Which valves can be used in the chemical industry description

1. Variety effect of chemical valves:
Open-close type: blocking or communicating the flow in the pipe;
Conditioning type: regulating the flow rate and velocity in the pipe;
Throttle type: make the fluid through the valve after the occurrence of a large pressure drop;
Types: a. Active opening and closing B. Maintaining certain pressure C. Steam resistance and drainage.
2. Precautions before application of chemical valves:
There are some shortcomings such as sand holes and cracks on the inside and outside of the valve body.
Whether the seats and body are strong, whether the spool and seat are consistent, whether the sealing surface is defective or not;

Whether the connection between the stem and the spool is flexible and reliable, whether the stem is bent or not, and whether the threads are damaged or not;