Improving Storage Tank Protection Podcast

by , , | Oct 28, 2020 | Oil & Gas

Chelsea McGovern

Chelsea McGovern

Author and Content Specialist

Storage Terminal Safety Podcast SeriesStorage tanks take up a lot of real estate in storage terminal facilities but are often less cared for in maintenance programs and operations due to difficulties in accessing tank roofs. Although they may not get the same level of attention as other parts of the facility, storage tanks have many inherent risks to personnel, the environment, and other assets if not properly maintained.

Tank protection maintenance covers a broad ecosystem of devices and equipment dedicated to the accurate measurement of pressure, temperature and liquid level changes, as well as the monitoring of equipment, which helps protect these assets (e.g. pressure vacuum vents, emergency vents, thief hatches, flame and blanketing, and vapor recovery regulators.) When driving continuous safety improvements, a well-informed facility manager needs to focus on tank integrity and the day-to-day challenges of tank farm personnel.

In this storage terminal safety podcast, we are joined by Emerson’s Dave Macedonia to discuss today’s most cost effective and innovative technologies to help prevent tank over pressure or under pressure events that jeopardize tank integrity and personnel safety.

Visit the Terminal Safety and Tank Pressure Control sections on for more on some of the technologies discussed. Also, links have been added in the transcript below for specific products and technologies discussed.


Jim: Hi, everyone. This is Jim Cahill from the Emerson Automation Experts blog. As part of our continuing podcast series on enabling storage terminal safety, today I’m joined by David Macedonia and we’re gonna talk about ways to achieve better tank protection. Welcome, Dave.

Dave: Hi, Jim. Thanks a lot for having me.

Jim: You bet. Well, why don’t we get started could you give us a little bit of your background, your education, and your path to where you are today?

Dave: Sure. So, I am the industrial business development director for Emerson’s pressure management business unit based in McKinney, Texas, just north of Dallas. So, I’ve been with Emerson for about five years mostly in marketing and business development roles, both in our natural gas side of the business and our industrial business within pressure management. And I have a bachelor’s degree in mechanical engineering from Northwestern University and an MBA from Carnegie Mellon’s Tepper School of Business. And in my old life, I was a submarine officer in the Navy for seven years operating nuclear propulsion plants.

Jim: Well, that sounds like a very diverse and interesting background! So, let’s apply that into what you’re doing right now. Can you tell us a little bit about, you know, today’s tank protection and how its impact on our listeners’ bottom lines and their operational performance?

Dave: Tank farms, both in refineries, chemical plants, and in terminals take up a lot of real estate in the plant, but don’t get as much attention as other parts of the plant. And there’s a lot going on inside of a tank, it’s really its own ecosystem. It has to be carefully controlled both on the liquid and the vapor side. So, at least in our business unit with Emerson and the equipment that I’m responsible for, we maintain the vapor side of the tank. And really there’s a lot of factors that go into this and a properly maintained tank can communicate that operational benefits and safety benefits for operators of these facilities.

Jim: Okay. When you look at these facilities, what are some of the common concerns that you see, you know, especially from a safety point of view?

Dave: I guess first of all, Jim, what I’ll say is a couple of statistics just for your listeners to set the stage here. So the contents inside of a tank are very valuable to our customers. Just for an example, an 80,000-barrel tank filled with naphtha or with crude oil at today’s market prices is about $3 million if it’s full. So it certainly would affect the bottom line if anything were to compromise those contents. Also, about 85% of tank accidents are caused by fire or explosions, and a flame can travel up to 4,000 miles an hour if you have a flame event inside of the system. So certainly a sobering statistic from a safety perspective. And then finally, from an environmental and an emissions point of view, in 2019 EPA in the U.S. reported that $4.4 billion of investment was needed to comply with emissions laws, and over $470 million worth of judgments were levied just in 2019 alone. It’s irrespective of administrations as well, so those numbers are ticking up over time. From a safety perspective, really we’re worried about tank integrity and personnel safety. So specifically implosions and explosions. If the tank were to over pressurize, if you did not have enough venting in a tank, that tank could over pressurize and then cause an explosion, something we certainly want to avoid. And then the reverse of that, if you were to draw a vacuum on the tank and not have the ability to restore pressure control to that tank, the tank could implode, and both of those results could result in lost product and damage to equipment and personnel, particularly if products inside were to leak out and ignite.

Jim: Wow, that sounds like a lot of issues, not only with safety but with regulatory and fines associated with it. Not to mention the company brand that this has happened to can sustain damage from the negative reporting and everything around it. So it sounds like it’s very important to make sure to get that tank protection the way it needs to be. So what are some other common concerns that you hear from these facilities?

