PIPE FREEZING | HOT TAPS | LINE STOPPING

Pipe Freezing • Hot Taps • Wet Tapping • Line Stopping
24 HOUR EMERGENCY SERVICE

American Piping Services
6625 S. Valley View Blvd Ste. 200
Las Vegas, Nevada 89118
Phone: 702.362.3622
Fax: 702.362.4225
Contractors License #49295
todd@apsnv.com

702-362-3622

AmericanPipingServices.com

Certified-Welding.com

Nation wide service for Pipe Freezing
Hot Taps and Line Stops

American Piping Services, Inc. , began Wet Tapping and Line Stopping services in Las Vegas, Nevada in 1999. We saw a need for a skilled and reliable 24-hour service in a town that works all day and night. Our staff is trained in all areas of Wet Tapping, Line Stopping and Pipe Freezing procedures. We take pride in a continuous safe and reliable service record. Our services will allow you to make repairs or modify your pressurized system while allowing uninterrupted service. Check out these photos.

Dual 2inch line freeze

Start of frost line

Freeze complete

What is a bypass? When you need to make a change in an existing system without interrupting the flow, a bypass is a great method. The process has several steps.

First, a set of bypass tees are attached to the pipe on either side of the area to be valved or repaired. Then a set of stop tees are attached on the pipe outside of where the pipe will be cut to add new valve or repair work. Then, on the very inside, vent holes are made to release the pressure in the portion of the pipe that will be cut.

Second, temporary sandwich type valves are installed on each of the tees and each one is hot tapped.

Then, the bypass pipe work is commissioned and installed and the up stream and down stream plugging machines are inserted into the fittings.

Once the bypass is functioning, the plugging machines are lowered and the pipe is plugged. The center section is ready to be de-pressurized through the vent hole fittings and that section can the be cut and altered in whatever way you need.

When the repair or modifications are finished, the center section is re-pressurized through the vent holes. Then the plugging machines are withdrawn and the main line becomes the line of flow.

To finish things off, the sandwich valves are removed, the fittings are all blinded and blanked off and the job is complete.

Another option is a pipe freeze (also know as a line freeze, freeze stop, freeze plug or cryo-plugging

The procedure here is much less involved and invasive. A special cuff, sort of like a tube split in half the long way, is attached to the pipe where you need the stop. The cuff is filled, little by little with liquid nitrogen (which is about 320 degrees below zero) to gradually cool the equipment and the pipe. Once the pipe is sufficiently cooled the flow of liquid nitrogen is increased until the contents of the pipe become a chunk of ice blocking the flow in the pipe. This creates a stable line stop. Pipe freezing requires no holes or permanent changes to the line. As soon as the work is complete, the liquid nitrogen is withdrawn, the cuff is removed, the pipe and frozen plug thaw and you are back in business.

Most type of pipe are tolerant of the temperature involved in pipe freezing. Types of pipe commonly frozen are

Stainless steel
Carbon Steel
Copper
Aluminum
Lead

Pipe freezing is commonly used to service many types of industries including hotels and resorts, apartment complexes, malls and shopping centers, water and sewage treatment plants, industrial and commercial production facilities, power plants, hospitals and many other institutions.

Applications where pipe freezing may be used include fire protection systems, pump replacement, chiller modifications, valve insertion or valve replacement, oil filled electrical cable pipe repairs, pressure testing and leak testing to name a few.

There is a bit of fun science involved in pipe freezing. Most people associate frozen pipes with water damage to property and costly repairs to systems. So why don’t the pipes break during this process? Well, here is the answer. When pipes freeze in an uncontrolled situation they freeze first along the pipe wall and then toward the center. When the ice slug completely blocks the flow in the pipe the ice keeps expanding along the length of the pipe which increases the pressure the water is under between the ice and a valve. The pressure of the water builds and builds until finally the pressure inside the pipe is more than the pipe can take and it breaks in the unfrozen area where the pressure was building. The pressure of the radial expansion of the ice does not create enough stress to cause a system to fail.

So, then there is the question of what keeps the ice in place? Won’t the pressure of the system just push the plug out? Do you remember the movie “A Christmas Story”? When the kid puts his tongue on the light pole there is an amazingly strong bond! In fact, ice adheres very, very well to steel. That alone would be enough to keep the ice intact under significant pressures. But we are not relying on that adhesion alone. When the pipe itself is cooled the metal actually changes its structure just a bit and the pipe contracts, not too much, but enough that the ice plugs takes on the shape of an hour glass, effectively wedging itself in place in the pipe. It is too large on either end to move through the frozen section. These two factors explain the stability of a pipe freeze.

Pipe freezing has some limitations:

PVC and most other plastics and a few other types of special pipes will not tolerate the temperatures involved.
When the contents of the pipe are warm or hot it will take longer to freeze
Plugs that must be held for a day or more can get costly
There must be sufficient space between the pipe freeze site and any valve or “dead end” to avoid damage to the pipe.There are several options for making the changes. First, is the line stop.

The important factors most people need to work around are, first and most important; the water must stay on to the main part of the facility. No matter what. Second, the changes (anything from a couple of repairs to adding a valve or meter where there is not one) need to happen in a tight time frame. Third, our budget.

Line stopping is a process used to modify a line in a pipe system or make repairs without interrupting service to the rest of the system or depressurizing the line. It reduces the amount of time the line is out of service and avoids having to drain the system, which can be expensive, messy and slow. The basics of a line stop are as follows:

Step 1:
A Hot Tap makes a hole in the pipe and a Line Stopping machine is bolted to the tapping valve.

Step 2:
Once secure, the valve is opened and the machine is filled with whatever flows in the pipe.

Step 3:
The Line Stop machine inserts a steel Plugging Head down through the open valve and into the pipe through the tapped hole.

Step 4:
Then a sensor touches the inside wall of the pipe, and the Plugging Head moves and turns into the sealing position.

Step 5:
The flow is then stopped and the pipe can be depressurized and modifications or repairs can be made. Once the changes are complete, the pipe is represurized and the plugging tees are blanked.

When you just can not interrupt service of a line to make repairs of modifications there is a way to keep continuous flow in the line and still do the work. This process is called a bypass.