Steam Traps

Steam Trap Selection and Maintenance: A Guide to Steam System Efficiency

A practical guide to steam trap selection criteria – pressure, condensate load and application – plus installation, testing and maintenance practices that catch steam leaks early.

ORFA Technical TeamUpdated: Oct 30, 20263 min read

Steam trap selection and maintenance guide

One of the most effective ways to save energy on industrial steam lines is to choose the right steam traps, which discharge condensate while holding back steam, and to maintain them regularly. Correct steam trap selection improves heat transfer, reduces the risk of water hammer and prevents live steam loss. A wrongly selected or faulty trap either leaks steam and wastes fuel, or waterlogs equipment and costs production.

This guide briefly recaps the trap types, lists the criteria to consider when selecting a trap, and gives installation, testing and maintenance recommendations for long, efficient service.

Steam Trap Types at a Glance

Float steam traps: Discharge condensate continuously as it forms; ideal for variable-load heat exchangers and process equipment.
Thermodynamic steam traps: Compact, robust and suitable for high pressures, they are preferred for mains drainage.
Thermostatic steam traps: High air-venting capacity; used on tracer lines and sterilisation units.

Key Selection Criteria

Criterion	Why it matters
Operating pressure	Determines body pressure rating and valve orifice selection.
Differential pressure	The difference between inlet and outlet pressure sets discharge capacity; back pressure (return line, lifts) must always be taken into account.
Condensate load	Besides the running load, consider the start-up load when heating a cold system, which is often much higher.
Application	Mains drainage, temperature-controlled heat exchangers, tracing or sterile duties call for different types.
Ambient conditions	Outdoor installation, freezing risk, water hammer and superheated steam rule out some types.
Connection and material	Threaded, flanged or welded ends and body material must suit the pressure-temperature conditions and piping standard.

Tip: Size a steam trap from the manufacturer’s capacity charts based on differential pressure and condensate load, not on pipe size. An oversized trap can wear faster and tends to leak steam.

Correct Installation

One trap per item of equipment: Connecting several units to one trap (group trapping) can cause condensate to back up in units running at different pressures.
Strainer: If the trap has no integral screen, fit a strainer upstream.
Isolating valves: Valves at inlet and outlet allow maintenance without shutting down the system.
Means of checking: A sight glass or test valve downstream of the trap makes checking its operation easy.

Testing and Maintenance

Steam traps fail in two ways: failed open, leaking live steam, or failed closed, causing condensate to back up in the equipment. Both create costs for as long as they go unnoticed. A regular checking programme can include:

Visual checks: Observing condensate and steam flow through a sight glass or test valve.
Temperature measurement: Comparing inlet and outlet temperatures to detect waterlogging.
Ultrasonic listening: Listening to the trap’s operating sound to identify continuous steam leakage.
Automatic monitoring: Continuously monitoring critical points for steam leaks with steam trap control devices.
Periodic cleaning: Cleaning strainer screens and renewing worn valves and seats with spare parts.

Frequently Asked Questions

Is a steam trap selected by pipe size?

No. A steam trap is selected from the manufacturer’s capacity charts according to differential pressure and condensate load. Even if the connection size matches the pipe, the capacity may not be suitable.

How can I tell if a steam trap is leaking steam?

Continuous live steam in the downstream sight glass or test valve, a continuous flow sound during ultrasonic testing, or unusually high temperature and pressure in the condensate return line can all indicate a steam leak.

How often should steam traps be checked?

It depends on pressure, criticality and operating conditions. High-pressure and process-critical points should be checked more frequently.

Conclusion

Correct steam trap selection and regular maintenance prevent steam leaks, cut fuel costs directly and reduce plant downtime. Browse trap models with stainless steel internals and easy maintenance in our steam traps product group, or contact the ORFA technical team for selection support.

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