Determining how to operate a valve is as critical as the choice of valve design itself. We design and manufacture a range of hydraulic and pneumatic actuators as a package with our valves; by designing the valve and actuator collectively we can ensure that the full specification is upheld. Designs take into account size limitations, weight restrictions, pressures, closing times and torque or thrust requirements. Because we have our own in house design department we have been able to develop actuator solutions for speciality situations including High Integrity Pipelines Protection Systems (HIPPS) and Emergency Shutdown (ESD) applications, along with standard flow control applications..
We understand that sometimes end users will specify a preferred supplier of actuators. That’s why we work closely with all the recognised leading actuator suppliers, to ensure we provide the right actuator, for the right situation that will deliver the best and most efficient solution to our customers.
‘Actuation’ choice includes:
Manual hand wheel
Bare stem supply
For automatic safety systems or remote operation hydraulic actuators are commonly used for subsea and surface application. We provide hydraulic actuation for our linear or rotary operated valves (gate and ball respectively); utilising either our own proprietary design or a 3rd party if preferred. Hydraulic actuators can either be single acting spring return or double acting, depending on service requirements, and specified for on/off or failsafe function (open or close). A range of additional accessories can be fitted that allow remote valve monitoring, such as limit switches, position transmitters etc. Subsea actuators can be fitted with a mechanical ROV override to allow mechanical valve operation. Our surface and subsea solutions have proven in service reliability dating back to the 1980s.
For surface applications the use of pneumatic actuation provides a particularly cost effective alternative for remote operation. Standard pneumatic actuators are delivered using our own designs or through our third party suppliers for smaller bore, low pressure combinations. Once you move to combinations of larger bore and higher pressure the torque or thrust requirements are met by a patented motorised pneumatic actuator. End users are finding that this enabling technology is delivering solutions for stranded and brownfield reserves where new hydraulic system installations are prohibited by cost.
‘Dry’ electric actuation is relatively commonplace and solutions are delivered through one of our actuator partners. However with the growing interest in subsea ‘all electric’ systems we also offer our own range of subsea electric actuators which are often used as an alternative to hydraulics for deep-water or long tiebacks where distance is the critical factor. When considering subsea electric systems as a whole you can immediately start looking at capital savings for the new installation of composite umbilicals; potentially removing the heavy and expensive hydraulic lines. If faster closure times are required, electrics may also be the preferred choice as you remove the factor of displacement of the hydraulic fluid. Our subsea electric actuator is AC driven and available as fail safe or fail as is; depending on the application.
Drawing upon our extensive experience in valve and actuator technology we also deliver hydraulic and pneumatic control systems, for the operation of linear or rotary operated valves in hazardous environments. Sold as a package with valves, our control systems are specifically designed around the valve specification; conforming to international and industry recognised standards.
Hydraulic Control Panels
Hydraulic control panels can be designed and supplied specifically to operate with our proprietary actuated valves. For applications such as Emergency Shutdown, Shut Down, HIPPS and Riser valve the actuator is typically supplied with a hydraulic control panel, allowing each valve to be controlled separately. The panels can be designed to operate either single acting spring return or double acting actuators. For the valves used in safety systems, such as HIPPS, ESD, Riser configurations etc., an accumulation skid is usually required to provide enough stored pressurised hydraulic oil for 3 strokes of the valve if, for some reason, the hydraulic supply is not available. The accumulation is connected to the control panel ensuring the valve is still available for operation until the problem is fixed.
Penumatic Control Panels
Like the hydraulic control panel but generally uses low-pressure air (between 4 to 8 bar) as the actuating medium. Typically, pneumatic actuation is used for remote locations where instrument air is available or, in some cases, (high-pressure) process gas is use as the actuation medium. Pneumatic actuation was common on some of the older platforms and continues to be used when actuated valves are replaced or modifications made to the platform. If the pneumatically actuation is being used in a safety function then an air receiver would be installed to provide adequate stored pressurized air to operate the valve three times in the event of loss of instrument air supply.
Hydro-Pneumatic Control Panels
In some applications, a suitable electric solenoid operated hydraulic directional control valve is not available or the use of electric solenoids is not permitted. In these cases, the solenoid operated hydraulic valve is replaced with a pneumatic pilot operated hydraulic directional control valve.
Traditionally actuated valves are supplied with control panels, to control the valve function, comprising of valves, pressure gauges, filters etc. all connected together with fittings and pipe. This arrangement makes the panel large and prone to leakage from the connections. The alternative is a manifold block, using cartridge directional control valves. The actual block at the heart of the manifold is made from stainless steel. Into this block all of the connecting passages, valve housings, filter and gauge connections are machined. This eliminates the need for pipe and fittings and condenses the control functions into a compact unit with minimum number of leak paths. The assembled manifold block can easily be mounted on to the actuator. The manifold blocks can be configured to give the same functions as those listed for the control panel. The Manifold systems may be supplied as Pneumatic, Hydraulic or a combination of both (Hydro-Pneumatic).
Hydraulic Power Units
Our Hydraulic Power Units (HPUs) are for surface installations only and are typically used to provide hydraulic power for surface and subsea applications. The means of raising the pressure in the HPU can be determined by available utilities but can be electric powered from plant electric supply or solar panels, or through an air driven pump or manual hand pump. The HPU can be used for direct valve-actuator drive or for accumulator skid charging unit. With the exception of manual hand pumped units, the HPU can be fully automated negating the need for human intervention.
Accumulator skids provide an emergency power supply to operate actuated valves automatically or manually through the control panel after an event has cause power loss. Alternatively it will maintain the hydraulic pressure in the actuator for a long period after the HPU is shut down. Accumulator skids come in many different forms and is largely determined by the required volume of stored hydraulic fluid. The most common being the stand-alone rack, which normally comprises of accumulators and nitrogen backup bottles built into a frame. The accumulation volume is sized to store enough hydraulic volume under pressure to operate the valve for as many times as required.