Vol. 227 No. 12

Rig floor equipment

Automated pipe handler is certified

The automated safety concept of DrillTec’s vertical drilling rig, VDD 370.2, has been successfully certified by the German TÜV SÜD Industrie Service GmbH, according to the European safety standard EN 61508. EN 61508 is based on the international standard IEC 61508. Since this new rig technology was introduced by DrillTec and its parent company, Max Streicher, in 2005, it has set a high-mobility benchmark and is anchoring new standards in rig automation and functional safety.

During the rigs’ design phase, one objective was to make working on the rig as safe as possible by reducing direct manual operations wherever possible.

The VDD 370.2 rig’s pipe handler keeps the drilling crew’s work safe.

A glance at VDD370 reveals that pipe handling’s manual operation has been automated. A mechanical pipe handler performs this task: after the driller has given the instruction “fetch pipe,” the handler travels down to the pipe rack, picks up a pipe, which may be of any diameter. The tool travels back up the to the rig floor, then swings the pipe into a vertical position and remains in a waiting position until the driller gives the instruction “swing pipe into derrick,” ordering the handler to pass the pipe to the elevator.

The pipe handler makes life easier for the drilling crew and keeps work safe, fulfilling its requirement. While people can be trained to avoid accidents, automatic handling systems have to be designed inherently safe.

In order to achieve this, engineers have to apply and abide by the relevant engineering standards. There are several functional safety standards to be observed: EN 954-1 (machinery safety – safety-related parts of their control systems), soon to be replaced by EN 13849 and EN 61508 (functional safety of electrical/ electronic/ programmable electronic safety-related systems). Streicher’s engineers decided to apply both EN 954-1 and EN 61508. While EN 954-1 is still mandatory in the European Community to fulfill the Machinery Directive (98/37/EC). EN 61508 can be applied on a voluntary basis.

In contrast to EN 954-1, EN 61508 describes a methodology that is especially useful for PLC-controlled systems. A further advantage is that it is an internationally known standard, which will be the future base for new developed safety standards (such as EN 13849).

The applied methodology covers:

• Risk evaluation
• Definition of safety functions based on the risk evaluation and the assignment of SIL-levels (risk quantification)
• Formulation of protective safety functions
• Assessment of SIL – level protective function
• Acceptance test of the protective function
• Change management

Streicher implemented this comprehensive methodology together with DrillTec’s contractor under the supervision of TÜV SÜD Industrie Service.

The pipe handler is just one example of how the company applied this methodology. Another of the rig’s sophisticated features is the top drive’s dynamic anti-collision system. In April 2006, the rig began drilling operations on a geothermal well in Groß-Schönebeck. During the past six months, the rig’s safety concept has proven its effectiveness and robustness.