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Culvert and Pipe Plugs Culvert and pipe plugs are used primarily to keep toxic materials inside a pipe or culvert, and away from sensitive wet lands or the environment in general. There are a lot of considerations that should be taken into account when designing a culvert plug. However we do our best to share our experience with you. These plugs sometimes have a huge responsibility to keep environmentally damaging substances out of sensitive wet lands, and they should be tested well past their designed intent to make certain that they meet the criteria they are designed for. We only have control over the information provided by the customer, and if it is not accurate, or if we use incorrect information, the problem they are trying to solve could become worse. For this reason, we take great care to send accurate images of the concept and dimensions before we start, and we ask the our customers test the concept fully. Design considerations We build each culvert plug to the exact diameter you request. However the material stretches about 2 to 3 % in one direction, and so the 4 psi air pressure tends to wedge a plug securely into place. Corrugated culverts have less surface area to grip to, and we often suggest that Quick concrete be laid in between the corrugations with a piece of construction plastic placed on top of that. The plug is then inflated to push the concrete into place and allowed to cure. the construction plastic acts as a release agent, With this set up, the seal around the bottom is better, and there is more grip on the plug. Please keep in mind that heavy head pressure inside the culvert may require a longer main section or attachment points to keep the plug in place, and these things are difficult to quantify, so we try to over build to make sure it works. With Head Pressure, we would like to have at least a 50% safety margin. Plugs need to be tested before endangering people or the environment. Trust the math, but always test first. There may be other factors we did not count on and did not factor in. Counteracting Head Pressure Here is a good idea for head pressure calculation. ON 24 in diameters we use a 5 psi, on 36 and 48 inch diameters we use a 4 PSI, and on a 60 we use a 3 psi PRV. Most of these have around a 400 % safety factor from the point of explosion. To calculate if the head pressure will overcome the pressure in the plug, with a 50% safety factor, we use come scuba diving math. 33 ft of head pressure =14.7 psi (gauge pressure). So 5 ft of head pressure will put 5/33*14.7 =2.23 PSI force on the face of the plug. If we use a 4 psi prv in the plug, then the safety factor is 4/2.23=1.79 or 79% safety factor. As you see we could raise the pressure on the PRV, but explosions are devastating and dangerous. We know we have been there. (Please scroll down to the bottom of Valve information section to learn more.) We have taken great care to design some plugs with attachments that help keep them from moving through the culvert. There are cases where culverts need to be plugged periodically to clear pump systems. these may not involve toxic substances but they still need to shut off flow for a period of time while routine maintenance is done. We rely on the customers experience to tell us if these are viable and safe uses for the product. Remember to always test the system before putting it into use. Have a look at a product for the Ohio Dept. of Wildlife here.
Prices for 2017 These prices are considered a standard offering for different diameters. Go to the image links (left) to see the options included in the price.
Pressure relief valve information: Pressure relief valves are designed by Mirada Research and Engineering. They are designed to be high flow. Therefore if a customer hooks up a small compressor to one of these units, it is not likely that the unit will pop. The PRV should flow more air than the compressor puts in to the system. Do not hook up a giant compressor, your plugs could explode. We are concerned about explosions, so here is some technical and practical data. Hoop stress, or the amount of stress on the fabric is proportional to surface area exposed to the pressure. The larger the diameter, the greater the hoop stress. In this destructive hydrostatic test, 23 psi was used to explode this unit that had and equivalent of 33 inch diameter. In this way we can determine what a 400 % safety factor would be. For a 48 inch diameter tube. Here is the math: Expected burst factor for this fabric on a 48 inch diameter = 33/48* 23= 15.81 psi. So we would not like to go higher than 4 psi on a 48 in dia to get that 400% safety factor. We do have experience where these PRVs and these units worked together with these pressures to do some amazing things, without a failure. I do want to keep the safety factor near 400% because there are other issues were failure could occur like a damaged plug from mishandling for instance. PRV for a 24 in diameter is 5 psi, for a 36 in diameter is 4 psi, as well as a 48 in diameter being 4 psi, then 60 inch dia Is 3 psi, and PRV for a 72 inch plug is 2 psi. Pressure relief for a 14 ft diameter plug is 1 psi, but in the example on this page we could only get a .8 psi valve, and it worked just fine. If you care to see how design effects the pressure please see this blog. Stress risers can be easily placed in the design that cause these inflation scenarios to fail. This is one of those. Surfaces that do not place stress on the fabric in appropriate ways will cause failure at lower pressure. These plugs are all designed individually for a specific need. Inflation is a huge consideration. plugs this size can not use disposable CO2 cylinders, some use boat valves, and 110 volt blowers, some use compressed air. When compressed air is used, a pressure relief valve ( PRV ) is always recommended. The one pictured here is an inflated cylinder. It has a pressure relief valve set at 4 psi. A boat valve for rapid inflation and deflation, and a clamp flange with a 3/4 NPT (national pipe thread) connection that can be used to plumb to any air source. This plug is designed to keep toxic materials that may leak out of a plant from entering a river. They are tested semi annually by the company. The plug pictured here is 42 inches in diameter.
This was a very large diameter plug, and it was only designed to plug a hole and keep snow out of the Ekati Diamond Mine in Canada. We also made a number of 13 ft. diameter, 36 inch diameter, and 48 inch diameter plugs for them. As well as this 23.5 ft. diameter arch to seal up a truck entrance to the mine. Note the curtain has a zipper that allows it to unzip from the arch, and a channel that allows the base to be staked down for heavy wind.
Pipe plugs were first used out in the oil and gas field to keep materials that were inside the pipe (drilling mud for instance) from spilling out on the road way when the drill pipe is in transit. Note that there is a small grommet strip to help locate the plug inside the pipe. We can also supply companies with a light weight high pressure hand pump called a top off pump.
This is an inflatable cylinder that was used on the side of a steel and concrete gate to seal that edge. More information is available here.
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Order inquiries: shop.jpwinc@gmail.com © 2011 Jack's Plastic Welding, Inc
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