Engineering

Maximum equivalent derrick load, abbreviated as MEDL, is the maximum load that a derrick or similar structure can safely handle during lifting or drilling operations.  This load includes all the dynamic and static forces acting on the derrick, such as the weight of the equipment being lifted, the tension in the drilling lines, and other operational loads.  Exceeding this load can lead to structural failure, posing significant risks to personnel, equipment, and the environment.

Calculating the MEDL involves a detailed analysis of the derrick's structural capacity and the loads it will encounter during operations.  This analysis is typically performed by engineers using specialized software and adhering to industry standards and guidelines.

Key Factors Affecting MEDL

  • Structural Design  -  The derrick's design and construction materials determine its load-bearing capacity.
  • Operational Loads  -  Includes the weight of the drill string, casing, and other equipment.
  • Dynamic Loads  -  Caused by movements such as hoisting, rotating, and drilling operations.
  • Environmental Loads  -  Wind, wave, and seismic forces that can affect offshore derricks.

Importance of MEDL

  • Safety  -  Prevents structural failure and accidents.
  • Efficiency  -  Ensures operations can proceed without interruption due to equipment failure.
  • Regulatory Compliance  -  Adhering to safety standards and regulations.


Maximum Equivalent Derrick Load formula

\( MEDL \;=\;  ( n + 4 \;/\; n )  \; F_h  \)     (maximum equivalent derrick load)

\( n \;=\;  4 \; F_h  \;/\;  MEDL - F_h   \)

\( F_h \;=\;  MEDL \; n  \;/\; n + 4  \)

Symbol English Metric
\( MEDL \) = maximum equivalent derrick load \(lbm\) \(kg\)
\( n \) = number of lines strung between crown block and traveling block \(dimensionless\) \(dimensionless\)
\( F_h \) = load hoisted \(lbm\) \(kg\)

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