For material thickness between 100 mm and 200 mm, roughness shall not exceed how many micrometers?

For material thickness between 100 mm and 200 mm, roughness shall not exceed how many micrometers?

• A. 25 micrometers
• B. 50 micrometers
• C. 75 micrometers
• D. 100 micrometers

Answer: (B)

For material in the 100–200 mm thickness range, the allowed surface roughness is 50 micrometers (Ra). This limit is set to balance manufacturability with inspection reliability: it keeps the surface smooth enough to avoid slag entrapment, ensure good fit-up of joints, and allow accurate nondestructive testing, while still being practical to achieve on thicker plates. Rougher surfaces could hinder weld quality and visual or radiographic inspection, whereas a finer finish is unnecessary here and would be more costly. So the maximum permissible roughness is 50 micrometers.