Jointing methods for RC MULTIsafe® and RC MAXIprotect® PP/PE pipes -part II
The heater plates in the welding devices must be electric. The butt welding machine should assure maintaining the required pressure on the surfaces of jointed elements and in case of error it should stop the process at any moment while indicating the error type. Before welding check condition of devices and tools.
The exemplary set for butt welding includes:
- butt welding machine,
- trimming tool,
- heater plate (mirror) with temperature controller, protective container for the heater plate,
- saw or pipe cutter for pipe cutting,
- electric power generator,
- contact thermometer for controlling the heater plate temperature,
- roller supports for pipes,
- welding tent.
Use only butt welding machine having valid calibration certificate. Movement of movable jaws of the device must be smooth. The heater plate should be clean, without any defects in the teflon coating. The general principles describe the conditions for the welding place and its direct vicinity, as well as preparation of jointed elements.
As pipes and fittings stored in the open warehouses or at the construction site may become dirty, one may use dry paper for the initial cleaning. The actual cleaning should be realized with use of clean paper and cleaning liquid, which removes grease and any moisture. The butt welding procedure should be approved by the network user, taking into consideration the welding cycle, according to technology specified by the manufacturers of the polyethylene pipes and welding machine. After melting the ends of jointed elements the butt welding machine should allow for removing the heater plate and jointing the elements in proper time, without damaging the melted surfaces.
The automatic butt welding machine for jointing of polyethylene elements should assure control and recording of welding parameters for each joint, i.e.:
- times of the welding cycle individual stages,
- pressure on the surface of the individual elements,
- temperature of the heater plate,
- ambient temperature,
- drag pressure required for overcoming the resistance of the welding machine moving part with fixed element to be welded.
Making the so called “dummy weld” is a good practice. Upon the basis of shape of obtained bead it is possible to verify the correctness of process parameters. The test goal is also cleaning of the heating plate in the contact point between the jointed elements before the actual welding. Tests should be realized before each change of diameter or wall thickness of jointed elements. Temperature of the heater plate depends mostly on the material type. For elements made of PE100 and PE100 RC the tool temperature is 220°C.