Steam and Condensate Leakage Causes and Corrections
My name is Kelly Paffel, Technical Manager for Inveno Engineering, LLC., Tampa, Florida. We’re an international engineering firm focused on steam and condensate systems. Today, I would like to talk about steam and condensate leakage, causes and corrections. Steam and condensate leakage prevention. To improve the steam and condensate system change must occur. Without no change no improvements will occur. What we did in the steam and condensate system five years ago is not what we to do today. So, we have to continue to change and improve the system by introducing new and latest technology.
Change means a raise to a more desirable quality or condition and make better. Steam and condensate leakage. Steam and condensate leak has a negative effect on the steam system and plant operation. Steam leakage has a loss of both sensible and latent energy and leakage erodes or wire draws. So, a small leak today will increase in size tomorrow, and the day after, and the day after. Therefore, we have to be very proactive in what we’re doing with the steam and condensate system regarding leakage, we must be very proactive. Permanent damage, it’s to the components, happens all the time due to steam leakage. The other thing with steam leakage or condensate leakage, it increases emissions, it’s more energy out to put in the boiler to produce the steam than losing through leakage.
Steam leakage correction. It’s one of the top five greatest paybacks in the steam system. Correction improvements in the steam system are greater payback than we have, let’s say, for steam traps, or other devices out there, so it has a great payback. It’s one of the top five. Mostly, it’s going to be corrected without capital expenditure, minimal capital expenditures, which is another great benefit to having a proactive program.
Steam leakage. Steam and condensate leakage has a negative impact on steam system and plant operation due to reliability failures with valves, connections, flanges. It causes production issues. This small leak that you will see right here, in the picture here, has a leakage of $1,780 per year. [inaudible 00:03:14]. And, to cost $1,780, just for a small leak, is something we cannot accept today.
The thing about leakage is that we have to understand what causes leakage and probably the number one on any steam leakage, or condensate tube leakage, assessment and a root cause analysis, connections. Number one, threaded connections. They are notorious for failure. This is number one. Every time we do an assessment. The other is tube fittings. Valve internal leakage, external leakage, waterhammer, flanges, piping, leakage costs. So, this small leakage here is costing $2,440 a year. So, to go by a leak and accept it as normal, it is not normal. It’s abnormal.
I was talking about NPT connections, threaded connections, highest failure in all steam leakage assessments. The thing about it is, do we know that the threads are made to NPT, or PT, or NPT? There’s so many variations. The other thing is is that no one out there gauges the threads to make sure they’re cut correctly and that also causes issues. And then, the thing about it is people go and use a Teflon tape, but do they know how many wraps it should be and how to wrap it? And then, what are the other sealants that we’re using to help seal the connection? The connection’s not going to be sealed by the materials that we’re putting onto the threads. The taper of the thread does the sealing of the thread. So, if you go and look at different technical papers on NPT connections you’ll get 10 different opinions on how to get these threads to seal.
Expansion and contractions. The thing is is that we’re asking the NPT to take up the expansion and contraction. It’s just not going to be very good for the threads. And then, corrosion. We have CO2 corrosion and we have oxygen corrosion, which will eat the threads away. And then, the next thing is the installation, how people are putting in the devices. How they are torquing the threads. There’s not a torque thread spec for NPT connections. The thing is tighten it until you tighten as possible and then hit with the wrench, with a hammer three times and try to get it even tighter. That’s not torque. So, it causes major issues. The people with proactive prevention programs with steam and condensate leakage has eliminated, eliminated NPT connections, unless it’s absolutely necessary. So, this leakage you see here has a cost of $4,190 a year. You take it and look at the plant and all the leaks the cost adds up significantly.
