Join us in unraveling the mysteries of overfill prevention valves as bulk fuel storage expert Shannon Oelkers addresses a listener request. We learn how to recognize and locate an overfill prevention valve on a tank before diving into how they operate and why they are essential. Our conversation covers the valve's role in SPCC regulation and how those can vary between different states, followed by Shannon's expertise shedding light on maintenance and how to avoid common mistakes when working with these powerful yet delicate machines. Tune in to get answers to your lingering questions regarding overfill prevention valves!
This podcast is for informational purposes only and should not be considered legal or regulatory advice. We are not responsible for any losses, damages, or liabilities that may occur from using this podcast. This podcast is not intended to replace professional regulatory or legal advice, and the views expressed in this podcast may not be those of the host, which would be me or Integrity Environmental. Thank you very much for listening. We would be happy to provide professional regulatory advice as part of our consulting services if you need professional regulatory advice.
Join us in unraveling the mysteries of overfill prevention valves as bulk fuel storage expert Shannon Oelkers addresses a listener request. We learn how to recognize and locate an overfill prevention valve on a tank before diving into how they operate and why they are essential. Our conversation covers the valve's role in SPCC regulation and how those can vary between different states, followed by Shannon's expertise shedding light on maintenance and how to avoid common mistakes when working with these powerful yet delicate machines. Tune in to get answers to your lingering questions regarding overfill prevention valves!
This podcast is for informational purposes only and should not be considered legal or regulatory advice. We are not responsible for any losses, damages, or liabilities that may occur from using this podcast. This podcast is not intended to replace professional regulatory or legal advice, and the views expressed in this podcast may not be those of the host, which would be me or Integrity Environmental. Thank you very much for listening. We would be happy to provide professional regulatory advice as part of our consulting services if you need professional regulatory advice.
Welcome back to Tank Talk. We are in season two. I'm excited to kick off our season with a listener request covering something that I don't really know much about Shannon.
Shannon:
Ooh, what is it? Tell me more.
Amanda:
We got a listener request to go over overfill prevention valves.
Shannon:
Oh, that is a good one.
Amanda:
Yeah, so what are they and where are they? On a tank.
Shannon:
Ooh, it's a mystery. Overfill prevention valves are usually along the top line of the horizontal tank and they are on top of a vertical tank. Technically they're an automatic flow restrictor or flow shutoff mechanism. There can be different ways to achieve this, but most overfill prevention valves are an inline flow that turns a valve component when it's floated. That effectively shuts off the flow into the tank as the float rises. So if you fill a tank up past a certain preset height, the float rises to, shuts off the valve and it stops fuel from going into the tank and overfilling.
Shannon:
They're a little bit of a mystery though, because they can be very difficult to spot on a tank. They're mostly inside of the tank because there's a float component and they're in line with your fill piping, and so most of what you can see is a hexagonal nut at the bottom of your fill pipe as it right as it goes into the tank, and not all of the overfill prevention valves have that hexagonal nut. Many of them do, but not all. So it's a little tricky, but generally if you're looking at the top of the tank and you see a big old hexagonal nut in your fill line, it's mostly safe to assume that there's an overfill prevention valve installed. The best way is to look at the construction documents of the tank and verify that that was part of the original tank design and that it was installed as directed.
Amanda:
So why are those important?
Shannon:
Well, there are two big reasons why they're important. The first one is really important. They prevent overfills, yay. They save the environment. They stop fuel from coming out the top of your tank. If people are human and make human errors, so that's the most important one. But they also meet regulatory requirements. They are required by certain regulatory components to be in place, specifically the spill prevention control encounter measures, plan SPCC, our old friend 40 CFR 112. If you have a double walled tank outside of containment, they have to have an overfill prevention device on the tank to be exempt from having secondary containment. And we can talk about that more later. But those are the two big reasons that people will have an overfill prevention valve on a tank to prevent the overfills and to meet regulatory requirements.
Amanda:
So how do these overfill prevention valves work?
Shannon:
Well, I covered a little bit of it earlier. But specifically, overfill prevention valves are passive systems in that once they're installed they will work without manual activation. You don't have to push a button, you don't have to remember to turn it on If you make an error, if you dip the tank incorrectly, if you're trying to fit too much fuel into a tank. If you've installed that overfill prevention valve correctly, it will stop the flow of fuel if the fuel level in the tank rises above a certain point. And that's sort of the basics of it. It's not complicated, it's a mechanical system. There are electrically based ones that sense fuel levels and shut off solenoid valves, but the vast majority of overfill prevention valves that we work with are simple mechanical systems with floats.
Amanda:
You mentioned regulatory requirements previously. What are those?
Shannon:
Sure, well, for most of our clients it's going to be the SPCC, like I mentioned previously, and that's tied directly to secondary containment requirements of four tanks of a certain size, although I do want to do a shout out.
