Spring type safety valve is an important accessory of pressure limiting and pressure relief for special equipment (boiler, pressure vessel, pressure pipeline, etc.). Spring type safety valve is generally installed directly on special equipment, and its design, manufacturing, installation, use and inspection shall meet the requirements of relevant provisions of special equipment, because its operation reliability and performance are directly related to the safety of equipment and personnel, and closely related to energy conservation and environmental protection.

1、 The common safety valves of spring safety valve are as follows:

1. According to the integral structure and loading structure, it can be divided into three types: heavy hammer lever type safety valve, spring type safety valve and control type.

2. According to the ratio of disc opening height to valve flow diameter, it can be divided into micro opening and full opening safety valves.

3. According to the way of gas discharge of safety valve, it can be divided into totally closed, semi closed and open type

2、 The proper selection of spring safety valve should be considered from the following aspects:

1. The structure mainly depends on the process conditions, working medium and characteristics of the equipment. Generally, when the discharge capacity of boiler and pressure vessel is not large, spring type safety valve is often selected, otherwise, full open type safety valve is better.

2. If the medium is toxic, flammable and explosive, closed safety valve shall be selected

3. Each safety valve has its own working pressure range, which should be selected according to the actual needs.

4. The discharge capacity of the selected safety valve must be greater than the discharge capacity of the equipment, so as to ensure that part of the medium is discharged and avoid the pressure rising continuously.

3、 Precautions for installation of spring safety valve

1. All safety valves shall be installed vertically.

2. There shall be no resistance at the outlet of safety valve to avoid pressure.

3. The safety valve shall be specially tested and checked for tightness before installation.

4. The safety valve in use should be checked regularly

4、 Common faults of safety valve in the application of spring safety valve:

In the normal use and calibration of safety valve, various faults will be caused due to improper design, manufacturing or use. If these faults are not eliminated in time, the efficiency and service life of the safety valve will be affected, and the life safety of the user will be endangered in serious cases.

1. Leakage of safety valve.

The leakage of the sealing surface of the valve disc and valve seat exceeds the allowable degree. The causes and solutions are as follows:

a. Leakage occurs because there is dirt between the valve disc and the sealing surface of the valve seat, and the valve can be opened several times and flushed down.

b. The damage of sealing surface can be repaired by grinding or grinding after turning according to the damage degree.

c. The valve rod is bent and tilted. Should be reassembled or replaced

2. When the specified pressure is reached, it will not open and when it is reached, it will not close. This is due to the inaccurate positioning of the safety valve. It is necessary to readjust the compression amount of the spring or the position of the heavy hammer or replace the spring.

3. The pressure continues to rise after the relief valve is vented. This is mainly because the discharge of the safety valve does not reach the discharge of the equipment, so the appropriate safety valve should be selected.

4. Valve disc frequency jump or vibration. This is mainly because the spring stiffness is too large, the spring with proper stiffness should be used instead.

5. The safety valve does not return to its seat after being discharged due to bending of spring, improper installation position of stem and disc or being stuck, which shall be reassembled.