NPT connections, just procedures. We’ve tried to follow ASME B1.20.1. It’s standard pipe thread and general purpose inch. It comes in dimensions and gauging. I’ve talked before, NPT, NPSC, NPTR, NPSM, NPSL. And then, it comes down to what is the correct method for sealing the threads? And, what is the material, what is the correct torque? And, the thing about it is, once you put a thread in does anybody validate that the thread does not leak? So, there’s so many things within PT connections and people say, “What’s the best solution?” Don’t use NPT connections. There are other ways that we can do to seal the connections. Number one is welding. So, we try to weld everything and 15 PSIG, or higher, require certified welders to do the welding. It’s per power piping code B31.1, which most countries in the world does recognize that code. The thing about it is, the certified welder, once he does the weld the welds do not leak. So, we make sure we have leak-proof.
And then, the thing is people ask, “Well, how do we work on the equipment?” Well, there’s different methods that we can do. There’s unions today that are like flanges that we can socket weld in and then there’s a gasket just like a flange that we can take equipment out. So, there’s a lot of technology changes today. And, the other thing is is tube fittings. Instead of you saying, “I don’t want to weld,” then use tube fittings. We use tube fittings all the way up to 5,200 PSI. So, it’s quite acceptable to use it in steam systems. If leakage occurs on a tube fitting it’s due to improper installations, because most tube fitting companies guarantee their connections do not leak. So, we use a lot of tube fittings today, and especially tubing is for installation purposes. As you can see right here, this is a steam trap station, just a common component in the steam and condensate system and we’re using tube connectors to put this assembly together, so we have no leakage. So, easy installation. And, this piping, or tubing, this piping arrangement is really in tubing. So, we get the benefit for that.
The next is to use flanges and people say, “Oh, flanges leak.” Flanges do not leak. You have to know the torque specification for flange gasket material today. Then, you also need to know the torque pattern. The other thing with flanges is that we want axial movement only on the flange. So, if we think that we’re going to have something other than axial movement then we will guide the pipe, not support, but guide the pipe. And, the guiding the pipe will make sure that we only have axial movement only. And then, the other thing is making sure we have the proper material selection for the flange installation. If it’s done correctly, I’ve seen flanges out there installed for 40 years and no leakage. And, flanges always show up as one of the least components in the steam system that has leakage issues.
The second thing that’ll show up is valves in, specifically, two areas as the internal leakage, or that means internally to the valve. The thing is is that I now talk about the specified in the correct valve, but do we have valves out there for blow-off valves, isolation, drain, and etc.? External leakage, probably the biggest thing with valves, we use gate and globe valves. And, it’s right here, the packing. The thing is is that you have to realize that the last great revolution we had in gate valves was 1941 and there’s not going to be anything new with gate valves. For one reason, is people buying by price. So, the thing is is that we’re looking at how to make the valve more cost-effective instead of reliability. So, the biggest thing is two things, is the packing and then the internal leakage of the valve and you can see the leakage there.
Now, the internal leakage, we go by FCI, which is the ANC standard, or the API. And, the FCI, we want all valves Class 4 or higher. So, these valves here, in the system here, which are common isolation valves here that we are looking to have these valves at Class 4 or higher, or the API. And, these valves here have zero bubbles per-minute per-API. So, that’s a very tight shutoff. The external leakage, technology has accelerated in the last 15 years with ball and butterfly valves, specifically in the seating of the rotating stand that goes in to activate the closing mechanism. So, I recommend to people to use ball or butterfly valves and we use butterfly valves up to 28-inch in diameter and we use ball valves up to 8-inch in diameter for pressures very high, all the way up to 1,200 PSI. So, quite acceptable. And, using a ball or butterfly valve, then we get away from two things, the internal leakage and we get away from the external leakage through the packing.
And so, the next thing we have to deal with is corrosion in the system. And, corrosion is mostly in the condensate system and most of the corrosion is due to CO2 corrosion, or carbonic acid. But, the plant also needs to check for oxygen corrosion. Any time that you have a concentration of oxygen above 200 parts-per-billion you will have corrosion to occur. The thing about the steam piping, CO2 corrosion is not very prevalent and the steam lines, oxygen corrosion is prevalent. So, we need to check the steam system for oxygen corrosion. And, you can see this is a condensate line here that’s been eaten away by CO2 corrosion. If you allow condensate to cool down, then, to roughly around 204 degrees F, the CO2 corrosion gets very aggressive.
