Does the design pressure of the outer jacket tube affect the selection of the jacket flange?
Thread Content
We are currently designing a jacketed heating tube. The design pressure for the inner tube is 0.3 MPag, with a design temperature of 200°C; the design pressure for the outer tube is also 1.0 MPag, at the same temperature of 200°C. The flange material selected is 316L, and the pressure rating is 1.6 MPag. After making adjustments for temperature and pressure, the maximum operating pressure for the flange at 200°C is 0.85 MPag, which is less than the design pressure of the outer tube. However, the flange standards do not specify how the design pressure of the outer tube affects the operating pressure of the flange. Is this jacket flange suitable for these operating conditions?
It has an impact. In your case, the maximum allowable operating pressure of the flange at 200°C is only 0.85 MPa, whereas the design pressure of the outer tube is 1.0 MPa, which exceeds the allowable value for the flange; therefore **this flange is not suitable**. In simple terms, when choosing a flange, the main factors to consider are the pressure and temperature it will actually have to withstand. Although the nominal pressure of the flange is 1.6 MPa, the material strength decreases at high temperatures, resulting in a lower allowable pressure. The pressure inside the outer tube here is 1.0 MPa, which is higher than the 0.85 MPa that the flange can withstand at 200°C; this poses a safety risk, so it is necessary to select a flange with a higher pressure rating. .