What is a Wellhead?

With the demand for renewable energy continuing to increase, Geothermal power is quickly becoming a focal point in generation company portfolios. Producing about one-sixth of the carbon dioxide emitted by a clean natural gas-fueled plant, geothermal energy production ensures a sharp reduction in greenhouse gas emissions. There are three types of geothermal power plant designs – dry steam, flash and binary cycles.

Regardless of plant design, everything begins at the wellhead. Often separated from the plant by significant distances, production wells include Emergency Shutoff Valves (ESVs) and flow control valves – both of which play key roles in the process. Therefore, they need to function reliably to ensure no interruption of the flow of steam or brine to the plant.


A Geothermal power plant in New Zealand recently experienced unstable control of their production wellhead valves and sought out REXA for a solution. The previously-installed pneumatic actuators were not able to accurately control the valves during both start-up and normal operation. This caused large pressure swings in the process and immense water hammer down the line. Consequently, this resulted in bending pipework and broken pipe brackets – causing unnecessary expenses for repairs.

Leaks within the valves’ stem packing required tightening, making it even harder for the pneumatics to overcome the packing stiction to control the valves. This stiction caused the water hammer as the pneumatic actuator built up pressure in the piston and dramatically jumped up once it overcame the stiction.

REXA Wellhead Valves Solution

This plant needed a solution and they needed it quickly. Luckily, they already had REXA Rotary Actuators installed on their Emergency Dump Valves.

The Rotary actuators were used to overcome brine build-up on the disc of the butterfly valves. This helped assure them REXA could overcome any stiction problems on the production wellhead valves. For this reason, and the fact the electro-hydraulic set up of REXA Actuators provides more accurate and reliable control than pneumatics, this plant successfully installed three REXA XPac Linear actuators.

Hover over the before image to see the after!

Before Pneumatic on Wellhead ValveAfter REXA Actuator on Wellhead Valve

Since the initial installation in March 2019, our customer has greatly improved their control of the production wellhead valves with no more large swings in the process. Water hammer down the line is now a thing of the past!

“Upgrading from pneumatic actuators to REXA Electraulic™ actuators provided a much-needed solution allowing us to achieve better control of our wellhead valves.” – Plant Manager

To learn more about our solution for accurate Well Head control, read our full Application Spotlight here. Experiencing problems with your production wellhead valves? Visit our contact page and fill out our form to get in touch with one of our product experts!