This week’s Pipeliners Podcast episode features first-time guest Deon Botes of ION PRO Services discussing the fundamentals elements of hot tapping and line stopping.
In this episode, you will learn about why pipeline operators utilize hot tapping and line stopping to perform repairs without interrupting the line, the keys to being successful with a very technical engineering and mechanical process, how the process works from beginning to end, the importance of documentation and technology, and more key aspects.
Hot Tap & Line Stop: Show Notes, Links, and Insider Terms
- Deon Botes is the president of ION PRO Services. Connect with Deon on LinkedIn.
- Hot Tapping is a method of making a new connection to an existing pressurized pipeline without interrupting flow or emptying the section of pipeline or vessel. This benefit to the asset owner of the pipeline is being able to can continue with normal operation while maintenance or modifications are being executed.
- Line Stopping is a controlled method to isolate a section of pipeline by inserting a line stop plug into the pipeline while the system continues to operate normally, allowing repairs and/or maintenance of critical components downstream.
- Read this article from ION PRO on the basics of hot tapping and line stopping.
- Arc eyes (a/k/a welder’s flash) is inflammation of the eyes resulting from exposure to UV radiation released by a welding arc.
- ID (Internal Diameter) is a measurement of the internal portion of a pipeline. Some pipe is measured by its ID or its OD (outside diameter).
- API 1104 Appendix B code (Welding of Pipelines and Related Facilities) covers the gas and arc welding of butt, fillet, and socket welds in carbon and low-alloy steel piping used in the compression, pumping, and transmission of crude petroleum, petroleum products, fuel gases, carbon dioxide, and nitrogen and, where applicable, covers welding on distribution systems. It applies to both new construction and in-service welding.
- NDT (non-destructive testing) is a group of noninvasive analysis techniques to determine the integrity of a material component or structure, without the need to take apart or destroy the test object. NDT includes several different types of tests and techniques to perform the assessment.
- Ultrasonic Testing (UT) is a type of NDT technique based on the propagation of ultrasonic waves in a tested object or material.
- Laminations are a type of defect that arises during the manufacturing of metallic pipe. Ultrasonic testing is commonly used to detect the presence of laminations.
- API 5L specifies the manufacture of two product levels of seamless and welded steel pipe for the use of a pipeline in the transportation of petroleum and natural gas. API 5L is currently in its 46th edition.
- NDE (non-destructive evaluation) uses quantitative measurements to identify a defect in a pipe. Measurements focus on the size, shape, and orientation of the defect and take into account the physical characteristics of the pipe.
- Boring bars are common tools used in metalworking. The tool is used to cut into the inner surface of pipe.
- Delta-P is the differential pressure in pipe. The measurement captures the difference in pressure between two segments.
- Cold-cutting is the process of cutting pipe without using heat. This allows for cutting pipe without generating flames or sparks, preventing the ignition of residual gases that could be contained inside out-of-service lines.
Hot Tap & Line Stop: Full Episode Transcript
Russel Treat: Welcome to the Pipeliners Podcast, episode 176, sponsored by P.I. Confluence, providing software and implementation expertise for pipeline program governance applied to operations, Pipeline Safety Management, and compliance, using process management software to connect program to implementation. Find out more about P.I. Confluence at piconfluence.com.
Announcer: The Pipeliners Podcast, where professionals, Bubba geeks, and industry insiders share their knowledge and experience about technology, projects, and pipeline operations. Now your host, Russel Treat.
Russel: Thanks for listening to the Pipeliners Podcast. I appreciate you taking the time and to show the appreciation, we give away a customized YETI tumbler to one listener each episode. This week our winner is Jim Collins with Duke Energy. To learn how you can win this signature prize, stick around to the end of the episode.
This week Deon Botes is going to join us to talk about hot tapping and line stop. This is a subject that I find fascinating because it’s a tough one to visualize if you don’t actually understand the details. Deon, welcome to the Pipeliners Podcast.
Deon Botes: Hey Russel, thanks for having me.
Russel: Listen, I’m actually really interested in having this conversation. I stumbled across your website and I stumbled across your video and I had to reach out because the whole idea of how do I do a hot tap, how do I do a replacement or repair on a pipe without impinging flow. That’s like magic. It’s like dark arts to me.
