HDPE pipe has become the most popularly used pipe in Nepal. The benefits HDPE pipe brings to the table simply cannot be ignored. From every aspect that we see, HDPE pipes seem to be better than other pipes, be it in performance or durability. As HDPE pipe in Nepal is used so commonly, we should also know additional information about HDPE pipes as it will definitely come in handy in this HDPE pipe loving nation.
We share a lot of information about HDPE pipes from time to time. In our last article, we had discussed about materials used for creating fittings of HDPE pipes. Today, in this article we will be sharing valuable information about how HDPE pipe fittings are joined. It is crucial that proper planning and preparation should be done before joining HDPE pipes as unplanned joining and fittings will only result in degraded performance.
HDPE pipes are made with two simple ends. While connecting these ends though, should be done in a proper manner. Often is the case that used HDPE pipe in Nepal don’t perform to their full potential as joining and fitting isn’t done properly. On top of that, people along with workers may not have the idea that there are various ways to connect the HDPE pipes and its accessories, which will result in low quality joints. Here are some of the most popular and effective ways in which HDPE pipes are joined.
Thermal Fusion, also known as Butt Fusion, is one of the most popular methods used for fitting HDPE pipe in Nepal. While implementing this technique, a special type of fusion device is used. The ends of the pipes that are to be joined should be placed in the same direction and also it should be made sure that the pipes that are to be joined should be totally clean. If we want to achieve better fusion, we should use the double-head straightening machine with the device and also should make sure that the pipe ends too are free of any defects.
In addition, butt fusion of HDPE pipes should not be carried out inside trench. For butt fusion, some criteria that should be met are that pipes of different thickness should not be fitted, the devices sued should be clean and dry and experienced people should be made to work on this project. Different conditions like temperature, edge pressure, cooling time, etc. should also be considered while thermal fusion.
Bushing fittings are used limitedly compared to other HDPE pipe joining methods and this type of joining is usually done in cases where there is presence of low diameters. For conducting bushing fittings, people should firstly have necessary ideas about this fitting procedure and all the needed tools should be provided to make the joint effectively.
In bushing, the pipes that are to be joint are inserted inside the bush. Then, the connection inside the bush is heated simultaneously with the outer surface of the pipe joined. After a certain period of time, the heating device is removed and the pipe is inserted into receptacle. The heating device’s removal time depends upon the pipe’s diameter and as per the manufacturer’s details. And finally, the connection is entered without any force until it is completely cool. Bushing isn’t the most popular fitting procedure but we can see this method implemented wherever applicable while joining HDPE pipe in Nepal.
Electrofusion fittings are often considered as the most reliable and trusted ways for connecting pipes and so it is also one of the most popular technique used for fitting HDPE pipe in Nepal. In electrofusion method, all fittings and accessories are equipped with an electric heating coil. When the coils are heated, adjacent materials begin melting and the outer surface of the pipe starts to melt.
To obtain proper connection using Electrofusion, several conditions need to be checked and fulfilled. Firstly, the heating coil should be placed as close to the surfaces as possible and checking should also be made to see if the heat is spread uniformly during welding. Temperature and pressure of the melted sections of the pipes should also be controlled as per the requirement. Proper protection for the fused parts should be maintained before, during and after the connection and the right time for electrofusion should be considered. Even the technical aspects like cutting the pipe in proper manner, maintaining cleanliness, proper marking of the notches, placement of parts, using appropriate clamps, etc. should be maintained to get the best results.
Flange based connection is a well-known pipe joining method mostly used to connect HDPE pipes to cast iron, galvanized steel or valves. Usually in this type of fitting procedure, one end is flanged and the other end is a perforated metal ring. The diameter of holes in the ring must be in accordance to the pipes or valves used. To make the connection, the metal ring must be placed on the simple end that is connected to the flange and then the parts are fused.
After fusion, the metal ring should be pushed to the flange and then, finally the metal ring should be pushed into the flange. The flanges can be connected using bolts and nuts and the HDPE flange will give a sturdy and reliable seal. We can commonly see this technique being used to join and fit HDPE pipe in Nepal.
Bolting is also one of the popular methods for joining HDPE pipes in Nepal. Usually, this method includes closing the nuts and bolts to the midsection and twisting it to establish the connection. Bolting techniques are most popularly used for connecting soft PE pipes or hoses. In order to make this type of fitting strong and reliable, conical gaskets can also be fit between the body of the nut and the pipe’s end which will provide additional strength to the nuts.
We see use of bolting techniques for HDPE pipe in Nepal mainly for use in distribution pipelines, which are usually buried underground. And this type of connection is usually done for connecting smaller diameter pipes so it isn’t used for main water supply pipes.
Extrusion is a popular method for connecting HDPE as well as other types of pipes with a thick wall. Consumption of this type of piping however is limited and can be verified by the pipe manufacturer. In extrusion process, heating is done by flame and the pipes are connected. After connecting, a molten material, usually of the type polyethylene is inserted between two ends of the pipe. We can see this type of fitting being used for fitting HDPE pipes in Nepal.
Rubber gasket method is popularly implemented for HDPE pipe in Nepal and this method can be implemented if the pipe manufacturer manufactures its own bowl and welds it to the pipe. Rubber gaskets are popular because it provides a strong and sturdy seal for the pipes that are connected.