Which material protects the duct or casting from the steel line?

Which material protects the duct or casting from the steel line?

• A. Duct iron
• B. Steel plate
• C. Concrete
• D. Insulation

Answer: (A)

When a steel line runs near a duct or casting, a protective metal sleeve is used to shield the duct from physical contact, heat, and potential wear. Ductile iron provides that protective barrier because it combines toughness and strength with good machinability, so it can be cast or formed to fit precisely around the duct or casting and withstand mechanical impact and abrasion from the nearby steel line. It also serves as a stable, corrosion-resistant enclosure between dissimilar metals, helping prevent damage to the duct or casting. Steel plate would be heavier and less practical to shape around existing components; concrete isn’t suitable for wrapping and protecting a duct or casting in close quarters; insulation protects against heat transfer but doesn’t provide a robust protective shell. Hence ductile iron is the best choice for protection in this scenario.

When a steel line runs near a duct or casting, a protective metal sleeve is used to shield the duct from physical contact, heat, and potential wear. Ductile iron provides that protective barrier because it combines toughness and strength with good machinability, so it can be cast or formed to fit precisely around the duct or casting and withstand mechanical impact and abrasion from the nearby steel line. It also serves as a stable, corrosion-resistant enclosure between dissimilar metals, helping prevent damage to the duct or casting.

Steel plate would be heavier and less practical to shape around existing components; concrete isn’t suitable for wrapping and protecting a duct or casting in close quarters; insulation protects against heat transfer but doesn’t provide a robust protective shell. Hence ductile iron is the best choice for protection in this scenario.