Correctly sized steam mains are critical. Over sizing increases radiation loss and under sizing increases pressure drops.
The design of steam mains and the steam distribution network requires critical examination. The safety margins included should be based on engineering inputs rather than speculation.
Over sizing steam main increases the material cost and erection cost (supports, insulation, etc). Importantly oversized steam main provides a larger heat transfer surface thereby increasing radiation losses.
Under sizing steam main leads to pressure drops and could lead to steam starvation in equipments. This impacts the process quality.