A range of hydraulic cylinders and torque motors form an essential part of an innovative pipe handling system that is being widely used in the oil and gas sectors for clamping drill pipe connectors and safety equipment The ST-80 Iron Roughneck is a pipe handling system that is widely used in the offshore oil and gas sector. Designed by National Oilwell Varco, the ST-80 improves operator safety and efficiency by allowing tubular connections, including drill pipe and drill collars between 108mm and 216mm in diameter, to be remotely clamped, spun together and locked at torque values of up to 81.5kNm. The system allows this work to be carried out quickly and safely by a single operator. In addition, it is lightweight and compact, can be mounted on any rig floor close to the well centre and 'mousehole', where joints of pipe are temporarily stored. It minimises the need for awkward and potentially dangerous hanging cables, mast modifications and the overhead equipment that is often used in this industry. All movement and control functions are entirely hydraulic. These include the movement of the clamping and spinning head from its standby position to the drill pipe, and the accurate manipulation of the head, clamping jaws and tools so that all pipe joint connections can be made quickly and reliably without the need for manual intervention. The ST-80 incorporates specialised pipe location mechanisms ensuring pipes and joints are aligned correctly, with each pipe joint being spun into position and locked to the adjoining section. It can also be used to break pipe connections, with an operating torque of up to 108.5kNm. The system comprises four specially designed Parker Hannifin Roundline cylinders - two 8in clamp cylinders, and two 4.5in torque cylinders - plus a special harsh-environment 4in duplex extension cylinder and a 3 1/4in elevation tie-rod cylinder. The clamp and torque cylinders are of a semi-welded design and are extremely compact; all cylinders feature stainless steel piston rods, and are supplied complete with pipes, fittings and rod clevises.
During drilling operations, when a segment of pipe needs to be added or removed from the drill string, the ST-80 remotely clamps the pipe above and below the connection, with the action being controlled precisely by the clamp cylinders. When making up the pipe, the two Parker high torque, low speed hydraulic torque-motors spin the pipe sections together. The connection is then made to an operator-specified torque by the two torque cylinders, enabling the safe and efficient make-up and break-out of all tool joint connections in less than 19 seconds.
Parker torque-motors have a number of features that extend their operating life and ensure the compact design demanded by this type of application, including low-friction operation and a special shaft seal that eliminates the need for drain lines and check valves. A 'zero leak' commutator valve, moreover, guarantees the consistent volumetric efficiency of the machine, reducing energy consumption and ensuring a high degree of precision.
"The Parker hydraulic cylinders play an important role in the success of the ST-80 Iron Roughneck system," says Darrin Yenzer, of National Oilwell Varco. "They are exceptionally reliable, despite the extreme conditions in which they are put to work, yet deliver the levels of power that we require for the ST-80 to operate effectively. Perhaps as importantly, Parker provides an outstanding level of customer and technical support throughout the world, so we know that even if we do have a problem, we have access to local expertise and parts regardless of where our systems are being used".