|There sre several types connection methods for PE 100 pipes. Most commonly used and can be easily applied methods are butt-welding and electro-fusion welding methods.
Butt-welding is the most common connection method used for PE 100 pipes. The principle of the system is heating the connection surfaces for certian amount of time and pressure, by use of a resistance plate. After the heating process is completed, the surfaces are connected with calculated amount of time and pressure and cooled afterwards. As the welding process does not require use of additional couplings, butt-wellding is considered to be an economical method. The method is recommended to be used for pipes with a diameter of large than ø63 mm dia.
ADVANTAGES OF BUTT-WELLDING
• No additional couplings are required for connection.
• Fittings such as brackets and Ts can be created by butt-welding.
• It is easy to provide a welding apparatus and to apply the method.
• Fittings are cheaper than other methods.
• The method can be safely used for pipes with a diameter of larger than ø63 (wall thickness of higher than 3mm).
• Lips created on the inner and outer surfaces as a result of the connection do not extend the welding section.
• Butt-welding is a reliable connection method.
• When a connection complying with the principles of the technique is formed, the welding zone offers the same amount of strength with the main pipe sections.
IMPORTANT POINTS TO CONSIDER DURING BUTT-WELDING
• Materials to be connected should have the same parametric values (same wall thickness or maximum 10% difference).
• Working environment should be clean and free form water, snow, oil etc. The connection surfaces should be handfelt before welding.
• Weather conditions should be appropriate (wind, moisture, dust etc.) Ambient temperature should be higher than -5..
• The welding operation should be performed by a well- trained, qualified operator.
SEQUENCE OF ACTIONS IN BUTT-WELDING
1- Place and fix the pipes into the welding machine.
2- Place the trimming device onto the column shafts of the welding apparatus and trim the surfaces carefully.
3- Check if the surfaces are on the same axis and if they are in contact.
4- Move away the connection surfaces from each other in order to place the heating plate between them.
5- Apply the heating resistance plate to the surfaces for certian amount of time, temperature and pressure specified by the technical specifications given by the producer of the welding apparatus or in accordance with the result of the formula calculations.
6- Remove the heating plate and apply pressure on the connection section for a certian amount of time and pressure.
7- Remove the pressure after the predefined time is over and allow the pipe to get cool.
ELECTRO-FUSION WELDING METHOD
This method is generally preferred for systems requiring very high safety levels and in cramped working areas where there is not enough space for performing butt-welding and for repair works. The connection process requires the use of electro-fusion welding machine and electro-fusion fittings. Special resistance wires are placed to the inner surfaces of these fittings at the manufacturing stage. The electro-fusion welding machine conveys electric current to these wires in order to carry the temperature of the inner surfaces to the melting point. The fitting and the pipe section are connected afterwards. This method also allows forming direct exits from the main pipeline.
ADVANTAGES DELIVERED BY ELECTRO-FUSION WELDING;
• It is possible to form direct exist from the main pipe by using this method.
• It is easy to repair pipes.
• The method can be applied easily even in very tight spaces.
• Electro-fusion welding does not require much excavation or fill work.
IMPORTANAT POINTS TO CONSIDER DURING ELECRO-FUSION WELDING;
• Materials to be connected should have to same parametric values.
• Working environment should be clean and free form water, snow, oil etc.
• The optimum temperature range for electro-fusion welding is -10 - +45.
• The welding operation should be performed by a well-trained, qualified operator.
SEQUENCE OF ACTIONS IN ELECTRO-FUSION WELDING
1- Pipe section are cut vertical to their axis.
2- The welding surface of the pipe is shaved by use of the shaving apparatus, in order to remove impurities such as dirt, oil etc.
3- The fitting is attached to the pipe.
4- Technical specifications of the fitting is provided to be read by the welding machine, or the values are entered manually.
5- Welding operations starts, a few minutes later copmlete.