Steam systems: What is the most likely consequence of installing an underdesigned (undersized) steam trap in a line or heat exchanger service?

Introduction / Context:
Steam traps remove condensate and non-condensables while retaining live steam. Correct sizing is essential to maintain heat-transfer performance and line safety. An underdesigned trap cannot pass the required condensate load during start-up and peak conditions, leading to operational risks.

Given Data / Assumptions:

• Trap is undersized relative to peak condensate formation.
• Normal industrial steam pressures and start-up surges.
• Downstream return piping is correctly installed.

Concept / Approach:
When a trap cannot discharge enough condensate, liquid accumulates upstream. In heat exchangers, this causes reduced heat-transfer area and temperature control issues; in steam mains, slugs of condensate can be accelerated to high velocities, striking fittings and creating damaging water hammer.

Step-by-Step Solution:

Verification / Alternative check:
Manufacturers specify sizing with safety factors for start-up (cold equipment loads). Field experience confirms that undersized traps lead to backed-up condensate and intermittent discharge, not to sustained live-steam waste (which is more typical of failed-open traps).

Why Other Options Are Wrong:

• (a) Live steam waste is associated with oversized or failed-open traps, not undersized ones.
• (b) Rapid cycling/erosion is more linked to differential-pressure variations or dirt, not primarily undersizing.
• (d) and (e) contradict real operating behavior and safety concerns.

Common Pitfalls:
Ignoring start-up loads, neglecting backpressure in return lines, and omitting dirt strainers that protect trap internals from plugging (which can mimic undersizing).

Final Answer:
It will back up condensate and may cause water hammer in the steam line