The use of airborne/structure borne ultrasound for leak detection extends way beyond compressed gas leak detection. There are many opportunities to inspect valve conditions, especially in steam systems.
Bypass valves around steam traps or control valves should be checked for leakage. They can easily be wire-drawn because of operator error or seat erosion. These valves have the potential to cause huge loss of revenue if they are passing steam. Imagine a three-quarter-inch bypass mistakenly left open for a prolonged period of time.
Control valves may be leaking through because of a seat that has become wire-drawn. Check for proper seat closure as you normally would when testing a steam trap. Touch the up and downstream sides and the closure point with the stethoscope (contact) module for leakage. If the valves have rubber diaphragms, use the airborne module to scan for external leakage. Also, use your infrared thermometer to see if seasonal valves are passing steam when they should be shut.
Relief valves should be tested like any other steam valve or steam trap. Use your handheld infrared thermometer to see if any leakage is occurring at the downstream vent line. Listen to the relief valve and determine if leakage across the seat has occurred.
Scan the external fitting and gaskets of all components of a vacuum system. Leakage can dramatically affect the proper operation of this system. Use your airborne module for external leaks and your stethoscope module to test system valves for internal leakage.
Packing glands or flange leaks can be real energy wasters in the steam system. They start off generally as a small leak and then escalate into larger leaks. Packing glands of control valves and shut-off valves should all be scanned with an airborne scanning module. Listen for turbulence, which will have a similar sound to that of a normal air or gas leak. Be sure to scan the gaskets of your air-operated control valves. On-the-spot fixes may be as easy as tightening the bolt arrays.
Loose check valves make a distinctive clicking or rattling noise when they’re loose. Although steam trap manufacturers suggest check valves be installed no closer than 3 feet from blast action traps, they are frequently damaged as a result of improper installation. For instance, a blast action trap from a thermodynamic trap is violent and will loosen check valves placed directly downstream of them. To test, touch the check valves with the tip of your stethoscope module. If doubt arises, make comparisons between other check valves installed in similar instances.
Shaft packing leaks around steam turbines can be especially annoying and difficult to determine. Ultrasound scanning with the airborne module has proven quite effective in identifying leakage. There are specialized modules for challenging leak environments. Check to see if the manufacturer of your ultrasonic scanner offers a choice of modules to help in these situations.
Solenoids can be damaged or fail due to normal wear. Dirty systems can see solenoids clogged or held open by debris. Touch the solenoids with your stethoscope module and listen to each of them. Are they open when they should be? Are they leaking? Use your airborne scanning module to see if any gasket or o-ring leaks exist.
Boiler casings may develop hairline cracks in them from fatigue. Use your airborne scanning module to scan the exterior of the boiler for small leaks.
Insulation in your steam system is only effective if it stays dry. Leaks under insulation are usually identified by scanning system steam distribution piping with your airborne module.
Cavitation in pumps is defined as the formation and collapse of vapor pockets or bubbles on the blade of an impeller. These pockets or bubbles drive water with such force they can cause pitting on the surface of impellers or casing. Pump cavitations can usually be identified by touching the casing of centrifugal pumps with the stethoscope module. The collapse of the bubbles makes a distinctive sound.
The old adage “use what you have first” should definitely apply to the expensive equipment you purchase to start your program of valve testing.
For more information, visit www.uesystems.com or call (800) 223-1325.
