The stop check valve KLJC50-1.6P is a key component to ensure safe operation in the generator hydrogen system. Its design combines the flow control function of the stop valve with the anti-backflow characteristics of the check valve, and shows unique technical advantages in high-pressure and high-purity hydrogen environments. The following analysis is carried out from three aspects: structural principle, application scenario and technical characteristics.

The KLJC50-1.6P model follows the standardized naming rules of the check valve, where “KLJ” represents the valve body type and connection method, “C” refers to the sealing auxiliary material of stainless steel or special alloy, “50″ indicates a nominal diameter of 50 mm, and “1.6P” corresponds to the hydrogen medium adaptation level of 1.6MPa nominal pressure. The valve adopts a lifting disc structure, and realizes opening and closing control through the dual effects of the valve disc’s own weight and the medium pressure: when hydrogen flows forward, the fluid pressure overcomes the valve disc’s gravity and spring resistance to open the channel; when the medium flows back, the valve disc closes quickly under the reverse pressure and self-resetting, effectively blocking the risk of hydrogen backflow. The internal flow channel of the valve body has been optimized, and the pressure drop loss is less than 15% of the industry standard. At the same time, it is equipped with a precision-ground sealing surface to ensure zero leakage of hydrogen.

In hydrogen-cooled generators, the stop check valve KLJC50-1.6P is mainly deployed at the following key nodes:

1. Hydrogen supply pipeline: As the connection hub between the hydrogen storage tank and the generator body, the valve realizes flow regulation during the system hydrogen filling and hydrogen discharge operations, and prevents hydrogen from leaking back to the gas storage device during shutdown.

2. Sealing oil system interface: In the double-flow ring sealing oil circuit, the valve is used to control the pressure difference balance between hydrogen and sealing oil to avoid purity reduction or explosion risks caused by oil-hydrogen cross-talk.

3. Safe discharge channel: When the system pressure exceeds the set threshold, the valve links the pressure relief device to quickly cut off the main channel and guide the overpressure hydrogen into the recovery or discharge pipeline.

The stop check valve KLJC50-1.6P has made a number of technical innovations for the special working conditions of the hydrogen system:

- Material adaptability: The valve body is made of ASTM A351 CF8M stainless steel, and the valve disc surface is plated with a nickel-based alloy layer to withstand hydrogen embrittlement corrosion and high-temperature oxidation in a hydrogen environment (working temperature range -40℃~200℃).

- Safety redundancy design: integrated double sealing structure (metal hard seal + flexible graphite packing), and passed the ASME B16.104 Class VI leakage level certification, meeting the nuclear power plant level sealing requirements.

- Intelligent monitoring interface: optional valve position sensor and pressure transmitter, real-time transmission of valve opening and front and rear pressure difference data to the DCS system, to achieve pre-maintenance diagnosis.

When selecting the model, it is necessary to focus on parameters such as hydrogen purity (≥99%), system pressure fluctuation range and opening and closing frequency. It is recommended to retain a 20% safety margin based on the rated pressure and conduct regular helium mass spectrometry leak detection tests.

To ensure long-term reliability, the following maintenance procedures need to be implemented:

1. Periodic calibration: The valve stroke test and sealing surface inspection are required every 8,000 hours of operation or during the overhaul of the unit. The opening and closing torque deviation should be less than 10% of the factory value.

2. Cleanliness management: The particulate matter content in the hydrogen system must be controlled below NAS 1638 level 6 to prevent impurities from scratching the sealing surface.

3. Emergency drill: Simulate hydrogen leakage scenarios to verify the valve’s rapid locking capability within 5 seconds and the effectiveness of the linkage control logic.

The stop check valve KLJC50-1.6P has been successfully applied in many million-kilowatt hydrogen-cooled units in China. Its design standards comply with GB/T 12235 and API 594 specifications, and it has passed ISO 15848-1 low-temperature cycle test certification. In the future, as generator hydrogen cooling technology develops towards higher efficiency, KLJC50-1.6P will continue to iterate in the fields of lightweight materials and intelligent control, providing key equipment support for the construction of new power systems.

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