Connection requirements for the safety valve of a 0.8 MPa gas storage tank
In industrial production, 0.8 MPa air receivers are common compressed-air storage vessels. As a critical safety component of the receiver, the safety valve automatically opens to vent excess pressure when the system exceeds its set point, thereby preventing overpressure. Consequently, the material and connection method of the safety valve’s discharge piping must meet the applicable strength and sealing requirements.
Feasibility of Using Galvanized Pipes as Connecting Pipes
For a working pressure of 0.8 MPa, galvanized steel pipes that comply with national standards and meet the specified wall thickness requirements are capable of satisfying the pressure‑bearing requirements. At ambient temperature, compressed air exhibits only slight corrosivity toward galvanized pipes; therefore, in practical applications, it is feasible to use galvanized pipe as the discharge connection for the safety valve of a 0.8 MPa gas storage tank.
However, when selecting galvanized pipes, the following key factors must be taken into account:
- Pressure rating matching:It must be ensured that the selected galvanized pipe’s nominal pressure rating and wall thickness are capable of withstanding a working pressure of 0.8 MPa as well as the impact forces generated when the safety valve opens instantaneously.
- Material Compliance:Pipeline materials shall comply with the relevant safety technical codes for pressure vessels, and the use of substandard pipe or pipe with wall thickness that fails to meet the specified requirements is prohibited.
Installation and Connection Precautions
Once the decision has been made to use galvanized steel pipes, proper installation procedures are equally critical:
- Avoid direct welding:The zinc coating on the surface of galvanized pipes is damaged during high-temperature welding, which not only compromises their corrosion‑resistant performance but also generates harmful gases. Therefore, threaded connections are typically used for galvanized pipes. If flanged connections are required, it is recommended to weld seamless steel pipes first and then subject the entire assembly to hot‑dip galvanizing.
- Guaranteed discharge cross-sectional area:The cross-sectional area of the safety valve discharge pipe shall not be less than that of the safety valve outlet, to ensure the smooth release of overpressurized gas and prevent excessive back pressure caused by restricted venting.
- Discharge outlet location:The discharge pipe shall be routed to a safe outdoor location, with the pipe outlet oriented downward or equipped with a protective device to prevent rainwater or foreign objects from entering the pipeline and compromising the proper operation of the safety valve.
Compliance and Routine Maintenance
Gas storage tanks are classified as special equipment, and the installation and modification of their safety accessories must strictly comply with the relevant safety technical inspection regulations. Before making any piping modifications, it is advisable to consult a qualified pressure vessel inspection agency.
In addition, during routine operation, the safety valve and its connecting pipelines should be periodically inspected for tightness. The safety valve must be calibrated at prescribed intervals to ensure it responds promptly and reliably at its set pressure.