What is permissible regarding flattening of tubing in bends?

When dealing with the bending of tubing, it's important to maintain the integrity of the material to ensure proper fluid flow and structural strength. Option B, which allows for flattening by not more than 25% of the original diameter, is correct because it strikes a balance between flexibility in installation and the prevention of significant alterations to the tubing’s performance characteristics.

Exceeding the 25% flattening limit can lead to increased resistance to flow, potential weak points in the tubing, and a greater risk of failure, especially under pressure. This standard helps ensure that while some modulation of the tubing can occur to fit specific configurations, the overall functionality and safety of the system are retained. Proper standards are crucial in fluid dynamics and engineering applications, where reliability and efficiency depend on the integrity of components like tubing.