Shannon:
Some states have their own overfill prevention requirements. Some states like California require them in addition to the SPCC and sometimes they require them outside of the SPCC as well. California is a special place in the regulatory world but basically in the SPCC it says all bulk fuel containers of a certain size have to have secondary containment to hold the volume of the contents inside of it. Fair enough, right? Well, if you have a large tank and it's double walled, way back in like 1993, when they were deciding all of these SPCC rules, somebody set forth that hey, double walled tanks are their own containment. It's a second wall all the way around the tank and if the main tank was to leak it would be held by this impermeable containment, the second wall of the tank. Therefore it's secondary containment. The EPA agreed, but with some caveats. So there's this document called Appendix H and I will attach it to the show notes, and it's referenced in the guidance and the EPA regional guidance which we've attached many, many times to many other episodes. But basically it says that the EPA has determined that a tank can be exempt from secondary containment requirements if double walled, and it has the following three things. One of those is an overfill alarm, so something that notifies a person in control of the transfer that the tank liquid level is above a preset amount. An automatic flow restrictor or flow shutoff, also known as an overfill prevention valve one of the three. And then all product transfers are constantly monitored. If you have those three things, you can have a double walled tank outside of secondary containment. So that's mostly where we see the regulatory requirement for overfill prevention valves is that they're meeting that regulatory requirement for that automatic flow restriction or flow shutoff. There's a couple other things that go with this. We could maybe talk about that later, but like product transfers, they can be monitored by a person. They can also be monitored by a tank management system as long as there is somebody where, if the alarm goes off, they are able to stop or shut down the transfer if needed. That's the basics of it.
Shannon:
There may be other things that certain states require and you'd have to go straight to the state regulations for that. In Alaska there are certain overfill prevention requirements in the 1880 AC 75, but they are specific to the vertical tanks and they are more set up. They're not set up in the same way that these horizontal tanks are, and so there's lots of options for overfill prevention. It's not as cut and dried as have an alarm, have a shutoff valve and have a means of monitoring the transfer. There's an infinite variety on the vertical tanks. So, for our purposes, for this discussion here generally, when people are talking about an overfill prevention valve, they're talking about an overfill prevention valve on a horizontal tank that's double walled and they want to have it outside of secondary containment, and that's one of the things that they have to maintain and have in place to have it remain outside of secondary containment.
Amanda:
All right, so we definitely want to keep these maintained. Would you be able to describe or recommend maintenance procedures? Hmm?
Shannon:
Well, a lot of the maintenance on an overfill prevention valve rests on installing it properly. They're little workhorses, they're very simple in design. They work really well. They work for a long time. A couple of things that we see pretty frequently is if and they actually warn you about this in all of the installation documents that too much thread sealant. If you use too much thread sealant it'll be forced inside that valve system and it can really gunk up the works. There's also a lot of care that needs to be taken when inserting the overfill valve because the float and linkage arms there's two little arms on the side that connect the float to the valve turning mechanism. If those arms get damaged from the float twisting it'll freeze up and the float won't lift appropriately and get hung up on the arms. And then, lastly, we definitely see that all the connections can be over tightened and that can cause leaks within the system. So when you've been in fuels a long time, you'll a lot of people think of leaks as external, right Like you have a leak and fuel is coming out of the flange or the valve or the pipe and it's spilling onto the ground. But there's internal leaks too, where you've got fuel going through the overfill prevention valve and if it's been tightened too much, even if it's activated, it'll be leaky and it'll still be going into the tank and filling it up more, even though the valve is fully engaged. So you want to make sure that you don't over tighten the connectors. And again, the installation instructions are full of warnings like only tighten three full turns clockwise to ensure that that doesn't happen.
Shannon:
And then my last thought on maintenance is that although overfill prevention valves are low maintenance, that does not mean no maintenance.
Shannon:
Ever I have seen 30 and 40 year old overfill prevention valves and they are in rough shape. We recommend that every time you're emptying the tank to clean it, repair it or inspect it, that the overfill prevention valve be removed and inspected at the same time. We've seen a lot of linkage arms that are stiff, seized, full of some kind of gunk from whatever product was in the tank or maybe greasing of fittings, stuff like that. Basically, the float becomes very difficult to operate and then it's not lifting like it should and so it's not actually rising anymore and so there is no shut off capability in that system anymore. But it can be hard to inspect these valves because they're all internal to the tank. So that's why we say if you're taking the tank down to clean it, go ahead and get up, you know, take the top apart, expect all your pieces, replace all your gaskets and then also inspect this overfill prevention valve, make sure the entire assembly is operating smoothly and is free to rise and fall with the level of the fuel.
Amanda:
So how do we know when an overfill prevention valve is working correctly? How do we test it? Take us through that process.