I’m really looking forward to this conversation. I want you to help me understand the engineering behind the process. Don’t share any secrets. Just enough so that we understand.
You’ve got this really interesting video on your website. We will link it up. When I saw that video, Deon, it was the first time I thought I had a clue how hot tapping and all that actually works. It’s really instructive.
Before we dive in, I’ve got to ask you. Tell me a little bit about yourself and how did you get into this?
Deon: It’s a quite interesting story. My dad was a pipeline welder born in South Africa. I spent a lot of my youth helping out on pipeline sites. I think my first bout of arc eyes was 13 years old.
I fell in love with the fact that I was always outdoors. At university, I was quite a lazy student so I opted for a bachelor’s of commerce degree thinking I’m going to go into something else.
I had my two-year compulsory military service in South Africa and that was the catalyst for me, being outdoors. Because construction — it’s a military mindset without the weaponry if you’re going to be successful.
Russel: I was a combat engineer, so I know exactly what you’re talking about.
Deon: Absolutely right. I started out as a very small pipeline contractor in 1988. Soon thereafter, about 10 years in, we were doing a lot of service welding for some customers of ours who earned their own equipment. I’m talking about hot tapping and line stop equipment.
Like you, it also fascinated me. In ’98, I found my way into Tulsa where I met with T.D. Williamson. We had a very good relationship where I learned a lot from them for about 12 or 13 years. I used all the profits I made and acquired a fairly extensive complement of equipment. We did work mostly through Africa and somewhat in the Middle East.
I got a bit of itchy feet about three or four years ago and decided it was time for a change. I’ve got a young family and I wanted to give them an opportunity and I made my way to Houston. I’ve been coming in and out of Houston since ’98, ’99 as well.
I just thought Houston or Texas being the epicenter of oil and gas in the entire universe, that was the right place for me to be. Most people my age would probably look at the twilight of their career and, for me, it feels like I’ve found a second win in all this.
Russel: Man, I can so relate to that. Deon, I could so relate to that. I’m very much the same way.
Let’s walk through the video. The video starts, and it shows you installing this fitting on the pipe, basically welding it over the top of the pipe. What is the nature of that fitting? What’s it designed to do?
Deon: With pipeline intervention, this is essentially what a hot tapper or line stop is. You’re intervening inside the ID of that line. It starts with an engineered fitting. The fittings that you see in the video are a full encirclement type fitting. A lot of people have different names for it, but that’s, in essence, a split tee.
Then you have two broad categories, a hot tap or a line stop. The basic difference between the two would be in the flange that you see where you bolt your equipment onto. A hot tap, you would leave the valve behind, and there’s no funny, engineered segments in it. It’s a normal, standard, weld neck, raised face flange that you can buy, and you’ll probably clean out the ID a little bit if you need.
Whereas, a line stop fitting is an engineered flange that contains segments, segment screws, seals, and everything else. It also has a plug that is part of that flange. There’s two types of plugs, but let’s discuss the one in the video clip. That plug allows you, under pressure, to remove your equipment that you’ve used to isolate during certain activities that you will be intervening in that line.
You can imagine the valves on, let’s say, a 24-inch line intervention or line stop. Let’s say it’s a set of valves, including bypass valves, that are the same size. That must be half-a-million dollars, and you can’t just leave those valves on every single time.
This flange allows you to recover those valves and put on an installer blind flange once you complete. You’re left with a blind flange. You can also go back at any time you want. It allows you to recover your equipment.
Russel: That’s a big deal on this kind of stuff.
Russel: The first thing you show is these valves being set over the flowing line. Then you show welding occurring. That raises a lot of questions for me. Welding on an in-service hydrocarbon pipeline sounds a little dicey to me would be the way to say that.
Deon: I understand that. There’s certain parameters that you will have to abide by. The code is very prescriptive in this. We follow the API 1104 Appendix B code. In the U.S., I see it’s the 20th edition. I’ve also got the 21st edition that we qualified in South Africa.
