Listen to Your Steam Traps

Checking the sounds they make and other tests can help minimize steam loss

By Riyaz Papar, Energy Columnist

During a recent energy assessment in Thailand, I had the opportunity to work with a steam trap expert at a petrochemical plant. What I saw there and the methodology and techniques used in the steam trap audit prompted me to write this column. I hope you can pick up some good ideas and best practices and implement them in your plants.

Manufacturers estimate that 10% of steam traps fail every year.

Different kinds of steam traps exist and their working principles rely on pure fundamentals of physics and thermodynamics. Knowing the trap type and understanding how it operates is imperative in testing its operating performance. The U.S. Department of Energy Steam Best Practices program advocates annual testing of all steam traps. Steam trap manufacturers and service providers estimate that 10% of steam traps fail every year. Should we care about this? Absolutely. Steam trap failures are classified generally as open and blowing; partially leaking; failed closed; and cold and plugged. Significant problems associated with these failures include energy loss, reduced operating capacity of process units, water hammer, and system reliability issues. So, the bottom line is we can’t afford to have failed steam traps in our plants!

The three main testing methods for steam traps include visual, thermography and ultrasonic. Most times, you will need a combination of these to confirm steam trap operation because a single methodology may not provide conclusive results. For instance, visual has limited applicability because most condensate return systems are closed systems.

Reduce costs associated with using and generating steam

I have used screwdrivers and stethoscopes to listen to steam traps but that’s really old school. Nowadays, ultrasonic methodology is considered state-of-the-art steam trap testing and for good reason. With enhanced technology and sensor advances in industry, ultrasonic testing of steam traps has become very cost-effective. On my energy assessment trip in Thailand, we used an ultrasonic tester along with a visual wave editor that not only provided me the capability to hear what was happening inside the steam trap but also a visual temporal signal of that audio file. In addition, we were able to estimate the flow through the traps. Doing all this in the field and going from one trap to another was an excellent experience for me and well worth it from a learning perspective as well as providing value to the energy assessment.

Training is absolutely essential before undertaking ultrasonic inspection of steam traps. This is because it’s important to differentiate the acoustics from the traps. Certain traps (thermostatic, float and thermostatic) can have a continuous mode of operation and you must know how liquid, vapor and two-phase flow sounds through the orifice. Other traps (inverted bucket, thermodynamic or disc) will always have an on/off operation; so you should be able to hear the exact transition from on to off. Steam trap manufacturers and their service provider partners are a very good resource for undertaking steam trap audits and can provide hands-on training and understanding of steam trap operations. I highly recommend you work with your vendor to implement an ultrasonic-testing-based inspection methodology for steam traps.

Like everything else around us, steam traps have become smarter and manufacturers have incorporated intelligent sensors for continuous steam-trap monitoring. This allows plant operators to know immediately a trap’s operating status. You often can justify smart steam traps at certain locations in critical processes. Never forget that implementation of a steam trap management program can offer important benefits beyond energy savings: the reliability of operations, safety, and avoiding unplanned costly shutdowns.

As we work to make our systems efficient, our steam traps also have evolved. For instance, I came across one interesting variation of a steam trap that had heat recovery built into it. Given the industry knowledge base and expertise, I am sure technology will continue to make more efficient and robust steam traps, and our testing methodologies will ensure proper operations for years to come. For now, let’s just go and listen to them!


Riyaz Papar lg2Riyaz Papar, PE, CEM, is director, Global Energy Services, at Hudson Technologies Company, Pearl River, N.Y. He has more than 20 years of experience in industrial energy systems and with best practices. He also is a U.S. Department of Energy (DOE) Steam Best Practices senior instructor and a DOE steam energy expert. He has provided energy consulting services in 100+ industrial plants in the U.S. and internationally. You can email him at rpapar@putman.net.

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Comments

  • Great article Riyaz! Good suggestions. For the most critical traps, we recommend going one step further and applying a more real-time approach. There are non-intrusive wireless sensors available from the likes of Emerson and Armstrong that use ultrasonic and thermal measurements with some intelligent analytics to reliably determine the state of a trap. Now maintenance is notified within minutes/hours of a failure rather than waiting months for the next trap audit. With some planning, these wireless systems pay for themselves within 12-18 months.

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  • Dear Mr. Gustafson: Thank you very much for your insight and information on the real-time state-of-the-art technologies in steam trap management. I agree with you very much on the ability of today’s wireless sensors and the combination of acoustic and thermal signatures to understand trap operations real-time. I have seen some of these in industry at critical locations – steam turbine inlet knock-out pots, exit of large heat-exchangers, reboilers, etc. It is good to see that they have become very cost-effective as you have mentioned. That would surely be a big plus for industry since most of our maintenance budgets are heavily reduced. We run our plants with minimal maintenance staff and these technologies would clearly help in keeping those traps working and inform us of any issues. I hope that industry moves more towards embracing these technologies and it would become a standard one-day. For now, I think we are still working with traditional but well-understood methodologies and I was hoping that my CP column would stir an interest for industry to start doing something about steam trap management. Hence, your comment is well appreciated and I am hoping to see the wireless smart steam trap technology become a standard in industry. --Riyaz Papar

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  • Thank you for this insightful article. Many years ago, I worked for the DOE and steam trap maintenance was a strong program at our laboratory in our efforts to manage the site facilities and non scientific equipment. In my private consulting business, I have begun advising on steam trap management for traps used in physical plant - facility operations. Your comments will be forwarded to clients as I encourage them to pursue a maintenance program and manage steam energy more efficiently

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  • Mr. Morrison, I wish all the best and success in your consulting work and in improving the energy efficiency of steam systems using state-of-the-art technologies for steam-trap management. -- Riyaz Papar

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