Rotork GP/GH Scotch Yoke Pneumatic and Hydraulic Valve Actuator

Overview

The Rotork GP/GH range is Rotork’s heavy-duty scotch-yoke actuator series for large quarter-turn valves. The GP is the pneumatic member and the GH the hydraulic member, and both are designed to operate ball, butterfly and plug valves in on/off or modulating duty. The design has been used in thousands of installations worldwide, and it covers a torque range that extends to 600,000 Nm, which makes it relevant to pipeline, terminal and power station valves that smaller actuators cannot drive.

Seven Star LLC supplies the Rotork GP/GH through its instrumentation division in Muscat to contractors, valve manufacturers and operators in the Sultanate of Oman and the GCC. We study the valve torque curve, spring direction, supply pressure and temperature class against the Rotork brochure and dimension data, then provide a quotation with accessories if required.

Operating Principle

In the Rotork GP/GH the cylinder pressure acts on a piston, and the piston rod pushes a yoke in a sliding block. The geometry converts linear piston movement into a 90 degree rotation. Rotork supplies two torque output profiles. The classic symmetric yoke delivers peak torque at both ends of the stroke, and the canted yoke, a Rotork design innovation, delivers peak torque at only one end. A canted arrangement can reduce the size, weight and cost of an actuator on a valve whose torque demand matches its curve.

Spring-return versions use a spring module on the centre body. Pressure compresses the spring during the powered stroke, and the spring returns the valve to its fail position if the supply is lost. The design places a pressure relief valve in the centre body and allows the spring module to be removed only after the spring force has been released, which protects maintenance staff.

Engineering Design of the Rotork GP/GH

The Rotork GP/GH uses a totally enclosed weatherproof centre body fabricated from carbon steel or ductile iron, depending on size. The scotch-yoke mechanism is supported by a chromium-plated alloy steel thrust bar that carries the transverse loads, and the cylinders are carbon steel with electroless nickel plating, with chromium-plated piston rods. Bronze sliding blocks and a floating piston seal reduce friction and avoid stick-slip even after long periods without movement.

O-ring sealing provides protection certified to IP66M and IP67M. Rotork lists operating pressure of up to 12 bar for pneumatic units and up to 210 bar for hydraulic units, and temperature ranges from -30 to +100 °C standard to -60 °C extreme low, with higher temperature on request. Options include manual override solutions, stainless steel cylinders and tie rods, custom paint and Fibreglide yoke bushings for modulating duty. The brochure lists ATEX, IECEx, PED and EAC certification of the actuators.

Key Features

The Rotork GP/GH range gives the strength and durability that heavy valves need. Key features of the Rotork GP/GH include:

• Pneumatic (GP) and hydraulic (GH) versions on one proven scotch-yoke platform for ball, butterfly and plug valves.
• Torque output up to 600,000 Nm (5.3 million lbf.in), with operating pressures up to 12 bar pneumatic and 210 bar hydraulic.
• Choice of symmetric or canted yoke to match the valve torque curve and reduce actuator size and weight.
• Spring-return fail-safe modules that can be arranged to operate in either direction.
• Centre body with pressure relief valve and a spring module that can be removed only when spring force is released.
• Electroless nickel-plated cylinders and chromium-plated piston rods for low friction and long life.
• Optional Fibreglide yoke bushing for modulating duty, stainless steel cylinders and tie rods, and manual override solutions.
• IP66M and IP67M sealing, and certification to ATEX, IECEx, PED and EAC directives.

Industrial Applications

The Rotork GP/GH is selected for large ball and plug valves on crude and gas pipelines, ESD and blowdown valves, tank farm butterfly valves, and cooling-water butterfly valves in power and desalination plants. In Oman, long-distance export pipelines and gas gathering systems are typical places for large pneumatic or hydraulic quarter-turn actuators, and the same actuators appear on metering stations and terminal manifolds. Valve makers commonly mount the Rotork GP/GH on large butterfly valves such as the XOMOX Type 800, then add a Parker Lucifer NAMUR solenoid for control.

Seven Star LLC supplies the Rotork GP/GH to projects in Sohar, Duqm and Salalah and across the GCC, with selected accessories and engineering support in Muscat. For safety applications where a self-contained electrical supply is preferred, we can also quote electro-hydraulic alternatives such as the Biffi RPD. Clients can compare the options and select the drive that suits their plant standard.

Technical Specifications

The table gives the main data for the Rotork GP/GH range from the Rotork brochure. Torque tables and dimension data are published for each size in separate documents.

Request a Quote for Rotork GP/GH

Send your RFQ for the Rotork GP/GH to Seven Star LLC with the valve size and torque curve, supply medium and pressure, fail direction, ambient temperature and area classification. Our instrumentation division in Muscat will propose the actuator, confirm the yoke type and fail module, and provide the Rotork brochure with the offer. Seven Star LLC supplies genuine Rotork equipment with warranty and local engineering support across Oman and the GCC, so contact us today to request the Rotork GP/GH.