Our company has an propylene storage tank with a design pressure of 2.16 MPa, a maximum allowable operating pressure of 2.2 MPa, and a set pressure of 2.2 MPa...
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Our company has an propylene storage tank with a design pressure of 2.16 MPa, a maximum allowable operating pressure of 2.2 MPa, and a set pressure of 2.2 MPa. Is this reasonable? I would appreciate it if experts could help explain this.
It’s definitely unreasonable; the maximum allowable operating pressure already exceeds the design pressure, and the set pressure shouldn’t be the same as the maximum allowable operating pressure. Check the standards – clear regulations exist for these values.
It is unreasonable to set the setting pressure at 2.2 MPa, as specified in GB150.1-2011 B4.6, the deviation of the safety valve’s setting pressure should not exceed ±3% of the setting pressure, or the larger of ±0.015 MPa.
This post was last edited by xukong_206 on 2017-9-11 10:40
However, according to GB150.1-2011 B.3.1, when a vessel is equipped with a relief device, the design pressure of that vessel is generally used as the starting pressure for the normal pressure limit. When the maximum allowable operating pressure is indicated on the design drawings and nameplate, the maximum allowable operating pressure of the container can be used in place of the design pressure.
It is correct. For toxic, harmful, flammable, and explosive substances, the setting pressure of the safety valve should be higher than the design pressure. During calculation, the strength of each component must be verified using the maximum allowable operating pressure. Therefore, at this stage, the design document must indicate not only the design pressure but also the maximum allowable operating pressure.
As a supplementary note, these are the requirements for conducting a gas-tightness test. Because the airtightness test pressure = design pressure. Therefore, the opening pressure of the safety valve must be higher than the design pressure. This is why the set pressure on the drawings of your unit is higher than the design pressure. However, the set pressure is generally chosen to be higher than the design pressure and lower than the maximum allowable operating pressure.
It makes sense; this device needs to undergo a gas-tightness test. As mentioned on floor 8, when we design it, the set pressure is set higher than the design pressure but lower than the maximum allowable operating pressure.
However, GB150.1-2011 B.4.7 states that when a safety valve is installed, the design pressure of the vessel is determined as follows: a) Based on the operating pressure Pw of the vessel, determine the set pressure Pz of the safety valve; generally, Pz is taken as (1.05~1.1)Pw； When Pz