Why do steam traps fail? What can you do about it?

Alan Bandes, UE Systems Inc.; Bruce Gorelick, Enercheck Systems
Tags: ultrasonic inspection

Properly functioning steam traps open to release condensate and automatically close when steam is present. Failed traps waste fuel, reduce efficiency, increase production costs and compromise the overall integrity of the steam and condensate systems. Traps should be tested on a regular basis – or the neglect may be quite costly. 

Failed steam traps negatively impact the entire steam system: They …

Steam energy conservation is important to our national interest; examine the government figures below:

Source: U.S. Department of Energy. Energy Efficiency and Renewable Energy.

OK, so just why do steam traps fail?
Obviously, anything mechanical will malfunction; steam traps are no exception to the rule. Proper maintenance improves longevity and helps reduce maintenance costs.

There are three general conditions which adversely affect traps:

A 600 psi rated steam trap is being ultrasonically tested

How do we keep problems to a minimum and keep energy costs in check? One simple way is to look for warning signs. Let’s review the most evident signs that should signal a distress call from your steam system.

After an ultrasonic test found the trap to be blowing, the downstream condensate line was shut and the test valve was opened to verify test results. The system pressure was 270 psi. At the cost of $10 per thousand pounds of steam produced, the energy loss for this single blowing trap is $21,000.

The action plan

Purchase proper test equipment
Even if outside technical professionals are contracted to test the steam system, from time to time, a problem will occur. Time is money. Having the proper equipment and just one trained employee can avoid costly downtime. The two basic pieces of equipment to own are an infrared thermometer and an airborne ultrasonic instrument. Such equipment is readily available in all price ranges. A thermometer with simple features is fine; however, an ultrasonic listening device should be selected more carefully and must have clear signal quality.

This is similar to purchasing an audio system for your home and comparing one set of speakers with another set. When listening to a quality speaker system, the nuances of what was actually recorded open your ears to a new level of listening. The same is true of listening to a steam trap. With a fine instrument, you can even hear the snap-crackle-pop of steam passing across the head and seat of a wiredrawn inverted bucket trap. After all, “hearing is believing.”

Before you begin
Before you spend your hard-earned money, consider some of the following characteristics of the ultrasound instrument:

Purchasing an ultrasound device should take intelligent consideration. The instrument must be capable of providing you a clear and discernable signal quality. Labor hours and equipment costs depend on it.

Why use ultrasound to test traps?
Of all the inspection methods, ultrasound is the most recommended and reliable. Ultrasound is a shortwave, high-frequency signal that does not travel far from its source. By listening to the ultrasonic components of a working steam trap, a user can isolate the signal and easily identify operational sounds. Ultrasonic testers translate high-frequency emissions generated from the mechanical and fluid flows of traps into the audible range where they are heard through headphones and seen as intensity levels on a meter. Some units have frequency tuning to filter out additional signals and to tune in to the sounds of steam and condensate. Testing steam traps with ultrasound provides results in real time. It isolates the area being tested by eliminating confusing background noises. A user can quickly adjust to recognizing differences among various steam traps.

The ultrasonic detector may be the easiest to use, most flexible and most accurate of the sound testing methods. However, the ultrasonic instrument cannot tell if a trap is cold or blocked. Therefore, first use a temperature indicator instrument to be certain that the system is operating. Then use the ultrasound instrument to determine if the trap is partially blocked or if back pressure exists at the traps outlet.

About the authors:
Bruce Gorelick is the vice president for Enercheck Systems, based in Charlotte, N.C., and Alan Bandes is the vice president of marketing for UE Systems, based in Elmsford, N.Y. For more information on these companies, visit www.enerchecksystems.com and www.uesystems.com.