Many commercial and industrial buildings use steam systems to provide intense heat where needed, often over long distances.
As with everything in life, it’s not a perfect system, and along the way, steam can condense back into water, forming condensate. This condensate, along with impurities and gases, must be removed to maintain efficiency and ensure the safe, long life of the system.
This task is the steam trap’s job. Proper trap maintenance, beginning with a survey and inspection, helps contain costs now and in the future.
There are many types of steam traps, depending on the system’s demands. But they all perform the same job. They are automatic valves that release condensate while minimizing live steam loss.
The majority of steam traps have moving parts and a float bowl. The condensate collects in the bowl and periodically flushes out of the trap by opening a valve. Otherwise, the valve keeps the trap sealed and the live steam contained in the system.
Moving parts can fail, and the components of a steam trap are no exception. So the valve can fail open, closed, or somewhere in between.
Failed open causes excessive energy use, noise, and unnecessary heat/steam in the condensate return lines. Failed closed causes condensate to build up in the trap, backing up and flooding the heat exchanger, rendering it inoperable.
Condensate can also back up into the main steam header under this condition. This condensate reduces the system’s efficiency and, if carried along with the moving steam in the main, can cause a condition called “water hammer,” which can be very damaging to the system. A valve stuck partially open can both waste heat and prevent enough condensate from draining.
Failed-open traps allow live steam to escape, resulting in energy loss and elevated operating costs. Multiply this condition by several traps, which can number into the hundreds, and building owners and management companies face significant unnecessary expenses.
The boiler uses more natural gas or electricity to produce more steam to make up for the leaking traps. The boilers may be able to provide enough steam to make up for the leaks. Or the system operator may have cold spaces or processes that cannot run at full speed because the required steam energy has leaked elsewhere.
Failed-closed traps do not allow steam to escape. But they affect the system’s efficiency because the space in the pipe that should contain high-energy steam is filled with low-energy condensate. Equipment will have a lower output, or the boiler will work harder to catch up, or both. Another issue is that condensate will travel through the system, often at high speeds.
A slug of condensate can be very destructive to the system by slamming into components. This condition, as mentioned above, is known as hydraulic shock, or water hammer. Resulting problems can range from annoying noise and vibration in the pipes to ruptured pipes.
A pipe rupture is extremely expensive, requiring not only a shutdown and repair of the system but also repairs to the surrounding area for steam and water damage. It is a safety issue and may cause injury to people in the area.
The US Department of Energy reports that steam systems that haven’t been maintained in the last 3 to 5 years are likely to have up to 30 percent of their traps fail. Routine steam trap surveys and inspections help mitigate costs by identifying issues before they escalate.
Remember, these tests have to be performed while the system is running and producing steam. So it’s essential to coordinate the survey with the system operator.
Failed traps are usually replaced when the system is offline. Or, if the designer was wise enough to install valves to isolate the traps, the valves can be closed, allowing trap replacement while the rest of the system remains operational.
A great example is space heating systems. Test them in early spring, just before the system is turned off. Then replace the bad traps right after the shutdown so the system is ready for the next heating season.
During the survey process, each trap is mapped, tagged, and assessed to determine its functionality. The assessment is usually done one of three ways – visual, thermographic, or ultrasonic – and each method has its own characteristics. Essentially, the technician is checking whether the trap is working correctly and, if not, whether it failed in the open or closed position.
A visual inspection involves looking at the condensate return receiver tank.
The technician must be able to distinguish between flash and live steam from the tank’s open vent line. Flash is caused when condensate rapidly expands due to atmospheric pressure, which is normal. Live steam would indicate a trap that failed in the open position.
Temperature readings provide essential information for trap evaluation. A Thermal Imaging Camera is used to observe the trap’s temperature and internal workings.
Trap temperatures, relative to the pipes leading to and away from the trap, can be analyzed instantly. Since the camera can be used at some distance from the trap, this method is useful when it’s not practical to be close to the trap as required by other methods.
A cold trap that is significantly cooler than the pipes indicates the trap has failed in the closed position and is likely filled with condensate.
A trap with a temperature equal to that of the nearby pipes can be in one of two conditions. It can either operate properly or fail open and release live steam. In this case, further evaluation is needed.
The flow of steam through a trap generates both sonic (audible) and ultrasonic (inaudible) sounds. With the right equipment, a technician can hear these sounds and assess the trap’s health.
Much like a doctor’s stethoscope, ultrasonic detectors amplify signals and convert them into sounds the tech can hear and evaluate. Not only will they hear the steam flowing through the trap, but they can also hear the mechanisms inside it working.
The ultrasonic method has typically been the preferred procedure for years, but the Thermal Imaging Camera has been gaining ground as the preferred method for accurate steam trap diagnostics.
Future cost savings and the prevention of potential catastrophic failures are the most significant benefits of completing a steam trap survey and inspection.
For instance, in a building where the cost to produce steam is $10.00 per 1000 lb/hr, an inspection reveals that a trap on a 15-pound-per-square-inch gauge (psig) steam line has failed in the open position, with a trap orifice of 1/8-inch in diameter. The US Department of Energy guide states that the estimated steam loss is 13.7 pounds per hour. If we assume the system operates continuously (8760 hours/year), repairing one failed trap saves $1,200 per year.
Yes – that’s the savings for repairing just one failed trap. If there are 500 traps and thirty percent of them are bad, that results in an annual energy savings of $180,000.
Remember, most of the numbers used in the example are very conservative, and the savings potential for higher pressures or larger trap orifices is much higher. So, knowing how your traps are performing with a survey pays off.
In many locations, utility companies offer financial incentives to repair or upgrade faulty equipment. The steam trap is no exception, and the incentive amounts often reflect the excellent energy savings it delivers. Incentive programs may require a survey and/or replacement of the failed traps within a specific time frame.
Check out DSIRE for incentives available across the US, and be sure to follow the requirements for the program in your area.
ACSI Mechanical Group routinely performs steam system inspections for our customers. We tag all traps, write up our findings in a full report, and provide photos and a map of all the traps in the facility.
Any traps that have failed will be noted, as well as any aging equipment that may not last much longer. Inspecting traps annually is ideal, with no more than 3 years between inspections.
In the end, it’s a simple formula – do a survey, replace failed equipment, and save energy and money. We have expertise with the equipment and experience with incentive programs. We can also help you with the paperwork for your incentive program.
We look forward to building long-lasting relationships with all our clients. Call (773) 737-9200 today to plan your steam trap maintenance program.