Essentially, it takes into account pipeline wall thickness and inner wall temperature when you qualify your well procedures. I think most people are mostly concerned about the risk of burning through the pipe wall, which is, of all the things that can go wrong, statistically I think that’s probably the lesser chance of occurring.
Unless you are talking about very thin wall pipe. When you’re talking about that, we’re talking about 0.125 of an inch. It’s pretty thin pipe. When you’re looking at that, it’s a function of pipeline pressure as well. Once you start having a weld pool and the inner wall can no longer sustain the pressure that’s inside, that’s when you’re going to have a bad experience.
Russel: Is there anything that you’re having to do or any special training required for the welders that are doing this stuff?
Deon: Yes, sir.
Russel: I would expect these guys are very specialized welders.
Deon: They are. I have found, over the years, that traditional pipeline welders — I’m talking about butt weld on new construction — have a very well-developed understanding already of the process.
Then you would simulate before you even weld on a line. While you’re doing your qualifications, you will simulate flow through line, but that’s mostly for the heat quenching effect because that’s where your hydrogen cracking can occur.
Those are the things that you should be as careful or mindful of as you would for burn through. Burn through, you’re talking about low penetrating electrodes, a vertical up process, using low hydrogen electrodes. You are taking care of that, but you also do ultrasonic testing beforehand on the weldment or the weld areas.
You’ll determine whether you have laminate imperfections, whether you have pipe wall…there could be internal anomalies. You take all that…
Russel: That makes a lot of sense. I didn’t even think about that, Deon, that you would get down in the ditch and do some NDT and really look at, “Here’s where I’m planning to put this encirclement valve or this encirclement fitting, and I wanna make sure that where I’m gonna do the weld can sustain the weld.”
Deon: Absolutely right. At that point, you do a bit of a roundness check as well. It depends on pipeline diameter. It depends on the way the pipes were manufactured. How round is your pipe? Everybody assumes that a pipe is perfectly round, but API 5L gives a bit of leeway there, too.
Deon: The seals we place into the ID of that line lay perfectly round. You try and match that up as best as you can because you also want to get a perfect seal.
Russel: Yeah, [laughs] lots of little details.
Deon: Oh, yeah. This is all about detail.
Russel: Obviously so. Just in listening to you talk about what you’re looking for from the welder and the practice of the welding itself, there’s a lot of detail there, a lot of knowledge required to do this safely.
As you’re doing the welding and as you’re getting these fittings mounted, how do you go about doing the leak testing to make sure you’re not having a leak? If you’re working on a live line, and you end up with a leak, you’ve got a problem.
Deon: Absolutely right. Good question. Once the welds have been completed, there is a rule of thumb that you wait a minimum of 12 hours. Some pipeline operators wait as long as 48 hours. Then you’ll do some more NDE to determine if you have cracks. Once the weld is all clear, you can go ahead and you’d mount your low-profile line stop valve onto the fitting. You’ll mount your equipment.
Then, what we do, and I think is probably industry norm, you introduce nitrogen into the whole assembly. You’ll leak test to at least line pressure, not exceeding line pressure by more than 10 percent. You do not want to inadvertently dent that section where you’re applying the pressure on the OD of that line.
Russel: Interesting. Once you have the fittings installed — in the video’s, there’s four (there’s two outer fittings and two inner fittings) where the outers are the bypass, and the inners are the stoppage — I noticed that, in each of these cases, you have to execute a cut.
To me, as I’m looking at the process, that looks like the most…At that point, there’s no turning back, I guess, is the way to say it. Once you start to cut that line, and that line’s under pressure, you better have everything right.
Deon: That’s almost where the rubber meets the tar. Once your pilot penetrates that line, there’s no return. You’re at the point of no return. Your processes, your equipment, everything that you’ve trained, practiced, and got experience for, that’s when you start requiring it, right there.
Russel: I have to ask this question. When I have these kind of conversations, I tend to put myself in the situation. I’m thinking about, if I was out there, and I was the person supervising a job like this, I think I would always be a little bit tight in my body when the cut was being done. [laughs]
Until that cut was complete, and I knew we had containment, I think I’d always be a little tight. I could do that a thousand times, I don’t know that I’d ever get over that.
