Looking at the diagram, how is the operating pressure of this pipeline determined?
Thread Content
This post was last edited by shiworkstation on 2017-4-19 09:46. When encountering such pipelines, how should the operating and design pressures be determined? If it is not at atmospheric pressure, then many such exhaust pipes can be pressure pipes.
Setting it to atmospheric pressure behind the safety valve will suffice.
Beyond the safety valve is atmospheric pressure, seemingly around 0.05 MPa; it connects to the vent main, and neither of these are pressure pipelines. Remember, it’s located before the PID valve. The two pipeline numbers behind the valve are needed in order to make a proper distinction
Do you design with two pipeline numbers, one before the valve and one after it? It makes sense, but it’s too troublesome.
Next, can the pressure of the safety valve be calculated using the pipe diameters before and after the safety valve?
A vent pipe is connected after the safety valve, leading to a flare or another venting location. The vent pipes within the facility are generally of DN300 or larger, so there is sufficient space to release pressure once the safety valve activates. During the design process, it was taken into account that there are water seal tanks in the device area, as well as main vent pipes within the plant, liquid separation tanks under the flare stack, water seal tanks, and the height of the flare stack. All these factors need to be considered as back pressure. The operating pressure of the vent pipes downstream of the safety valve, along with the set pressure of the safety valve, must also be taken into account; since the back pressure is generally around 10 KPa, it has little impact on the set pressure of the safety valve and can be ignored.
Why, for the 120-kilogram reaction system we commissioned for design last time, was the pressure in the pipeline downstream of the safety valve equal to the pressure upstream of the valve when it opened? :dizzy:
I’m not sure if it’s troublesome when submitting applications for pressure pipelines; for pressure pipelines listed in the pipeline register, it’s the pipeline number that matters
It depends on how long the pipeline is behind the safety valve and on the discharge capacity of the safety valve; it cannot be generalized. Assuming there are several hundred meters of pipe downstream of the safety valve, and that the discharge volume of the safety valve is sufficient to fill the entire discharge pipeline, the resistance downstream of the safety valve will be very high; it may even equal the pressure upstream of the valve.