Isolate a line without hot work using a freeze plug, a cold work method that safely uses liquid nitrogen to freeze a pipe medium to create an isolation plug in your pipe.
Freeze plugs are a great alternative to hot tapping that can save you 3 days or more by avoiding hot work and the costs that come with it. You’re also improving safety by eliminating the hot work hazard.
In this article, I’m going to share with you how the freeze plug process works. I’ll also dive into the testing that’s gone into to it to ensure safety and the benefits it can bring to your facility.
How It Works
The plug itself is formed using nitrogen gas to freeze the pipe medium from the outside in.
A double walled chamber, divided into two halves, is bolted onto the pipe. This chamber ensures that all the nitrogen gas is captured and vented to a safe location, putting worker safety first.
The freeze plug itself relies on the adhesion of ice to steel, which produces two opposing forces.
You probably know that water expands when it freezes. So the liquid inside the pipe is going to expand against the inner pipe wall.
But that’s not all – the pipe steel itself shrinks as the freezing is applied, causing two opposing forces that lock the freeze plug into position.
You get expanding liquid and contracting pipe, which prevents all moving and slipping of the plug.
This makes a freeze plug a very safe, effective solution for creating an isolation plug.
The Right Conditions
As you might expect, you need a freezeable medium for the freeze plug option to work. Anything with 70% water content or more is ideal.
This doesn’t mean you can’t freeze other mediums, but 70% is the standard for a freeze plug.
You also need a no flow condition. Not very little flow – no flow.
Imagine that even with very little flow, as the plug forms inside the pipe it will squeeze that tiny stream of water flowing through, increasing its pressure more and more which will prevent the plug from fully forming.
Temperature comes into play as well, but if you have a static flow condition, the nitrogen gas will overcome the temperature and the plug will form.
And of course something to look at is the condition of the pipe. We want to make sure the integrity is intact, so we perform non destructive evaluation to make sure there’s sufficient wall thickness and no surface cracking.
With all this being said, the two most important conditions for a freeze plug are 70% water, and no flow.
Freeze Plug Testing
We’ve tested freeze plugs and we know competitors that have also tested them, and we know that these plugs can withstand up to at least 5000 psi.
Third parties are always testing it and get hired by different industries. The big one is the nuclear industry, who hired an organization called EPRI(Electric Power Research Institute), that did a large study confirming the effectiveness of freeze plugs.
We base our predictions on these type of third party reports, and ASME also gets into some online freezing options well.
Freeze plugs are an industry-wide accepted service.
Benefits Of A Freeze Plug
A Freeze Plug simplifies your isolation process by avoiding hot work and cutting time spent on the isolation by 75% or more. Here’s a summary of what you can expect when you choose to isolate pipe with a Freeze Plug.
- Freeze the fluids inside the pipe, providing on the spot isolation
- Reduce your isolation time to one day, versus the 3 to 4 usually required for hot work. You’re also avoiding hot work permits and other associated labor costs.
- Drive safety by eliminating the possibility of a fire or explosion hazard at your facility
- Reduce your environmental footprint
With a Freeze Plug, you can get an isolation done in one shift without hot work, saving you money and driving efficiency at your facility.
The freezing does not damage your pipe, and it thaws easily on its own within or day or two.
To learn more about Freeze Plugs and how they can benefit your facility, hit the “Lets Talk” button, and get in touch!
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