Steam Valve Internal Leakage Detection – Part One
My name is Kelly Paffel, Technical Manager for Inveno Engineering, LLC, located in Tampa, Florida. We’re a domestic and international company focused on steam system engineering and designs. Today I want to talk about steam valve internal leakage detection and testing methods. This is part one of a series. And today I want to go through the type of equipment used for testing steam valves.
Steam valve internal leakage testing. Steam valves installed in industrial plants create a perplexing problem because of the difficulty to determine if the steam valve is leaking steam through by conventional testing methods. Due to the testing difficulty to analyze, therefore it really costs industrial plants millions of dollars in unwanted downtime. Using high-frequency ultrasound and the proven test methods, then internal leakage can be easily determined.
So this valve leaking through, we don’t know if this valve is leaking through or this valve is leaking through, and we end up shutting down part of the production or the whole plant to fix steam valves.
The steam valve testing by temperature. The thing with temperature is if we take a temperature here, it’s a 100 PSI. It’s going to be 338 degrees Fahrenheit. The thing with temperature, the temperature is transmitted through the valve, and back on this side of the valve, it could be 280 degrees Fahrenheit and the valve is seated. Or it could be 280 degrees and the valve is leaking through.
So profiling by temperature is very difficult to do. Therefore, we tend to use high-frequency ultrasound and high-frequency ultrasound is like riding a bicycle. The more you use it, the more proficient you get with this. In segment two, we’ll go through and talk about testing points on the valves, where the tests, the different readings that you’re going to get. And from the readings, you can determine if the valve is leaking through or not. It’s really the most reliable test method and ultra high frequency ultrasound, we want to look at frequencies about 25 kilohertz, which is above the human threshold of hearing.
The test method has many advantages. It also has disadvantages. And it’s more important to understand that disadvantage is a work around that, but it’s been proven to be an easy and accurate test method. And for about 98% of the applications that we find in steam valves. So it’s highly accurate. It’s fast and easy. Today the high-frequency ultrasounds are electronic versus the digital versus the old analog units. The other thing is, is that the information can be displayed. And this is a simple unit of the different units that are produced today for high-frequency ultrasound, which other units even give you more information.
So technology has really improved for testing valves. The thing about it is, is one of the things with high-frequency ultrasound is blocking now competing high-frequency ultrasounds in the system for coming down here and testing this valve versus this valve. The thing is, is that we can block out the ultrasound that might be high-frequency ultrasound that might be generated with this valve here. And then we can get an accurate test on this valve here. So the thing is, is that going through an SOP; standard operating procedure for testing valves, then the person can get very accurate with testing steam valves for internal leakage.
Like I said, it’s fast and easy, highly accurate. Can detect many other defects in the system. So it’s used for testing steam traps, fire, air leaks, vacuum leaks. Always with any tool training is required. The thing with training is when you started to learn how to ride a bicycle, somebody trained you or give you guidance how to get onto the bicycle and start to pedal. The more experience you get with it gives you a higher accuracy, and it’s the same thing as riding a bicycle.
The more you use it, the more proficient you get with it. And that’s the same thing with high frequency ultrasound. A little bit on the technology, is that anything passing through a leak point will have a turbulent flow. So steam passing through a valve that’s closed and that’s a steam passing through the valve seat and the device that’s closing, which is a cage, globe, gate, or ball that steam passing through that restriction will generate a turbulent flow. This turbulent flow will generate a high frequency ultrasound, which this unit will pick up.
Now how to adjust the answer meant for testing. The thing is, is that you can adjust the sensitivity and the thing with sensitivity, it’s not volume, it’s sensitivity. So the thing is, is that the higher number detects lower sound levels. So as you go up in the numbers, the more sensitive that you’ll make the unit. The thing is, is understand that because when we get into part two, we’ll talk about baselining the valve to determine if it’s leaking through or not, and it will show you how to set that up.
But anyway, the thing is, is that we want to look at typically around 40 kilohertz and some people use 25 kilohertz. Other people use 40. It’s really up to your preference where you get the best clarity for the valve that you’re testing. So I guess what we’re saying is you have options with it, but it’s for the person going up to the valve, start at 40. You don’t like the clarity, you can go to 25.
The thing with valves is how to get started. How do we get started? Let’s let testing team members. Typically two people is better than one. Then you can go out and you’ll have a person to write information down and the other person to do the testing. Select the correct equipment. When you go out like to do anything, you always have the correct equipment. As I said before training. The thing about it is, is any testing determine the data collection process.
And the other thing is priority for testing the valves. And anything else is correction roadmap. Where’s the roadmap? Which are the higher priorities, the lower priority valves? And of course, after the new valves are installed or corrections have been made, validation. A very critical part of it. Steam valve types. There’s three major ones that we use in steam system. Probably one of the big one is isolation valves are used throughout the steam system for isolating segments actually in valving.
The next one is control valves. And again, we control the steam for pressure reduction or temperature control. And other types can be warm up valve and safety valves. So those are the three major areas. So isolation, probably the most dominant steam valve out there, but we also have control valves and other types of valves are used. Our website right here, all the technical papers are up there. There’s right now, I believe almost 70 technical papers plus articles and videos on a multitude of different things regarding steam systems for your reference and use.
The little bit on our company, we have short-term and long-term impacts. We do steam system engineering assessments, steam system reliability, engineering and training, implementation for engineering, project design, project management.
Contact information. You can contact me or contact Graham or come to our website and use the contact [inaudible 00:09:18] or any of our people in our office. And the last is thank you for your time and if we can be a service, we would love to. Have a great day.
