What is the minimum thickness of a pipe for a steam header with 152.4 mm O.D. at 8440 kPa and 420°C?

To determine the minimum thickness of a pipe for a steam header, we consider factors such as the external pressure, internal pressure, temperature, and the material properties of the pipe. The design of the pipe must comply with relevant codes, such as the ASME Boiler and Pressure Vessel Code, which outlines how to calculate the required wall thickness based on the hoop stress formula.

For a given external diameter and pressure, the most appropriate equation to find the minimum thickness can be represented as:

t = (P * D) / (2 * S) + C

Where:

• t is the thickness of the pipe,

• P is the internal pressure,

• D is the outside diameter of the pipe,

• S is the allowable stress of the material at the given temperature,

• C is a corrosion allowance (if applicable).

In this situation, to calculate the required thickness accurately:

1. Convert the given values (pressure, O.D.) into consistent units.

2. Use the properties of the material at 420°C to find the allowable stress (S).

3. Substitute these values into the formula to derive the necessary thickness.

The choice indicating 10.90 mm provides a thickness that considers standard safety margins and accounts for both the internal pressure at 844