Corrosion correction, a proper chemical program in the boiler plant using a means to counter the CO2 corrosion. Condensate lines, we definitely want to use stainless steel. Most people, due to the cost that want to do that, or we use Schedule 80 pipe. So, if we’re going to put a condensate line we will put in a heavier wall pipe. That’s just going to take a little bit longer for the line to eat out. The steam piping, the deaerator needs to be tested. We talked about before for dissolve oxygen, or oxygen corrosion, the dissolve oxygen content and the deaerator should be seven parts-per-billion or less. And unfortunately, people do not test the deaerators, so we’re producing more oxygen out in the system than what they should be producing. And, the thing is is that we want to test the steam system for oxygen, dissolve oxygen, excuse me.
For the leakage and cause and issue, erosion, a small leak will be this size today and tomorrow it’ll be a larger leak. Steam will wire draw or erode the material causing a larger leak. So, the thing is is that once we have a leak and we must get proactive. And, people say, “Well, I can’t shut down,” there are other companies that will come in and seal leaks online. So, we want to look at all aspects to make sure that we have a proper operating system. Leakage and loss of steam pressure causes production issues. Once you drop, have a leak the steam pressures drop, because leakage lowers steam pressure, lowers steam temperature for the process and it happens all the time. A lot in steam tracing systems, when we have leakage in the steam tracing systems and the loss of pressure also equals the loss of temperature and then we get into issues with the process piping either freezing, or starting to plug, major issues. So, the thing about it is is that steam leakage does cause production issues, which we need to be proactive with.
Loss of reliability, and the thing is is that when it comes down to leakage, valve selection, steam trap selection, blow down valve, and material selections, that this happens to be a valve that was recently put in and you can see the leakage here that’s occurring. And, the thing that I talked about before, making sure that [inaudible 00:17:55] for the PCI standard, so we don’t have these issues. The next thing is leakage causes issues, specifically in safety. Personnel injury burns, I can’t tell you how many times I’ve been in a plant and hot condensate coming down from a leak gets onto me and causes irritation, or a slight burn. It’s not very safe. The other thing is is leakage during cooler weather. You get foggy conditions and it becomes a visibility issue. Steam condenses to a condensate, creates water in the air and leakage forms ice in the plant, and it’s slippery, and I can go on with the multitude of things that occur with steam leakage. So, the thing is is that our focus, or roadmap has to be to eliminate steam leakage.
Root cause analysis has to be part of your program to understand what caused the leak and then make changes so it does not occur again. And, one of the things as I look at components, valves, flanges, that they’re leaking, what caused the failure and then make changes in design, selection, installation, so the leaks do not occur again. The other thing is do not accept leakage as normal, it is abnormal. To have a leak, leaks in the system, I’ve been very large paper mills and tell them that I will give you, maybe, two steam leaks per year is acceptable. Anything more than that is not going to be acceptable. So, understand that plant personnel is to not to accept leakage as normal, it is abnormal.
Now, analysis says energy losses can be as high as 19% of the total steam production. So, then that’s an extreme cost, but I want you to understand leakage can be a pretty significant cost. It’s not uncommon to be five, or six percent of the energy produced is lost through steam leakage. I work with a large refinery in North America and they’ve been on this change program for a multitude of years, and they’re down to no more than eight leaks per year, and that’s fantastic, but that is the mindset we need to go through.
One of the things that we talk about in steam leakage versus compressed air, and both you should not ever have leakage at either one, a steam leak costs you $3,591 and compressed air costs you $2,095. Steam leakage has a higher cost to it and more emissions. The other thing is is how do we determine the losses from steam leakage? I think it’s a little bit difficult to estimating the steam loss at atmosphere. You need to know the size of the diameter of the leak, the steam pressure upstream, which is P1, and downstream, P2, will always be atmospheric, or zero.
