When Major League Baseball players return to Florida and Arizona for spring training, they don&#;t dive right in with a full nine-inning game on day one. They start by going back to the basics &#; the fundamental elements of the game of baseball. The building blocks of success. Without mastery of the simple elements, winning games will not come to fruition.
When it comes to high-density polyethylene (HDPE) &#; nothing is more basic than fusing pipe. Heat fusion, butt welding or most commonly &#; butt fusion, is the act of joining two pieces of thermoplastic pipe. When performed correctly, the strength of the permanent, monolithic joint is equal to or greater than that of the pipe itself.
So &#; what exactly is butt fusion and how is it done?
This is information we are happy to share, but please recognize that this is a primer &#; it does not give you free reign to begin fusing without the proper training like ISCO can provide.
Improper use or an inaccurate operating sequence can cause a poor fusion, and may be hazardous.
Also, be sure to equip yourself with any recommended protective gear, and if you are not outside, ensure that the interior space that houses the fusion equipment or generator is appropriately ventilated.
If you have questions, concerns or need training, contact one of our McElroy certified fusion training specialists: ISCO Fusion Equipment Training
1. Selecting the equipment
Ensure that you have the proper fusion equipment that accommodates the diameter of pipe and fittings that you are working with. Using poorly maintained, damaged, or incorrect equipment can also cause a bad fusion. Use only the correct tools and equipment for the job, and follow the equipment manufacturer&#;s procedure for equipment maintenance.
Butt fusion welding machines can be used to allow precise control of factors, such as:
The range of fusion machines begin with fully manual in its operation to highly automated with hydraulics and computer touchpad controls. Your needs depend on the job you are executing and is worth consulting an expert before you make the selection.
Many of the newer McElroy models feature the McElroy Datalogger built in to the machine. The Datalogger provides real-time feedback and data collection during the fusion process, allowing users to monitor the fusion process through a live graphical interface giving immediate and responsive feedback. The data can be readily accessed and analyzed making it a valuable tool for quality control. Some of the older McElroy fusion machines, while not equipped with a built-in Datalogger, allow you to integrate that technology into the fusion equipment.
But more in-depth details about the McElroy Datalogger is for another blog and another day.
2. Preparing and Cleaning the Pipe:
Whether you are fusing a length of pipe to a fitting or another piece of pipe, the inside and outside of the pipe needs to be cleaned thoroughly of dirt and debris with a clean, lint-free cloth or paper towel. Some piping material manufacturers or fusion processes call for a cleaning solution to be used.
Electrofusion requires an alcohol solution, but because the facing portions of the pipe will have ribbons shaved off with butt-fusion, it is only necessary to remove dirt and debris from the ends of the pipe adjacent to the weld.
Dirt and debris that enters the fusion zone can compromise the process, so be certain that before you proceed, the two ends that are to be fused are properly cleaned.
3. Alignment and Clamping:
It is crucial that the two ends that are to be fused are secured into the clamps of the fusion equipment and adequately aligned from top to bottom. If the alignment is off, the fusion may be compromised. When the two ends that are to be fused are pushed together by the fusion equipment and locked into place, it should be a seamless transition from one piece to the next with no gaps, and no ridge or drop off from one piece to the next.
If the alignment needs to be adjusted, it is best to tighten the side that is too high down to meet the other pipe or fitting. Adjust the alignment until the point of fusion is smooth like a single piece of pipe.
The next step is exposing a clean, virgin surface on the aligned pieces of pipe or fitting so the fusion can be performed.
4. Facing Process:
Butt fusion requires a clean, smooth, virgin surface of HDPE in order for the fusion to have the optimal result.
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This is done with the facing tool on your fusion machine. Securely mount the facing tool between the pieces of pipe, slide the pipe into place and begin the facing process. Depending on the fusion machine, there are different variables that indicate when the process is complete, from proximity of the pipe and fitting to the clamps, to the sound and speed of the facing tool or the facing tool actually coming to a stop. Once again &#; proper training on any piece of equipment is imperative to properly executing effective butt fusion.
5. Inspecting and Cleaning:
After moving the facing tool, clear the excess pipe shavings or ribbons that have been removed by the facing tool. Avoid touching the clean ends of the pipe as the oil from your skin or other debris can compromise the fusion.
Re-check the alignment to confirm that there are no gaps and the alignment is still satisfactory. If it is not, re-align and perform the facing process again until it meets the standards.
Once the facing and alignment are on point, the actual fusion can begin.
6. Heating and Fusion
Confirm the heating plate is at the correct temperature (typically between 400 and 450 degrees).
The heating plate needs to be carefully mounted between the cleanly faced ends, and the pipe is securely but not forcefully placed in contact with the plate and locked into place. The pipe must remain in place against the heating plate for a process called the heat soak, based on the outside diameter and thickness of the pipe and fittings.
Once the timer expires on the heat soak, the lock is released, pulling the pipe apart and the heating plate is carefully removed. Timing is of the essence here, but the melted ends need to be inspected to confirm that the surface of the pipe is smooth, completely melted and flat. If the pipe appears to be concave, it will have to be allowed to cool and the process must start over from the beginning.
7. Inspection and Rejoining
Upon the quick, but efficient inspection of the pipe ends, once it is confirmed that the pipe meets the three standards, the pipe can be re-joined smoothly but firmly, and once again locked into place.
The patented &#;double bead&#; will roll into place if performed correctly &#; the closest you&#;ll get to autonomous sensory meridian response (ASMR) in the world of HDPE. If you know &#; you know, and if you don&#;t &#; you will when you witness it.
8. Cooling Process:
Like the heat soak, the cooling process is one based on the outer diameter and wall thickness of the pipe. When the proper cooling duration has been completed, the fusion is complete. Until that time, the pipe needs to remain in the clamps and not disturbed, so as not to damage or alter the fusion.
9. Troubleshooting and Bead Inspection:
With training, inspection of the bead can reveal problems with the joint based on the size and shape of the bead. Some of them include:
If the bead does not meet the appropriate standards, the fusion needs to be cut out and the fusion process must begin again from step one.
And that is the Cliff Notes version of butt fusion. All nine innings if you will.
Sometimes it&#;s nice to get back to basics.
Play Ball!
There are two methods for joining HDPE pipes. Butt Welding, Electrofusion Welding, or mechanical fasteners are used to connect HDPE Pipe. Pipes made of materials other than polyethylene can be connected using compression fittings, flanges, or other suitable adapters. Connection parts provide convenience based on where they will be used.
Welding is done with heating resistors inside the fusion fitting during the electrofusion welding process. After the pipes are inserted into the Ef fittings, the welding machine's ends are connected to the resistors of the Ef fitting and heated. As a result, the HDPE pipe will be connected to the electrofusion fitting. Pe 100 pipes can be welded using the Electrofusion welding method with HDPE pipes ranging in diameter from 20 mm to mm. The DVS standard is followed when performing electrofusion welding.
Butt welding is the most commonly used welding method for joining HDPE pipes and fittings today. The pipe joining method is a process in which the two ends of the pipes are heated and welded using a butt-welding machine, and then pushed toward each other by pressure at a specific temperature The welding method can be used to join HDPE pipes with diameters up to mm. The butt-welding method adheres to the DVS standard.
For more information, please visit HDPE Pipe Couplings.