Polyethylene pipes are gaining in popularity
They are used in sanitary, plumbing or even gas installations. Rules for the qualification examination of welders and welders who perform welding and sealing of thermoplastics, is defined by EN 13067.
There are several methods used to join PE pipes. One of the most effective is electrofusion and butt welding.
Electrofusion welding is a method of joining PE pipes using fittings that have built-in heating elements. It requires suitable conditions and preparation of the welding site.
Electrofusion welding should be carried out at temperatures between -5 and 45 degrees Celsius. It should not be carried out during precipitation or in strong winds. It should also not be carried out when there is heavy dust or high humidity. In the event of lower temperatures, a special protective tent should be set up at the work site and the air inside warmed by a special blower. Such a tent is also used to protect the work site from the wind.
Preparation of the pipe
If we have already prepared our work area, it is now time to prepare the pipes properly. There are a number of steps to be remembered. These are:
- cutting pipes perpendicular to their axis;
- removal of the outer layer for a minimum of 0.2 mm;
- degreasing the sealing surface with a special product.
The parts to be joined must be completely dry.
The next step is to immobilise the pipe and fitting with a clamp, which will prevent the components from moving.
Electrofusion welding - welding machine
The next step is to use an electrofusion welding machine. It must be placed on a properly prepared site. It should be standing on a firm surface. It cannot be placed in tall grass, on uneven ground or in mud. The action of the welding machine is to transmit voltage to the fittings. The current flowing through the wires causes the polymer to melt. This leads to the fusion of the fitting with the pipe. The process ends with the cooling of the joint and the removal of the clamps that immobilised the pipe and fitting.
Butt welding is mainly used to join plastic pipes with a wide range of diameters. It is a reliable and safe method of joining pipes and fittings. It consists of heating the pipe surface to a suitable temperature and joining it by mechanical pressure. The result is a homogenous joint. Butt welding does not require a lot of time. It provides high strength and is economical.
The welding surfaces must be protected from adverse weather conditions such as:
- Strong sunshine;
If the pipe is heated by the sun, the temperature of the weld area should be evened out by covering it.
The surfaces to be welded must not be damaged and must be clean. Cleaning of the surfaces should be carried out immediately prior to the process. Pipe ends that are delivered in rings may show ovalization after unrolling. They must be properly prepared for welding. Min catalysts, which are applied to the pipe end, are used for this. End caps, which are fitted at the factory, should be removed from the designated pipe end before welding itself.