Certified Pipefitter Steam Traps and Steam Systems

Question 1

What is the primary function of a steam trap in a steam distribution system?

Accepted Answer

To discharge condensate and non-condensable gases while retaining live steam

Answer

A steam trap automatically discharges condensate (water that has condensed from steam) and air/non-condensable gases while preventing the escape of live steam. Allowing condensate to accumulate reduces system efficiency and creates conditions for water hammer.

Question 2

Which type of steam trap uses a floating ball that rises with accumulating condensate to mechanically open a discharge valve, providing continuous condensate removal?

Accepted Answer

Float and thermostatic (F&T) trap

Answer

The float and thermostatic (F&T) trap uses a float that rises as condensate accumulates, mechanically opening the discharge valve. A separate thermostatic air vent releases non-condensable gases at startup. It discharges condensate continuously and handles high condensate loads well.

Question 3

What is 'water hammer' in a steam piping system?

Accepted Answer

The violent pressure shock wave generated when high-velocity steam contacts a slug of subcooled condensate

Answer

Water hammer occurs when fast-moving steam collides with a slug of cooler, liquid condensate that has accumulated in the line. The sudden deceleration creates a severe pressure shock wave that can split pipe, destroy fittings, and damage equipment.

Question 4

What distinguishes superheated steam from saturated steam at the same pressure?

Accepted Answer

Superheated steam has been heated above its saturation temperature and contains no liquid water

Answer

Saturated steam exists at the boiling point for its given pressure and may carry moisture. Superheated steam has been heated further — above the saturation temperature — so it contains no liquid droplets, carries more energy, and behaves more like a gas. It is used where dry steam is critical (e.g., turbines).

Question 5

Why should steam mains be pitched (sloped) in the direction of steam flow?

Accepted Answer

To allow condensate to drain by gravity to trap stations and prevent accumulation

Answer

Proper pitch (typically 1/8" to 1/4" per foot) ensures condensate drains by gravity toward steam trap stations rather than pooling in low spots. Accumulated condensate is the primary cause of water hammer and can also accelerate internal corrosion.

Certified Pipefitter Practice Test

Certified Pipefitter Practice Test

Certified Pipefitter Steam Traps and Steam Systems