Deon: There’s tight, and there is tight when you set the plug. I can assure you your body does, and I don’t want to say certain parts of it more, but your body does tighten up when you start cutting into the line.
No matter how many times you’ve gone over your equipment and how well your process works, you always in the back of your mind realize you’re dealing with mechanical equipment. There’s fatigue, there’s failure, materials fail.
Russel: Yeah, stuff happens.
Deon: Stuff happens.
Russel: However careful you are, however many times you go through it, stuff still happens.
Deon: There’s one thing there that I didn’t touch on. It’s also measurements. Remember, you’re going into this process completely blind. When you start cutting, you need to know exactly where that cutter is. You need to know where your pilot is. The shell cutter is a certain depth, and the pipeline requires a certain cutter, especially for a line stop.
That’s where the tolerances are very important. You’re looking at measurements by a measuring rod that fits through the boring bar, and it holds onto the cut at the bottom. It also tightens the cutter into the bar. You can see fractions of an inch where you’re cutting your pilot with every single thing in relation to the boring bar traveling down that line.
Russel: That’s a great point. Again, it’s interesting to me, as we walk through this — this is why I want to have the conversation — how much detail is involved. It makes absolute sense that you’d want to monitor this operation. The better you can monitor it, the more confidence you can have that it’s going to work out the way it’s planned.
Deon: Absolutely right.
Russel: You’ve already talked about NDT. Now you’re talking about getting actual spatial measurements. Is there other kinds of measurement you’re doing, like are you monitoring pressure in the pipe? Are you looking at circumference of the pipe, all that kind of stuff as you’re doing all of this?
Deon: We’ve established pipe wall thickness. We’ve established flow. Especially when you start looking at a line stop, even double position line stop, there are certain maximum flow requirements.
You can imagine, if you’re traveling on the motorway, and you’re traveling in a fancy Tesla, and you’re doing upwards of 150 miles an hour. You open the window and you stick your hand out, that’s not the kind of flow you want in that line. Because you’re inserting two almost cup or disk-like items into the line to (a) initially divert and (b) when you put the second one in, to create the stop of that section of line. You’ve got to be mindful.
It’s maybe not as bad as I’m saying, but that particular set-up would be maximum flow in a gas environment of 15 foot per second. If you exceed that, the operator needs to tell the service provider to throttle back.
Russel: Right. It’s not just measuring the mechanical properties of the pipe. It’s actually understanding the operating characteristics of the flow.
Deon: Absolutely. That is super important because when you talk about pressure and temperature — in a midstream environment, that’s not really that big of a deal. You get a lot of flow there. Pressures we can deal with. It depends what equipment you’ve got. We can go up to 5,000 PSI with some of the equipment we’ve got. Flow is definitely a factor.
When you start going to plants and refineries, temperature and all the different kinds of chemicals that you can encounter becomes a bit of a challenge as well.
Russel: It makes sense to me that you’d be doing this maybe even more often in a refinery environment because the consequences of taking various processes offline and what that means.
Once you’ve got the cutting done and then you put in your stoppage valves, one of the things as I’m looking at this I notice that… In particular, the one you’re showing there’s a bypass line. You get the flow going in bypass before you try to put the stoppage valves in place. That makes sense to me.
As you were talking about this, originally I was thinking that pressure was more the issue, but I actually think that flow would be more the issue. And, particularly how that creates differential pressure across those stoppage valves.
Deon: A good process or methodology that I have found is that when you are executing a double line stop — the one that you’ve seen in our corporate video — it is important that everybody establishes and you’re comfortable with the integrity of that entire bypass.
We normally let it run for a few hours, make sure that on the bypass everything is fine. We’ll insert the downstream line stop and its actuator with an articulator plugging head, which allows it to travel down.
It touches the nose wheel and it articulates either inside or outside — it depends on where there’s downstream or upstream. You’ll set the downstream one first and you’ll still get probably a 20 percent pass over that cup, because that’s how they design. They collapse a little bit.
You’ll continue to monitor the bypass. Then you will insert the upstream articulator plugging head. That seal is now energized. If the pipe is round and there’s no funny build up of any material on the ID, chances are you’re going to get a seal. You’ll be able to get a workable seal. The industry likes to refer to it as a workable seal.
