How to Select Valves Suitable for High and Low Temperature Conditions?

 

In the process of using the valve, we will encounter various working conditions, such as high temperature and low temperature. In this case, how should we choose the valve?


1. High Temperature Conditions

When selecting valves, it is necessary to consider using shell materials and internals materials with high temperature strength, such as austenitic stainless steel valve and bidirectional stainless steel. The selected materials should not be bonded, plasticized and creep due to high temperature, the gap cannot not be too small. Applicable valve types include gate valve, butterfly valve, etc.


If the temperature has exceeded the temperature range that the metal can bear, the special valves with ceramic lining can be used, and the cooling jacket structure can also be used to keep the internal metal within the allowable stress range through circulating water cooling.


2. Low Temperature Conditions

When the temperature is lower than - 29 ℃, low-temperature resistant shell materials and internals should be selected. In the low temperature range of - 29 ~ - 196 ℃, it is required that the shell material and the inner part material have sufficient impact toughness.


After the valve is closed, some liquid will remain in the valve chamber. With the increase of time, the liquid remaining in the valve chamber will gradually absorb the heat in the atmosphere, rise to normal temperature and re vaporize. After vaporization, its volume will expand rapidly, which will generate extremely high pressure and act on the inside of the valve body. This situation is called abnormal pressure rise. This is a unique phenomenon of low-temperature valves. This abnormal pressure rise will cause the valve plate to press tightly against the valve seat, resulting in the valve plate cannot be opened. At this time, the high pressure will flush out the flange or damage the packing or the valve cover, causing serious accidents. Therefore, we should prepare measures to prevent abnormal pressure rise in advance.


After we understand these in detail, it will be easy to solve such problems.

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