What is the use of the lead seal on the safety valve?

Technical Information, 10-08-2018

The function of the lead seal is to protect the safety valve in the normal position and prevent someone from closing the valve by mistake. In this way, the safety valve will not play a safety role. In addition, the purpose of adding hand valve to safety valve is: if the safety valve needs to be calibrated, close the hand valve to isolate the safety valve for calibration, so that production will not be affected. Therefore, it is necessary to add a hand valve in front of the safety valve. The hand valve of the safety valve is sealed with lead to prevent the operator from opening the handle valve by mistake.
The lead seal of the safety valve plays the role of preventing the safety valve from being adjusted privately and ensuring the tripping pressure on the safety valve device. After the setting pressure of the safety valve is adjusted, the lead seal shall be applied to prevent the adjusted setting pressure from being changed at will. After the safety valve has been calibrated to set pressure, rated pressure, discharge pressure, return pressure, etc., and after the pressure maintaining test, approved by the safety supervision department and the mechanical and electrical management department, the safety valve is jointly sealed to seal the adjustable spare cap and the detachable part of the valve body, so that the pressure of the safety valve cannot be adjusted and the valve body cannot be disassembled. When it is necessary to overhaul the safety valve, the position of adjusting screw and adjusting ring shall be recorded before disassembling the valve, so as to facilitate the adjustment work after finishing. When the setting pressure is readjusted, lead sealing shall be applied again.
After all the safety valves are adjusted, the lead seal must be used. The purpose is to prevent arbitrary changes in the adjusted situation. When the safety valve leaves the factory, unless otherwise specified, it is usually adjusted with normal temperature air according to the online high pressure value of the working pressure level. Therefore, users generally need to adjust according to the actual working conditions. Then, reuse the lead seal to achieve the effect of normal operation.
From the above, it can be concluded that the lead seal of safety valve means that after the verification of safety valve is realized, the adjustable or rotating loose parts of its internal components are tied up with lead wire to avoid the action failure of safety valve or the change of setting pressure caused by random movement or loosening.