Theoretically, because I’m talking about the ready at this moment, you’ll get a proper seal and your bypass will now be 100 percent carrying whatever product you’re transporting between point A to point B. Your bypass is now critical.
Russel: I’m going to walk this back through it, make sure I understand what you just told me. You put into position the downstream valve first. When you do that, the seal is designed such that some of the flow is actually continuing to go past that plug.
Deon: Yeah. Remember, it’s not a valve. You open the valve. This is an articulated plugging head.
Russel: It’s more like a plug in your bathroom on the drain kind of thing than it is a valve.
Deon: Yeah, correct.
Russel: So when the flow is pushing past it one way, it’s actually going to flow past. When you go upstream, it’s the opposite. That flow actually causes the seal to expand and get contact. Then once the flow is fully redirected, the downstream one does the same thing because it’s getting the backflow.
Deon: Correct, exactly that. The pressure on the downstream side will now energize the seal, and it will seal properly.
Russel: It needs to be a plug, not a valve, because it’s got to deal with any out-of-roundness or any other issue with the pipe wall so it can make a good plug, even though it’s not a perfectly round, perfectly smooth…
Russel: That makes a huge amount of sense, but I would have never figured that out just watching the video.
Deon: There are certain things that I didn’t want to show in there because there’s no point in having a conversation after.
Russel: That’s true, I guess. That’s true.
Deon: To me, once you’ve got all that done, the actual cutting out a piece of pipe or putting in a permanent valve or something like that is fairly straightforward once you’ve got all that in place. Then the issue becomes backing out.
Russel: Well, it’s straightforward only if you remember to vent that section. Remember, you’ve got two plugs in the line, and you’ve got a Delta-P of zero across those plugs. Now — through a purge and equalization fitting — you’ve got to…I’ve one shown the four main taps. In fact, I did show the smaller two-inch tap, which allows you to vent whatever product you’ve got between the two plugging heads. Now, you have your Delta-P with zero pressure between the plugging heads.
We use a cold-cutting method, and we’ll cut and bevel the line. If it’s a valve or take-off for repair of a damaged section, that goes ahead. You’ll replace the section and do all your NDE, making sure that your integrity of the material between the plugging head is sound.
Then, yes, you’re right, backing this out, it’s just in the opposite direction, so you need to be mindful. Delta-P is now going to be either your friend or your foe. You need to be very mindful right now because this is where you need to keep your wits about you.
Russel: To get those line plugs out, you’ve got to get to zero pressure between the segment you isolated and the flowing segment.
Deon: Correct. The Delta-P, there’s got to be no delta for you to safely retract that.
Russel: Beyond getting the pressure equalized, if I’ve got these plugs, and it’s the flow that’s causing them to seal, how do I get them to the point that it’s not flow that’s causing them to seal, so I can back them out?
Deon: Remember, flow is not really what’s causing them to seal. It’s the pressure behind. Once you insert the upstream plugging head, theoretically, there should be no more flow. There’ll only be flow if you have a bypass or a leak across the seal.
It’s the pressure behind that energizes that seal. There’s still flow in the line, but it stops at the seal and is diverted through the bypass and downstream…
Russel: Once you get that pressure equalized, the seal disengages?
Russel: That’s why you’ve got to do that just so.
Deon: Yep. It’s just physics. [laughs] You can try as much as you want. You can put a bigger hydraulic ram on there. You can pull as much as you want. Who knows what type of damage you’re going to cause?
Russel: I learned from my dad when I was very young…My dad did everything around the house, did all the work on his cars and all the work on the house and all that kind of stuff. He would spend a whole lot of time measuring and thinking and very little time doing.
If anything, he never tried to force anything. If something was jammed or stuck or something like that, he would think his way through. It was before all the fancy YouTube videos that were helpful in thinking those kinds of things through. I suspect it’s the same kind of thing here. The quantity of thinking to the quantity of doing is thinking is a lot more than the doing.
Deon: Typically, the individual that’s involved with this is somebody who is methodical — I’m talking about successful people — and with an attention to detail. Those two characteristics in itself will go a long way to ensuring success and safety.
