A Computer Controled System For Automated Racking Of Pipe of Drilling Vessels
Authors: Ward Donald H. , Thale James S. , Tomaskek James H. , Howard J.A. , Sheldon L.B. 
Published: October 2008

ABSTRACT
Hydraulically powered pipe-handling systems have allowed offshore drilling operations to be conducted with greater speed and safety and have permitted tripping pipe under adverse weather conditions. Computer control provides an additional advance, eliminating the need for a man in the derrick, and putting the racker operation under push button control of the driller. Such a system has been developed and is installed on the BJ test derrick in Houston.
In this system a computer is used to control the operation of hydraulically powered racker arms as well as the various auxiliary functions involved in vertical pipe-racking operations. The equipment functions upon initiation by the driller so that, in coming out of the hole, the two racker arms move to the well centerline, grasp the pipe, carry the stand into the proper rack position, lower it onto the setback and lock it in place. The process is reversed for going into the hole.
The computer keeps track of all pipe lengths in the well; the length of pipe in the hole at any time is presented on a cathode ray tube display. In addition, the total well depth is given. Other pertinent data related to the drill string makeup and the racking operation are presented for the driller's information.
The automated system is described including the input-output signals, the computer, the racker servo system, and the lifting head control. Tests indicate that the computer controlled racker operation is smooth and accurate and provides reduced operating times as compared to manual control.

INTRODUCTION
The application of computer control to the Byron Jackson vertical pipe-racking system is the latest advance in the development of automated pipe-handling equipment for offshore drilling vessels. The manually operated hydraulically powered system has allowed more efficient drilling operations by increasing the ability of the rig to operate in bad weather, increasing crew safety and reducing the trip time. Now, computer control provides the means for taking the man out of the derrick. In addition, faster operating times can be achieved with substantial reduction in-operator fatigue. It will provide the driller with a continuous record of the pipe in the hole, the hole depth, and bit depth as well as the number of stands in the rack.
The computer controlled power racking system has been designed as an integrated system providing all the sensors and control devices necessary for safe and efficient automatic operation and yet retaining the full capability of manual control.
Thus, should it be necessary to perform maintenance on the automatic controls, the racker system may still be operated in a manual fashion.

DISCUSSION

1. Power Racking System
A photograph of the computer controlled test rig is shown in Figure 1. The small building on the rig floor houses the computer and auxiliary control equipment.
The power racking system is shown in simplified form in Figure 2.
The manually controlled power racking system includes the following principal components.