Heating element butt welding machine for pipes and fittings out of polyolefines from OD 450 up to OD 2000 mm for the use on building sites and in trenches. The machine has a double clamping system on both the tight and movable side that is placed on two guiding shafts. For an easy and fast erection resp. dismantling upon maintaining, the hydraulic cylinders are screwed next to the guiding shaft. Two flexible hoses with quick-action cou- pling enable the connection to the hydraulic controlling device. The double clamping tools are screwed to the steel pipe subconstruction. The external tight clamping tool can be dismantled easily by removing seven screws in order to weld at difficult accessible places like trenches or at branches of T-pieces. The electric hydraulic unit for the movement of the right double clamping device and for the exact control of the welding forces has a post-pressure facility to support these forces while cooling down and two quick-action couplings. The planer is fixed to the guiding shafts, has a chain drive in closed aluminium housing with a gear motor and an automatic chip removal. The heating element is fixed to the guiding shafts, anti-stick coated, has an electronic temperature control with display, controlling lamps, an on/off- switch and a connecting cable with shock-proof plug. For the heat-protected storage of the heating element and the planer, a reception box is available. Smaller pipe dimensions can be clamped by means of reducer inserts depending on the pipe diameter. A lift-off device for the easy inserting and removing of the heating element and the planer is available. All components are covered by the WIDOS works warranty. The WIDOS welding machine can easily be equipped subsequently with the WIDOS SPA weld log recorder (see page 22) and can also be supplied in CNC-controlled version. The WIDOS welding machine has a voltage of 400 V. Other vol- tages on request.