Hydraulic innovations for drill pipe connectors

New hydraulic cylinders and torque motors create an innovative pipe handling system now widely used in the oil and gas sectors for clamping and torquing drill pipe connectors and safety equipment

A range of hydraulic cylinders and torque motors, specially developed and manufactured by Parker Hannifin, form an essential part of an innovative pipe handling system that is being widely used in the oil and gas sectors for clamping and torquing drill pipe connectors and safety equipment.

Called the ST-80 Iron Roughneck, the pipe handling system has been designed by National Oilwell Varco, one of the world's leading suppliers of high performance drilling and well servicing equipment for use in both on and offshore oil and gas applications.

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 high torques of up to 81,500Nm.

The system allows this work to be carried out quickly and safely by a single operator.

In addition, the ST-80 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, and minimises the need for the awkward and potentially dangerous hanging cables, mast modifications and overhead equipment that is often used.

All movement and control of each ST-80 Iron Roughneck is by means of hydraulics systems.

These move the clamping and spinning head out from its standby position to the drill pipe, and then accurately manipulate 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.

In addition, the ST-80 system can be used to break pipe connections, with an operating torque of up to 108,500Nm.

Each ST-80 Iron Roughneck system incorporates four specially developed Parker roundline cylinders - two 8'' clamp cylinders, and two 4.5'' torque cylinders.

Additionally, each ST-80 uses a special harsh-environment 4'' duplex extension cylinder and a 3.25'' elevation tie-rod cylinder.

The clamp and torque cylinders are extremely compact, with a semi-welded design, and 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 torquemotors spin the pipe sections together.

The connection is then made up to an operator-specified torque by the two torque cylinders, enabling drillers to be able safely and efficiently to make up and break out all tool joint connections in less than 19 seconds.

Parker torque motors have been specially developed to reduce friction and internal leakage to extend the life of the motor, and include a patented shaft seal that eliminates the need for drain lines and check valves, allowing the ST-80 to remain as compact and reliable as possible.

In addition, the zero leak commutator valve in each Parker torque motor guarantees the consistent volumetric efficiency of the machine, minimising wastage of energy and giving the ST-80 maximum precision, therefore allowing it to function effectively in the restricted spaces.

Darrin Yenzer, of National Oilwell Varco, explains: "The Parker hydraulic cylinders play an important role in the success of the ST-80 Iron Roughneck system.

They are exceptionally reliable, even in the extreme conditions experienced in many oil and gas field applications, 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 that 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".

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