Minimum thickness requirement: What is the least wall thickness of a class B cast iron (spun) pipe used in water supply systems?

Introduction / Context:
Cast iron pipes are widely used in water distribution systems due to their durability and strength. Standards prescribe minimum thickness values to ensure the pipe can withstand internal pressures and external loads safely.

Given Data / Assumptions:

• Pipe material: Cast iron (spun type).
• Pipe classification: Class B.
• Property to determine: Minimum wall thickness.

Concept / Approach:
The minimum thickness is specified by Indian Standards (IS 1536:2001) and similar international codes. For class B spun cast iron pipes, the least thickness required is 7.2 mm.

Step-by-Step Solution:

Verification / Alternative check:
Cross-check with code tables shows Class A has lower values, and Class C has higher. This confirms 7.2 mm is correct for Class B.

Why Other Options Are Wrong:

• 7.9 mm, 8.6 mm, 10 mm: These are thicker values but not the specified minimum for Class B pipes.
• None of these: Incorrect, since 7.2 mm is valid.

Common Pitfalls:

• Assuming thicker is always the answer without checking standards.
• Confusing with Class A or Class C pipe values.

Final Answer:
7.2 mm