Deon: To my mind, methodical, attention to detail, and paperwork, the document process and procedure, that’s the definition of a good engineer.
Deon: Absolutely right.
Russel: If you’re doing engineering on the fly, you’re not doing engineering.
Russel: There are situations where you have to do things like that, but you get my point.
Deon: Sure. This is not a back-of-a-napkin approach.
Russel: No, no, [laughs] absolutely not. It’s kind of the opposite of that. Once you’re all done, what’s left on the pipe?
Deon: As I mentioned earlier in the discussion, we have those flanges. We call them I lock or line stop flanges. Those are the ones with the segments and the plug. Those plugs, at this point, once you’ve now done your isolation and you’ve retracted, your valves are all closed except the two bypass valves. Those remain open because your bypass and your main line is now functional.
Once the NDE is all clear and everything is done, documents are signed, now you can start recovering equipment. You close your bypass down. You remove the bypass, and you are left with the two bypass valves on the outside fittings. You’re left with the two line stop valves as well on the inside two fittings.
What you do now, you’ll attach the plug to your hot tap machine and reinstall it onto the valve, get the pressure equalized across the valve, open the gate, set the plug into the segment grove. That’s where your O-ring will be energized. You will set your segments. Bleed off. Leave it on there, make sure it’s got a proper seal, and remove your hot tap machine.
Once the hot tap machine is removed, you’ll also see in the video, I went into the detail of showing the plug holder. The plug holder is removed, and a blind flange is installed. That’s how you will repeat the process four times until you’ve removed all your unrecovered or your equipment that’s on the line. What you’re left with are four fittings and blind flanges.
Russel: To me, that’s pretty fascinating. All the equipment that costs the real money is gone when you’re done.
Deon: Correct. The beauty of that is as well, if you ever, for whatever reason, want to go back into that line or that position, you don’t have to drill the holes. You remove your blind flanges and reverse the process as you did with the setting of the plug, remove the plug, and install whatever equipment you need to either line stop it or you can even use it as a take off later on.
Russel: Interesting. Deon, if you were talking to pipeliners, in general, and particularly pipeliners that weren’t familiar with this process for hot tapping and line stoppage, what would you want them to know about the process?
Deon: I have found over the years that this is something that people seem to have to trust you. They seem to want to get to know that you are a safe operator. There’s a lot of merit to that as well. What I would want them to take away from this is that considering they are well-documented procedures, it’s a very well-used technology, at least a safe technology.
You’ve got to look at the service provider and look at what kind of processes they follow. Their equipment, how is that maintained? How are their people trained? What kind of experience do they have amongst themselves?
I’m not going to use this as saying that one company’s better and we’re the best. As an industry, having the proper processes and approach, as I mentioned before, methodical and an eye for detail, and also open communication to the customer.
What we try and do is be as transparent as we possibly can be. We’re in this together. If I have an incident, it doesn’t only affect us. It affects the pipeline owner and operator as well.
Russel: That’s absolutely right. I think pipeline operators understand just how valuable this kind of contractor can be to their operation. They understand the need to work together, to share information, and leave no stone unturned, if you will.
Deon: Absolutely right.
Russel: Deon, thank you very much for coming on the podcast. This has been awesome. I feel like, for the first time, I have a clue about this process. I know enough to know I don’t know, and that’s always a good thing. I know enough to maybe find somebody who could do this type of work well. I really appreciate you coming on.
I encourage the listeners, if you’ve never seen or don’t have an understanding of how this process works, go to Deon’s website at ION PRO and have a look at the video. It’s pretty compelling.
Deon: Thank you for that.
Russel: All right.
Deon: Been great, thank you.
Russel: I hope you enjoyed this week’s episode of the Pipeliners Podcast and our conversation with Deon. Just a reminder before you go, you should register to win our customized Pipeliners Podcast YETI tumbler. Simply visit pipelinepodcastnetwork.com/win to enter yourself in the drawing.
Russel: If you have ideas, questions, or topics you’d be interested in, please let me know on the Contact Us page at pipelinepodcastnetwork.com or reach out to me on LinkedIn. Thanks for listening. I’ll talk to you next week.
Transcription by CastingWords