Dave: Especially nowadays emissions is one thing that is starting to come up a lot more. So as we know, a company, our customers are being a lot more environmentally conscious especially with fugitive emissions. And these tanks do vent off vapors to the atmosphere that could be harmful to people in the environment. So you might’ve seen in the news recently, so especially in Europe, a lot of companies are now signing up for emissions targets in accordance with the European Commission guidelines. So companies like our Royal Dutch Shell, BP and Total have pledged to be net zero emissions by 2050. So this is something that’s it’s an ambitious target, especially for a hydrocarbon-based company, but something that we can help them with, with our technology that exists today. So we will be able to partner with customers like these to better control their storage tanks, but also meet their mission.

Jim: Interesting. And, you know, you mentioned the role technology can play in addressing some of these. So can you talk about the types of technologies that can help ward off some of these issues that we’re talking about?

Dave: So a properly maintained and protected tank will have redundant pieces of equipment kind of stacked with setpoints between a normal band and kind of an emergency condition. So on the positive pressure side, usually the tank is maintained at a slightly positive pressure with nitrogen or some other inert gas to be able to protect that tank contents from impurities and also maintain an environment that is below explosive or flammable limits. There’s a slightly maintained pressure. Usually, it’s in inches of water column, but it can be an in pounds depending on the, I think, on the tank, but usually, we see it in inches of water column. And then the next step up from there, a protective device is called a PVRV. So a pressure vacuum relief valve. So that would vent off excess pressure if it gets too high. And then one step above that would be an emergency pressure valve or vent, which is really the last line of defense from between that tank over pressurizing and a potential rupture. So those three devices should be staggered with their set points such that they’re not operating at the same time. And then conversely on the negative pressure side, we have the same stacking of redundant devices. So we have a vapor recovery unit could have where it takes excess vapors from the tank and then puts it back into the tank. You could have the pressure vacuum release valve also works in the opposite way, where if you’re drawing a vacuum in that tank can draw air from the atmosphere into the tank to restore pressure control. And then finally an emergency vacuum vent, which would be the last line of defense from an implosion. So you have all of that equipment in the tank, as well as flame devices called flame arresters to prevent flames from propagating within the system to include tanks or other flammable parts of the system. So ultimately that device, you want to contain a flame event wherever possible when that is installed.

Jim: Yeah, it sounds like managing the pressure around that tank from overpressure, from underpressure, keep the integrity of that tank and protect the valuable contents within it, then the safety of all the personnel around. So what are some important selection criteria around some of these technologies that you just talked about?

Dave: Sizing and selection is the most important thing. So you have to have the right tool for the job, and it has to be the right piece of equipment, and it has to be able to do what you need it to do. So I would say for blanketing regulators, it needs to have capacity, enough capacity to be able to maintain pressure control in that tank depending on its size. And we use the API 2000 [Venting Atmospheric and Low-pressure Storage Tanks]. So it’s really the worst-case conditions for that tank has to be able to be maintained with that device. With tank vents, it’s along the same lines. So both PVRVs and emergency release vents, both of those need to be sized appropriately to be able to relieve enough pressure in worst-case conditions. And then for flame arresters, it really depends on your design of your system. So some of that is actually choosing the right type of product. So for flame arresters, there are two different types, detonation arresters and deflagration arresters. So I mentioned this statistic earlier where a flame front can travel at 4,000 miles an hour. So that is a detonation and explosive region where a deflagration is a lower pressure, slower-moving flame event. A detonation is your worst-case scenario and sometimes the configuration of your piping, the different conditions may necessitate you using that. So, you know, that’s something to also consider in sizing and selection and our inside sales folks, our impact partners in North America are very well-versed in it.

Jim: Okay. It sounds like a number of different technologies to address things at different levels. What are some solutions that we offer to assist these operators?

