An NPS 12 (12.75" o.d.) seamless pipe made from ASTM A-53 Grade B material operates at 600 psi and 600 degrees F. The conditions require that a corrosion allowance of 0.125" be maintained. Calculate the minimum required thickness for these conditions.

To calculate the minimum required thickness for the NPS 12 seamless pipe operating under the given conditions, we need to use the formula provided by the ASME Boiler and Pressure Vessel Code, Section VIII, Division 1, for calculating the thickness of cylindrical shells under internal pressure.

### Given Data:
- **Outside Diameter (OD):** 12.75 inches
- **Pressure (P):** 600 psi
- **Temperature (T):** 600°F
- **Corrosion Allowance (CA):** 0.125 inches
- **Material:** ASTM A-53 Grade B

### Step 1: Determine the Allowable Stress
The allowable stress for ASTM A-53 Grade B at 600°F needs to be determined from material tables. For ASTM A-53 Grade B, the typical allowable stress values at elevated temperatures are provided in codes like ASME B31.3.

Let's assume:
- **Allowable Stress (S):** 13,750 psi (at 600°F for ASTM A-53 Grade B)

### Step 2: Use the Thickness Formula
The required thickness of the pipe, without considering the corrosion allowance, can be calculated using the following formula:

\[
t = \frac{P \times D}{2 \times S \times E + P}
\]

where:
- \( t \) = required thickness (inches)
- \( P \) = internal pressure (600 psi)
- \( D \) = outside diameter (12.75 inches)
- \( S \) = allowable stress (13,750 psi)
- \( E \) = weld efficiency (since it's seamless, E = 1)

### Step 3: Plug in the Values

\[
t = \frac{600 \times 12.75}{2 \times 13750 \times 1 + 600}
\]

\[
t = \frac{7650}{27500 + 600}
\]

\[
t = \frac{7650}{28100}
\]

\[
t \approx 0.272 inches
\]

### Step 4: Add Corrosion Allowance
The final required thickness includes the corrosion allowance:

\[
t_{min} = t + CA
\]

\[
t_{min} = 0.272 + 0.125
\]

\[
t_{min} = 0.397 inches
\]

### Conclusion:
The minimum required thickness for the NPS 12 seamless pipe, considering the operating conditions and corrosion allowance, is **0.397 inches**.

Would you like further details, or do you have any questions?

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Here are five relative questions to consider:
1. What would the minimum thickness be if the operating pressure increased to 800 psi?
2. How does the allowable stress change if the temperature were 700°F instead of 600°F?
3. What role does weld efficiency play in this calculation if the pipe wasn't seamless?
4. How would the result differ if the corrosion allowance were 0.25 inches?
5. What are the implications of reducing the corrosion allowance to 0.1 inches?

**Tip:** Always ensure to cross-check the allowable stress at operating temperatures from relevant material standards to avoid overestimating or underestimating pipe thickness.

Learn how to calculate the minimum required thickness for an NPS 12 seamless pipe made from ASTM A-53 Grade B material under specific operating conditions. This problem involves determining the pipe's thickness considering internal pressure, temperature, and a corrosion allowance of 0.125 inches.

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