Uncover the technological secrets of high temperature valves

Live from the front line of flames ‌
In Baosteel's hot rolling workshop, red steel billets are passing through a 1250℃ heating furnace. On the pipe gallery, just 3 meters away from the flames, the valve body of a gate valve is burned red. "This is the capability of Inconel 718 material," said Zhang Gong, the equipment supervisor, wiping his sweat. "Looking at the thermal imager, the valve cavity temperature is 732℃, but the flange surface is always controlled below 180℃."

‌Hard-core technology disassembly‌
☛ Temperature-resistant armor:
• High Temperature Gate Valves double-layer structure: the outer layer is ASTM A351 Gr.HK30 cast steel to resist thermal shock, and the inner lining is ceramic fiber blanket (density 280kg/m³) for insulation
• Valve stem "ice sleeve": active circulation cooling system, using 38℃ soft water to continuously take away heat, the measured valve stem temperature does not exceed 80℃
• Sealing black technology: The expansion rate of the flexible graphite packing ring at 600℃ is 11%, which can compensate for thermal deformation autonomously

☛ Thermal expansion game:
The gate adopts a 3.5° elastic slope design. When the valve cavity expands 2.7mm due to heat, the wedge structure automatically compensates for the gap. Last year, in Zhanjiang Power Plant, this design successfully resolved the blockage crisis caused by thermal displacement of the steam pipeline.

‌Extreme working condition record‌
Measured data of an ethylene cracking unit:
▸After being flushed with 890℃ cracking gas for 48 hours continuously, only 0.03mm oxide layer was generated on the gate surface
▸In the sudden temperature change fluctuation (650℃→200℃→580℃), 6 opening and closing were completed within 15 minutes
▸The supporting water cooling system takes away 31700kJ of heat per hour, which is equivalent to cooling 20 air conditioners at the same time

‌High temperature survival rules‌

Lubrication restricted area: Traditional grease will carbonize at 400℃, and molybdenum disulfide-based dry film lubricant must be used
Operation taboo: When the environment exceeds 500℃, the opening and closing interval must be greater than 15 minutes to prevent heat accumulation
Detection secret: Scan the valve stem bracket with an infrared temperature measuring gun, and the temperature difference >50℃ will warn the cooling abnormality system
According to the latest supplementary provisions of ASME B16.34, high-temperature gate valves must pass the "three-temperature test" (normal temperature→hot state→after cooling) for sealing verification. This hard-core equipment, which can "fish chestnuts out of the fire", protects the industrial lifeline of 21 high-temperature scenes, from glass melting furnaces to aircraft engine test benches. Its surface coking control technology has recently been transplanted to the field of rocket engine fuel valves.