Dave: Sure. So tank blanketing are really our flagship products. Maybe the ACE95 vapor saver regulator, and the Fisher 1190 tank blanketing regulator. Both of those are really our standards that we use in refining, chemicals and terminals. The 1190 is the largest of our tank blanketing regulators. Some of the largest tanks like the 80,000-barrel tanks would require something of that size and it has really the best in class capacity and ease of maintenance as well. So that product can actually be configured such as on the ground at grade and not actually on top of the tank. And you can do maintenance with your feet on solid ground and not 20 feet in the air on a piece of scaffolding. And that product can also be configured with a Fisher 4320 position indicator. So we can talk about that a little later about some different monitoring technologies that Emerson can provide with a lot of these products to provide more visibility to customers when it comes to tanks. Emerson can also offer some Enardo branded products. So the series 950 PVRV, and the Enardo Model 2000 ERV. Both of those have a feature for wear resistance. It’s called a saber to make sure that that seating surface is clean so that when it seats, it moves up and down in a straight line and seats properly to prevent excess wear over the lifetime of that product. And both of those have wireless options as well to be able to communicate to customers or operators when that device is open or shut. And also the Enardo detonation arrester that I mentioned before, it has a certification from the United States Coast Guard, which actually has the most stringent requirements in the market today. And that product also has a built-in instrument port, which can have an instrument inserted into the product for temperature, for differential pressure, for different parameters to provide information to operators to indicate whether cleaning is required or in the worst-case scenario, if a flame event has taken place.

Jim: Yeah, traditionally these relief valves and pressure regulators and flame arresters, and all the others, there’s no electronics or wires going into it. And you had mentioned wireless options to these for monitoring. Could you talk a little bit more about that?

Dave: Absolutely. So I alluded to this with the Fisher 1190. So that product can be equipped with a Fisher 4320 position indicator. It measures the travel of that unit, and it can provide an indication of the position of that regulator. And that could be useful in that it could be able to communicate to operators when that regulator is open or shut. So during the course of any day, a regulator is going to a cycle depending on normal operations. So for that tank, if liquid is being pumped in or out of that tank, that vapor space will expand or contract, and you will need more nitrogen. You have to vent or put in nitrogen to maintain that pressure at the setpoint. Also temperature. So ambient temperature is another thing that that can change. So as that temperature changes, the density of the gas will change thus requiring adjustments to that pressure in that inside of that tank over time. That regulator will cycle over time just in normal operations, but if that regulator is open, for example, when you don’t expect it to be, that could be the indication of a problem. If you have leakage in that tank, or for example, if maybe your vent opened but hadn’t reseated, you would never know that because that pressure would continue to be maintained by that regulator. It could be open, but you could be just venting excess nitrogen to the atmosphere. We have seen customers that I mentioned these setpoints, it could not be staggered enough, such that if the regulator were to be open at the same time as at PVRV, that’s stacked on top of it, then you would just be venting excess nitrogen to the atmosphere and you might never know it, especially, if not many people ever go up to the top of the tank. So that’s something we actually check for in our tank walk downs when we visit customer sites, but you would have that indication if you have that wireless device equipped to that product. So that’s one option that customers have. With our tank events, our EPVs or PVRVs, we do have certain models that are equipped with a TopWorx GO switch, so the top works business unit within Emerson, and coupled to a Rosemount transmitter. So it’s a proximity switch, so when that valve is open or shut, it would give that indication to operators. And for example, with an emergency event, that should never be opened during normal operation. You will see some cycling of the PVRV at times, that is normal, but it would give customers that indication that there is an abnormality. So those are a couple options that we have today for customers, especially those who are kind of further down the line of sensing or monitoring a lot of different devices from their control rooms.

Jim: Yeah, it sounds like before it had to all be manual inspection to check or maybe the process is picking up on overpressure or something in that way. But now it seems like not only can you verify it should be doing what you expect it to do based on what the other sensors are telling you the process is running, but things like alerting operators that it needs to be looked at. So it just seems like overall to help with having safer, more reliable operations, is that fair to say?

Dave: It is. And a lot of it still is. A lot of that, all the equipment that we’ve talked about usually is on the tank top, which most of the time is out of sight, out of mind. A lot of say more junior operators would man the tank farm than say a processing unit and not many people go up there whether to take logs or do periodic inspections. And it could be hazardous. You’re climbing up a ladder, you’re very high off the ground. Not a great place to be if you’re on shift. So a lot of issues with these products and with a tank pressure control can go unresolved just because they don’t know that they’re happening.

Jim: Yeah. It seems like more and more these wireless options, basically, the industrial internet of things can really help making sure things are as they should be. Well, this has been very informative. Where can a listener go to learn more and connect with us at Emerson, Dave?

Dave: Absolutely. So if you’re in North America, you can contact you or your Emerson Impact Partner in your area, and for your international listeners, your Emerson sales office in your region for local service and support. And then online, check us out at Emerson Exchange 365, or you can Google “Emerson tank pressure control,” and our tank pressure control page will come right up and you can read more about our services, our solutions, and our products at your own time.

Jim: All right. Well, thank you so much for joining us today, Dave.

Dave: Thanks a lot, Jim. It’s been a pleasure. Thanks for having me.

End of transcript

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