The valve that tells steam and water apart
A steam trap has one job: let condensate and air out of the system while keeping live steam in. Every heat exchanger, drip leg, and tracer line depends on one. When traps work, the system is quiet and efficient. When they fail — and they fail constantly in unmaintained plants — steam blows straight through into the condensate system, and you pay to make that steam twice.
The three families
- — Mechanical (float & thermostatic, inverted bucket): a float or bucket physically rides the condensate level. F&T traps dominate heat exchangers; inverted buckets shrug off water hammer.
- — Thermostatic: open and close on temperature difference — condensate cools slightly below steam temperature. Common on radiators and tracing.
- — Thermodynamic (disc): a single disc snaps shut on flash steam velocity. Cheap, compact, great on drip legs — and the most commonly misapplied trap in industry.
Failed open, failed closed — both hurt
A trap failed open blows live steam into the return — pure fuel waste, often thousands of dollars a year per trap. A trap failed closed floods equipment with condensate: water hammer, corrosion, and heat exchangers that suddenly can't keep up. Industry surveys routinely find 15–25% of traps failed in plants without a testing program.
Servco carries Spirax Sarco and other major trap lines and our technicians test and survey traps as part of steam system service. If your plant has never had a trap survey, the payback is usually measured in months.
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Quick answers
How often should steam traps be tested?+
Annually at minimum; critical or high-pressure traps more often. Ultrasonic and temperature testing catch failures a visual check can't.
How much does a failed-open steam trap cost?+
Depends on orifice size and steam pressure, but a single mid-size trap blowing through commonly wastes several thousand dollars of fuel per year.
Why does my heat exchanger hammer and bang?+
Classic sign of a failed or undersized trap letting condensate accumulate. Water hammer is condensate being slammed by steam — fix the trap before it fixes your gaskets for you.