As shown in the figure, the part marked 175mm is the lengthened part. Under the condition of ultra-low temperature, the valve stem and valve body can only be of stuffing box or bellows structure. There are many restrictions on the use of bellows. Generally, the stuffing box seal structure is used. The stuffing box seal structure is simple to process and convenient to maintain. However, its sealing effect cannot be guaranteed when the temperature is less than - 40 ℃. Therefore, ultra-low temperature valves are designed to keep the stuffing box away from materials as far as possible and choose the packing with low temperature characteristics.

4. Installation
1) Remove the protective covers on both sides of the flange end, and flush and clean the valve when the valve is fully opened.
2) Before installation, the whole machine shall be tested according to the specified signal (electricity or gas) (to prevent vibration caused by transportation from affecting the service performance), and can be installed online only after it is qualified (wiring shall be in accordance with the circuit diagram of electric actuator).
3) Before preparing to connect with the pipe, the residual impurities in the pipe must be flushed and removed (these substances may damage the valve seat and ball).
4) During installation, please do not use the actuator part of the valve as the lifting point to avoid damage to the actuator and accessories
5) This type of valve shall be installed in the horizontal or vertical direction of the pipeline.
6) The pipeline near the installation point shall not sag or bear external force, and the pipeline support or support can be used to eliminate the deviation of the pipeline.
7) After connecting with the pipeline, please cross lock the flange connecting bolts with the specified torque.