Is your company's boiler room abnormally warm? Is the boiler's pressure difficult to maintain? These are the tell-tale signs of a steam leak. Leaking steam means wasted energy and wasted energy means wasted money. Therefore, it stands to reason, that for a heating system to be truly cost efficient, regular testing for steam leaks must be observed. In fact, following a simple testing plan can help a facility save as much as 34% on steam energy costs. Leaks can appear throughout the heating system but they tend to reoccur in a number of places. Keeping that in mind, following are a few informal tips for testing key trouble areas:

Some common culprits for steam loss are exchangers, boiler casings and shutoff valves. In these cases, its to a tester's advantage to understand how each trap or valve works under a variety of conditions in order to discover any possible leakage. To detect a leak, the tester should use an ultrasonic measuring device to monitor sounds emitted by the valve or trap upstream. If its necessary to hear the specific sound quality of the fluid, the tester can tune the frequency until the sound becomes clear. The tester should then touch the ultrasonic instrument downstream of the valve or trap and compare intensity and sound pattern levels. If the sound level is greater downstream, it means that the fluid is passing through without problems. If the sound level is lower, it means that a leakage or blockage is present further upstream.

A reoccurring risk area is wherever check valves are positioned closer than three feet downstream of blast action traps. In these situations, flappers occasionally loosen or break free, making them noisy. Using an ultrasonic instrument, the tester can distinguish between normal machine sounds and those of a broken flapper. Another area to be aware of is the diaphragm of air operated control valves. The tester can monitor the area around the diaphragm by listening for the turbulence that accompanies a leak, using ultrasonic equipment to test for internal leakage as for any other valve. Keeping in mind that it is necessary to close the valve, the tester should listen for leakage at the small bleed hole. A leak here is a sure sign that a rupture has taken place.

As for solenoids, the tester should pay close attention to those that are in a closed position. If the tester is ever in doubt about whether or not a valve is leaking, they should compare it with similar valves. Relief valves that have opened by excess pressure may not reseat properly. Some, with softer seats, may suffer microscopic steam and water cuffing. Ultrasonic testing will detect the turbulent passage of steam or vapor as it moves through the leak site. The tester should touch the instrument to the point on the valve closest to the opening and then touch the downstream piping. Once again, the sound of turbulence betrays a leak's presence. If further testing is needed, a hand-held infrared thermometer can detect differences in temperature.

Instituting a regular testing program for leaks in steam heating systems is a sound economic practice. By being proactive, rather than reactive, a company can see significant savings in their steam energy consumption.

Source: Ultrasonic Testing Tips For Steam Traps and Valves
Bruce Gorelick
Maintenance Resources
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