Geothermal energy is a reliable source of renewable baseload power. At the same time, next-generation geothermal developments – including superhot and supercritical systems – expose wellhead equipment to operating conditions that go far beyond conventional standards.
Temperatures of up to 500°C (932°F), aggressive geothermal fluids, mineral scaling and repeated thermal cycling place exceptional stress on valves and wellhead components. Under these conditions, conventional valve concepts often reach their functional limits.
Hartmann Valves develops API 6A ball valve solutions specifically engineered for these extreme geothermal environments. The design is focused on maintaining operability, sealing integrity and long-term reliability even under the most demanding conditions.
Superhot geothermal wells are characterized by a combination of high temperatures, chemically aggressive fluids and pronounced scaling effects. Mineral deposits form inside valves and adjacent components, while continuous thermal cycling leads to changing mechanical loads within the system.
These conditions directly impact valve performance, particularly in applications where reliable operation after shut-in periods is required. Components must remain functional even after prolonged exposure to high temperatures and deposits, which places increased demands on both design and material selection.
Gate valves are widely used in wellhead systems. However, in superhot geothermal environments, their design reaches fundamental limits. At elevated temperatures, mineral scaling accumulates inside the valve, particularly in seat pockets, cavities and sealing areas.
These deposits directly affect the sliding movement of the gate. Over time, scaling can block the gate, prevent full closing or reopening and significantly increase operating torque. Thermal cycling further accelerates wear on sealing surfaces, leading to leakage and loss of sealing integrity. As a result, reliable operation cannot be ensured after shut-in periods, and high actuation forces often lead to operational failure.
In superhot geothermal applications, this behavior represents a critical reliability risk.
Hartmann Valves ball valves address these limitations through a fundamentally different design approach. Instead of a sliding gate, the valve uses a rotating element that operates within its own defined volume. This eliminates seat pockets and geometries where deposits typically accumulate and interfere with movement.
As a result, Hartmann Valves ball valves remain operable even in scaling environments where gate valves fail. Metal-to-metal sealing ensures reliable performance at high temperatures and in aggressive geothermal fluids. The design supports operation under full differential pressure, while robust actuation systems are capable of handling high torque and breaking through deposits if required.
This enables reliable switching and long-term operability under conditions where conventional gate valves reach their functional limits.
Video: Why Ball Valves instead of Gate Valves at the Wellhead?
The design of Hartmann Valves ball valves is optimized for high-temperature geothermal applications. By avoiding cavities and dead zones, the valve reduces deposit accumulation and maintains operability in scaling environments. Elastomer-free metal-to-metal sealing ensures stable performance up to 500°C and resistance to aggressive fluids. The design also accounts for thermal cycling, full differential pressure operation and high torque requirements, ensuring reliable switching even after extended service periods. A grease-free concept further enhances reliability.
Material concepts for high-temperature geothermal environments
Hartmann Valves ball valves can be manufactured using carbon steels, stainless steels and corrosion-resistant materials, including cladding solutions such as Inconel 625 or solid nickel-based alloys. Material selection is tailored to temperature, fluid composition, corrosion conditions and mechanical loads.
Applications in advanced geothermal systems
These ball valves are used in superhot and supercritical geothermal wells, enhanced geothermal systems (EGS) as well as deep and high-enthalpy applications.
With more than 80 years of experience in valve engineering and extensive wellhead application know-how, Hartmann combines high-temperature expertise with project-specific design capabilities.
The result is valve technology designed to replace conventional valve concepts in critical geothermal service and to support the development of next-generation geothermal energy systems.
Talk to us about your tailored superhot wellhead solution — solving challenges beyond the valve, including thermal expansion.
Or call us or send us an e-mail. We look forward to your inquiry. You can reach us by this phone number: +49 5085 9801 0.