Shannon:
Well, that's an interesting question because inspectors like to ask this question a lot from state and federal agencies. How do you know it's working? Generally, if fuel continues to flow into your tank, it is working. However, we know from what I just said and from what I've observed that the float can become frozen in the down position and not work at all. And so we hear a lot in the field that they fill the tank up to that preset max height and then it'll shut everything off and that'll tell you that it's still working. And technically, yes, that is a way to determine if the valve is working. But I have thoughts on this. So hold on. When you test a system like that in that manner, you're creating a pressurized segment of your fill line and when you disconnect it can spill product with back spray from that pressure that you've now introduced into the system. If you're truly filling the tank to the max fill height or just a little bit beyond, there isn't a lot of room for that fill line to drain back into the tank, right, the tank level itself is gonna keep the pressure up. Truck drivers call that taking a bath, because they disconnect after that valve goes and the valve engages and then the whole system's pressurized and then they go to unhook their hose after stopping the transfer and it sprays all over them.
Shannon:
My thoughts are that this should not be your main way to test an overfill alarm. It's risky. There are other ways to ensure you can test it. You can utilize nearby appurtenances, like a lot of them have, empty appurtenances with threaded caps. You can remove the cap. You can reach a stick-in or a tool-in to make sure that it's still floating freely or moving up and down freely when the tank is lower in volume. You can also just remove the valve assembly at tank cleanings, like we mentioned.
Shannon:
I think a perfectly legitimate answer to a regulatory agency would be we pull it apart, verify it functions and maintain it at every 10 or 20-year interval that we have it inspected. That's a valid way of testing and verifying that it's still working. So, lastly, these valves work really well for a really long time, but nothing lasts forever and it's wise to have a plan for making sure it's working, and the reason is that if this fails, you will have an overfill. Humans are human and eventually they make a mistake in how much foliage the tank has, how much space is in the tank for filling it up, or they tell somebody to put 500 gallons in but it gets written down as 5,000, whatever Mistakes get made, because people are people and so these passive systems need to be maintained and in place and everyone who operates that tank needs to understand how they work so that they can be part of that maintenance and ongoing understanding of what's going on.
Amanda:
All right. So where can we learn more about Overfill Prevention Vows?
Shannon:
There's a couple places, morrison Brothers Company, who makes a lot of Overfill Prevention Vows. They're not the only one, but they do make quite a few. They have a really great video series of their website and I've linked them both. There's two parts. Part one is a lot about installation, but there's a whole section there about how to install it carefully to avoid damaging the mechanism from the very beginning. And then part two talks a lot about sort of documenting and understanding that flow and how it works once it's in place. So you should definitely watch both parts.
Shannon:
There's good stuff in there for both. And then I also will include a link to 40 CFRs, appendix H and that sort of explains why double walled tanks need those three things to be exempt from secondary containment areas. It's a little funky because it's not part of the main body of the SPCC regulations, but we still have to consider it and it still has to be adhered to if you are operating a double walled tank outside of secondary containment and you are subject to the SPCC rules. So those are the three. Find out more resources that I have for you.
Amanda:
All right, that sounds great. Shannon, thank you so much for walking us through Overfill, prevention, vows and, for my favorite part, what are some stories you might have from the field about these little contraptions? Have you ever witnessed a backspreading?
Shannon:
I have not witnessed one, but I've definitely interviewed people who have been, who have taken baths, about why they were taking a bath and trying to problem solve which part of the system was creating the pressure, and in one investigation it was absolutely the Overfill Prevention Valve was malfunctioning and it was causing. It was engaging during the transfer and then it would fall back and then reengage, and so there was a lot of start and stop pressurization and so it was difficult to understand what was going on. We also had one on a tank that was 23 years old and we took it out and it was so stiff that even the biggest burliest guy in the shop could not get it to engage. But they cleaned the linkage arms off and had a whole bunch of either grease or emulsified gunk from being in the tank for 23 years. And they cleaned those little linkage arms off and they're stainless steel and once they got them going it was actually right back to full function. It was pretty amazing, I mean the 23 year old Overfill Prevention Valve and it was working great.
Shannon:
So that was interesting to me just to see. I mean we were kind of like treating it like an arm wrestling match, right, like who can get this to go. Nobody was strong enough, but once it went back in the tank, it was probably fine for another 10 years, I mean as long as everything's working and it looks like it's in good order and it's moving freely and flowing. But what I learned from that, though, is that I don't know how long that float had been frozen up right, and 23 years was too long. There is no way that fuel was floating that float if I couldn't even get the biggest, burliest guy to move it with his, you know, trying to force it. So that's where we come in with the hey. If you're going to get this tank cleaned and updated and inspected at the tenure mark, then go in and make sure that it's clean there, because I have a feeling it was still operating at 10 years, but it just was no longer by year 23.
Amanda:
All right, well, thank you so much for your time, Shannon, or truly appreciate you sharing your expertise.
Shannon:
Yeah, I love talking about all these pieces of the tanks. This is one that it's a little harder because it doesn't stick out of the tank, so it's always a little mysterious and I think people struggle to identify them and know more about them, although people who have them they definitely know that they have them because they have passed that preset fill level on the tank at least once.