Which materials require a heating expansion safety valve?
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As required by standards, closed pipelines need to be equipped with safety valves due to thermal expansion, in order to ensure their safety. Generally, liquefied hydrocarbons, gasoline, methanol, etc. require addition, but do materials that are difficult to vaporize such as diesel and aromatics need to be added as well?
Liquids are incompressible; if the inlet and outlet valves are closed, the medium in the pipeline will expand when heated, which can damage the pipeline, so it is necessary to add something in such cases
What about feasibility, what about the consequences? Which device can accomplish this?
I guess in practice this problem isn’t that serious; the main reason is internal leakage in the valves. The pressure generated by the thermal expansion of the liquid in the pipe can be quite high, but in reality such high pressures aren’t reached before the valves start to leak internally, especially hard-sealed valves. As for when a safety valve is necessary, the situations that come to mind are: 1) long pipes filled with liquid, particularly those carrying liquefied gases. 2. The valve is shut off with good sealing at both ends. 3. The pipes lack insulation, resulting in large temperature fluctuations. 4. Overpressure leakage is absolutely not allowed, as the consequences are severe.
For the heat exchanger bank on the heated side, which is equipped with isolation valves at the front and back, a safety valve can be added to prevent errors in operation.
The Design Fire Protection Code for Petrochemical Enterprises GB50160-2018 specifies that safety valves must be installed on liquefied gas, as well as on methane and ethane.
5.5.6 For pipelines carrying liquefied hydrocarbons, Class A B, and Class A C liquids, in which the valves at both ends are closed and external factors may cause an increase in the pressure of the medium, pressure relief safety measures must be implemented