What statement representing the primary purpose of a steam trap is true?

Correct Answer: Option A — By draining the low point of a horizontal run of steam piping, a steam trap is used primarily to keep the steam line dry and eliminate water hammer.

Steam traps are installed at the low points of steam lines to remove condensate. By preventing the accumulation of water, they eliminate the risk of water hammer, which occurs when steam velocity accelerates slugs of water, potentially causing catastrophic damage to piping, fittings, and connected machinery components.