Instructions for Welding of RAKtherm Pipes & Fittings
The welding machine is heated up to 260 °C (described in “Using RAKtherm Welding Device & Tools”).
1 Use RAKtherm pipe cutter to cut the pipe. Make sure that a straight and clean pipe end results and not at a skewed angle. This is to ensure that the welding adheres to the right conditions.
The joining process during RAKtherm fusion welding can be divided into three stages:
Stage I: Initial heating and fitting expansion.
Note: Stages I and II are commonly termed ‘fusion time’. For successful joining of pipes, at least three preparation stages must be followed:
Stage II: Heat soaking to create the joint.
Stage Ill: Joint cooling.
Firstly, pipe ends must have properly finished squared ends as opposed to having a chamfered or broken edge. This ensures that the central cold zones come in full contact with the welding tools and proper heat conduction will accordingly be achieved. Before welding Stabi composite pipes peel-off the aluminum polypropylene layer completely.
• Secondly, the pipe surfaces to be joined must be properly cleaned to remove contaminants and foreign material. Otherwise, any contamination on the pipe surface is retained at the joint interface, which can significantly reduce the strength of the joint.
• Finally, the pipe and fitting should be clamped during welding to eliminate relative movement. This ensures that the molten polymer is allowed to fuse fully at the fusion interface, developing a strong joint.
2. Mark the welding depth with a pencil and measurement plate which are provided with the RAKtherm welding kit.
3. Enter the end of the pipe into the tool up to the marked depth without twisting it and simultaneously and also without twisting, push the fitting onto the heating tool, observing the general guidelines for heating up times outlined in table 4.1.
Timing for heating should not start until the pipe and fitting reaches to the marked welding depth. Both fitting and pipe should be heated for a set time, known as the heating time. When heating time is complete, the pipe and fitting should be removed from the heating tool, and pressed together to the marked welding depth for a few seconds without twisting a homogeneous structure of the same material is thereupon formed. The major alignment should be done before insertion of the pipe and fitting.
Use fusion time for minor alignment before fusion is complete and the assembled parts have cooled. Never mechanically stress the welding joint before cooling time. A cross-section of a properly welded RAKtherm joint will normally show a smooth transition between the two initial parts. This is because the components have uniformly melted and fused into each other to form one single piece. RAKtherm Electro Fusion coupling welding procedure please see in Technical Manual Installation.