Internal leakage of safety valve
Thread Content
The safety valves in our company’s liquid nitrogen tank area experience internal leakage every time they activate, resulting in significant losses of liquid nitrogen. Could anyone tell me what might be the cause? The safety valve is a spring-loaded, slightly open type made entirely of stainless steel, and the medium is liquid nitrogen.
Imported safety valves are used, ensuring safety and practicality — Shanghai Jingtai Group
Generally, a row of drain pipes is installed at the lowest point behind the elbow, without the need for valves. Due to internal leakage in the safety valve (the main cause), or factors such as rainwater and air humidity, water accumulation is inevitable behind the safety valve. During operation, the safety valve can open at any time; if water is present when it opens, water hammer will definitely occur, which may cause pipe vibration in mild cases and lead to more serious accidents in severe cases. Therefore, drilling holes is one of the measures to drain the water accumulation here.
The key component of a spring-loaded safety valve is the sealing surface. When the safety valve opens, the medium inside the container (oil, gas, water, etc.) flows out through this sealing surface. When the sealing surface closes, impurities present in the contents (such as water rust and oil deposits) get trapped between the surfaces, preventing them from sealing completely and thus causing leaks. Therefore, even a new valve that has been calibrated for proper pressure may leak after being opened just once. The repair method involves removing the safety valve and cleaning its sealing surfaces; if these surfaces are severely damaged, they need to be ground. Do not attempt repairs by yourself! It must be calibrated and repaired by a qualified inspection unit; it is recommended to have it disassembled and inspected once a year. If it is a safety valve with a handle, the valve can be forced to open several times; this process may help dislodge impurities from the sealing surface, and that will suffice.
If there is internal leakage, it also increases pollution of the environment.
Attention should be paid to why the safety valve keeps tripping; it would be better if this issue is resolved
It’s normal for such self-acting safety valves to leak; it seems they haven’t returned to their proper position completely
After the safety valve activates, the pressure must be set again.
The safety valve operates constantly; it is necessary to check whether there are issues with the design of the safety valve or with the valve itself；
It is recommended to find a unit specialized in adjusting safety valves, such as staff from a boiler inspection agency, to carry out the inspection