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D.A.R.T. Masts

Dart Mast

The design of land drilling rigs over the past few decades has yielded significant improvements in personnel safety, and improved operations. The introduction of hydraulic cylinders for the raising and lowering of masts has reduced the catastrophic failures by eliminating reliance on cables during these operations. While this improvement is notable there continues to be serious potential for failure due to induced tension at high stress areas in the mast legs and supporting members.

Modern land rig masts are still constructed as a beam leg, angle leg, or tubular steel legged mast, all of which have advantages and disadvantages. The common disadvantage of these designs is the rig up and raising of the mast structure. These operations place rig personnel and equipment at its highest risk for damage and personnel injury or death. Raising and lowering operations take a significant amount of planning, inspection, and supervision to minimize these risks. Our goal when designing a new breed of rig that focuses on minimizing or eliminating these inherent problems has led to the development of the D.A.R.T. mast system.

Design Features of NRG Manufacturing D.A.R.T. Mast System

At a glance the D.A.R.T. mast system may resemble other mast systems in the field today. A closer review of this technology will reveal significant improvements in personnel safety, reduced fatigue on the mast components, reduced rig up and rig down times, and a reduced life cycle cost for the mast system. Below is detailed information supporting the above statements.

dart mast design dart mast construction

Rig Up

During the raising of any mast there are forces induced throughout the structure that have been accounted for during preconstruction design. Although mast systems are designed to handle these forces under normal operating conditions with industry safety factors applied, it is not at all uncommon for the conditions and parameters to be exceeded. In the real world, raising and lowering of the mast is completed in less than optimal environmental or operational conditions. These facts at times may risk or hinder personnel in completing these operations safely. No system is designed to be fool proof. Design parameters such as size, weight and cost force calculated balances to produce systems that customers want. We emphasized safety while designing the D.A.R.T. mast while maintaining a high level of functionality.

Another factor that plays a major role in mast raising and lowering accidents is the training and supervision of the crews. In today’s economy and the cyclic nature of the oil industry there is a significant gap in operational knowledge in the field. Rig designers have to take into account this one factor and try to design their system to reduce this as much as possible. NRG Manufacturing DART system has eliminated the one step that sets up catastrophic mast failures. We achieved this by eliminating the requirement for the mast to be preassembled horizontally and then raised to the vertical operating position. While there are other systems that also do this; they do not have the safety features that we have incorporated into the DART mast system.

mast design guides

Easily upgradeable
Flexible mast shoe foot prints allowing the D.A.R.T. mast system to adapt to existing client’s substructures.
Mast width dimensions are easily changed by replacing the boot’s rear structure.

The DART system is assembled without operational personnel handling the sections. The DART mast system is captured and guided on all four corners of the mast within the lower boot assembly for the duration of raising and lowering the individual sections. The four guide system translates into a smoother more controlled raising and lowering operations. The erection is driven by two hydraulic cylinders that are integral in the mast boot section. Both cylinders are also guided to prevent side loading. The entire system is operated via remote control that allows the operator move around the rig floor to better see the operation making it safer for the entire crew. Below is a picture showing the guides in the boot section. These guides capture not only the rear of the mast but the front of the mast. This feature will allow the mast to elevate and lower smoother during rig up and rig down operations. These guides have replaceable high load carrying capacity plastic surface guides that require no lubrication.

Below is a picture of the mast raising cylinder and guide system. The cylinders are mounted into each side of the boot assembly thus protecting the cylinders from damage. During the rig up and rig down process of the rig the cylinders and guides ship as a single piece. This reduces the chances of damaging the cylinders during transit and handling. The cylinders are mounted into the boot section so the cylinder is free to move in the vertical &horizontal plane. This keeps the cylinder from seeing side loads during rig up and rig down operations. This greatly reduces the size of the cylinder as the rod will not be subjected to buckling forces.

dart mast guide

Mast cylinders and the guides are mounted in the boot assembly.
Each boot section ships with the cylinders thus protecting the cylinders from transit and handling damage.
Cylinder guide system incorporated into the boot structure.