The thing about basics of a leak is people want to be against P2, and they can use Napier’s equation to come up with the leak flow. The thing you have to remember about the Napier’s equation, it’s a perfect orifice and a leak is not a perfect orifice. And so, we use a constant in the equation to compensate for a jagged edge leak orifice. And, the thing is is that we found use of high-frequency ultrasound, about 55 kHz, using that information, and knowing the pressure, and through testing through different flow meter through leakage that we’ve come up with a pretty accurate method of determining the pounds-per-hour of flow through a leak point. Now, with that said, remember, it is an estimation. Nothing can be perfect, because of the jagged edge of the orifice. But, the high-frequency ultrasound method has been very, very good.
Saturated steam systems, we can just determine the temperature, or determine what P1 is upstream, because people have a tendency not to put gauges at their system. So, we’re trying to assume what the gauge is. So, just knowing pressures upstream using high-frequency ultrasound, 55 kHz, and we can come up with a method of determining how many pounds-per-hour will flow through an orifice. The other thing is is the emission levels. For every leak we can come up with how many pounds of CO2 and NOx, SO2 is emitted, because the steam leak, the more leakage the more fuel we have to put into the boiler to compensate for the leakage that’s occurring outside.
Now, I’ve heard the thing about the steam leakage by the plume and I just don’t think it’s very accurate, because who’s going to go down and measure this plume? And, it’s a ballpark estimation at best. And, you have to know the pressure, the person has to be trained to understand the velocities coming out of it and that valve that’s there, how far it’s open. There’s so many determining factors. So, I go back to what I was talking about before, using high-frequency ultrasound to determine the flow of leakage.
Now, the thing about it is is that we use a variance of Napier’s equation that’s just shown right here to 22.88 times pressure absolute times diameter square. And, you can calculate it out, but there’s no imperfect orifice. So, that’s, again, we go back to using the high-frequency ultrasound. But, anyway. Napier’s equation, eighth-inch orifice, just a couple things on this chart regarding the energy. It’s one-eighth inch at 100 PSI is $3,591. So, it has a pretty substantial energy loss. And then, we get a larger leak, a three-eighths inch leak and on this, here, 100 PSI. Three-eighths is very large, is 32,000. So, that’s a pretty substantial leak. But, anyway. The same in condensate leakage, it costs you money.
So, a roadmap for standard condensate leakage management, institute change. And, the change is knowledge for the people to not accept leakage as normal. The thing is is that we want to go out and correct all condensate leakage, but the thing about going out and correcting a leak that we have to do root cause analysis to understand what caused the leak and make changes so we don’t have the leak again. The other thing is that we want to validate the changes if we’re successful, because the thing is we don’t want to institute a program and then come back two years from now and have the same amount of leakage that was occurring. So, we want to validate and institute the change and go from there.
So, today’s operation, zero leaks. There’s no reason to have steam, or condensate leakage today, there’s not. I go into plants all the time and there’s just no leakage. People have instituted the correct changes. So, then I go in plants, every two feet there’s leaks all over. So, this is what we want to see today. There are no steam leaks anywhere in the facility. So, it costs too much money to have them.
The world of steam, I travel the world and in the next few weeks I will be traveling back to Asia. The thing is is that there’s plants all over the world that achieve zero leakage and that’s the same roadmap it should be for your plant, zero leakage. But, anyway, that is my presentation for today and we’ll go back over to here. So, if you have any information you may contact me here at this right here. If you ever have questions regarding steam and condensate, by all means, contact me. Give me an e-mail. The thing is is that I know what works, but I also know what does not work. So, I’ve seen everything that does not work at least once or twice. So, anyway, have a great day and remember steam is perfect.