Steam Turbine High-Pressure Main Steam Valve Stem

The high-pressure main steam valve stem serves as the "transmission core" of the turbine's steam control system, responsible for accurately translating electrical or hydraulic control commands from the turbine control unit into mechanical motion to drive the valve disc. During turbine startup, it controls the valve disc to open gradually, avoiding sudden steam impact on turbine blades and ensuring smooth speed rise. In normal operation, it adjusts the valve disc's opening in real time according to load changes—maintaining stable steam flow into the turbine and matching the unit's output with grid demands. It directly bears continuous high-pressure steam impact and cyclic thermal stress caused by temperature fluctuations. In emergency scenarios such as turbine overspeed or system failure, it must respond within 0.3 seconds to drive the valve disc to fully close, cutting off the steam supply immediately to prevent equipment damage or safety accidents. Poor performance of the regulating stem—such as motion lag or structural deformation—can lead to unstable turbine speed, delayed load adjustment, or failure to shut down in emergencies, seriously threatening the unit's safety and efficiency.

Structural Design

Our turbine high-pressure main steam valve regulating stem adopts an integrated one-piece forging structure, manufactured from high-strength heat-resistant alloy steel (20Cr1Mo1V or 2Cr12NiMo1W1V). This forging process eliminates internal defects like pores or cracks in the material, enhancing the stem's overall tensile strength and fatigue resistance to withstand long-term cyclic loads. The entire rod surface undergoes precision grinding and polishing, achieving a straightness tolerance of less than 0.05 mm/m and a surface finish of Ra 0.8 μm—reducing friction with the valve cover's guide sleeve and ensuring smooth axial movement without jamming.

One end of the stem is processed with a high-precision threaded or flange connection to match the turbine's oil actuator or electric regulating mechanism, ensuring zero lag in force transmission. The other end is designed with a rigid positioning structure (such as a taper fit or keyway connection) to fasten tightly with the valve disc, preventing relative displacement during motion that could affect control accuracy. The middle section of the rod is equipped with a dedicated guide section, which has a fit clearance of 0.02–0.05 mm with the guide sleeve in the valve cover—limiting radial shaking of the stem and avoiding wear on the valve disc's sealing surface caused by eccentricity.

Multiple annular sealing grooves are machined on the stem's outer surface (near the valve cover end), designed to match with high-temperature-resistant packing seals (such as graphite or metal wire braided packing). These grooves increase the steam leakage path, reducing the leakage rate of high-pressure steam along the stem to less than 0.05% of the rated flow—minimizing energy loss and preventing corrosion of the stem's outer surface by leaked steam.

Custom Fabrication per Drawings

We provide precision manufacturing of turbine high-pressure main steam valve regulating stems strictly in accordance with your technical drawings and industry standards. Our production process adheres to strict dimensional tolerances—with key sections like the guide section and connection ends controlled within ±0.01 mm.

Secure Turbine Control—Trust Our Regulating Stem!

Our high-performance regulating stems ensure accurate, fast, and reliable steam control for your turbine. Contact us now for free technical consultation, customized quotation. We guarantee compliance with your drawing requirements, on-time delivery, and lifelong after-sales maintenance guidance to support your turbine unit's long-term stable operation.