Ex-proof solution for hazardous applications

Electrohydraulics is the most widespread motion control technology in Oil & Gas applications such as top drives; skidding and chain jack hydraulic systems for offshore drilling platforms; hydraulic stabbing arms for drill string mating (Figure 1).

These applications demand advanced automation, high performances, steady reliability and operational cost reductions; in addition they have to provide high level of safety in any classified hazardous areas according to International safety prescriptions.

The whole range of Atos electrohydraulics components is available in ex-proof execution, certified to ATEX Directive 94/9/CE, Group II for surface applications, including ISO 6020-2 cylinders and fixed vane and variable displacement axial piston pumps (Figure 2).

Ex-proof valves ensure the best force/stroke performances with only 8 or 12 watt power supply and they are available in on-off and in proportional executions suitable for directional, pressure and flow control valves. They are certified according to ATEX, UL, IECEx or ROSTECHNADZOR norms and also to SIL 3 Safety Integrated Level according to IEC 61508 (Figure 4).

Low temperature version is designed to withstand ambient temperature down to -40?C, which is considered extreme borderline of hydraulic applications.

Thanks to its know-how in the oil & gas market, Scoda srl, the Atos system division, designs and realizes modern hydraulic power units tailored to the specific application and equipped with proper solutions to withstand aggressive environment, such as insulated cabinets, zero leakage connections and special painting treatments, homologated for naval and offshore applications (Figure 3).

Power units and systems are supplied with technical handbook, including the declaration of incorporation and assembly instructions plus ex-proof certifications, i.e., all the documents needed by the operator to speed up the commissioning procedures.

A prominent example of successful modern electrohydraulic application is the top drives drilling operation in the oil derrick. They are equipped with stabbing arms that automatically mate the drill string chain. These advanced automations are performed by the new Atos' servoproportionals equipped with ex-proof on board electronics (Figure 5). The integration of digital electronics to the ex-proof valves allows to manage standing alone closed loop controls and to limit the remote communication with the central control unit for command signals and diagnostic only, through CAN-Bus or PROFIBUS interfaces. (For further information: www.atos .com and www.scoda.it)