For an unstayed full-hemispherical head with a diameter of 1.0 m and a pressure of 1500 kPa, what is the required thickness if the material is SA-285 C?

To determine the required thickness of an unstayed full-hemispherical head under a specific pressure, one can use the formula derived from the ASME Boiler and Pressure Vessel Code. For a hemispherical head, the formula for thickness involves the internal pressure, the material's yield strength, and the head's radius.

In this case, we have a head with a diameter of 1.0 m (which gives a radius of 0.5 m) and an internal pressure of 1500 kPa. The appropriate material for this calculation is SA-285 C, which has a yield strength typically around 138 MPa.

Using the formula for the thickness of a hemispherical head:

[ t = \frac{P \cdot R}{2 \cdot S} + \text{ corrosion allowance} ]

Here:

• ( P ) is the internal pressure (1500 kPa = 1.5 MPa),

• ( R ) is the radius of the head (0.5 m),

• ( S ) is the allowable stress (which is a fraction of the yield strength, commonly taken as a safety factor).

For steel, it's common to use an allowable stress of around 100 MPa after